What’s Plastic Fabrication? A Complete Guide

Plastics are versatile materials with plenty of polymer options. They are among the most common materials used in producing end-use products. Such products range from consumer products to medical materials. Plastic fabrication is a crucial part of the plastic industry, and it has been for many years.

It involves designing, manufacturing, and assembling plastic products through different methods. There are many plastic processing techniques. The various options make it difficult to choose the best for individual applications.

This article will guide you through the widely used fabrication processes for plastics. It’ll help you understand the factors to consider to help you choose the best plastic manufacturing process. Let’s get straight to it!

What’s Plastic Fabrication?

We can see plastic components and products everywhere, from home appliances to cars and electronics. To convert raw plastic materials into the desired functional shape, they must be processed with a suitable fabrication process. So, plastic part fabrication is the process of converting plastic pallets or sheets into designed geometry. It might or might not involve the melting of raw plastics. For example, vacuum casting melts the plastics to mold the shape, whereas CNC machining removes the material using rotating cutting tools.

The fabrication techniques can shape both types of plastics; thermosetting plastics and thermoplastics. However, you must be careful about the methods compatible with the plastic you want to fabricate.  Subsequently, the malleability, low weight, strength, and cost-effectiveness of plastics make them ideal for diverse engineering industries for both prototyping and full-scale production.

Plastic Fabrication Processes and Methods

A wide variety of plastic fabrication methods have developed over the years. These methods are aimed at covering several applications, plastic types, and part geometrics.

Therefore, it becomes crucial for every person involved in product development to get familiar with the options available. Below, you’ll find the most common plastic-forming techniques regarding how to fabricate plastic parts.

Injection Molding

This method is one of the most common plastic processing techniques. The injection molding involves the melting of thermoplastic plastic pellets, which could be thermosetting or thermostatic polymers.

The next process involves the injection of the melted plastic pellets into a mold cavity at pressure once they are malleable enough. Injection into the mold cavity fills and solidifies the plastic to make the final product.

Plastic injection molding is a standard method in any plastic fabrication company. It may involve an aluminum mold or a steel mold.

The most commonly used mold is the aluminum variant. It transfers heat more efficiently than steel mold. Therefore, cooling channels are not needed.

The first step in this process is the loading of plastic pellets into barrels or similar containers. Here, the melting and compression of the mold occur. Then, shooting of the melted hot pellets into a mold cavity occurs. The method may require ejector pins to remove the molded parts from the mold and have them boxed.

Injection molding helps to produce parts in large quantities. Its typical application is in mass-production processes where there’s a need to create the same part thousands of times in succession.

 Vacuum Casting

When you need a cost-effective alternative to the injection molding technique, then vacuum casting is a perfect choice. It is a form of ‘copying’ technique for custom plastic fabrication.

Vacuum casting involves producing a small series of functional parts or prototypes. Therefore, there’s a need for a master model with a high-quality surface finish for an efficient vacuum casting process. Most manufacturers use Laser Sintering or Stereolithography to create the master model. The next step involves encapsulating the master model into a silicone mold.

Curing of the silicone mold occurs at high temperatures, ensuring strength and durability. After curing, the mold is cut open, revealing a hollow space with the same dimensions as the master model.

The cut mold is then filled with the designated resin material in a vacuum chamber. Many manufacturers often mix the resin with coloring pigment or metallic powder. Therefore, you can be sure of achieving aesthetic or certain functional characteristics. The resin’s final curing occurs in the oven at high temperatures, after which there’s the removal of the silicone mold.

Using the vacuum casting plastic forming process ensures a highly precise final product. Even if there’s complex geometry, the finished product looks exactly like the original. Also, vacuum casting is more cost-effective due to the affordable nature of silicone. Moreover, you can make several other products from an already-used mold.

Blow Molding

The blow molding process creates hollows and tubular shapes by blowing air in a thin plastic film called parison (Continuous sleeve-like structure). When pressurized air enters the parison, it inflates the soft plastics into the cavity and captures the shape. Once the part is cured, the air is released and ejected from the mold.

You can get three options in blow molding.

● Extrusion Blow Molding: Extrusion of melted plastic inside the parison and inflating inside the mold cavity.

