Injection moulding is one of the most widely used plastic manufacturing processes in the automotive industry. From interior trim to under-the-bonnet parts and electrical components, you can use it to develop consistently high-quality, complex parts at high production volumes.
But the reality of whether injection moulding is suitable for your automotive part depends on what it needs to do and the production context. This page explains how to determine whether injection moulding is the right choice for your automotive application.
Why injection moulding is widely used in automotive manufacturing
The tight tolerances in the automotive industry demand precision, repeatability and efficiency at scale. In short, that’s why injection moulding is the obvious choice for many applications. It delivers all three by nature. Once your tooling is established, injection moulding produces near-identical parts across thousands, or millions, of units.
Injection moulding also allows for complex geometries that would be difficult to achieve with other processes. For instance, features such as clips, housings and mounting points can be moulded directly into the part. This reduces assembly time and improves the component’s reliability.
What automotive parts are made with injection moulding?
The automotive industry relies on injection moulding for an enormous range of components. You might be surprised just how many parts in a typical car started life as molten plastic being injected into a precision-engineered mould. As you’ll see below, injection moulding covers everything from small precision components to larger structural and exterior parts:
Interior components
Injection moulding is often used for interior components that need detail, consistency and a high-quality finish. Some of the main examples of parts made using injection moulding include dashboard panels, instrument housings, centre consoles, air vents and door trims. They can be as complex as needed, usually including structural features, mounting points, clips and dedicated areas for running or fixing electronics. These components are typically moulded using materials such as ABS, polypropylene, PC/ABS and, occasionally, TPO.
Exterior components
Automotive manufacturers also use injection moulding for a number of exterior components, including bumpers, grilles, mirror housings and wheel arch trims. These must withstand impact, temperature variations and environmental exposure (rain, UV, snow, dust, etc.) while maintaining their shape, function and aesthetics. They must also be lightweight. For this reason, the most common materials used are engineered plastics such as TPO and PC/ABS blends for smaller components.
Under-bonnet components
Plastic components under the bonnet are subject to some of the greatest stresses. Standard injection moulded parts in this area include air intake manifolds, engine covers, fluid reservoirs and battery housings. Because these components must tolerate heat, vibration and exposure to oils and other chemicals over extended periods, manufacturers often use high-performance materials such as nylon, often glass-filled PA66, specifically.
Electrical components
Injection moulding is routinely used to produce electrical components like connector housings, fuse boxes and sensor brackets. The process supports tight tolerances and reliable electrical insulation. Consistency is particularly important here, as even minor deviations may affect an electrical system’s performance and reliability.
Key material considerations for automotive injection moulding
Speaking of performance, material selection is a critical consideration. Here are some of the most common options in the automotive industry:
- ABS resists repeated contact and minor impacts, as well as UV exposure.
- PP offers strong resistance to moisture, road salt and automotive chemicals (coolant, washer fluid, etc).
- PA withstands high temperatures, continuous vibration and exposure to oils and fuels without structurally degrading.
- PC is often blended with ABS. This material is ideal for high impact resistance, temperature fluctuations, UV exposure and, in some cases, optical clarity.
- TPO offers strong impact and weather resistance, as well as flexibility in low temperatures.
- PBT provides excellent dimensional stability, low moisture absorption and reliable electrical insulation.
- POM delivers low friction, high wear resistance and consistent precision under repeated movement.
Of course, there are a wide range of pros and cons to consider for each material in its application that fall outside the immediate scope of this article. Reach out to discuss more about your material options for automotive injection moulding.
When injection moulding may not be suitable
Injection moulding is very adaptable across contexts. However, it’s not always the right solution. For example, if you have very low production volumes or your designs are still evolving, the costs and commitments associated with tooling may outweigh the benefits. Other manufacturing approaches, such as CNC machining, may be more appropriate.
Injection moulding is also less suitable where your parts require very high structural strength or stiffness beyond what standard thermoplastics can provide. In these cases, a more appropriate alternative could be compression moulding. Compression moulding is widely used for fibre-reinforced composite components, such as those made from SMC or BMC. It’s particularly effective for larger, structural automotive parts, including body panels (bonnets, tailgates, etc), structural dashboard backings, underbody shields/undertrays, and commercial vehicle applications.
For most automotive parts, injection moulding is the most appropriate, efficient and cost-effective approach, but not in every case. At Talisman Group, we specialise in both injection and compression moulding. Chat with our team to discuss the most appropriate process for your components.
So, is injection moulding right for your automotive part?
If your project demands plastic manufacturing expertise, you need a reliable automotive moulding specialist. At Talisman Group, we specialise in high-quality plastic component manufacturing for demanding applications. Whether you require precision injection moulding or structural composite solutions through compression moulding, our team can support you from design through to full production.
If you’re developing an automotive part and need clarity on the right process, get in touch with our team to schedule a commitment-free discovery call, where we can discuss your requirements and spec out a quote for your project.