Automotive Injection Molding for Car Parts Applications

custom automotive parts, injection molding solutions

One of the most popular plastics production techniques is injection molding. This is understandable since it provides a workable way to produce large quantities of excellent injection automobile parts made from a variety of polymers. Automotive injection molding is a crucial production technique in the automotive sector, where quality, safety, and consistency are primary concerns.

We shall cover automotive injection molding from a number of angles, such as its background, benefits, uses, substitutes, and composition. Browse on by swiping down!

Automotive injection molding - custom plastic car parts production

Development of Automotive Injection Molding

During the early stages of the automotive industry, cars were predominantly constructed using metal, resulting in bulky and excessively heavy vehicles. However, as the industry progressed, the plastics market experienced a significant boom in the 1940s and 50s. Consequently, automobile manufacturers began exploring the integration of plastic components in their production processes.

In the 1970s, manufacturers introduced the first cars featuring plastic decorative elements. Subsequently, in the 1980s, they further incorporated functional parts such as plastic headlights, bumpers, and fenders.

Advancements continued in the early 2000s when automotive manufacturers unveiled the initial plastic structural components for cars. These components offered the advantage of being lighter in weight compared to their metal counterparts, thereby enabling improved fuel efficiency and more cost-effective production. Presently, automotive injection molding has become the predominant production method for manufacturing plastic car parts.

Advantages of Injection Molding for Automotive Applications

Automotive injection molding is a well-established production process utilized by automotive mold manufacturers to inject molten plastic materials into a mold cavity. The plastic solidifies as it cools, resulting in high-quality finished parts. While mold design plays a critical role in preventing defects, automotive injection molding itself offers several benefits for automotive plastic parts production:


Repeatability is crucial in the automotive industry, and injection molding excels in producing identical parts consistently. With robust metal molds, the resulting molded automotive parts are virtually indistinguishable. Proper mold design and finishing ensure a highly repeatable process, although certain factors may still impact it.

Scalability and Cost

Although mold production can be costly, injection molding is highly scalable, and the overall cost decreases as more parts are manufactured. This makes it advantageous for mass production applications. However, for smaller production runs, the tooling costs may limit the cost efficiency of the process.

Material Versatility

Injection molding offers a wide range of compatible materials, including rigid, flexible, and rubber plastics. The automotive industry utilizes various polymers like ABS, polypropylene, acrylic, acetal, nylon, and polycarbonate, enabling manufacturers to meet diverse application requirements.

Precision and Surface Finish

Injection molding is ideal for producing plastic parts with simpler geometries, ensuring high precision and surface finish quality. Manufacturers have the flexibility to incorporate different surface textures directly into the mold, such as glossy, rough, or matte finishes. However, the choice of plastic material can influence the final surface appearance.

Color Customization

Automotive plastic injection molding allows easy color modification to match the vehicle’s color scheme. Unlike other processes, injection molding allows dye mixing with the raw material pellets before manufacturing. This results in consistent and solid coloration without the need for post-molding painting or tinting.

Rapid Prototyping with Rapid Tooling

In addition to mass production, injection molding serves as a valuable tool for automotive prototyping. By utilizing rapid tooling techniques like additive manufacturing or CNC machining to create fast, low-cost aluminum molds, automotive mold manufacturers can quickly produce prototype molded car components. This approach significantly reduces turnaround time compared to traditional steel tooling methods.

Production Applications of Automotive Injection Molding

Injection molding is a widely employed method in the automotive industry for the production of plastic parts. While it is challenging to compile an exhaustive list of all plastic components in a car made using automotive injection molding, let’s explore some significant examples:

Under-the-Hood Components

Over the past couple of decades, manufacturers have transitioned numerous under-the-hood components from metal to plastic. Automotive injection molding is commonly used for manufacturing parts like cylinder head covers and oil pans. Robust polymers such as ABS, Nylon, and PET are often utilized, offering lighter weights and cost advantages compared to metal counterparts.

Exterior Components

Automotive injection molding plays a crucial role in producing various exterior automotive components, including fenders, grilles, bumpers, door panels, floor rails, and light housings. An excellent demonstration of the durability of injection molded parts is seen in splash guards, which protect the vehicle from road debris and minimize splashing. These guards are typically made from rubber or other resilient and flexible materials.

Interior Components

Automotive plastic injection molding is extensively employed in the production of interior components. This includes instrumentation components, interior surfaces, dashboard faceplates, door handles, glove compartments, air vents, and more. Additionally, automotive injection molding is utilized for manufacturing decorative plastic elements found in the car’s interior.

While this list provides an overview, automotive injection molding finds application in numerous other plastic components throughout the automotive industry. Its versatility and ability to produce high-quality parts with precision make it a vital production method for various automotive applications.

