Plastic Fabrication: The Complete Guide

If you’d wish to make various plastic products, then this guide is for you. Why?

Because I am going to show you how to thermoform, cut, bend, drill, weld, bond or form plastic material, to get any shape you want.

Obviously, you need suitable equipment such as CNC machines, routers, extruders, etc. Also, you must know the exact process you should follow.

The best part? I am going to discuss every aspect of plastic fabrication here.

So, keep reading to be an expert in plastic fabrication.

What is Plastic Fabrication?

Plastic fabrication is as any procedure you apply to design, assemble or manufacture items made from plastic or composites of plastic.

There exists many plastic fabrication methods, each with their distinct advantages and disadvantages.

Moreover, certain techniques are better suited for specific parts – fabrication of large body panel will probably not apply the same method as fabricating small kitchen materials.

Whatever you would wish to make, there is a method of plastic fabrication out there fit for you!

Plastic Fabrication Basics

As I have explained, plastic fabrication is the design, production or assembly of plastic products using one of the many methods available.

Some manufacturers prefer to work with plastic over other materials like glass or metal due to the advantages of fabricating plastic in specific applications.

Injection molded visors

Injection molded visors

The cost-effectiveness and malleability of plastics qualify it as a versatile and durable raw material for a spectrum of different products.

Plastic is not Metal

This is the first observation you will make on your first attempt of fabricating plastics.

While you can technically fabricate both materials, the similarities end at that point.

Plastic has the potential of expanding five (or more) times its original dimension and has varying heat tolerance.

When fabricating metals, there is a predictable pattern with reduced creep.

Metal fabrication

Metal fabrication

But when fabricating plastic materials, you need to make quick adjustments to take care of substantial creep.

Additionally, you should bear in mind that plastics have high chance of chipping and melting during fabrication.

Drilling acrylic sheet

Drilling acrylic sheet

Therefore, with correct material selection, appropriate handling techniques and proper tools, fabricating plastic materials is achievable.

Why Fabricate Plastic Materials?

Though the outcome of plastic fabrication is largely dependent on the type of plastic you use (HDPE, acrylic, ABS, nylon, among others), the process itself comes with lots of advantages including:

· Ease of forming

Because of its high malleability and low melting point in comparison to other materials, you can form with relative ease simple and complex products from plastics.

· Reduced finishing

Different from most metals, you can color plastics before fabrication, doing away with some post-fabrication procedures, such as painting.

· Faster production

Fabricating plastic often entails fast cycle times and quick turnover rates.

· Lighter weight

Plastics generally weigh less compared to metals of similar dimensions.

· Chemical resistance

Plastics are typically less prone chemical reactions like rusting or oxidation than metals.

Disadvantages of Plastic Fabrication

Though plastic is essential for fabricating a broad range of products, it also comes with demerits as a material of production.

Let’s explore the disadvantages of plastic fabrication.

· Limited wear resistance

Plastics have low resistance limit for high temperatures, acidity, and other corrosive compounds.

· Structural weaknesses

Majority of plastics are unfit for uses wanting high structural strength, like most building materials and heavy equipment parts.

Classification of Plastic Materials

Broadly, you can classify all plastic materials as either thermoplastic or thermosetting.

classification of plastic material

Classification of plastic material

I know you have at some point asked yourself the differences between thermoplastic and thermosetting plastics.

Though the two sound similar, they have varying features and applications.

I’m going to highlight the differences between thermoplastics vs. thermosetting plastic, their benefits and limitations, and the curing process of each.

Understanding the difference in their performance can assist you reach better purchase decisions and boost your product designs.

The basic physical difference is that thermoset plastics retain their permanent solid state, whereas you can re-melt thermoplastics back into liquid.

View thermoplastic as butter; it is possible to melt and cool butter several times to produce various shapes.

Thermoset is like bread since provided the final state is attained, any extra heat would result to charring.

Due to these physical differences, thermoset plastic products have the ability to sustain high temperatures without loss of austerity.

While thermoplastics cannot withstand because of their low melting point.

Thermoplastics Curing Process

When you heat thermoplastic materials, they soften and get more fluid as you administer more heat.

The curing process reversibility is 100% since no chemical bonding happens.

This feature makes it possible for you to remold and recycle thermoplastics without any negative impact on the physical aspects of the material.

You have numerous thermoplastic resins that provide varying performance benefits to choose from, but most of them offer easy flexibility, high shrink-resistance, and strength.

Based on the resin type, some of thermoplastics applications include low-stress uses like in plastic bags and high-stress mechanical components.

Examples of Thermoplastics Polymers

  • Polyethylene
  • PVC
  • Nylon

Thermoplastic Advantages:

  • Highly recyclable
  • High-Impact resistance
  • Reshaping capabilities
  • Chemical resistant
  • Aesthetically superior finishes
  • Rubbery or hard crystalline surface options

Thermoplastic Disadvantages:

  • Expensive
  • Can melt on heating

Thermosetting Plastic Curing Process

Thermoset plastics, normally fabricated through reaction injection molding.

It comprise of polymers that join together to form a permanent chemical bond during the curing process.

This process leads to weak bonds joining the monomer chains within the thermoset eliminating the risk of re-melting of product when you apply heat.

Thermosetting plastic

Thermosetting plastic

Thermosetting plastics largely boost the mechanical characteristics, heat resistance, chemical resistance and structural integrity of your material.

Applications of thermoset plastics comprise of high-heat uses such electronics and other appliance.

It is because of their ability not to re-melt, and applications for sealed items due of their deformation resistance.

They are among the most impact resistant plastic materials available.

Examples of Thermosetting Plastic Polymers

  • Polyurethane
  • Phenolics
  • Silicones
  • Polyesters.

Thermosetting Plastic Advantages:

  • Have more high-temperature resistance
  • Highly flexible design
  • Thin to thick cross-section capabilities
  • High dimensional stability
  • Cost-effective

Thermosetting Plastics Disadvantages:

  • Non-recyclable
  • More difficult to do surface finishing
  • Difficult to remold or reshape

Types of Plastic Fabricates

Before you think of any fabrication process, you need to choose a suitable plastic material.

This is one critical aspect you cannot ignore.

In this section, I am going to introduce you to a number of plastic materials you can fabricate to your specific needs.

These plastic material include:

· ABS

Acrylonitrile Butadiene Styrene is a low-cost plastic with excellent machinability, impact resistance, and thermoforming features.

It is a perfect option for machine casing, retail shop fixtures, and point-of-sale displays when durability and impact resistance is needed.

ABS plastic

 ABS Polymer

ABS plastic is available in UV resistant, fire-rated, machine grade, scratch resistant and general purpose grades in various colors and textures.

Physical Features of ABS

ABS Physical features

ABS Physical Features

Acetal

Polyoxymethylene, commonly known as Acetal, is a high strength, low friction plastic material that has outstanding wear characteristics in both dry and wet surroundings.

Because of its ease of machinability, acetal makes an excellent option for uses that need complex, tight tolerance.

Polyoxymethylene

Polyoxymethylene

Acetal Material Options

You can find both homopolymer and copolymer acetal.

  • Homopolymeracetal has superior stiffness, toughness, and room temperature strength.
  • Copolymer acetal has outstanding performance in continuous hot water and high heat environments. This type of acetal equally seems to have reduced porosity compared to homopolymeracetal.

Physical Features of Acetal

Acetal

 Acetal

Acrylic

Acrylic is a plastic produced from one or more of the acrylic acid derivatives.

Polymethyl Methacrylate acrylic (PMMA) is the most commonly utilized acrylic because of its superb weatherability, versatility, strength, and clarity.

PMMA

PMMA

We have several grades of acrylic polymer ideal for injection molding and extrusion plastic fabrication processes.

You can get opaque, translucent, and transparent acrylic polymer grades with differing light transmissions, heat resistance, release abilities, impact strength, and flow rate.

PMMA acrylic sheet manifests glass-like attributes – clarity, brightness, translucence, transparency, at half the weight and an impact resistance ten times that of glass.

To boost performance attributes such as anti-fogging, scratch resistance, solar, reflectivity, and glare reduction, you can add coatings to acrylic sheet or completed part.

Being a thermoplastic thus softens with exposed to severely high temperatures, you are capable of fabricating acrylic to essentially any shape.

Because of its durability, acrylic is an appropriate solution covering a wide range of temperature and possesses outstanding weathering features in comparison to other plastics.

Advantages of Acrylic

  • A very useful thermoplastic for uses needing transparency but high impact resistance is not a concern.
  • Acrylic offers higher scratch resistance in comparison to other transparent plastics.
  • A lighter option to glass and cost-saving alternative to polycarbonate in usages where strength is not a vital consideration.
  • Possible to cut into exceptionally fine shapes applying laser cutting technology since it vaporizes on interaction with the concentrated laser beam.

Disadvantages of Acrylic

  • Comparatively low strength and impact resistance in general.
  • Prone to brittle failure thus cracking instantly without much bending.

Applications of Acrylic

In the present market, acrylic has various applications that normally exploit its natural clarity and impact resistance of specific varieties.

Typical applications of acrylic comprise paint, furniture, acrylic nails, lenses, medical devices, LCD screens, and security barriers.

Acrylic mirror

Acrylic mirror

Due to its transparency, it is as well frequently used for windows, product displays, and tanks.

Physical Features of Acrylic

Physical properties of acrylic

Properties of acrylic

Nylon

Nylon is a strong, stiff plastic with better bearing and wear traits.

Nylon is often used to substitute metal bearing and bushing thus doing away with external lubrication.

Using nylon will also your minimize wear on parts in contact, reduce component weight and reduced operating noise.

Nylon Material Options

Nylons are usually categorized based on numbers which represent their molecular structures.

Though there exist various nylon types, the two most popular found in rod, tube, and sheet are Nylon 6 and Nylon 6/6.

Nylon

Nylon

Nylon 6– is generally fabricated rod, tube, and sheet through a liquid casting procedure.

Casting is usually the most economical technique of fabricating broad diameter tube, rod, and thick sheet.

Nylon 6/6– rod, tube, and sheet are normally fabricated by melting the solid polymer pellets and processing them via a thermoplastic extruder.

Extrusion fabrication is a swift and economical technique of fabricating small cross-section tube, rod, and thin sheet.

You can produce extruded Nylon6/6 rod, tubing, and sheet, unlike cast Nylon 6, to any length and this can be an advantage for economically fabricating finished parts.

Physical Features of Nylon

Nylon features

Nylon features

Polycarbonate

Polycarbonate is a tough, clear plastic material with remarkable strength, rigidity and impact resistance.

Commonly, PC production is through bis-phenol A and carbonyl chloride reaction in an interfacial process.

It is a member of the polyester family of plastics.

Polycarbonate is a better material option not only because of its features, but equally, because its fabrication is eco-friendly, and also possible to recycle it.

Polycarbonate

Polycarbonate

Properties of Polycarbonate

Polycarbonates are strong, rigid, glassy engineering thermoplastics, which can sustain rigidity to a maximum of 140°C and toughness up to -20°C or specific grades even lower.

PC is amorphous, has a heat resistance of up to 135°C and is considered as slow burning.

Distinct flame retardant grades are available which pass various extreme flammability tests.

Limitations to the application of polycarbonate comprise limited scratch and chemical resistance and its likelihood of yellowing on prolonged exposure to UV light.

Nonetheless, you can readily overcome these limitations by adding the correct additives to the compound or fabricating via co-extrusion process.

Polycarbonate Grades Available

Polycarbonate comes invarious grades depending on the use and selected method of fabrication.

The available polycarbonate grades constitute film, branched, reinforced and stress crack resistant, flame retardants, and other specialty grades.

There are also polycarbonate blends with, for example, polyesters or ABS, which are have wide application in the automotive industry.

Polycarbonate Fabrication

Fabrication of polycarbonates involves transforming of its pellets to the required design.

By choosing an appropriate fabrication process, you can make many products.

Polycaebonate goggles

Polycarbonate goggles

The typical methods of polycarbonate fabrication include:

  • Injection molding
  • Extrusion
  • Structural Foam Molding
  • Blow molding
  • Vacuum Forming

Applications of Polycarbonate Plastic

In present years blends of polycarbonate have gotten progressively commercially essential.

Polycarbonate blend is in extensively use because of its outstanding compatibility with a variety of polymers.

Common blends consist of:

  • Rubber altered PC, enhancing impact characteristics
  • PC/PBT blends, which enable toughness retention at lower temperatures and offering enhanced weather and fuel resistance

However, the most important polycarbonate blends are those containing Acrylonitrile Butadiene Styrene (ABS).

PC/ABS blends display high rigidity at low temperatures, high melt flow, and boosted stress crack resistance in comparison to PC.

All Blends are manufactured using a compounding process to mix the polymers.

This compounding technique is very key for forming the optimal morphology and contact between the two stages.

Combined with the correct additive knowledge (reinforcement, flame retardant, stabilization), you obtain blends with optimally proportionate set of features.

Polycarbonate goggles

Polycarbonate goggles

Polycarbonate application covers various markets, especially in the medical, automotive, optical media, glazing, lighting, business machine, and appliance markets.

Some of the plastic products from PC consist of:

  • PC’s excellent strength puts it fit for shatter- and bullet-resistant glass applications
  • PC’s comparatively low weight and it high ductility qualifies it for the making of windows and lenses
  • Used as electrical insulator and flame retardant
  • DVD’s, CD’s, cell phone automotive, and laptop parts

Physical Features of Polycarbonates

Polycarbonate properties

 Polycarbonate properties

Polycarbonate Film

Polycarbonate film is a clear, general purpose film made from the thermoplastic polymer family.