● Injection Blow Molding: This method involves injecting plastic into a mold to create a preform, which is a test tube-shaped piece. The preform is then transferred to a blow mold, inflating to achieve the final shape.

● Stretch Blow Molding: It involves vertical stretching of heated preform before blowing air, which enhances the strength and clarity of the final product.

Moreover, blow molding is ideal for manufacturing of plastic components, which are axially symmetrical and hollow in shape—for example, fuel tanks and bottles.

Plastic Extrusion

This plastic fabrication produces continuous cross-section profiles by forcing the molten liquid plastic through an extrusion die. The die includes flow channels, heaters, and cooling systems. First, granular beads or pallets are passed into an extruder funnel, where the screw passes the material into the heating chamber. Then, a molten form of plastic enters the die cavity. Meanwhile, pressure is continuously applied by the screw. Finally, it creates long continuous profiles from another opening or die. The cutter breaks the long extruded parts into the desired size.

Plastic extrusion is ideal for fabricating uniform plastic products in large quantities. It creates products or components with consistent properties, dimensions, surface finish, and tolerances.

Plastic Pultruson

The term “Pultruson” is a combination of “pull” and “extrusion”. Hot plastic polymers are pulled through a resin bath and a hot die.  After curing, you will get a continuous and uniform composite profile. Some examples are beams, insulting rods, and custom profiles.

• Fiber Impregnation:  Pulling of continuous fiber through a resin bath for resin-impregnation.
• Operation and Curing:  The resin-impregnated fibers are pulled through a heated die, where the resin cures and solidifies.
• Cooling: The final profile exits the die, which contains cooling mechanisms inside it.
• Final Profile: The profile is cut to length and may undergo additional finishing processes.

This plastic fabrication process produces parts with high strength and low weight. The parts remain structurally intact over time due to corrosion and wear resistance properties.

Plastic Welding

You might think the metallic joints when it comes to welding. But welding can also join the plastics molecularly by melting and solidifying the material at the welding position. However, plastic welding requires different sets of equipment and tooling than metallic welding. The process typically involves melting the material with heated air and fusing it with pressure. It develops a cross-link molecular chain between two joining parts.

There are distinct methods of plastic welding, ultrasonic, induction, hot platen, and vibration. These methods use different sources to heat the air, which later strikes the welding point through a welding torch.

This plastic production process is popular for producing electronic enclosures, chemical processing components, automotive repair, piping, etc.

Rotational Molding

Rotational or roto-molding is one of the simple plastic fabrication processes that involves placing the polymer powder inside the heated mold and rotating it into two axes, vertical and horizontal. Often, the heat melts the powder (often mixed with fiberglass), and rotational motion coats the interior surface of the mold with the molten material.  Then, cooling and demolding produce hollow parts with uniform thickness.

Some examples of roto-molding applications include food and chemical tanks, medical supplies, sanitary products, etc. Subsequently, it is the non-pressure molding. There is no such injection or compression mechanism in the rotational mold. This allows to use of mold made with less expensive materials.

Plastic CNC Machining

What is CNC Machining? It is the subtractive manufacturing approach to producing precise plastic components, ABS, Nylon, PE, PP, and thermosets. CNC lathes, milling machines, CNC turning centers, or other suitable equipment use multipoint cutting tools, which remove the materials from plastic workpieces to achieve the desired shape.

Computer Numerical Control (CNC) technology automates the tool movement and material removal. As a result, plastic fabricated parts from CNC machining maintain tight tolerances (±0.005″) and smooth surface quality.

Furthermore, the diverse CNC machining techniques, like cutting, milling, turning, routing, drilling, tapping, etc., can process complex geometrical features like deep holes and undercuts. Automotive, aerospace, medical, electronics, and many other industries rely on CNC plastic parts for all kinds of fabrication projects, prototyping, bridge production, and mass production.

3D Printing

Based on the uploaded CAD design, the 3D printer builds the plastic components by piling up the layers of molten plastic filament or powder. However, the mechanism of depositing the material layer can differ based on a particular 3D printing technique.

● Stereolithography: This technique uses a UV laser to cure and solidify the thin films of photopolymer resins. Then, layered structures form the final object.

● Fused Deposition Modeling: It involves extruding thermoplastic filament through a heated nozzle to deposit the layers.

