When most people think of cars and the construction of cars, metal will most likely be the first thing to come to mind. Steel plays a significant role in the creation of virtually every car on the road today, and with good reason: it offers an exceptional strength-to-weight ratio and is incredibly malleable, allowing manufacturers to create reliable, intricate frames. But despite this excellent material, there’s much more to a vehicle than steel.
However, focusing only on the car’s metal frame and what’s under the hood is missing the forest for the trees. What about all the plastic parts you touch? From the moment you reach for the door handle to your interaction with the radio and your eventual exit from the vehicle, you constantly engage with plastic components.
In today’s vehicles, 50% of the entire dry mass of the vehicle may comprise plastics in one form or another. Of the hundreds of plastic components in a car, many are items the driver or passengers interact with directly, which is why these components must be of reliable quality.
Automakers opt to use injection molding for automotive parts, relying on special equipment like moulding plastic machines to fill specially made molds with liquid plastics that harden into the final component. This injection molding for automotive allows them to shape their parts as they see fit, regardless of the shape of the car’s frame.
Here are some of the reasons why this process is beneficial for the production of plastic automotive parts:
In the automotive industry, repeatability – or the ability to consistently produce the same parts – is critical. Because automotive plastic injection moulding machine typically relies on a robust metal mould, the final moulded automotive parts produced from that mould are virtually identical. Certain factors can affect injection moulding, but if the mould is well-designed and finished, injection moulding is a highly repeatable process.
2. Size and cost
Injection moulding can be an expensive process due to the cost of the mould. However, it is a highly scalable process, and the overall cost decreases as the manufacturer produces more parts. For mass production applications, injection moulding is therefore advantageous to the manufacturer. However, for anything that is not mass-produced, the cost of injection moulding can inhibit the cost effectiveness of the process.
3. Material availability
A major advantage of using injection moulding in automotive production is that the process is compatible with a wide range of rigid, flexible and rubberised plastics. Manufacturers use a wide range of different polymers for a variety of automotive applications, including ABS, polypropylene, acrylic, acetal, nylon, polycarbonate and more.
4. High precision and surface finish
Injection moulding is ideal for producing plastic parts with relatively simple geometries, allowing high-quality surface finishes. Manufacturers have a number of surface finish options for producing parts, including a variety of surface textures (e.g. glossy, rough or matte) that are applied directly to the mould rather than moulding the part. However, different plastic materials can also affect the final surface finish.
5. Colour options
With automotive plastic injection moulding machine, it is easy to change the colour of the moulded automotive part to match the colour scheme of the vehicle. Unlike other processes, injection moulding allows colours to be mixed with raw material granules before production begins. This produces a solid, consistent colour when the moulding is complete, without the need for painting or tinting.
6. Rapid prototyping with fast moulds
Although car manufacturers use injection moulding machines extensively for the mass production of car parts, they also use them as a prototyping tool. By using rapid tooling to produce fast, low-cost aluminium moulds – often through additive manufacturing or CNC machining – automotive toolmakers can produce small batches of prototype automotive parts much faster than with conventional (steel) tooling.