Polycarbonate film

Polycarbonate film

They are available in graphic, light diffusing, and blended films and die cutting polycarbonate film is very easy.

Polycarbonate Film Fabrication and Characteristics

Polycarbonate film is long-lasting, clear, tough, and offers high heat resistance and exceptional clarity.

Thermoforming and molding are the common, easy methods of fabricating polycarbonate film, and you can form it either hot or cold.

Additionally, it is possible to produce exceptional print on polycarbonate film with standard inks utilizing digital or screen printing due to its outstanding ink adhesion feature.

Applications of Polycarbonate Films

  • polycarbonate film is suitable for labels, menu boards, and nameplates
  • The tamper-proof characteristic of polycarbonate film makes it a good option for identification cards.
  • Polycarbonate film is an exemplary printing medium since it can dry fast at raised temperatures.
  • Polycarbonate and polycarbonate blend films are superbly multipurpose and can be put into various applications, comprising trade show displays, instrument panels, control panels, membrane switches, and decals.

Physical Features of Polycarbonate Films

Features of polycarbonate film

Features of polycarbonate film

Methods of Plastic Fabrication

We have various categories of methods of fabricating plastic based on the technique applied and the specific features of the end products.

I will take you through some of the most popular plastic fabrication techniques.

1. Plastic Molding

Molding is any technique which allows you to fabricate plastic into a shape by enabling it to harden inside a pre-formed mold.

This is the most versatile method of fabricating plastics as it allows for the development of everything from exceptionally large components to exceptionally complex ones.

You can apply plastic molding to produce toys, household appliances, heavy machinery, and aeroplane parts, among other plastic fabrication products.

This technique is very popular with plastic fabricators due to its cost and time-efficiency and the stiffness, strength, and durability of the finished components.

Injection molded helmet visors

Injection molded helmet visors

However, as a plastic fabricator, you will have to choose from various plastic molding sub-types, which are separated based on:

  • Whether pressure, heat or a blend of both (for example an autoclave, a machine that release both pressure and heat concurrently) is applied to cure the final product
  • The technique by which the plastic gets into the mold
  • The existence or non-existence of reinforcing fibres such as glass, aramid or carbon.

I will briefly describe the most popularly applied plastic molding processes, their advantages and disadvantages and some of their applications.

· Compression Molding

Compression molding is among the oldest of the numerous plastic molding procedures.

Many fabricators avoid using this process because of costly equipment and the need of skilled labor.

However, it still comes in handy when your fabrication involves large production runs, like automobile bumpers or fenders, clothing fasteners such as buttons or buckles.

However, you should know that this molding method does not offer the advantage of using highly economical materials: sheet molding compound (SMC).

It does provide the benefit of using a highly affordable material: sheet molding compound (SMC).

Compression Molding Process

Straightforward and versatile, compression molding uses an open, heated mold chamber.

You make through compression, a thermoset plastic composite to occupy the entire surface of pre-shaped mold.

This will enable you to form a myriad of plastic components with unique lengths, thickness, and detail levels.

Compression molding

Compression molding

The completed products you will get from this method of fabricating plastics will tend to be exceptionally strong.

Usually offers the added advantages of corrosion resistance and lightness courtesy of the utilization of complex base materials.

Materials Used in Plastic Compression Molding

As I have stated, this traditional method of plastic fabrication is used to mold thermosets.

Nonetheless, you can now use the process in molding thermoplastics, elastomers, and natural rubber.

Common Applications of Compression Molding

Versatile and cost-saving, compression molding is your right solution for fabricating several kinds of components.

Fit for a broad range of industries, your choices are virtually unlimited.

Some of the most common applications comprise:

  • Production of home and food appliance, for dimensionally stable and lightweight components
  • Fabrication of oil and gas parts which are wear, corrosion and chemicals resistant.
  • Manufacturing of electrical and electronic components with both dimensional and thermal stability
  • Utility tools providing thermal and UV stability
  • Safety equipment, for fire- and impact-resistant performance
  • Medical gadgets fabricated with lightweight accuracy
  • Aerospace and defense components involving simple plastic fabrication processes and enabling wear-resistance performance
  • Automotive and transportation plastic parts with insulating features and simple builds.
  • Sporting devices with enhanced toughness and safety features
  • Power components produced for lightweight strength
  • Indoor and outdoor lighting solutions

Advantages of Compression Molding

  • Compression molding is a straightforward and versatile plastic fabrication process that enables you to turn traditionally metal component designs into molded plastic
  • The finished product tends to be stronger, stiffer, and light compared to their metallic peers.
  • You can use different plastic materials in an existing compression molding system.
  • Allows for fast assembly and production, guaranteeing minimal waste, attractive end products, and low-maintenance.

Disadvantages of compression molding

  • More waste– For you to attain the right pressure needed for compression molding, you are required to overfill the mold chamber to a certain level, which results to waste material.
  • Not suitable for complex molding– though you can apply this plastic molding technique in producing more sophisticated products, depending on the material used and distinct design, this method is best fit for larger and simpler parts.
  • Slow process time – Since plastic is a relatively poor heat conductor, you will need quite some time to create enough heat necessary for the working of compression molding, specifically when molding bigger components requiring large amount of raw materials.

2. Injection Molding

Injection molding is a famous method of fabricating plastic due to numerous reasons.

It has proven essential to those producing consumer products.

Plastic materials are crucial ingredient of majority of consumer goods, and injection molding is among the best methods of plastic fabrication.

Injection Molding is a plastic fabrication process for manufacturing components in large volume.

The process is suitable for mass-production fabrication where similar parts are developed many (thousands or millions) times in succession.

The process fabricates large amount of parts of exceptional quality with great precision, very fast.

Let’s have a look at the three key stages of the injection molding procedure, and then highlight the advantages and disadvantages of the procedure.

Process of Plastic Injection Molding

First, your plastic fabricate should be in granular form.

Then you melt it soft enough capable of being injected under pressure to occupy a pre-shaped mold.

The outcome is that the mold shape is precisely copied.

The plastic mold cools down as it harden, and then the injection mold opens to release the formed product.

The entire injection molding process starts again.

Plastic injection molding

Plastic injection molding

Here are the major stages of plastic injection molding in summary.

i. Close Mold

Clamping – the fixed and moving platens of the injection molding machine fasten the mold together under controlled pressure.

ii. Inject Molten Plastic

  • Injection – your molten plastic raw material is released into mold

iii. Hold Mold Closed

  • Dwelling– after injecting the molten plastic into the mold, you apply pressure to ensure copying of all cavities.
  • Cooling – the plastic component is then given time to cool and solidify in the mold.

iv. Open mold and eject product

  • Opening – the moving platen drifts away from the fixed platen opening the mold tool.
  • Ejection– use air blast, rods or a plate to remove the finished part from the injection mold machine.

The duration from when you close the injection mold to the time of ejecting the completed plastic mold is the plastic injection molding cycle.

Advantages of Plastic Injection Molding

  • Mass production – injection molding helps you fabricate products in large quantity.
  • Low production cost – once you have taken care of the initial costs, your subsequent cost per unit during injection molding fabrication will be very low.
  • Low scrap rates – compared to traditional plastic fabrication processes such as CNC machining, injection molding produces minimal waste.
  • Repeatable process – simply put, the second product you fabricate will be an exact resemblance of the first one. This is an awesome characteristic when you want to maintain part reliability and brand consistency in mass production.

Disadvantages of injection molding

Though the most preferred plastic fabrication method, injection molding initial costs seems to be relative high because of tooling requirements, design, and testing.

Let’s have a quick look at some of the disadvantages of injection molding of plastics.

  • More lead times needed and high tooling costs – you will realize that tooling is probably a project on its own and just a stage of the whole injection molding procedure.

Prior toactualizing injecting molding of plastic parts, first you will have to design and prototype the part (through 3D printing or CNC).

Secondly, you will embark on designing and prototyping a mold tool that can fabricate an exact copy of the part in large volume.

Eventually, and normally after thorough testing in phases mentioned above, you begin to injection mold your components.

As you can see, all of the procedures you ought to go through in order to get it right before commencing mass manufacturing needs both money and time.

  • Difficult to make alterations – you may experience difficulties, and incur extra costs when trying to alter the injection molding tool since the tools are mostly steel- or aluminum-made. In case you want to put additional plastic to the component, you will need to increase the size of the cavity by cutting away its metallic wall.

Conversely, when you want to decrease the quantity of raw material used, you will have to reduce the cavity size by thickening its metallic wall.

This is very difficult, and in most scenarios, you might be forced to dismantle the tool and start afresh.

  • Cannot produce large parts – typically, you cannot produce large parts through injection molding as one piece.

Components bigger than a typical injection molding machine ability are usually produced in multiple pieces.

This is brought about by the size limitations of the mold tools and injection mold machines.

Though there is machine capable of molding very large pieces, using it is very costly.

3. Blow Molding

Blow molding is the procedure of making molten tube (commonly called preform or parison) of thermoplastic material.

During the process, you place the parison inside a mold cavity and inflate it using compressed air.

The inflation makes the preform assume the cavity shape, and is allowed to cool before removing the finished part from the mold.

Blow molding

Blow molding

You can blow mold all hollow thermoplastic component.

It does not just restrict you to fabrication of bottles, where there is a single opening that is always smaller in diameter compared to the general body dimensions.

Though these are among the typical shapes employed in consumer packaging, there exists other kinds of blow molded plastic products including:

  • Industrial bulk containers
  • Household, garden, and lawn items
  • Medical supplies parts
  • toys
  • Building industry products
  • Automotive-under the hood components
  • Appliance components

Process of Blow Molding Plastic

There exist three key types of blow molding:

  • Extrusion blow molding
  • Injection blow molding
  • Injection stretch blow molding

The major dissimilarities among the three types of blow molding plastic fabrication are:

  • The method of producing the parison; either injection molding or extrusion
  • The size of the parison, and
  • The movement method between the blow molds and the parisonis either stationary, linear, shuttling or rotary.

4. Extrusion Blow Molding (EBM)

Here, you melt the plastic raw material; then the molten material is extruded via a die to produce a hollow tube or parison.

Two cooled halves of a moldare made to join around the preform, and then you blow pressurized air.

The air inflates the parison making it take the mold shape, and after allowing the plastic to cool, you open and remove the part from the mold.

We have two main types of extrusion, intermittent and continuous.

In intermittent extrusion, the extruder accumulates plastic within a chamber, then forces them through a die to produce the preform.

However, continuous extrusion enables you continuously extrude the parison,and the mold moves back and forth from the preform.

Some of the parts you can fabricate by extrusion blow molding comprise of most hollow products like toys, bottles, automotive parts, home appliance components, and industrial parts and packaging.

5. Injection Blow Systems (IBS)

Here, you injection mold the thermoplastic material onto a core inside a chamber to form the preform (hollow tube).

The preform is made to rotate on the core rod to the blow mold where it is inflated and cooled.

This process is commonly used to fabricate small bottles, normally 500ml or less in large volumes.

Blow molding technique

Blow molding technique

Injection blow systems fabrication is split into three phases: injection, blowing and ejection.

All the three stages take place in an integrated machine.

Completed components come out with precise finished dimensions and able of accommodating tight tolerance.

Examples of parts you can fabricate by injection blow systems process include medical parts, pharmaceutical bottles, and consumer product packages

6. Injection Stretch Blow Molding (ISBM)

The process is similar to injection blow systems since you also injection mold the preform.

After molding, the preform, in a conditioned state, is taken to the blow, but prior to the eventual blowing of the shape, you first stretch the preform both in length and radius.

The stretching is important because it boosts the barrier and strength features at much lighter weight and enhanced wall thicknesses.

The ideal polymers for this plastic fabrication process are PP and PET that have the physical properties that are boosted by the stretching phase of the procedure.

Materials Used in Blow Molding

You can use these plastic materials in blow molding plastic:

  • High-Density Polyethylene
  • Low-density Polyethylene
  • Polypropylene
  • Co-polyester
  • PET
  • PVC
  • Nylon
  • Polycarbonate
  • Polystyrene
  • ABS

Advantages of Blow Molding

  • Blow molding significantly increases your plastic fabrication capabilities.
  • The method allows you to produce large amount of parts within a shorter duration of time.
  • Blow molding fabrication tools 3D moldings and significant reduction in flash.

Blow molding plastic pallet

Blow molding plastic pallets

Disadvantages of Blow Molding

The greatest limitation may be the negative impacts of plastic use to the environment.

Plastic is not biodegradable and large amount of it finds their way into landfills.

7. Plastic Compounding or Blending

Compounding is a plastic fabrication method where you blend two or more plastic materials into an amalgam, before fabricating them into one part.

In this process, you mix molten plastics to exact specifications and eventually form them with a die, mold or other shaping tools.

Compound is mostly applied when you want to enhance a product performance or improve the ease of producing a particular material.

Different types of plastic

Different types of plastic

By blending the merits and demerits of various plastic types, plastic fabrication through compounding can give you a unique product complementary to a particular use.

Plastic Materials Suitable for Compounding

Compounding is normally a mixture of copolymers such as SAN, ABS, SMA, among others with additives like UV-stabilizers, anti-oxidants, and other value-adding agents.

In some cases, you may also add strengthening constituents like glass fibre.

Examples of plastic compounds include:

  • Polymer fillers
  • Base resins
  • Pigment master batches
  • Purge compounds
  • Blowing agents
  • Flame-retardants

Compounding Plastic Process

The process of plastic compounding include the following:

i. Binders

Binders help you in holding together other components during plastic fabrication and are normally natural or synthetic resins.

The binders are usually high molecular weight compounds, which impact the properties of your finished plastic part.

Binders also influence the choice of treatment you will apply in the molding operation.

