The application of injection molding in the production of automotive parts

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Injection molding is one of the most common production processes for plastics. This is true because it provides a viable solution for the mass production of high-quality injection molded automotive parts from a variety of polymers.

In the automotive industry, where consistency, safety, and quality are critical, automotive plastic injection molding is an important manufacturing process.

Advantages of injection molding for automotive applications

Injection molding is a well-established manufacturing process in which an automotive industry mold maker injects molten plastic material into a mold cavity.The molten plastic then cools and hardens, and the manufacturer extracts the finished product.

Although the mold design process is critical and challenging (poorly designed molds can lead to defects), injection molding itself is a reliable method for producing solid plastic parts with a high-quality finish.

The following are a few reasons why the process is beneficial for the production of automotive plastic components and parts.


In the automotive industry, repeatability – or the ability to consistently produce the same part – is critical. Because automotive plastic injection molding parts typically rely on a robust metal mold, the final molded automotive part produced using that mold is virtually identical.

Certain factors can affect injection molding, but if the mold has good design and finishing, injection molding is a highly repeatable process.

Size and Cost

The injection molding process can be an expensive process due to the cost of the mold. However, it is still a highly scalable process, and as manufacturers make more parts, their total cost decreases. For mass production applications, plastic injection molding is therefore beneficial to the manufacturer.

However, for anything that is not mass-produced, the cost of injection molding may inhibit the cost efficiency of the process.

Material Availability

A significant advantage of using injection molding in automotive industry production is that the process is compatible with a wide range of rigid, flexible, and rubber plastics.

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

Injection molding is ideal for producing plastic parts with relatively simple geometries that achieve high surface finish quality.

Manufacturers have many surface finish options for producing parts, including a variety of surface textures (e.g., glossy, rough, or matte) that are applied directly to the mold rather than to the molded part. However, different plastic materials can also affect the final surface finish.

Color Options

In the automotive industry injection molding, it is easy to modify the color of a molded automotive part to fit the vehicle’s color scheme. Unlike other processes, plastic injection molding allows you to mix dyes with the raw material pellets before manufacturing begins.

This produces a solid, consistent coloring after molding is complete, without the need for painting or tinting.

Rapid Prototyping with Rapid Tooling

While automakers use plastic injection molding extensively to mass produce automotive parts, they also use it as a prototyping tool.

By using rapid tooling to create fast, low-cost aluminum molds – often through additive manufacturing plastic car parts or CNC machining – automotive toolmakers can produce small-volume prototype automotive parts much faster than with traditional (steel) tooling.

Production Applications of Automotive Injection Molding

In the automotive manufacturing sector, injection molding is one of the main methods used by manufacturers to form plastic parts.

However, it is difficult to list the list of plastic parts in automobiles produced using injection molding, so we will take a look at some of the major components.

Under the hood components

Over the past two decades or so, manufacturers have transitioned to plastics for many under-the-hood components that were previously made from metal.

For these applications, strong polymers such as ABS, nylon, and PET are common. However, manufacturers are now using injection molding to make parts such as cylinder head covers and oil pans. This method offers lower weight and cost compared to metal parts.

Exterior Automotive Components

Injection molding is a well-established process for many exterior automotive prototype molded car components, including fenders, grilles, bumpers, door panels, floor rails, light covers, and more.

Splash guards are a good example of the durability of injection molded parts. In addition, plastic car parts that protect the car from road debris and minimize splash are often made of rubber or other durable and pliable materials.

Interior Components

Manufacturers also use automotive plastic injection molding to produce many automotive interior components. They include instrument assemblies, interior surfaces, dashboard panels, door handles, glove boxes, vents, and more. In addition, they use injection molding to produce decorative plastic components.

Low-cost alternatives to injection molding for automotive prototypes

In many cases, molded plastics can be used as an alternative to metal. Previously, manufacturers used metal only to make items such as brackets, trunk lids, seat belt modules, and airbag containers. Today, injection molding is the preferred automotive plastic parts production method for these plastics.

On the other hand, manufacturers can sometimes replace molded plastic parts with 3D printed plastic automotive parts. Although automotive manufacturers widely use injection molding for mass production of auto parts, they also use it as a prototyping tool.

This happens especially in prototyping, where there is less need for extreme durability or smooth surface finishes.Many moldable plastics can be used as FDM 3D printer filaments or as SLS 3D printer powders for nylon. Some specialty and high-temperature 3D printers can also print reinforced composites for high-strength parts.

For one-off prototypes, especially non-mechanical parts, 3D printing may be a cost-effective alternative to molding. With no injection molding tooling costs, production prices are not as high.

In some cases, automotive manufacturers may even use 3D printing for a few end-use automotive parts. They may use SLM 3D printing to make fluid handling plastic structural components such as valves (which are not typically injection molded).

Yet another option is to use SLS 3D printing to make parts such as bumpers, trim, and windbreakers, which are sometimes injection molded.


The characteristics of injection moulding make it an irreplaceable advantage in the production of automotive components.

In the actual process of making automotive parts, the requirements are high whether it is to do with appearance, strength, function and deformation.

It is advisable to find automotive mould manufacturers with relevant industry experience and which have both injection moulding factories and injection moulded product production plants, as automotive-related products need to be debugged in all aspects of performance through several trial moulds after the mould is made to meet the requirements of the project.

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