Injection plastic mold 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.
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.
- Color options
When plastic injection molding automotive parts, it is easy to modify colors in order to fit within the color scheme of the vehicle. Unlike other processes, injection molding allows you to mix dyes with the raw material pellets before manufacturing begins. This produces solid, consistent coloration without the need for painting or tinting after the molding is complete.
- Fast prototypes with rapid tooling
Although injection molding is widely used for mass production of auto parts, an automotive plastic parts manufacturer can also use it as a prototyping tool. By creating fast, low-cost aluminum molds with rapid tooling — usually by additive manufacturing or CNC machining — manufacturers can turn around short runs of prototype molded car components much faster than they can with traditional (steel) tooling.