If you use a binder that has a low molecular weight, then it will be easy to mold the plastic part and vice versa

ii. Fillers

Filler helps you have enhanced finish, hardness, tensile strength, opacity and workability of the plastic material.

The quantity of filler used depends on the plastic type used, and you can have them up to a maximum of 50% of the overall molding mixture.

They may either be organic or inorganic.

Reinforcing fillers are added to boost your plastic component mechanical strength by reducing brittleness and shrinkage.

iii. Pigments/Dyes

Dyes and pigments are used to give the plastic parts your desired colour.

Inorganic pigments and organic dyes are suitable for this role in small amounts

iv. Catalysts

Catalysts help you speed up the polymerization rate of fusible resin binder to create intertwined infusible form during molding process.

In most cases, thermosets involve use of catalysts, commonly basic or acidic catalyst dependent on the type of thermosetting plastic you use.

You add them in small proportions, and the popularly catalysts include benzoyl peroxide, hydrogen peroxide, and metallic oxides.

v. Plasticizers

Plasticizers assist in increasing the plasticity of your plastic parts and are frequently used in thermosoftening plastics.

They can make between 8-10% of the general weight of your plastic blend mixture.

It is important to note that you cannot use plasticizers on thermosetting plastics; they are applicable with thermosofterning resins only.

Plasticizers increase the completed part flexibility and are usually in liquid form.

vi. Lubricants and stabilizers

If you are planning to mold at low or room temperature then lubricants will come in handy during the molding process.

Using lubricants ensure a flawless and glossy appearance to the finished plastic product.

Famously used lubricants comprise of soaps, waxes, and esters of fatty acids stearic and oleic acids.

Stabilizers assists in enhancing the stability and rigidity of the plastic component.

Methods of Compounding

You have four basic methods of compounding which include:

  • Dry mixing
  • Continuous mixing
  • Batch mixing
  • Compounding by Screw extruder

When selecting the method of compounding to use for your plastic fabrication needs, you should consider factors such as:

  • Condition of the material
  • Volume of finished product needed
  • Sensitivity of the plastic you will break down during shear

WeeTect face shield

WeeTect face shield

Dry Mixing

The plastic blend is mixed in a 500-pound capacity paddle mixer.

You turn the paddles till the blend is homogeneous.

However, if you prolong the blending, it will form lumps of glass, while a too short blending will develop a non-uniform dispersion of glass fibers.

I recommend dry mixing for plastic pellets with fibers, powders, and blending plasticizers with PVC.

Dry Mixer

A dry mixer is made up of an enclosed container having a higher speed impeller fixed at the bottom.

An impeller resembles a helicopter’s rotating blades.

Typically, the impeller is capable of making 80 to 3600 revolutions per minute.

To ensure fast mixing, you should blend the plastic materials within 2-4 minute cycles.

In order to prevent the formation of lumps and retard decomposition of the plastic raw materials, you should draw off the heat generated in the course of the process via a cooling jacket.

Types of Dry Mixers

There exist four types of dry mixers that you can choose from:

  • High-speed impellers
  • Paddle mixers
  • Ribbon mixers and
  • Drum tumblers

Dry mixer

SaintyCo ribbon mixer

Drum tumbler

Drum tumblers is commonly used in plastic blending process for dispersing powdered colorants within the raw material blend.

In this type of dry mixer, you put plastic pellets and about 1 to 2% colorant in a 250-gallon drum.

The blend is tumbled dry for roughly 30 minutes.

Drum tumblers are effective when the additives disperse with ease within the blend without tending to form lumps or cluster together.

Ribbon Blender

Ribbon Blender is essential for convective mixing.

In a typical convective mixer, a mixing rotor that moves raw material blend from one region to another is enclosed within a static housing.

This blender rotates at a speed of 10 to 60 rotations per minute.

There are both batch and continuous ribbon mixtures.

Section of ribbon mixer

Section of ribbon mixer

High-Speed Mixture

High-speed mixture is commonly used for dry blending PVC and for dispersing pigments and colorants.

Additionally, the mixture other use blending polymer powder with pellets.

High-speed mixture features an impeller fixed at the base of a stationary vessel, with the impeller, by help of a motor, rotating at a speed of up to 1000 rpm.

High speed mixer

High speed mixer

In short, choose a mixer machine that is suitable for your unique application.

Compounding by Screw Extruders

Screw extruders are plastic fabrication process tools utilized in blending, extrusion, extrusion blow molding, injection molding, and injection blow molding.

Screw extrusion technology is applied as the plastic melting and mixing device.

There are Two Types of screw extruders:

Single Screw Extruder

This type of screw extruder is categorized by the ratio of the screw length to the screw inside diameter, with standard extruders having 30 to 1 ratios.

The single screw extruder sizes varying from small laboratory designs with 1/2 inch diameters to mass manufacturing extruders having 8″ diameter barrels.

Single screw extruder has a long steel screw which circulates a steel tube referred to a barrel.

Heating elements covering the barrel help in sustaining the barrel at the melting temperature of the plastic raw material.

Rotating the screw pumps the plastic blend in and out of the extruder.

The speed at which you rotate the screw determines the rate of plastic movement from the inlet to the outlet of the extruder.

Single screw extruder

Single screw extruder

Twin Screw Extruder

The effectiveness of compounding plastics using the single screw extruder relies on maintaining greater friction between the raw material blend and the barrel wall.

It does not focus on maintaining greater friction between the raw material blend and the screw surface.

Plastic will stick on the surface of the screw, decompose, and block the blending process when friction on the screw surface is higher.

For this reason, twin screw extruder was invented to help overcome these challenges experienced during single screw compounding of plastics.

The twin screw extruder consists of two screws arranged side-by-side that intermesh.

The intermeshing feature of the two screws continually self-wipe the flights of the screws.

This action makes it difficult for sticking of plastic on the screw surface.

The positive pumping feature of the intermeshing screws makes it possible to compound all types of plastic materials not practical with single screw extruders.

8. Plastic Extrusion

Whether you want to produce a thousand straws or one hundred meter pipe, plastic extrusion is your ideal method of plastic fabrication.

It is because the process is simple to work with and readily available.

This technique of fabricating plastics consists of melting plastic material, shaping the material into a continuous profile by forcing it through a die, and then reducing it to desired length.

Plastic extrusion process is a perfect choice when you desire final products having uniform cross-section.

Plastic extrusion process

Plastic pipe extrusion

The high rate of production and low cost make it a popular plastic fabrication method for products including plastic sheeting, wire insulation, weather stripping, piping, and adhesive tape.

Equipment and Materials used in Plastic Extrusion

Before commencing the plastic extrusion process, you must obtain the right machinery and supplies, particularly a plastic extruder.

This is a relatively simple machine that enables the extrusion operation from beginning to end.

Then key constituents of a plastic extruder consist of a screw drive, screw drive motor, barrel, and hopper.

Plastic pipe technique

Plastic extrusion technique

The second most crucial constituent is the thermoplastic material meant for extrusion.

Plastic extrusion process in most instances rely on resin plastic to facilitate straightforward loading and fast melting times.

Plastic materials popularly utilized in extrusion operation include polyethylene, ABS, PVC, polypropylene, and high impact polystyrene (HIPS).

Finally, you need the die for successful plastic extrusion.

The die acts as the mold for the thermoplastic – in plastic extrusion, dies necessitate uniform flow of the melted plastic.

Dies commonly should be custom made and may need extra lead time before commencing the plastic fabrication process.

The Process of Plastic Extrusion

The plastic extrusion procedure starts with you putting raw resin into the hopper of the extruder.

In case the resin lacks the needed additives (colorants, UV inhibitors, or anti-oxidants) for the particular process, you then add them into the hopper.

Once this is taken care of, the resin is gravity-fed via the hopper’s feed throat down into the barrel of the extruder.

A long, rotating screw contained within the barrel moves the resin to the die from the barrel.

The resin is exposed to very high temperatures as it moves along the barrel to the die, till it begins to melt.

Barrel temperatures can varying between 400 and 530 degrees Fahrenheit based on the type of thermoplastic you want to fabricate.

Majority of extruders are fitted with barrels that steadily raise temperature from the inlet to the feed pipe to facilitate gradual melting and reduce the chances of plastic degradation.

As soon as the molten plastic arrives at the end of the barrel, it pushed via a screen pack and directed into the feed pipe that conducts it to the die.

The screen, strengthened by a breaker plate because of high pressures within the barrel, assists in removing contaminants that may be in the molten plastic.

You are free to manipulate the number of screens, porosity of the screen, and other factors till even melting takes place due to the sufficient amount of back pressure.

You then direct the molten plastic into the die cavity, where cooling and hardening takes place.

In order to quicken the process of cooling, the freshly fabricated plastic gets a sealed water bath.

In instances of plastic sheeting extrusions, cooling rolls substitute the water bath.

Plastic pipe extruder machine

Plastic pipe extruder machine

Temperature Maintenance

Maintaining the resin’s right melting rate and temperature levels is a critical consideration during plastic extrusions fabrication.

Optimal temperature maximizes even fluidity of the plastic and reduces the likelihood of stress and warping of the end product.

Variables like friction and pressure that accumulate in the barrel of the extruder indicates that the temperatures are not staying constant.

For this reason, you must monitor, decrease, increase, or shut off the heaters as required to sustain constant heat inside the extruder.

Cast-in jackets and cooling fans also assist in maintaining appropriate extrusion temperature.

Importance of Screw Design

The screw, the moving component in the plastic extruder, directly affects the feed rate, heating rate, and other key extrusion variable.

Thus, careful consideration of the design and size of this part is essential.

Determination of the screw length and diameter depends on the type of raw material, size of the resin, melting rate, and amount of pressure necessary to maintain uniformity.

Screw extruder design

Screw extruder design

For plastic fabrication processes where compounding of the materialshappens inside the extruder’s barrel, a twin-screw design can be utilized to facilitate sufficient mixing.

Specialty Plastic Extrusion Processes

Many applications require customized extrusion procedures to attain appropriate results or fasten the fabrication process.

Popular specialty extrusion procedures include:

  • Blown film extrusion: Applied in fabrication of plastic film products like food storage and grocery bags. The die in this application constituents an upright, cylindrical model that pulls the melted plastic vertically as it forms and cools.
  • Coextrusion: The simultaneous extrusion of several material layers. Two or more extruders inject different plastic types into a single extrusion head.
  • Overjacketing: Extrusion is applied to cover a product with a protective plastic coating. Exterior cable and wire jacketing is the most popular use of overjacketing.
  • Tubing extrusion: Same as traditional extrusion, only that the die consists of interior mandrels or pins, which enable formation of hollow plastic materials.

Plastic extrusion is employed to fabricate a broad range of products, from consumer products to building materials to industrial components.

Fence, tubing, pipes, edging, electrical covers, weather stripping, and window frames are some of the common products manufactured by plastic extrusion, coupled with thousands of specialized profiles.

Corrugated plastic extruder pipe

Corrugated plastic extruder pipe

Advantages of Plastic Extrusion

Let’s look at the three major benefits of plastic extrusion.

  • Low Cost 

In comparison to other methods of plastic fabrication, plastic extrusion is more efficient and has a lower cost.

The extrusion molding procedure utilizes thermoplastics that experience repeated melting and hardening, which facilitates reuse of waste instead of discarding them.

Minimized raw material and waste disposal fees.

Plastic extrusion is an ongoing process and capable of mass production, this makes it a more economical technique of fabricating plastics than other fabrication processes.

  • Better Flexibility 

Extrusion molding offers substantial flexibility in the fabricated parts with a constant cross-section.

Provided the diameter remains the same, the extrusion moldingis capable of forming complex shapes.

With minimal changes to the plastic extrusion procedure, you can apply it for plastic sheets or fabricate products that blend plastic characteristics.

  • After Extrusion Alterations

Plastics stay hot when released from the extruder, and this facilitates for post-extrusion changes.

Many fabricators will capitalize on this and employ different dies, shoes, and roller to alter the shape of the plastic as wanted.

Disadvantages of Plastic Extrusion

Some of the disadvantages of plastic extrusion include:

  • Expansion

After releasing the hot plastic from the extruder, it is likely to expand many times.

Thisis referred to as die swell.

It is difficult to predict the precise degree of expansion.

And since it is tough to predict the precise degree of expansion, manufacturers usually accept significant deviation levels from the product dimensions.

  • Product Limitations

Plastic fabrication by Extrusion puts limit on the kind of plastic products that you can manufacture.

There exist options that calls for purchase of a different kind of extrusion machine.

9. Plastic Welding

Plastic welding is a method of fabricating plastic by forming a molecular bond between two thermoplastics that are compatible.

Welding gives great strength, and reduced cycle times for chemical bonding (adhesives) and mechanical joining (screws, snap fits).

Typically, welding entails three main steps: pressing, heating, and cooling.

The pressure application, common during the entire heating and cooling phases, is applied to maintain the components in the right orientation.

Besides, it boosts the flow of melt across the interface.

The role of the heating phase is to enable intermolecular diffusion from one point to the other throughout the faying surface (melt bending).

Cooling is important in solidifying the freshly created bond; the undertaking of this phase can significantly impact the weld strength.

Welding plastic

Welding plastic

Thermoplastic Welding Process

All Thermoplastic Welding processes comprise of five steps briefly explained as follows:

a) Surface Preparation

This stage is normally conducted by mechanically scrubbing out the outer layer of the thermoplastic.

It removes the oxidized surface layer and any contaminant, and as well produce the right geometry for welding.

For instance, in the scenario of extrusion and hot air welding, a V joint typically gives the best outcome

b) Heating

The joint surfaces and weld material heating is done by direct contact, embedded elements, infrared radiation, hot air, friction, or some blend of these.

