Injection Molding for Automotive Applications

May 15, 2019

Injection Molding for Automotive Applications

Injection molding is one of the most commonly used production processes for plastics, as it offers a viable solution for mass producing high quality and consistent parts from a broad range of polymers. In the automotive industry, where consistency, safety and quality are all of the utmost importance, injection molding has become a staple.

In the early days of the automotive industry, cars were made almost entirely of metal, which meant that they were clunky and extremely heavy. As the industry advanced and the plastics market erupted in the 1940s and 50s, automotive manufacturers began to explore the use of polymer parts for vehicle production. In the 1970s, the first cars with plastic decorative elements were rolled out, while more functional parts like plastic headlights, bumpers and fenders were introduced in the 1980s.

In the early 2000s, the first plastic structural components for cars were introduced, which had the advantage of being more lightweight than their metal counterparts, unlocking improved fuel efficiency and cheaper production. Today, injection molding is still one of the dominant production methods for manufacturing plastic parts in the automotive industry because it is well suited to mass production.

Advantages of Injection Molding for Automotive Applications

Injection molding is an established production process in which a molten plastic material is injected into a mold cavity. The melted plastic then cools and hardens and the finished part is removed. Though the mold design process is critical and challenging (a poorly designed mold can result in defects), injection molding itself is a reliable method for producing solid plastic parts with a high quality finish.

  • Repeatability

In the automotive industry, repeatability—or the ability to consistently produce identical parts—is crucial. Because injection molding typically relies on robust metal molds, the final plastic parts produced using the mold are practically identical. There are factors that come into play with injection molding, but if the mold is well designed and made, injection molding is a highly repeatable process.

  • Scale and cost

Though the injection mold-making process is expensive (as well as the cost of the mold), injection molding is a highly scalable process whose overall cost decreases the more parts are made. For mass production applications, injection molding is thus beneficial to the manufacturer. For anything less than mass production, however, injection molding tooling costs may curb the cost efficiency of the process.

  • Material availability

A significant benefit of using injection molding for automotive production is the wide range of rigid, flexible and rubber plastics the process is compatible with. In the automotive industry, a range of different polymers are used for various applications, including ABS, polypropylene, acrylic, acetal, nylon, polycarbonate and more.

  • High precision and surface finish

Injection molding is ideal for producing plastic parts with relatively simple geometries and results in parts with high surface finish quality. Manufacturers have many finish options when producing parts, including various surface textures—such as glossy, rough or matte—which are applied directly to the mold rather than the molded part. Different plastic materials also influence the final surface finish.

Production Applications for Injection Molding in the Automotive Industry

Within the automotive sector, injection molding is one of the predominant methods used for forming plastic parts. Looking at a completed car, it would be difficult to list every single component produced using injection molding, so we’ll take a look at some of the main ones.

  • Under-the-hood

For the past two decades or so, many under the hood components that were once made from metal have been transitioned to plastic. For these applications, robust polymers such as ABS, Nylon and PET are common. Parts such as cylinder head covers and oil pans are produced using injection molding and offer lower weights and costs compared to metal parts.

  • Exterior

Injection molding is an established process for many exterior automotive components, including fenders, grilles, bumpers, door panels, floor rails, light housings and more. Splash guards are a fine example for demonstrating the durability of injection molded parts. The components, which protect the car from road debris and minimize splashing, are often made from rubber or other durable and flexible materials.

  • Interior

Many automotive interior parts are also produced using injection molding. They include instrumentation components, interior surfaces, dashboard faceplates, door handles, glove compartments, air vents and more. Decorative plastic elements can also be produced using injection molding.

RapidDirect Injection Molding Services

At RapidDirect, we offer professional injection molding services, delivering mass produced parts to clients in the automotive and other industries. Our services include thermoplastic injection molding, over molding, insert molding and mold making. In the case of the latter, our experts work with clients to produce high quality molds for prototyping or large production runs.

We also offer a broad range of injection molding materials, including strong, heat resistant and rigid thermoplastics; flexible, fast curing thermoplastics; and durable, high temperature rubber plastics. Our professional finishing services enable our automotive clients to obtain high quality finishes that meet their application requirements.

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