● Selective Laser Sintering: It utilizes a laser to fuse powdered material and produce continuous layers, resulting in durable and complex parts.

3D printing requires no specialized tooling like in machining or molding methods. Additionally, 3D print production is quick and maintains close dimensions. So, it is ideal for custom plastic prototypes and small batches. Often it is compared with plastic 3D printing in low-volume production as 3D printing can mimic the parts from injection molding without any significant investment for tooling. You can read more about injection molding vs 3D printing here.

Types of Plastics Used in Fabrication

Several types of plastics can be processed with plastic fabrication to produce designed parts and products, PE, PP, PVC, ABS, etc. These plastics have unique properties in applicability. Below is the typical material list of fabrication plastics;

Material	Key Properties	When to Use?
Polyethylene (PE)	Chemical and impact resistance, low cost, and lightweight	Packaging, containers, piping, and plastic bags
Polypropylene (PP)	Resistant to chemical resistance and electrical insulation	Medical tools, textiles, containers, laboratory equipment, and car interiors
Polyvinyl Chloride (PVC)	Rigidity (for uPVC), flexibility (for plasticized PVC), and chemical inertness	Pipes, cable insulation, flooring, medical devices
Polystyrene (PS)	Rigid, brittle, clear or opaque, electrical insulation, etc.	CD cases, laboratory ware, insulation materials, etc.
Polycarbonate (PC)	Excellent impact resistance, transparency, and good heat resistance	Optical disks, eyewear lenses, automotive and medical components
Acrylic (PMMA)	Optical clarity, weather resistance, rigidity, and lightweight	Signage, aquariums, lenses, display cases
Acrylonitrile Butadiene Styrene (ABS)	Impact resistance, toughness, good heat resistance, and machinability	Automotive parts, electronic housings, LEGO bricks, consumer goods
Polyamide (Nylon)	Mechanical strength, good wear resistance, chemical resistance	Bearings, gears, automotive parts, textiles
Polyethylene Terephthalate (PET)	High strength, chemical resistance, good barrier properties, transparency	Beverage bottles, food packaging, fibers for clothing
Polytetrafluoroethylene (PTFE)	Chemical resistance, thermal resistance, low friction, non-stick properties	Non-stick cookware, gaskets, seals, bearings, chemical container

Here, many options might confuse you about which plastic material to choose. It depends on what particular properties you are looking for and the compatibility of the material with the available fabrication equipment.

Applications of Plastic Fabrication

Plastic materials are essential in almost every sector, from consumer items to aerospace and medical industries. The low weight, strength, durability, insulation properties, and low prices make plastics prevalent in countless applications.

Here are the applications of plastic fabrication with examples;

Aerospace Industry

High-performance plastics are used in aerospace components like ABS, Nylon, Polyethylene, Teflon, and PEEK.  The low weight and high strength of these materials directly contribute to the fuel efficiency and safety of aircraft or other aerospace items. Meanwhile, plastic Machining, molding casting, and 3D printing are the most common plastic fabrication methods in this industry. The application examples are as follows;

● Passenger windows and seat components

● Interior trim and panels

● Seals, gaskets, and fasteners

● Cable insulation

● Radar covers

● Structural parts

● Fuel hoses

Automotive Industry

Like aerospace, plastic applications are crucial in automotive manufacturing for lightweight parts. They apply to cars, motorbikes, trucks, and all types of vehicles. Moreover, plastics can meet stringent standards for automotive components. Some examples are;

● Dashboard panels, interior trim, seat components, bumpers

● Steering wheels

● Engine covers and radiator grilles

● Fuel tanks

● Air intake manifolds and coolant reservoirs

● Body panels (e.g., fenders, hoods)

● Exhaust system components

Electronics Industry

The design flexibility, durability, impact resistance, and electrical insulation properties of plastics are beneficial for electronic components like enclosures and circuit boards. Additionally, the plastic fabrication processes can manipulate the raw materials into various electronic items. Some examples include;

● Laptop, speaker, and remote enclosures

● Power supply and connector housings

● Cable and wire insulation

● Printed circuit board (PCB)

● Keyboard keycaps

● Touchscreen panels

● Router and modem casings

Medical Industry

Plastic fabrication is heavily used in the medical industry for various diagnostic equipment components, surgical tools, prosthetics, implants, and device covers. Typically, medical applications require the fabrication of sterilizable and biocompatible plastics to meet industry standards—for instance, polycarbonate, polypropylene, PEEK, and Polyurethane.