However, in fusion welding, you apply direct contact.

The right heating time and temperature are crucial to make sure the plastic is soft adequately for a longer duration to allow for autohesion.

Although not so soft that the plastic starts to decompose or gets squeezed from the joint.

Ensure a melt layer is formed by the plastic welding process at the faying surface to facilitate intermolecular diffusion for development of a molecular bond.

Polymer chains cannot flow when the plastic remains in the sold state.

Therefore, in order to enable diffusion of the plastic molecules through the interface, and facilitate its bonding with the other part molecules, you must melt both parts joint surface.

More molecular movement takes place when the melt is hotter, allowing a short cycle time welding.

You should heat semi-crystalline polymers beyond their melting temperature while amorphous polymers ones beyond their glass transition temperature.

In all methods of plastic welding, it is recommended you melt only a thin layer of the parts close to the joint.

It does not make sense to heat the whole part due to a number of reasons

  • Heating just a small portion requires less time and minimizes cooling time
  • Limiting the melt minimizes areas affected by heat
  • The molded microstructure of a bigger portion of the part is maintained
  • Prevents excess warpage or shrinkage during cooling
  • Enables rigid support of the part when welding

c) Pressing

Pressing helps you achieve molecular level contact by bringing the surfaces very close; this enables intermolecular diffusion to take place.

In hot air plastic welding, the base material and the welding rod are heated using hot air.

The welding is achieved by pressing the heating welding rod against the work.

But, if you exert insufficient pressure, inadequate contact is made between the surfaces.

Still, if you apply excessive pressure, the softened thermoplastic is squeezed out from the joint. Both scenario leads to a poor weld.

The application of pressure during plastic welding plays multiple roles:

  • Flattens surface asperities leading to more contact between parts at joint
  • Maintains part orientation
  • Presses melt layer to enhance intermolecular diffusion between the surfaces you are welding
  • Prevents development of voids due to shrinkage of part when cooling

Traditionally, plastic fabricators have used pneumatic presses to apply pressure during plastic welding.

Nonetheless, some plastic fabricators have employed the use of servo motors for some of the common welding processes.

Pneumatic welders are cost-saving and suitable for majority of simple procedures.

But, the precision of servo motors provides greater control and accuracy which is necessary in more difficult welding procedures.

Or, when you use the device in a broad variety of processes.

d) Intermolecular Diffusion

Intermolecular diffusion and autohesion is the intertwining of long plastic molecules around each other to create a bond.

This process is dependent on the temperature, characteristics of the specific plastic, and the time it takes the plastic to stay hot.

e) Cooling

Cooling enable the plastic to lose the heat and harden by allowing the weak intermolecular bonds to reform.

The cooling stage can be long, specifically with thicker pipe and sheet since plastics are poor conductors of thermal energy.

Plastic welding

Plastic welding

With the appropriate equipment and method, it is possible to make a strong and economical welded joint with virtually all thermoplastics.

It doesn’t matter whether you’re dealing with thin flexible film or thick rigid sheet and in any desired geometries.

The bonded polymer, during the cooling stage, hardens into a single solid component, completing the weld.

The “hold” phase, as the cooling stage is known for semi-crystalline plastic materials, presents a chance for the polymer to re-crystallize.

Also, the cooling rate will impact the final microstructure.

The microstructure of amorphous polymers hardens into the orientation formed by the melt flow during the cooling stage.

Normally, the time allocated before subjecting the part to stress, the pressure exerted, and the cooling rate all have substantial impacts on the eventual weld strength.

The duration of cooling and application of pressure are mechanical considerations which may differ from equipment to equipment within the entire process category.

Methods of Plastic Welding

There are a number of methods of plastic welding, which are mainly differentiated by their methods of heating. Let’s discuss some of the plastic welding techniques.

· Ultrasonic Welding

In this method of welding plastic, AC is converted (using piezo-electric ceramics) to mechanical vibrations, which are then move across the part to the joint.

They cause strain and stress in the contact surface between the two parts resulting in localized heating which melts the polymer.

Ultrasonic welding of plastic usually has a weld time ranging from one-tenth to two seconds.

This welding technique is suitable for fabricating amorphous polymers (ABS, polystyrene)

· Vibration

Vibration welding process is happens through either orbital or linear movement of one part relative to its mating component.

The motion leads to surface friction that results in generation of heat and melt layer formation at the joint.

Vibration plastic welding

Vibration plastic welding

Vibration welding of plastic commonly has weld times spanning from one to five seconds.

  • Linear vibration welding employs the frictional heat produced at the joint of the two components you want to weld to melt the plastic. The thermal energy production takes place by causing the movement of one piece against its mating part while exerting pressure through a specific amplitude or displacement.

After achieving the required melt amount, you stop the vibration, and the pieces are joined together using necessary force for a short duration of time, enabling the solidifying of the weld area.

  • Orbital vibration welding is also a friction welding procedure. During orbital vibration welding, the upper segment is caused to vibrate using continuous velocity orbital motion (circular movement in all directions). The plastic is raised to its melting point by the heat produced by the orbital motion.

You stop the motion once melting has taken place, allowing for solidifying of the plastic parts to form a permanent bond. You can achieve minimum distortion of parts by applying low clamping pressure.

It is possible to orbital weld parts with diameters up to 10″.

· Spin Welding

In this process, the thermoplastic parts are joined with a circular joint area.

Under a circular, spinning motion while applying pressure, you bring the pieces interfaces into contact.

You hold one piece stationary in a fixture, as you rotate the other against it while exerting pressure.

You must ensure that at least one part of the plastic is circular.

The heat generated due to friction leads to melting and fusion of the part interfaces.

This creates a strong, hermetic welded seal.

Spin Welding of plastic is essential in fabrication of floats, aerosol bottles, and other circular parts.

· Hot Plate Welding

This is a direct thermal welding method that employs the use of a heated platen to join the mating area of the plastic pieces to be welded.

The method offers various possibility of designing plastic components having complex, irregular shapes.

It is possible to curve the joint in all planes and weld interior walls.

Hot plate welding is suitable for majority of thermoplastics though, particularly efficient on semi-crystalline resins like polypropylene and polyethylene.

Hot plate welding

Hot plate welding

The procedure is fit for plastic parts to a maximum of 72”x 24″ or several smaller parts.

· Infrared/Laser Welding

You have two options of infrared/laser welding to choose.

The first option is heating the joining surfaces of the two pieces to form a melt layer; then you compress the parts together to create a weld.

The second option is using one plastic piece that is transparent to infrared/laser rays, and the other that absorbs the rays.

In this manner, the infrared/laser rays penetrate the transparent piece to the absorbing one which eventually heats up.

Consequently, the melted polymer of the absorbing piece heats up the surface of the transparent one.

The weld times of infrared/laser welding of plastic normally ranges from three to five seconds.

· Radio Frequency

This method of welding is only practical with thermoplastics having high dielectric constant.

With this plastic welding method, you create an electric field close to the joint, with the formed electric field alternating about twenty-seven million times per second.

With every electric field alternation, the dipole molecules try to turn around in order to realign themselves in the direction of the new filed.

The molecules do not turn around in unison since friction and inertia hinder the movement.

This continuous motion of the molecules leads to intermolecular friction which generates heat, which eventually causes melting.

Radio Frequency welding usually has weld times spanning from two to five seconds and capable of handling parts from about 1/1000 to 50/1000 inches thick.

· Implant

In this technique of plastic welding, a foreign substance which generates the required heat is implanted into the weld joint.

It is possible to generate this heat using two methods, induction and resistance.

In resistance implant welding, you pass electrical current across a conductive implant (usually a wire) that is positioned in the weld joint.

Due to electric resistance, the implant heats up leading to melting of the polymer surrounding it.

In induction implant welding, a gasket, commonly composed of similar polymer to be welded and filled with ferromagnetic or conductive material) is inserted at the joint.

You then place the parts in an electric field where heating of the gasket heating via induction happens .

Consequently, the polymer in the gasket melts as the plastic parts close to the gasket get heated through convection and conduction.

This forms a weld between the gasket and the parts.

Implant welding normally has weld cycle times ranging from one-half to one minute and capable of handling parts from about one-inch diameter to a maximum of eight feet long.

Advantages of Plastic Welding

  • Very fast process.
  • Comparatively low cost of machine
  • Very clean procedure, minimal to no weld flash.
  • . Plastic welds are lighter compared to mechanical fasteners
  • A weld is permanent, which hinders tampering with the interior components.
  • High standard welding for a broad variety of thermoplastic.

Disadvantage of Plastic Welding

  • A weld is permanent, making it impossible to open the part and reseal through the same method.
  • Hot plate plastic welding procedure is somehow slow.
  • Hot polymer melt frequently sticks to the surface of the hot plate.
  • Vibration method of plastic welding requires high capital cost (fixture and machine).

Applications of Plastic Welding

Some of the applications of plastic welding are listed in the table below:

           Consumer Products                Automotive              Medical           Film & Fabric
  • Bowls, Serving Utensils, Cups,
  • Microphones, Radios
  • Juice Boxes, Toys, Drink Caps
  • Filter Housings
  • Lens Housings
  • Valve Components
  • Testing Equipment
  • Tubing
  • Breathing Aides
  • Surgical Instruments
  • Polymer Clothing
  • Clamshell Packaging
  • Filters
  • Shower Curtains

 

               Military
  • Gun, Missile,
  • Grenade Components, Helmets, Radio Housings, Camouflage

10.      Plastic Lamination

This is a method of plastic fabrication that offers a protective coat on the plastic item.

Laminated plastics products are aesthetically attractive, long-lasting, and need minimum maintenance.

It can as well be an economical measure of shielding a deterioration-prone or sensitive plastic material.

The two most popular types of plastic lamination are resin and film.

Both processes involve the application of pressure and heat to a fabricated film in order to facilitate its sticking to a moving base material.

Paper, metal sheet, fabrics, and flexible foam are popular lamination base materials.

Film lamination is effective for creating a protective plastic coat on the external surface of an item.

Plastic lamination

Plastic lamination

On the other hand, resin lamination is essential in forming an adhesive surface between two base materials.

There exist several types of plastic lamination processes to select for your fabrication needs.

Procedures like co-extrusion are technically considered laminate.

It is possible to laminate different materials together as is the situation in bullet resistant polycarbonate.

Such materials are composed of acrylic, polycarbonate, and some urethane interlayer.

Other plastic lamination processes produce either low- or high-pressure laminates.

Let’s take a look at some of the common plastic lamination methods applied presently in the table below:

Type of Lamination Adhesive Applications
Extrusion Lamination LDPE Multi-material packaging (blend of plastic with paper, for example,  fruit juice cartons)
Extrusion Lamination EVA Bonding PE to PVC
Extrusion Lamination Adhesive containing acid: EMAA or EAA

Ionomers

Terpolymers of acid, ethylene and acrylate (e.g., isobutyl acrylate or methyl acrylate)

Applied for bonding plastic with aluminum foil
Extrusion Lamination Polyolefins modified by anhydride: terpolymers of maleic anhydride, ethylene, and acrylates (e.g., butyl acrylate, ethyl acrylate)
Dry-Bond Lamination Solvent-based PUR adhesives Flexible packaging like lamination of plastic films (bags, snack food wraps, pouches, boil-in-bag food pouches, cheese and meat packs,)
Wet-Bond Adhesive Poly (vinyl acetate) emulsion (or vinyl acetate copolymers and acrylic esters or ethylene)
Wet-Bond Adhesive Crosslinking copolymer of acrylic-vinyl acetate emulsions Snack packages including potato chip bags
Wet-Bond Adhesive pressure-sensitive Acrylic emulsion adhesives Pressure-sensitive labels
Wet-Bond Adhesive Polyurethane dispersions plastic films Lamination in medium-performance flexible packages that need some chemical resistance
UV-Curing Acrylics and acrylates, vinyl and vinyl esters, epoxies, silicones, polyurethanes, and polyesters Flexible plastic packages (one of the webs should be transparent to enable UV penetration)
EB-Curing UV-curable adhesives
Solventless Lamination Polyurethanes
Hot-Melt Lamination EVA
Ethylene-butyl acrylate
LDPE For creation of paper bonding, bag seaming, case seaming, and sealing
Block copolymers of styrene, butadiene or isoprene Hot-melt pressure-sensitive adhesives for labels and tapes, PE-base cups attachment to polyester soft-drink bottles, film-laminated frozen-food boxes sealing.
Moisture curing hot melts of PUR
Hot-Melt Lamination EVA
Hot-Melt Lamination Ethylene-butyl acrylate
Hot-Melt Lamination LDPE For construction of paper bonding, bag seaming, and sealing, case seaming,
Hot-Melt Lamination Block copolymers of styrene, butadiene or isoprene Hot-melt pressure-sensitive adhesives for labels and tapes, PE-base cups attachment to polyester soft-drink bottles, film-laminated frozen food boxes sealing
Hot-Melt Lamination Moisture curing of hot melt PUR

 

Advantages of Plastic Lamination

  • Durable when taken care of properly
  • Plastic laminate is grease and stain resistant
  • Possible to design shapes with plastic laminate
  • Relatively easy to fabricate Plastic laminate
  • Less expensive compared to other plastic fabrication methods
  • Offers various options in terms of design aesthetic
  • Lower noise level compared to stainless steel works

Disadvantages of Plastic Lamination

  • Delamination due to inappropriate lamination technique
  • Delamination and separation due to improper cleaning and maintenance techniques.
  • Blistering and bubbling due to excessive heat exposure
  • Failure as a result of proximity to steam and water
  • Failure as a result of moisture absorption and surface imbalances

11. Plastic Foaming

Also referred to as expanded plastics, foams have inherent characteristics that make them fit for certain uses.