Alternatives to Injection Molding for Low-cost Automotive Prototypes

While automotive injection molding is commonly used for producing plastic parts in the automotive industry, there are alternative methods that can be employed, particularly for low-cost prototypes. Here are a few alternatives to consider:

For certain applications, 3D printing can replace molded plastic parts, especially in the prototyping stage where extreme durability or a smooth surface finish is not essential. Moldable plastics can be used as filaments for Fused Deposition Modeling (FDM) 3D printers or as powders for Selective Laser Sintering (SLS) 3D printers, particularly nylons. Some specialized 3D printers can also produce high-strength parts using reinforced composites. 3D printing can be a cost-effective alternative for one-off prototypes, as it eliminates the need for expensive tooling, resulting in lower production costs.

Manufacturers may utilize SLM 3D printing for certain end-use automotive parts, such as fluid handling components like valves. These parts are typically not produced through injection molding. SLM 3D printing employs a laser to selectively melt metal powders, enabling the production of complex and high-quality components.

SLS 3D printing can be utilized to create parts like bumpers, trim, and windbreakers, which are commonly injection molded. SLS uses a laser to sinter powdered materials, such as plastics, into solid objects. It offers design freedom and can be a viable alternative for producing automotive prototypes.

Looking ahead, additive manufacturing techniques may expand to include a wider range of injection auto parts in the near future. This could involve using techniques like Selective Laser Melting (SLM) for doors and body panels, as well as Electron Beam Melting (EBM) for powertrain and drivetrain components.

While injection molding remains the dominant method for mass production of automotive plastic parts, these alternative processes offer flexibility, cost-efficiency, and rapid prototyping capabilities for certain applications in the automotive industry.

Injection Molding Materials for Automotive Parts

When it comes to manufacturing automotive parts through plastic injection molding, selecting the appropriate materials is crucial to meet safety standards and certifications. Here is a non-exhaustive list of common plastics used in automotive injection molding, along with the parts they are commonly used for:

Acrylonitrile butadiene styrene (ABS)

ABS is a durable and weather-resistant plastic widely employed in automotive injection molding and 3D printing. It finds applications in automotive parts such as dashboards and covers.

Polyamide (PA)/ Nylon

Nylon offers good abrasion and chemical resistance, although it is not resistant to liquids. It is often molded into automotive components like bushes and bearings.

Poly(methyl methacrylate) (PMMA)

PMMA, known for its transparency and shatterproof nature, serves as an excellent substitute for glass. Molded PMMA is utilized in automotive parts like headlight covers and internal screens (e.g., SatNav or radio).

Polypropylene (PP)

PP is a popular choice for high-intensity automotive parts, particularly in exterior components, due to its resistance to water, chemicals, and UV light. Bumpers, cable insulation, and battery covers are examples of PP parts.

Polyurethane (PU)

PU is commonly used in flexible and cushioning applications, such as foam seating in cars. It also finds usage in automotive parts like seals and gaskets, insulation panels, and suspension bushings.

Polyvinyl chloride (PVC)

As the third most popular synthetic plastic polymer globally, PVC is utilized in various molded parts within the automotive industry that require excellent chemical resistance. Interior panels, dashboards, and cable insulation are commonly made from PVC.

Reinforced composites

Manufacturers can enhance the strength of plastics by incorporating glass or carbon fiber reinforcements. These reinforced composites are significantly stronger than ordinary resins and are often used in the production of car bodywork and bumpers.

It’s important to note that this list provides a general overview, and there are additional plastics and composite materials used in automotive injection molding depending on specific requirements and applications.

Frequently Asked Questions

What is the best material for automotive injection molding parts?
The choice of material depends on the specific automotive part. However, some widely used plastics for automotive injection molding include PP (seating, body, under the hood), PU (seating, upholstery), and PVC (seating, interior trim, electrical, upholstery). We can provide guidance on selecting the most suitable material for your automotive parts.

Should I use injection molding for automotive prototypes?
The decision depends on the required quantity. If you need a low-cost run of molded parts, manufacturers can create rapid tooling for production. However, for one or two units of a prototype, it may be more practical to use specialized prototyping technologies like additive manufacturing. These methods have fewer upfront costs and are suitable for small-scale production.

What about metal parts?
Injection molding is not compatible with metals. In the automotive industry, metal parts are typically produced using metal casting processes. Manufacturers use metal casting for components such as aluminum transmission housings, pistons, engine blocks, and cylinder heads. Another popular production process for metal parts in the automotive industry is CNC machining.

Sungplastic Automotive Plastic Injection Molding Services

At Sungplastic, we provide skilled injection molding services, supplying customers in the automotive and other industries with mass-produced plastic automobile parts. We offer insert molding, over molding, thermoplastic injection molding, and mold creation. In the latter instance, our professionals collaborate with customers to create superior molds for large-scale production runs or prototyping.

We also work with a broad variety of plastic injection materials, such as flexible, quick-curing thermoplastics; robust, heat-resistant, and rigid thermoplastics; and resilient, high-temperature rubber plastics. With the help of our expert automotive plastic injection molding services, our clients may get high-quality molded car components that satisfy their needs.

You can get in touch with us directly for additional information.

Get a free quote and design analysis today.

We’ll reply to you within 6 working hours.
We respect your privacy.

+86 139 2927 4777 (WhatsApp, Wechat)