Plastic Injection Molding Applications in the Automotive Industry

automotive parts mass production

Injection molding is a popular manufacturing process for producing plastic parts — it offers a viable solution for the mass production of cost-effective, high-quality plastic parts for the automotive industry. Since quality, safety, and consistency are some of the basic requirements of this industry, it immensely benefits from plastic injection molding.

As one of the leading plastic injection molding companies in China, we discuss the applications of this manufacturing process in this evergreen industry:

A brief history

During the early 2000s, the first plastic structural components for cars were unveiled. Compared to metals, they were cheaper to produce, improved fuel efficiency, and didn’t weigh much. Today, injection molding has become one of the most dominant methods for producing car parts.

With new technological advancements, plastic injection molding continues to evolve. The automotive industry continues to work a greater percentage of plastic injection molded parts into every new round of vehicle designs — and demand isn’t an issue with plastic injection molding because this process can always keep up.

Why do automakers choose injection molding?

Most automakers choose injection molding due to the following reasons:

  • Capable of greater complexity than some other plastic manufacturing methods
  • More cost-effective over high product runs
  • Provides high-durability parts suitable for long-term use
  • Scales easily for mass production

Applications in the automotive industry

In the automotive industry, manufacturers mainly use injection molding to produce plastic parts. The following are some of the most popular applications of plastic injection molding in this industry:

Interior components

To manufacture automotive interior components, manufacturers use automotive plastic injection molding. These components include vents, glove boxes, door handles, dashboard panels, interior surfaces, instrument assemblies, and more. Besides this, decorative plastic components are also built using injection molding.

an automotive water box pipe

Exterior components

Injection molding also helps in the creation of exterior components like light covers, floor rails, door panels, bumpers, grilles, fenders, and more.

One great example of the strength of injection molded parts is splash guards. Plus, plastic car parts that minimize splash and safeguard the car from road debris are usually made of rubber or other pliable, durable material.

Under the hood components

Over the past few years, many manufacturers have transitioned to plastics for a range of under-the-hood components that were originally made from metal.

For applications like these, strong polymers like PET, nylon, and ABS are common. However, manufacturers are now using injection molding to manufacture parts like oil pans and cylinder head covers. Compared to metal parts, this method provides lower cost and weight.

Benefits of plastic injection molding for automotive applications

There’s no doubt that injection molding is a deep-rooted manufacturing process. Here, molten plastic material is injected into a mold cavity. Then the molten plastic cools and solidifies and the finished product is extracted by the manufacturer.

While the mold design process is challenging and crucial (as poorly designed molds may lead to defects), plastic injection molding is itself a dependable method for manufacturing solid plastic parts with a high-quality finish.

Injection molding is perfect for manufacturing plastic parts with relatively simple geometries that accomplish high surface finish quality.

Fortunately, manufacturers have a lot of surface finish options for manufacturing parts, including a range of surface textures (for instance, matte, rough, or glossy) that are directly applied to the mold instead of the molded part. However, certain plastic materials may also affect the final surface finish.

Following are some more reasons why this process is advantageous for the production of automotive plastic parts and components.

automotive air-condition covers made by PTMS

Rapid tooling and prototyping

While car manufacturers use plastic injection molding for mass production of automotive parts, they also use it as a prototyping tool.

The automakers use rapid tooling to produce low-cost, fast aluminum molds — usually through CNC machining or additive manufacturing. Compared to traditional (steel) tooling, toolmakers can produce small-volume prototype automotive parts without consuming a lot of time.

Color options

In the automotive injection molding industry, modifying the color of a molded automotive part to fit the color scheme of the vehicle is easy. Compared to other processes, plastic injection molding enables you to combine the raw material pellets with dyes before the manufacturing even begins.

This leads to consistent, solid coloring after molding is complete, without needing to tint or paint afterward.

Material availability

One of the best benefits of using injection molding in the automotive industry is that this process is compatible with an array of flexible, stiff, and rubber plastics.

Manufacturers use a number of different polymers for various applications in the automotive industry, including polycarbonate, nylon, acetyl, acrylic, polypropylene, ABS, and more.

Cost and size

Due to the mold’s cost, injection molding can be a costly process. However, it’s a scalable process. Plus, as manufacturers make more parts, their total cost declines. For applications that require mass production, there’s no better process than plastic injection molding.

However, for anything that isn’t mass-produced, the injection molding’s cost may inhibit the cost efficiency of the entire process.

an automotive air in-let pipe


Repeatability (or the ability to produce the same part consistently) is crucial in the automotive industry. Since automotive plastic injection molding parts usually depend on a robust metal mold, the molded automotive produced using that mold is virtually identical.

Yes, some factors may affect injection molding. However, if the mold has good finishing and design, you can expect repeatability.

PTMS is your one-stop plastic injection molding company

PTMS is one of the leading injection molding manufacturers in China that offer full services including mold design, plastic injection tooling, plastic injection molding, silicone parts, metal parts, and product assembly. We’ve produced all kinds of top-notch custom plastic parts and metal parts at a reasonable price for different customers around the world.

Contact us now, we’d like to share over two decades of experience in every kind of plastic injection molding mass production with our clients.