For example, plastic foams have lower thermal conductivity in comparison to that of solid polymer.

A foamed polymer is also more rigid in comparison to a solid polymer for any particular weight of the material.

Additionally, compressive stresses normally make foams to shrink while absorbing excess energy, an essential benefit in protective packaging.

Customization of characteristics such as these to fit various uses is possible depending on the polymer choice, and the method of foam fabrication.

Some of the main techniques include:

The Low-Pressure Process

In order attain uniform quality products, it is advised you use dedicated distinct purpose injection molding equipment.

The equipment injects a gas into the molten plastic, which when released into the sealed mold tool consequently foams the plastic you are fabricating.

Conventional Molding Machines

Another broadly applied method of plastic foaming is the utilization of standard injection molding equipment with additional “blowing agents” included in the material.

Injection molding machine

Injection molding machine

Employing the use of dry chemical blowing agents blended with the plastic granules, melting of the plastic happens in the equipment’s barrel.

You then inject measured charge into the mold tool.

Heat from the molten plastic causes the reaction of the blowing agent, leading to gas formation, which subsequently results to plastic foaming

Foamed Thermoplastics

You can impregnate polystyrene pellets with isopentane under modest pressure and room temperature.

On introduction of heat, the pellets fuse together as isopentane evaporates, causing the polystyrene foaming and assembly cooling simultaneously.

Typically the pellets are pre-foamed to some degree prior to being molded to create a cup or some rigid packaging.

Also, under pressure, you can heat and extrude the isopentane-impregnated pellets, which results in formation of a foamed polystyrene continuous sheet.

While still warm, the sheet can be used to fabricate, dishes, egg cartons, or packaging.

It is equally possible to produce structural foams by introducing, under pressure, nitrogen or other gas into a melted thermoplastic in an extruder.

Foams produced through this method have higher density compared to the ones explain above.

The boast of outstanding rigidity and strength, making them fit for furniture and other architectural applications.

One technique of developing foams of various thermoplastics is by including a substance that is capable of decomposing to produce a gas when heated.

To qualify as an effective blowing agent, the substance needs to:

  • Decompose at approximately the plastic’s molding temperature
  • Have narrow temperature range of decomposition
  • Generate large amount of gas, and be safe to handle

Azodicarbonamide is one such commercial agents and is normally blended with other ingredients so as to modify the temperature of decomposition and assist in the agent dispersion in the resin.

Motorcycle visor

Motorcycle visor

Plasticized PVC, polyethylene, polystyrene, polyamides, and polypropylene are some of the polymers you can foam with blowing agents.

Foamed Thermosets

It is possible to foam Polyurethanes and isocyanates with hydroxyl-bearing prepolymers.

Simply include a volatile liquid, which vaporizes under the reaction heat and foams the reactive blend to a high degree.

The toughness of the network is dependent on the ingredients selected, particularly the prepolymer.

Phenol-formaldehyde resin is another rigid thermoset that you can foam into a desired plastic product.

The final phase of this plastic foaming is achieved by introduction of acid catalyst when a volatile liquid is present.

Materials used in Plastic Foaming

Some of the plastic materials suitable for fabrication by foaming include:

  • Polystyrene
  • Polyurethane
  • Polypropylene
  • Polyethylene
  • Polyamides
  • plasticized PVC
  •  Phenol formaldehyde

Advantages of Plastic Foaming

  • Lower cost due to low multiple nozzle injection pressure
  • Can utilize recycled post-consumer plastics
  • Products are recyclable and reusable
  • Substantial cost reduction and rise in productivity
  • Lower cost of raw material because of utilization of commodity resins use
  • Lifetime tooling

Applications of Plastic Foaming

Foamed plastic biggest markets are in home insulation and food packaging, comprising various drink and disposable food containers.

Hydroxyl-terminated polyethers are generally applied to fabricate flexible foams that find their application in furniture cushioning.

Hydroxyl-terminated polyesters are famous for manufacturing rigid foams like those applied in custom appliance packaging.

Polyurethanes exceptional ability to adhere on metallic surfaces has enabled some novel applications, such as making rigid and filling certain aircraft parts (for example elevators and rudders and elevators).

12. Vacuum Forming Plastic

Vacuum forming is a simplified model of thermoforming.

Thermoforming is among the oldest and most popular methods of fabricating plastic parts.

Vacuum formed items are all over within our immediate surroundings and play an essential role in our day-to-day lives.

The process entails heating a plastic sheet till soft and then enveloping it over a mold.

A vacuum is exerted drawing the thermoplastic sheet into the mold, and then you eject the sheet from the mold.

Vacuum forming fabrication, in its improved form, employs complex heat, hydraulic and pneumatic controls.

Hence, facilitating faster rates of production and more comprehensive vacuum formed plastic products.

Vacuum Forming Process

Vacuum forming

Vacuum forming

i. Clamping

The clamp frame should be adequately powerful enough to ensure firm holding of the plastic sheet during the process of vacuum forming.

It should be able to grip the thickest thermoplastic that is possible to form on the device – up to 6mm a 10mm with single and twin heater machines respectively.

When you employ an automated procedure, make sure to guard and interlock the functioning of the moving parts to avert accidental destruction.

Moreover, ensure to protect the operator of the machine at all times by providing him/her with safety guard.

ii. Heating

Heaters are typically infra-red elements placed inside an aluminum reflector plate.

So as to achieve the best vacuum forming outcomes, using any plastic material, it is crucial to heat the sheet uniformly throughout its thickness and surface area.

To attain this, you should have a sequence of zones modulated by energy regulators.

The high thermal mass of ceramics makes them disadvantageous since it slows down their rate of warming up (about 15 minutes).

It also increases their response time when you make adjustments.

Advanced quartz heaters exist which have reduced thermal mass permitting faster response time.

Pyrometers facilitates precise heat temperature modulation by detecting the melting temperature of the thermoplastic sheet and connecting with the process control.

A computer-controlled system operating concurrently with the pyrometer ensures accurate temperature readout.

Also, I recommend you use twin heaters when you want to vacuum form thicker products since they aid in enabling more homogeneous heat inflow and quicker cycle times.

Typically, use twin quart heaters when you want to form high-temperature plastics that have extreme forming temperatures.

Close monitoring of ones of heat intensity can help you totally compensate for the heat losses about the margins occasioned by clamp areas absorption and convection air current.

Beaides, these  guarantee consistent outcomes on an ongoing basis.

Using specified quartz heaters can also help you cut cost significantly since there is an adjustable energy fall when you position the heaters at the rear during the process of forming.

iii. Sheet level (auto-level)

Though not available in all equipment, a photo-electric ray is integrated in the device to scan between the plastic sheet and the bottom heater.

In case the sheet dips and interrupts the beam, the machine automatically injects a small quantity of air into the rear chamber.

Hence, raising the plastic sheet to prevent it from dipping.

iv. Pre-stretch (bubble)

To ensure uniform wall cross-section during vacuuming, you can pre-stretch the plastic once it reaches its forming temperature.

The measures of regulating the height of the bubble should be in place so that you obtain consistent outcomes.

With the help of air pressure, vacuum and alternative aids like plug assist, you eventually mold the heated, stretched thermoplastic.

v. Plug assist

I recommend plug-assisted vacuum forming in cases where it is not possible, using straight vacuum forming, to spread the plastic sheet uniformly to all mold areas.

The plug helps in the even spreading of the sheet by pushing it into the mold before you apply the vacuum.

This procedure makes sure that more of the plastic reaches the mold’s bottom.

Thus, more thermoplastic contents is available to pack the corners of the mold and inhibit thinning out of the plastic.

Vacuum forming plastics

Vacuum forming plastics

vi. Vacuum

Once the sheet is adequately pre-stretched, you can then apply vacuum to aid in the fabrication of the plastic.

Using a dry vane vacuum pump, you draw the trapped air between the mold and the sheet.

The pump ought to maintain a differential pressure of about 27” mercury.

With larger machines, you use a vacuum reservoir jointly with a high volume vacuum pump.

This allows for application of a two-stage vacuum, which ensures fast forming of the heated sheet.

vii. Cooling and release

Before releasing the formed plastic, you must allow it to cool because immediate release can lead to mold deformation thus, reject part.

After forming the parts, you fit and activate fans to fasten the cooling cycle speed.

Also, there is an option of a spray mist with nozzles attached to the fans, which spray fine mist of cooled water onto the sheet.

Moreover, you can also find mold temperature modulating units which control the temperature inside the mold.

This facilitates accurate and constant cooling times if cooling down crystalline and crystal-forming polymers like PET, HDPE, and PP.

viii. Trimming and finishing

After cooling and releasing the formed component out of the machine, you trim the excess material.

Some of the finishing operations include reinforcing, printing, decoration, strengthening, and assembly.

Depending on the desired result, you can as well drill cut-outs, slots, and holes into the completed part.

There are several methods of trimming that you can employ to trim the formed product.

The kind of equipment used rely greatly on the part size, type of cut, material thickness, draw ratio and desired production quantity.

Trimming of thin gauge parts is usually done on a mechanical trim press, commonly called roller press.

Plastic Materials used in Vacuum Forming

It is possible to vacuum form virtually all thermoplastics, however, the commonly used plastic fabricates consist of:

  • Acrylonitrile Butadiene Styrene ABS
  • Polystyrene PS
  • Polyester Copolymer PETG
  • Polypropylene PP
  • Polycarbonate PC
  • Polyvinyl Chloride PVC
  • Both foamed sheet and sheet Polyethylene PE
  • Acrylic PMMA

Advantages Plastic Vacuum Forming

Vacuum forming gives several benefits over other plastic fabrication processes.

The use of low forming pressures offers relatively reduced cost of tooling.

Because the procedure uses low pressures, you can make the mold of inexpensive materials and the time of making the mold can be considerably short.

Consequently, it becomes economical to produce prototype, medium size and large thermoplastic parts.

Vacuum forming main raw material is extruded plastic sheet unlike in other types of plastic fabrication, where resin or powder are the beginning point.

Additionally, you can re-grind and recycle the trimmed waste.

Disadvantages of Plastic Vacuum Forming

  • Continual automated high volume fabrication requires more advanced molds and
  • Trimming the formed sheet to get the finished product may require additional tooling and this mean extra cost

Applications of vacuum forming of Plastic

Here are some of the common plastic products made through vacuum forming:

  • Baths and Shower Trays
  • Ski-Boxes
  • Yoghurt Pots
  • Machinery Guards
  • Boat Hulls
  • Refrigerator Liners
  • Vehicle Door Liners
  • Parts of vehicle cabs
  • Sandwich Boxes
  • Exterior Shop Sign

 13. Cutting Plastic

Selecting the best method of cutting plastic can be tough, however, I have summarized some of plastic cutting techniques suitable for you. However, you need to consider these three factors when choosing a plastic cutting method:

  • The plastic material
  • The application
  • Any extra components like pressure sensitive adhesives.

With that in mind, let’s go straight to the best plastic cutting methods and see how they differ.

Die Cutting

We can describe die cutting (also known as blanking or dinking) as the process of cutting shapes from plastic with a shaped knife, and pushing the margin into one (or several) sheeting layers.

The dies used in this procedure are normally known as steel rule dies.

After completing the cutting, you apply pressure by use of either mechanical presses or hydraulic.

Type of Plastic Die Cutting

There are several types of die cutting, however, the most popular are rotary and flatbed die cutting.

· Rotary die cutting

Also called gasket die cutting, the cutting process encompasses unwinding the material and then passing it across a hydraulic press.

After that, by using a precision engraved steel cylinder die, you turn the material over and then cut various shapes and sizes from it.

It is very easy to manage the material at this point.

You can use a release liner to carry and roll it onto a new core or if desired, you can fabricate the sheets into pads.

The rotary dies can either cut fully through the plastic material and its associated release liner (known as metal to metal die-cut).

Or, cut through the plastic material up to but not through its release liner (called butt-cut or kiss-cut).

Advantages of Rotary Die Cutting

  • Die cutting enables continuous replication of the part to a tolerance as tight as .02” and components are consistently within tolerance.
  • Rotary die cutting allows you to form shapes and sizes as you desire as opposed to employing pre-formed prototype.

Flatbed Die Cutting

In this type, you use steel rule dies to stamp out material shapes.

It is possible to adjust the dies accordingly to different degrees of hydraulic presses.

Advantages of Flatbed Die Cutting

  • Comparatively reduced tooling costs
  • The vertical cut enables a tighter tolerance for materials thickness over 1/8″
  • The tooling results to minimal rounding (or curvature) of used material
  • Flatbed die cutting is suitable for various combination of plastics compared to rotary die cutting.

Plastics Materials that can be Die Cut

These are some of the plastic from which you can make die cut products:

  • Styrene
  • HDPE
  • Polypropylene
  • High Impact Polystyrene
  • Polyester
  • Polycarbonate
  • ABS
  • LPDE
  • Vinyl
  • Polyethylene
  • PETG
  • UHMW

Application of Plastic Die Cutting

Some of the plastic products fabricated by die cutting include: gaskets, credit cards, medical products, insulation, packaging, toys, just to name but a few.

14. CNC Routing


In case the component to be cut has a complicated shape, you can programme its profile into a computer.

A CNC machine is capable of producing duplicate numbers of plastic components.

Several interchangeable cutters normally incorporated in CNC machine allows for fabrication of sophisticated and varying parts.

https://youtu.be/xMIy18omkfM

CNC routing or machining is the process of cutting, shaping, milling, drilling, and surfacing of plastic materials with the help of a computer-controlled milling machine or router.