The following are the medical application examples of plastic fabricating components;

● Syringes, catheters, blood bags

● Surgical instrument handles

● Prosthetic limb components

● Orthopedic implants (e.g., hip and knee replacements)

● Diagnostic device housings (e.g., blood pressure monitors)

● Medical vials and containers

Construction Industry

Plastics are the best alternatives for many construction materials. Acrylic and polycarbonate are transparent and robust, which can replace glass in structures. Similarly, vinyl is durable and suited for exterior uses.

Next, the easy customization in shape, size, and aesthetic allows to production of unique and attractive construction items.  Here are some application examples;

● Piping systems

● Insulation panels

● window frames

● Roofing membranes (TPO, PVC)

● Wall panels and cladding

● Fencing components

● Decking and railing

Consumer Items

In our everyday lives, we use many plastic consumer items, from kitchen appliances to food packaging. Cheap cost and low weight are the key reasons behind these consumer applications.

● Water bottles, plastic bags, and toys

● Food storage containers

● Kitchen utensils (spatulas, mixing bowls)

● Laundry baskets

● Disposable cutlery and plates

● Toothbrushes

● Sunglasses frames

● Furniture

Advantages and Disadvantages of Plastic Fabrication

Plastic fabrication processes are highly versatile regarding material compatibility, design complexity, and customization capability. However, there are some concerns also, like environmental impact, low melting point, etc.

Advantages

● Machinability and Moldability: Plastics are easily machinable, and their low melting points also ease the molding and casting processes. It also enhances the production speed.

● Customization: You can customize the color, texture, and composition with other materials to meet specific requirements.

● Cost-effective Production: The cost of producing plastic parts is often lower than that of metals or other materials for both prototyping or high-volume production.

● Lightweight: One of the prime reasons for widespread plastic applications is the lightweight nature, which boosts the end performance.

● Durability: The corrosion resistance, wear resistance, and impact strength all contribute to the longer life span of fabricating parts.

● Complex Shapes and Features: The availability of distinct plastic fabrication approaches allows for converting any complex designs into workable physical items.

Disadvantages

● Environmental Concerns: Plastics are non-degradable, which poses the risk of environmental pollution and a high carbon footprint.

● Thermal Restrictions: Plastics tend to lose their properties at high temperatures due to their low melting points. Some increments in operating temperature can lead to the failure of parts or systems.

● Low Structural Strength: Plastic does not have excellent strength like metals, and it can lose further when exposed to corrosive materials (not good wear resistance).

How to Choose the Right Plastic Fabrication Technique?

There is no straight answer to “Which is the best plastic fabrication method for your project?”. It mainly depends on which materials you are using and what kind of design specifications you have (size, geometry, thickness, production volume, etc.). Furthermore, desired tolerances, lead time, and cost can also affect your choice.

The following are the critical considerations to choose the correct plastic fabrication technique for your project;

Type of Plastic

First, which type of plastic are you going to fabricate? Is it thermoplastic or thermoset? Every technique is not compatible with each plastic material. For example, injection molding and plastic welding might not be ideal for thermoplastics. So, short-list the fabrication techniques that are compatible with the chosen materials.

Part Shape and Size

Secondly, analyze which plastic fabrication methods are feasible for your part’s size and design complexity (internal channels, deep cavities, undercuts, etc.).  For example, blow molding can be ideal for large hollow shapes, whereas injection molding could suit complex features like internal channels and cavities.

Desired Precision

Each fabrication technique has a distinct capability of precision and accuracy.  CNC machining (±0.001 to ±0.005”), injection molding (±0.002 to 0.010”), and 3D printing are high-precise techniques, whereas other methods are not as precise as these two. So, shorten the list further according to which techniques can achieve your desired tolerances.

Parts Quality

The parts quality primarily refers to dimensional accuracy, retention of original properties, and surface finish of the plastic fabricated parts. Here, you must identify the quality of the parts required for performance and aesthetics. For example, CNC-machined parts retain all the original properties of raw materials. Furthermore, you might also need to consider the requirement of post-processing.