You can cut, shape, mold, drill, surface, contour, among other plastic fabrication processes using patterned router cutters.

CNC routers permit high-speed automated machining of all plastic types.

CAD software like Solidworks and Alphacam is the language understood by the CNC router, and through which it converts your design into a magnificent completed product.

Types of CNC Routers

For you to understand the available types of CNC machining center, I can express that there exist three main types:

  • 3 Axis CNC router which is capable of processing a component from X, Y and Z axis (i.e. TOP, FRONT and BACK)
  • 4 Axis CNC router which is capable of processing a component from X, Y, Z and An axis (i.e. TOP, FRONT, BACK and whatever angle from FRONT to BACK)
  • 5 Axis CNC router capable of processing a component from X, Y, Z, A and C axis (i.e. TOP, FRONT, BACK, whatever angle from FRONT to BACK and LEFT to RIGHT). Moreover, a 5 Axis machine can perform cutting, notching and also do processing from the profile’s bottom.

Materials used in CNC Plastics Routing

  • ABS
  • Acrylics
  • Polystyrene
  • Polyethylene
  • Polycarbonate
  • PETG
  • Co-extruded materials
  • Polyethylene
  • TPO
  • Flame retardant materials
  • Conductive materials

Advantages of CNC Machining of Plastic

We can summarize the advantages of CNC routing as follows:

  • Allows cutting of sophisticated shapes and designs that would otherwise be impossible to producing using analog machine.
  • CNC machines have the ability to cut hundreds or thousands of components swiftly – all replica of each other and at exceptional tolerances.
  • The produced components have outstanding dimension stability, and both programming and set up are quick.

Disadvantages of CNC Routing of Plastics

  • CNC machines are more costly compared to the manually operated ones, though costs are gradually dropping.

Applications of CNC Routing of Plastics

The applications of CNC machining of plastics materials is infinite.

Some of the products consist of shadow boxes, point of purchase displays, lighting panels, acrylic furniture, trays, prototypes, windshields, museum cases, machine guards, acrylic art, aquariums pedestals, among other items.

The sectors served by CNC technology form equally an awesome list.

Military, aerospace, food, medical, automotive agriculture, transportation and industrial production are only a few examples.

15. Laser Cutting

It is possible to use laser beams to cut and profile specific acrylic types and other plastics though not thermosets.

Laser cutting plastic process applies industrial laser to heat and melt the plastic frequently followed by computer-controlled profile

Laser cutting acrylic plastic

Laser cutting acrylic plastic

Laser beam heats the thermoplastic to a high temperature, and since the type of plastic differs, the wavelength required for the laser will differ as well.

For instance, Acrylic will have varying requirements compared to silicone.

Laser cutting procedure scores and swiftly flame-seals the margins, leading to negligible to no residues, chips, or imperfections.

A computer feeds the designs to the machine, meaning that you can complete intricate designs minus much user engagement.

https://youtu.be/0FnHd3XQqds

Observing lasers cut plastic is astounding, as the machine-controlled laser can finish very complicated tasks at incredible speeds!

Advantages of Laser Cutting of Plastic

As we now know, it is practical to mold plastic into virtually any shape.

With the assistance of a plastic-cutting machine, you can continue to alter and tailor already hardened plastic materials into amazing finals products.

Most fabricators opt for laser-cutting plastic due to many crucial reasons.

  • Reduced wear and tear on the equipment and product since there is no friction between parts, unlike with mechanical cutting.
  • One can produce more sophisticated shapes and designs, specifically with harder thermoplastics such as acrylic. Laser cutting tends to be faster in comparison to other procedures, particularly when the process entails complex design works.
  • Lastly, this process can include more efficient customization, allowing for on-the-spot changes and personalization.

Disadvantages of Laser Cutting Plastic

  • The laser cannot cut any plastic material made up of Chlorine, such as PVC and Vinyl, since when cut.

The vaporized thermoplastic emits lethal Chlorine gas that changes to hydrochloric acid on mixing with water vapor contained in the air, resulting to tremendous destruction to the machine and our lungs!

  • Laser cutting has high consumption of energy. Its efficiency and consumption of energy is dependent nature of the laser beam and type of section you want to carry out.

Plastic material used in Laser Cutting

  • ABS
  • POM,
  • Acrylic
  • Polyimide
  • acetal
  • HDPE
  • polyester
  • PETG
  • Polyethylene (PE)
  • Nylon
  • Styrene
  • Polypropylene (PP)

Applications of Laser Cut Plastic

Laser-cut plastic is a preferred material for toy creators, professional signage shops, creative designers, and individuals operating within the competitive plastics sector.

Due to the sheer versatility and durability of this procedure, you are capable of fabricating virtually anything using this system.

  • Trophies
  • Display screen protection
  • Aerospace
  • Membrane keyboards
  • Filter

16. Plastic Sawing

Sawing of plastic is particularly for cutting part of plastic from stock bar for succeeding fabrication by other plastic machining processes.

Designed purposely for cutting through plastic, a plastic saw is suitable for cutting materials having thickness above 25mm, an operation which may be difficult with hacksaw due to its thin blade.

Types of Plastic Saws

You can cut plastic utilizing band or circular saw though; the choice relies on the stock bar shape.

However, you should be very careful with your selection because the heat produced by the tooling when fabricating plastic and eventual destruction of the plastic is a danger.

Due to this fact, you must use the appropriate blade for every plastic shape and material.

Band Saws

Most fit for cutting to size circular tubes and rods.

I recommend that you use sharp and appropriate set saw blades and support wedges.

Also, you should ensure correct chip removal, avoid blocking of saw blade, excess thermal build-up, and excessive friction between the material and the saw blade.

Advantage: ˌ

  • Heat produced by sawing effectively dissipates courtesy of the long blades of the saw.
  • ˌBand saws permits flexible use for irregular, straight, or continuous cuts
  • ˌGives a good cutting border quality

Circular Saws

Most fit for cutting to size plates leaving a straight cutting boundary.

For straight plate cuts of thickness up to 4’’, you can use table circular saws coupled with the correct power drive.

A good saw should have its blades made of strengthened metal.

Use adequate offset and sufficiently high feed rate.

Sawing polycarbonate plastic

Sawing polycarbonate plastic

Advantages of Cutting Plastic using Circular Saws

  • Results in good chip deflection
  • Prevents saw blade sticking
  • Prevents plastic overheating during the saw cutting
  • Results in good cutting boundary quality

17. CNC Milling of Plastic

The CNC mill applies the technique of computer numerical control (CNC).

This method of cutting plastics enables direct cutting through the material applying digital milling machines.

Due to this reason, CNC milling of plastic is suitable for single manufacturing, in the appropriate material, for instance for functional testing.

CNC milling is cost-saving and quick for amounts less than ten prototypes since it does not need creation of a mold.

It is powerful as well since it enables creation of parts that are complete replica of each other from the right material.

Nonetheless, I do not recommend CNC milling above ten parts, since the economies of scale given is relatively lower than with vacuum forming.

As I had earlier explained, vacuum forming enables faster rates of production.

Further, CNC milling is a method of material cutting, meaning the non-reusable cut parts represent an extra cost.

The principle of CNC Milling

CNC machining applies numerical control machine tools and milling equipment with 3 to 5 CNC axes.

These are automatic machines controlled by computer.

Machining entails cutting of plastic material; CNC milling machines cut through the material based on the computer-saved files to attain the completed part.

The Process of Plastic CNC Milling

The saved 3D file in the computer permits the determination of the direction of the milling machinery, which cuts through the material using its cutting tool.

The cutting tool facilitates milling in 3D to attain the component.

CNC milling equipment undergoes a feed motion (known as feed rate) and cutting movement (known as cutting speed) to facilitate the production of the prototype components

The Main Stages of CNC Machining

  • Develop a digital file of the wanted part applying the right software: CAD/CAM. This file dictates the geometry and dimensions of the final part
  • Connect the computer and the CNC machine: the saved file modulates the milling machine automatically
  • Put the material on the machine; holding is place with hydraulic clamping
  • Let the milling machine to function, which will cut the wanted part from the plastic
  • Remove the cut component and place another if need be.
  • Finishing operation (painting, laminating, polishing, etc.).

CNC milling plastic

CNC milling plastic

Advantages of Plastic CNC Milling

  • Broad variety of resins in the “correct material”: plastic CNC machining permits obtaining of parts with mechanical features almost same to the injected part, dependent on the desired final appearance and functionalities. Therefore, you can, for instance, attain transparent parts
  • Broad variety of finishes: You can polish to remove rough margins after machining. You can also paint the prototype with your color of choice.
  • A high-performance technique:this plastic cutting method enables top performance based on quality for even highly complicated designs.
  • Suitable for large size parts:using the method enables easier and efficient development of prototypes bigger than 600mm compared to vacuum forming.
  • Economical and fast:Because of lack of a mold, there is considerable reduction in costs and times. This is the fastest and most efficient technique of quick prototyping for amounts less than 10 parts, facilitating greater responsiveness to your fabrication desires.

Disadvantages of plastic CNC Milling

  • Minimal economies of scale: this method of cutting plastic does not permit substantial economies of scale in absentia of a mold.
  • Fabrication of small quantities: because of minimal economies of scale, this technique cannot produce above 10 plastic models or prototypes.

Plastic Materials used in CNC Milling

  • ABS
  • Acrylic
  • PEEK
  • Acetal
  • Phenolic
  • Nylon
  • Polycarbonate
  • Polystyrene
  • PET
  • Polyester
  • PET Clear
  • Polyethylene
  • PTFE
  • Polypropylene
  • PVDF
  • PVT
  • PVC
  • Noryl
  • CPVC

Applications of Plastic CNC Milling

You can apply the CNC milling process to fabricate advanced components from all plastic types.

Manufactured parts find use in a myriad of applications in several sectors, commonly, food and beverage processing, check valves and fittings, sanitation and water treatment, among other uses.

Bending Plastic

Bending thermoplastics is impossible when they are cold.

You can bend them using a line bender or strip heater which heats up the thermoplastic in a straight line, making it possible for you to bend it using hand.

Bending plastic

Bending plastic

Line bending is categorized as a thermoforming process, i.e. it is a technique of forming a thermoplastic after heating it till it gets soft and pliable.

Line bending entails heating a plastic sheet above a strip heater till it gets soft and pliable.

Thereafter, bending it, normally over a former.

You can bend thermoplastics to any angle, with the help of a former or a jig, or in case the angle is not so tight, simply by bending the plastic using hand and then grasping it till it has cools.

Materials Used in Plastic Bending Fabrication

  • Acrylic
  • ABS
  • Polystyrene
  • Polypropylene
  • Polycarbonate
  • HDPE

Advantages of Plastic Bending

Line bending of plastic has benefits which include the following:

  • Produces straight bends very efficiently
  • Low costs of set up
  • Involves no tooling

Disadvantages of Line Bending Plastics

  • Not as precise as other methods of plastic fabrication even with the help of jigs.
  • Not fit for large volume production

Applications of Line Bending Plastic

Majority of line bending applications have the tendency of concentrating on single or parallel bends to develop objects like equipment housings and rectangular covers.

However, you can fabricate some fairly intricate designs using this method.

Finishing Operations on Plastic Materials

Bending, drilling or cutting plastic is not enough.

You may need to improve appearance, strength, functionality, among other things.

So in this section, I am going to take you through various finishing operations.

1. Sanding and polishing plastic

Polishing a material simply means scoring the surface of the plastic material up to the bottom of the deepest scratch, in order to make it glossier and smoother.

When polishing a material, ensure to scrub from coarse to fine.

· Sanding plastic

First, establish whether the material you desire to polish requires sanding.

You should sand a material before polishing it when your fingernail can feel the edge of a scratch.

Do the sanding starting from the coarsest to finest paper.

Sand in a uniform movement without scoring along the grain of the plastic part, if visible.

Sand until you cannot see any scratches and after attaining a glossy finish (1000 grit wet dry is normally a good grit to finish with prior to polishing).

· Polishing plastic

The most popular methods of plastic polishing are mechanical buffing, flame polishing, and vapor polishing.

Each polishing method is suitable for specific profile and material.

Common methods of plastic polishing

Below are some of the main plastic finishing operations you can consider.

· Flame polishing

The polishing technique applies a hot flame to cause the flow of a plastic surface.

This method requires exceptional operator skill, and when completed appropriately, flame plastic polishing gives a very transparent finish, particularly if polishing acrylic.

In this method of polishing is suitable for flat exterior surfaces.

· Vapor polishing

The technique employs a chemical vapor which reacts with the plastic surface, making it to flow.

Unluckily, Acrylic, ultem, polysulfone, and polycarbonate do not react to this polishing method.

This procedure needs special handling and equipment to attain the desired outcomes.

You can achieve an optical quality part when a qualified plastic machinist accurately does the machining.

On the other hand, when you do the machining incorrectly, vapor polishing can result to a worse situation, and the component assumes a blurred white appearance.

In severe circumstances, the plastic components instantly stress crack and are assumed useless in the vapor plastic polishing operation.

You can apply this method in both interior and exterior surface polishing, including drill holes and threads.

· Mechanical plastic polishing

The most popular, easiest to perform, useful plastic polishing procedure.

This technique is prone to leaving ultra-fine abrasions on the surface and will always appear pleasing but is not appropriate for optical work.

Buffing will degenerate the surfaces of the other two methods discussed above.

· Direct machining

The most effective though technically hard method to create transparent acrylic components.

Applying this polishing procedure, you fine-tune the tooling and machine settings to create polished acrylic components straight from the machine.

Plastic polishing through direct machining develops some of the most transparent and consistent acrylic parts.

2. Buffing plastic material

Commonly applies a cotton wheel fitted with cutting compound.

Same to flame polishing, the method is suitable for large external surfaces.

It has minimal applications in internal work and typically cannot give a uniform finish.

Buffing is preferable where main goal is aesthetic.

When observed using a lens, buffing generates ultra-fine multidirectional abrasions, influencing its capability to create true clarity.

One condition: Same as plastic painting, polishing depends all in the preparation.

In case you inaccurately set the CNC machine, all the polishing in the universe will not fix the plastic materials.

Generally, metal shops lack the technical know-how of preparing the plastic part for polishing.

Accurately machine-polished wholly processed at one place tends to have the highest quality.

Furthermore, all of the mentioned plastic polishing methods need annealing to prevent stress cracking.

Polished plastic parts will most probably crack during operation if you fail to anneal them.

Plastic materials that can be polished

  • Acrylic
  • Ultem
  • Polycarbonate
  • Polyethersulfone (PES)
  • Polysulfone
  • Radel (PPSU)

Advantages of plastic polishing

  • Boosts an opaque or dull surface finish into a high gloss (commonly known as optically clear).
  • Enhance manifold uses of acrylic and polycarbonate by facilitating the manifold’s interior viewing for liquid presence.
  • Critical for parts that should transmit light unblocked like light emitting diodes in product
  • Improves the aesthetic look of the finished component by giving it a glossy professional appearance.

3. Plastic Printing

With various methods of plastic printing available for you to select from, it can be very tedious to understand which process is suitable for a specific operation.

Printing on plastic

Printing on plastic

For this reason, below, I discuss six of the best techniques of printing on plastic.

· Digital Ink jet printing

Fast and pace-setting digital print technology progresses have greatly widened the scope of what is achievable.

Digital inkjet printing is one of those such advancements and allows you to print images of top-notch quality in complete color onto a variety of plastic materials.

The process requires minimal setup, making it ideally fit for short fabrication runs or one-off prints.

Although similar to ink jet printer used in office, inks are costly.

Thus, long production operations are not cost-effective.

Normal inkjet ink absorbs into the paper.

However, this unique ink dries up by vaporization, making printing onto virtually anything possible, from broad-format sheets of self-adhesive vinyl to wide, tough parts like doors.

· Screen printing

Though the demand for conventional screen print has reduced thanks to advent of digital print technology, it is still a suitable option for specific applications.

In Screen printing, you utilize blocking stencils on a thin silk mesh which squeegees ink so as to pass on the stencil design onto the plastic surface.

A high-powered UV light then dries the ink, giving a long-lasting print with pronounced colors.

Screen printing limits the quality of image though vector graphics replicate well, making this plastic printing method ideal for most plastic types

· Flexo printing

Under flexography, you place the part to be printed on a printing plate relief (made from rubber).

You then ink the plate, and the inked image consequently transfers to the printing surface.

This type of printing is also suitable for cellophane, paper, metals, and other materials.

Flexo printing is a quick and cost-effective procedure suitable for printing on finer, flexible surfaces like food packaging, vinyl stickers on a roll, plastic bags, among others.

Though flexo printing can give higher print quality compared to screen printing, it produces images of lower resolution than litho UV, gravure, and inkjet printing.

· Gravure printing

Also referred to as rotogravure, this printing technique involves engraving an image into a printing cylinder.

The cylinder has ink which consequently transfers to the plastic material.

This printing method is fit for high volume applications such as producing plastic packaging.

· Laser printing

Yes, even an ordinary office laser printer is capable of printing onto some plastics!

You should be cautious by making sure that the plastic material is laser-compatible.

This is due to the fact that the fuser unit within the laser printer becomes extremely hot, and melting of plastic sheets inside the printer can be catastrophic.

Advantages, disadvantages and applications of plastic printing

a) Polystyrene

  • Advantages:  high impact resistance, low cost, machineable, multiple opacities, bright white, formable, recyclable, good for general purpose application
  • Disadvantages:  Can get brittle, Poor solvent resistance, poor thermal stability,  can break under environmental strain, does not gouge and fold well poor thermal stability
  • Common Uses:  Molded applications, signage, point-of-purchase display, packaging, backlit applications, affordable general purpose use

b) Polypropylene (Synthetic Paper)

  • Advantages:  Good chemical resistance, recyclable, flexibility, gouges and folds well, soft hand feel
  • Disadvantages:  High thermal expansion, lower tear resistance compared to PET or PVC, difficult to bond, suffer from UV degeneration, and shrinkage
  • Common Uses:  Synthetic menus, tags, signage, packaging, cost-cutting high transparency applications

c) Rigid Vinyl (PVC)

  • Advantages:  Outstanding durability, most commonly utilized print plastic, easy to use, UV degradation resistant, low flammability, good rigidity
  • Disadvantages:  Not fit for laser cutting, not considered eco-friendly in majority of applications, does not gouge and fold well, lower thermal stability
  • Common Uses:  Signage, credit cards, gift cards, general purpose plastic, point-of-purchase displays, uses needing good rigidity, shelf wobblers

d) PET (Polyester)

  • Advantages:  High optical clarity, high impact resistance, good chemical resistance, high toughness, higher thermal stability
  • Disadvantages:  Lower impact strength compared to PETG, expensive, can be hard to cut
  • Common Uses:  Button panel, packaging, nameplates, high heat applications (thermal stabilized types)

e) Polycarbonate

  • Advantages:  High heat stability, high impact strength, very long-lasting, formable, high clarity, unbeatable rigidity
  • Disadvantages:  Prone to cracking due to stress, Frequently engineered excessively for application, expensive, needs high fabrication temperatures, production involves use of harmful chemicals
  • Common Uses: button panels, Nameplates, outdoor weather-able applications overlays, harsh environment items,

4. Hot Stamping plastics

This is a dry printing procedure that transfers metallic material or color pigments from a continual film conveyor to a plastic part.

The pressure and heat of hot stamping perpetually moves the picture to the plastic.

A silicone rubber die matches to fix the slightly bumpy surfaces frequently observed in molded parts.

Hot stamping plastics

Hot stamping plastics

It offers outstanding resolution and  to fit the slightly uneven surfaces often found in molded parts and allows for excellent resolution and replication.

The process of plastic hot stamping

During the process of plastic hot stamping, you begin the operation with the development of the dies that you will use for marking.

Making of the dies can either be through direct shaping or casting, and can entail highly detailed designs.

First, you heat the die after mounting it on the stamping equipment, with the product you want to stamp under it.

Before stamping the item, you place dry paint or foil in between through a roll-leaf conveyor.

After stamping the item, the roll-leaf conveyor perpetually heat-transfer the pigment on it to the hot stamped plastic material.

In a nutshell, hot stamping is a lasting marking operation used for plastic materials labelling.

The process employs a heated silicon or metal die that engraves the component with a picture or a plane silicon pad which stamps a picture on the lifted surface of a component.

A marking foil, enclosed between the plastic item and the die, helps in adding color to the brand during stamping.

Advantages of hot stamping of plastic

  • The procedure is clean, dry, quick, and lack the production limitations.
  • The stamping or marking operation is comparatively eco-friendly and non-harmful mainly due to the utilization of dry materials.

Disadvantages of Hot Stamping

  • Generally restricted to stamping on plane surfaces

Applications of plastic hot stamping

The process mostly find use in items decoration, finishing print, and security and marking print, for example by using holographic foils.

5. Plastic plating

Though most people view plating a metal finishing operation, it is equally practical to plate successfully non-conducting materials.

Specifically, plating of plastic materials can be exceptionally fruitful in a broad variety of industrial uses.

Chrome plating plastics

Chrome plating plastics

Adding a metal layer on plastic is a high-accuracy procedure that is possible to customize for decorative and functional applications.

Process of Electroplating on Plastic

You need specialized before you start plating plastic.

First, you etch the material in a chromic acid-based mixture to boost its adhesive abilities.

Ensure to neutralize any extra chromic acid generated. Thereafter, you add a solution containing tin salts and palladium to the material.

Next, you then coat the material surface using copper or nickel from an electroless plating mixture.

The tin salt and palladium solution act as catalyst if they combine with the copper or nickel.

At this point, the material is set for electroplating applying standard plating technology.

Another alternative is to spread a conductive paint on the surface of the plastic material before beginning the electroplating operation.

Materials that can be used for Plastic Plating

Although ABS makes about 90 percent of plastic used in plating operations, you can plate successfully other plastic resins, and they consist of:

  • Phenolic
  • Polyethersulfone
  • Urea formaldehyde
  • Diallyl phthalate
  • Polyacetal
  • Teflon
  • Polyetherimide
  • Polycarbonate
  • Polyarylether
  • Mineral-reinforced nylon (MRN)
  • Polysulfone
  • Polyphenylene oxide (modified)

Advantages of plastic plating

  • Aesthetics are an essential benefit of incorporating metal to a plastic part. A metal coating such as silver or gold, for example, can substantially brighten the look of the surface of a plain plastic
  • The process adds color to the plastic material.
  • Boosts the corrosion resistance and strength of the plastic.
  • Increases the chemical resistance of the plastic material

Disadvantages of plating on plastic

  • Electroplating plastic is comparatively costly than electroless plating.
  • It is harder to attain consistent thickness on the plastic item, as the thickness seems to develop quicker on the margins than on the surface.

Applications of plastic plating

  • Automotive-nickel plating is currently in wide application to give brilliant, chrome-like finish on various plastic car components
  • Electronics
  • Plated plastic plumbing items.

6. Painting Plastics

There are specialized processes and precautions employed when painting plastic to guarantee durable quality finish.

Painting plastic

 Painting plastic

In five or less steps, you can quickly transform plastic surfaces to express your style:

i. Clean the plastic surface

Apply an ammonia-based cleaner for old plastic surface and paint thinner to cleanse new plastic surface.

ii. Lightly sand the surface in case it was previously painted

iii. Dust off the surface using a tack cloth

iv. Let the plastic surface to dry

v. Spray paint the surface based on the instructions attached on the spray can.

Products for painting plastics

Anchor primer

As the name suggests, this product initiates a reaction on the plastic’s surface which boosts the adherence paint onto the plastic.

You apply anchor primer directly without dissolving, and 1 or 2 layers is enough for the painting task.

Specific cleaners

The cleaners are gentle to plastic since they do not have aggressive chemicals.

Their antistatic features help prevent the attraction of dust on surface after you have finished cleaning.

Elastifying additive

When working with acrylic-polyurethane paint (2k), you’ll have to add some elastifying additive.

The additives offer more flexibility so as to prevent cracks thus acting like an additional layer to the plastic.

Plastic Materials

You can paint almost all plastic materials. However, you should not use PP, PE and low polarity plastics due to their low surface energy.

Also, you should be cautious when handling plastic materials like PC and PS due to exposure to harmful solvents.

Advantages of Painting plastics

  • Form protective coating
  • Possible to have thin coat layer
  • Offers richer color compared to internal colorants
  • Similar color after assembling of parts

Disadvantages of Painting plastics

  • Poor adhesion to specific plastics
  • Air pollution from waste disposal
  • Variation in paintability among plastics

Factors to Consider when Choosing a Plastic Fabrication Method

Getting your plastic parts fabricated depends primarily on five factors:

Drilling acrylic

Drilling acrylic

i. Form

What shape do you desire to produce?

This is largely influenced by the operation and restricted by the limitations of the available fabrication processes.

ii. Budget (Tooling and part costs)

Some plastic fabrication techniques have very high set up costs while some are less costly though there is always a trade-off.

Majority of mass production plastic fabrication methods are costly to tool, but give cheap parts, while low volume fabrication methods are economical to set up but give costly parts.

iii. Volume

Annual volume and part price are some key considerations you should factor in when selecting a plastic manufacturing method.

Most methods of fabricating plastics provide multi-impression tool which implies that you are capable of producing several parts per cycle.

They considerably reduce part cost though cooling will be relatively expensive.

iv. Time

Tooling and fabrication take time, and a more costly tooling normally implies longer set up time.

For instance, it will take you between 10 to 16 weeks to make injection molding tools.

Multi-impression equipment can decrease the production time since several components are produced every cycle.

v. Material

The choice of material is dictated by the function, cost and form.

In addition, it depends on the fabrication method you select, for example, injection molding is not the right method to work with in case you need to produce a Bakelite product.

Still, I know you could be having many questions about plastic fabrication and finishing operations.

That’s why I have this last section for you – keep reading.

FAQs on Plastic Fabrication

In this section, I am going to handle some specific questions you may have about plastic fabrication and machining.

I will do that in form of questions and answers.

Keep reading to be a specialist in plastic fabrication and machining.

1. How do I choose the ideal plastic material for my fabrication?

Cost vs. performance

There is still a common notion that conventional metals are better than plastics when in essence it is the contrary.

Plastics are a perfect substitute for stainless steel, cast iron, and bronze; they perform well in high-temperature and severe working conditions.

However, the high-performance levels come with associated costs.

Plastics material are not your typical “cheap stuff,” some high-performance varieties are significantly more costly than metal.

For instance, Polybenzimidazole (PBI-Celazole) is fifteen times the price of type 303 stainless steel, and twenty-five times more costly than cold-rolled steel.

Considering these price aspects, it is crucial to apply professional machining methods to use expensive materials effectively and minimize scrap.

Ultimately, the choice of the type of material you use in plastic fabrication should be an investment in performance.

Selecting a higher-quality plastic material will give top-notch quality finished part.

In addition, top quality parts can help you prevent costly recalls or in-field failures down the supply chain. Better to invest in advance and prevent these hazards.

So, when should you select plastic materials over metal?