Flexibility in Design

It means how easy to change the design and adjust the fabrication process accordingly. So, here, consider the possibility of design changes throughout your project period. If yes, the chosen method must be feasible when changing the design (technical and economic). For example, CNC machining or 3D printing can be the best choices. On the other hand, injection molding needs complete new tooling for any slight change in design.

Cost Efficiency

It involves considering the initial setup, tooling, and per-unit production costs to determine the most economical method among you listed so far. The production volume heavily influences the per-part price, where tooling and setup costs are high, such as injection molding and casting, are high. However, they can be economical for large volumes. On the other hand, CNC machining and 3D printing are cost-effective for small volumes due to their low tooling costs.

Production Lead Time

Do you need to release the products in the market early? If yes, then faster plastic fabrication processes are suitable, which could be CNC machining, 3D printing, or even Injection Molding in some cases. However, you can have more options if you are flexible with the lead time.

Furthermore, the comparison table of various plastic fabrication techniques based on the above considerations can help you analyze which one is the right choice.

Process	Compatible Plastics	Part Shape	Precision	Parts Quality	Design flexibility	Cost Efficiency	Lead Time
Injection Molding	ABS, PE, PP, PS, PC, Nylon	Complex shapes with detailing	High (±0.004 to ±0.008 in)	High	Moderate	High for large volumes	Long setup and short production time
Vacuum Casting	ABS, PC, Nylon	Complex shapes	Moderate ( ±0.012 to ±0.020 in)	High	High	Moderate	Moderate to long
Blow Molding	PE, PP, PET	Hollow parts	Moderate ( ±0.020 to ±0.040 in)	Moderate to high	Low to moderate	High for large volumes	Moderate to long
Plastic Extrusion	PE, PP, PVC, PS, Nylon	Continuous shapes	Moderate (±0.020 to ±0.040 in)	High	Low	High	Short to moderate
Plastic Pultrusion	Nylon, PET, PP	Continuous shapes,	Moderate ±0.020 to ±0.040 in)	High	Low	High	Short to moderate
Plastic Welding	PE, PP, PVC, ABS	Large parts or assemblies,	Low to Moderate (±0.040 to ±0.080 in)	Moderate to high	Moderate	Moderate	Short to moderate
Rotational Molding	PE, PP, Nylon	Complex shapes	Low to Moderate (±0.040 to ±0.080 in)	Moderate to high	High	Moderate	Long setup and short production time
Plastic CNC Machining	PC, PMMA, ABS, Nylon, PTFE	Complex shapes	High ( ±0.004 to ±0.008 in)	High	High	Low for small volumes	Short
3D Printing	ABS, PC, Nylon, PET, PMMA	Complex shapes with intricate features	High ( ±0.004 to ±0.008 in)	Moderate to high	Very high	Low to moderate	Short

Lastly, choose a method for plastic fabrication that can fulfill all of these considerations and other specific requirements (if any).

RapidDirect Plastic Fabrication Service

Many product designers, entrepreneurs, and engineers have been exposed to low-quality plastic fabrication results. Do you need the best plastic fabrication company to handle your manufacturing processes?

Then, choosing RapidDirect will be one of the best decisions you can make. At RapidDirect, we support a wide range of plastic fabrication services, including CNC machining, injection molding, vacuum casting, 3D printing, and more. We consider plastic fabrication a crucial part of prototype operations for quality applications.

Our large number of expert engineers will refine the design of your parts and ensure efficient fabrication. All of our engineers specialize in relevant technologies and processes. Therefore, you can be sure of high-quality on-demand services. Once you’re ready to work with us, we provide you with all the information related to your project.

We also provide updates on the manufacturing process and a faster turnaround period. We carry out heavy research, consistent analysis, and rigorous tests. This helps us ensure that your finished product meets industry standards. You’ll get all of this at a very affordable rate.

Conclusion

There are several techniques to fabricate plastic parts and products, injection molding, vacuum casting, extrusion, CNC machining, 3D printing, etc. These techniques have different material and process capabilities, benefits, and drawbacks. Therefore, which method to choose is entirely decided by your project specifications and requirements, such as material type, precision, complexity, budget, etc. Overall, plastic fabrication allows you to produce cost-effective yet precise components for diverse industries. You only need to choose the appropriate fabrication process and reliable plastic fabricator.

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