Consider the benefits of plastic machined components; they have the capability to:

  • Reduce component weight
  • Lower noise level
  • Eliminate corrosion
  • Extend service life
  • Improve wear performance
  • Insulate and isolate (both electrically and thermally)

2. How can I remove scratches from acrylic?

This is a common question that plastic machinists ask, and the reply is, it depends

You can buff light surface abrasions out of acrylic.

Conversely, deep abrasions are a little more tedious to handle though I will provide recommendations of how to go about both.

So, let’s see how to handle light scratches:

  • You will require some metal polish and 800 grit and 1200 grit wet and dry paper.
  • Bend the 800 grit and applying water do the rubbing in a circular motion till it gets difficult to notice the conspicuous abrasions. Keep the paper adequately wet so that a small slurry forms
  • Change to the 1200 grit and use the same procedure using water till there is totally no indication of any abrasions.
  • Once contented that you have eliminated all abrasions cleanse dry using a clean, soft cloth.
  • Then you polish the buffed area (that may appear duller than the rest of the plastic surface) using a soft dry piece of fabric to bring back the plastic’s shine.
  • In order to get goods outcomes, you may to apply and rub the polish severally, and always remember to do the rubbing in a circular movement.

Deeper scratches:

  • You can buff out deep abrasions in a similar manner as with light scratches though; it may be necessary you begin with 600 grit before changing to 1200 grit and finally metal polish.

However, it is not worth it if the abrasion is to a depth of .5mm and above.

The abrasion may be excessively big for buffing if your finger catches in the score if you run it over the scratch

3. Is acrylic similar to glass?

Acrylic is comparable to glass, though acrylic boasts of features that make it better than glass in several ways.

It is stronger than glass several times, safer, and more impact resistant.

Actually, an acrylic piece of 32mm thickness is in fact bullet-proof.

Also, the weight of acrylic is only 50% that of glass, and you can saw it giving more design and shape possibilities.

Finally, according to my explanation in the preceding question, you can buff out scratches in acrylic but cannot in glass.

4. Is it possible to weld plastic using a soldering iron?

When the plastic cover of an item cracks or breaks into pieces, majority of individuals just purchase new one.

Nonetheless, it is very simple to melt and rejoin the pieces using a soldering iron because of the incredible malleability of plastic.

Though the mended surface will not be exact as it appeared before, after practicing consistently, you can performing plastic welding without cosmetically obvious welds.

Welding plastics using soldering iron is not restricted to repairs only; you can equally use it for fabrication of plastics and artistic applications.

If you already have a soldering iron or station, then there is no need of purchasing a plastic welding gear – you can commence welding plastic today.

Let me take you through the procedure.

But I recommend that you should experiment with scrap plastic to understand the duration of time you will require to press down the soldering iron on distinct areas on the plastic, before trying your initial weld.

Welding plastic

 Welding plastic

You begin by rigorously cleansing the plastic using degreaser and soap, regardless of the cleanness of the plastic surface.

Remove the jagged nature of the edges by sanding them down, then power on the soldering iron and allow it to heat, which should only consume a few minutes.

Fuse the two plastic parts together and maintain them in that state as you move the soldering iron end across the seam till the pieces get partially molten together.

While the two parts are still hot and adjustable, remodel them to your level best till they join together.

You can boost the weld’s strength by adding minute pieces of plastic (preferably thin strip) to the seam.

Completely melt these plastic pieces by compressing them using the soldering iron end till they liquefy.

Spread the molten plastic across the seam using the soldering iron end.

The final stage involves going over the joint and the plastic around it using the soldering iron applying quick, smooth strokes.

After repeated practice of how to apply this procedure, you should be capable of doing uniform, smooth plastic weld.

5. What is Thermal Heat Staking?

In thermal heat staking, you use restricted heat and light pressure, to guide the flow of molten plastic to trap another component to give a rigid mechanical fusion between the two parts.

A thermal device operating at a user-determined temperature joins with the plastic, and thermal heat transfer happens between the plastic and the device.

Once the plastic reaches its melting temperature, you apply force to remodel the plastic usually to the shape of the tailor-made thermal device chamber.

Thermal staking offers an option to ultrasonic plastic welding if there are restrictions or needs that ultrasonic technology cannot manufacture.

Also, the process offers an option to ultrasonic welding.

That is, if the two components you want to join are of dissimilar materials which will not join together.

Or, when a straightforward mechanical retention of a component comparative to the other is sufficient.

Popular heat staking applications comprise of:

  • Joining of plastic to plastic
  • Plastic to metal
  • Simultaneously staking multiple staking bosses at varying heights and sizes

Other heat staking uses include heat sealing, inserting, date coding, degating, and embossing.

6. What is the difference between heat transfer and hot stamping?

Both heat transfer and hot stamping need pressure, heat, and dwell time to engrave a picture on a plastic part.

Nevertheless, heat transfer uses pre-printed pictures applying flexography, silkscreened, gravure, or digital printing techniques on a release film or paper.

Hot stamping

Hot stamping

While the art in the die creates the pictures in hot stamping.

Additionally, heat transfer can be single-color or multiple colored picture, whereas hot stamping is commonly single color.

7. Which is the best option between hot stamping and cold stamping?

For this type of question, each industry player will having differing answer.

From my perception both methods perfectly augment each other and allow a broad spectrum of possibilities to you.

Considering the numerous printing needs that a selection of suitable decoration, factoring the technological requirements of the operation, is a big challenge.

Moreover, should take into consideration the budget of every project.

I am certain that, from the economical, practical, and technological perspective, every person engaging in printing would want to have the two technologies.

Only such a scenario would offer a freedom of adjusting the technique of printing based on the budget, project requirements, and quantity.

It is a fact that when possessing only a single printing method, you need to decide between the quality and the price.

It compels you to reach a compromise, which in instance of prime packaging is inconvenient and not usually satisfying.

Presently, hot-stamping tends to be a widespread technique in respect of cost and design.

Both methods have their benefits and limitations.

Nonetheless, taking into account that cold-stamping is fairly a new technology, I presume there is room for improvement.

In the future, I foresee significant possibilities of cold-stamping dominating hot-stamping in the present state.

In a nutshell, it is upon you to make the ultimate decision.

Both methods provide similar outcomes, save that hot-stamping, enjoys a broader application (facilitates use on both textured and smooth surfaces) and is readily available.

8. What should I know when painting plastic?

Color differences, chemical sensitivity, adhesion problems, etc. are among of the most popular challenges you may face when undertaking repair operations on plastic parts.

When discussing plastic, we understand that corrosion will not be a challenge, but exposure to UV radiation, temperature, and humidity will result to bad aging of the paint.

Color of the material will begin to fade and cracking will ensue, as they lose their mechanical integrity.

That is the reason why an excellent treatment is essential to prolong lifespan.

Painted acrylic

Painted acrylic

Most common problems:

  • Lack of paint adhesion

Chemical properties of some plastics make their adhesion to be very difficult.

When working with polypropylene and polyethylene, you need to pretreat them to enable their wettability and consequently, paint adhesion.

  • Sensitivity to chemicals

Specific plastics may get very susceptible during a cleaning process involving solvent.

Selecting the correct cleansers to eliminate particles and other exterior agents is among the most critical steps to attain a good outcome

  • Greater malleability than metal

When spreading a paint coat, you must take into consideration that the plastic parts are going to be more malleable.

This signifies that with an ordinary paint, the surface will likely crack when it dries.

9. Why is it important applying primer before painting?

Applying primer prior to painting is very crucial.

Primer being an adhesive agent, assists in improving the adhesion ability of paints to the plastic surface.

Applying primer is essential to boost the useful lifespan of paints. It hinders peeling.

There are primers which stop alkali (which results efflorescence on the surfaces).

These primers as well fill small crevices and gives a translucent, glossy layer.

This is crucial in instance of external painting.

10. What is plastic thermoforming?

Thermoforming is a method of plastic fabrication that heats a 2D tough thermoplastic sheet and applies pressure or vacuum to mold the sheet into a 3D shape.

It is a one-sided procedure implying that the tool surface can control only a single side of the sheet.

Thermofomring plastics

Thermoforming plastics

As a result, you determine the wall thickness of the completed part majorly by the design of the part.

The production quantities of thermoforming is about 250 to 3000 annually, providing fast product creation cycles, lower tooling costs, and components with color and texture.

11. Is resin a form of plastic?

It’s, in fact, the contrary: plastic is a type of resin.

Natural resins are viscous, sticky biotic liquids that are indissoluble in water.

The secretion of coniferous trees such as pine is a resin.

The substances we refer to as plastics, for example, polycarbonates, acrylic, polyethylene, ABS, among others are artificial resins.

They are in the configuration of long-chain polymers commonly obtained from petroleum.

Celluloid is also eligible to be a plastic.

Making it involves using sulfuric and nitric acid.

They transform cellulose (the primary component of plant cell walls) into cellulose nitrate (an intensely explosive compound referred to as guncotton).

Eventually mixing the cellulose nitrate with camphor stabilizes it.

12. What do I need to consider when designing my fabrication process?

If you want to engage in mass production of parts, then you should make it a point to have the right design.

Drilling polycarbonate sheet

Drilling polycarbonate sheet

This is more sophisticated than you may reckon, and to get the design right you should:

  • Design and then prototype the part to provision.
    • Initial development of prototype is generally done using a 3D printer and usually in a varying material than the one that you will use to fabricate the final part.
  • Design an injection mold equipment for the first round of production
    • Usually producing 300 to1000 injection molded templates in the material of fabrication needs the creation of injection mold tool.
  • Fine-tune any constituents in the injection mold equipment before commencing the high volume production.

13. Why should I consider Digital Die Cutting?

Digital die cutting biggest advantage is the fact it ensures optimal precision since it does not depend on die.

Other key benefits include:

  • Shorter turnaround times — the speed of the digital die cutting equipment is slightly faster than that of conventional cutting equipment, therefore, switching out die shapes is not necessary. This facilitates faster turnarounds by reducing the general production time.
  • Cost savings — because the cutting system does not involve using die shapes, there are no expenses related with production and application of a die. This, in turn, makes the procedure more economical than conventional die cutting.
  • High precision — since cutting using digital machine uses small blades, bits, or lasers; it is highly accurate.
  • Software integration — digital die cutting employs a variety of software. After you have chosen a specific kind of cutting equipment, integrating software is very straightforward.

Digital die cutting ensures shorter lead times while guaranteeing clean, accurate result.

14. What is meant by stress in plastic fabrication?

When you heat any material, it will expand, and when cooled, it contracts.

Because majority of plastics are poor heat conductors, any rapid or unbalanced heating and cooling can initiate stress into the substance.

Some of the stress-inducing operations consist of drilling, casting, cutting, molding, extrusion, machining, and heat- or cold-forming.

Machining stress often develops during:

  • Deep hole drilling
  • Machining within corners without appropriate radius
  • High-speed removal of great amount of material, or when there is unequal material removal when reducing the thickness of completed part, for example in hollow box- or cup-shaped part.
  • Applying insufficient coolant.

Stress in a plastic component can lead to poor application performance comprising twisting, warping, and other dimensional alterations.

It may equally result in poor chemical resistance, cracking, and decreased wear resistance.

Moreover, certain plastics are more vulnerable to stress than others, particularly when you apply chemicals or temperature cycling (sterilization).

15. Why is the annealing critical in plastic fabrication?

Plastic annealing is the procedure of heating and cooling the plastic slowly.

Or, the process of heating and cooling them slowly to alleviate the stress and stop it from reappearing.

The time and temperature cycle differ for every plastic type and part diameter.

Generally, the process of annealing involves heating the material to a temperature slightly below it melting point.

Then, maintaining it at that temperature for a time duration, then getting it cool down slowly till it gets backs to room temperature.

16. What is the difference between dosing and blending?

Dosing involves injecting one selected material element, like strong color, into the jet of the material getting into the processing equipment.

For example, you can fit a simple feeding component to the throat of a fabrication equipment.

It will regulate color concentrate into the flow of material conveyed from a hopper, located above the machine’s throat.

Note that you can use this system for other additives as well and not just color.

There are two types of dosers (also known as Feeders).

  • Volumetric doser depends entirely on free-flowing substances, and it does require calibration to attain any level of precision.

Typically, though more affordable in relation to the initial cost, these dosers are not as accurate as the gravimetric type.

  • Gravimetric Dosersnormally function in a “loss in weight” modus in order to precisely control and maintain correcting the required dosing degree.

They achieve this by determining the weight of the hopper dispensing the additive.

Another advantage of this type of doser is that it copes with substances of poor rate of flow.

Blending nonetheless, not only regulates the additive flowing into the processing equipment, it also controls all the required ingredients for the process.

For example, color, regrind, and virgin material which it accurately blends in a regulated and repeatable process.

They are two types of blenders as well.

  • Volumetric Blenders are usually taken as appropriate when the percentage of additive and regrind you are utilizing are not essential to the quality or appearance of the final product.

These type of blender depends on the timed material dispensing with a free-flowing property.

  • Gravimetric Blenders, though having the greatest initial buying cost, these blenders attain staggering outcomes and a swift reclamation of the initial of the initial investment.

These equipment ensures constant proportion of ingredients during the entire process.

Gravimetric blenders will operate without intervention once put in place with the right ingredient, calibrating itself to ensure accurate portion and combining of the constituents of the blend.

Conclusion

Products made of plastic are everywhere, and there are several processes of manufacturing them.

Understanding which plastic fabrication method to select is essential in producing a quality part.

Also to getting a supplier that can assist you in realizing your production objectives.

Over the years, we have been fabricating and machining plastic materials.

It depends on your unique shapes and designs.

And as plastic fabrication and machining experts, we are here to make your business profitable.

For and questions or consultation on plastic fabrication – contact us today.

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