Polymers help automotive manufacturers save weight and reduce costs. Readily formed into rigid shapes and complex geometries, they play important roles in the interior, exterior and the engine compartment. Making automotive components takes materials expertise and the right manufacturing processes. C-Plex has both. Here’s a closer look.
Polymers For Automotive Applications
Polymers divide into two groups: thermosets and thermoplastics. The thermosets are rigid and can’t be remelted. They’re used in applications like steering wheels. Thermoplastics on the other hand are flexible, although they can be formed into stiff shapes. They have a wide range of automotive applications.
The polymers we use most for automotive applications are:
- Polyurethane – produced as both a thermoset and a thermoplastic, polyurethane is readily formed into foams and solid shapes
- HDPE and UHMW – these are the high-density and ultra-high-molecular-weight forms of polyethylene with high strength, toughness and wear resistance
- PEEK – Polyether ether ketone is considered an engineering thermoplastic because of its high strength and melting point
- Acrylic – a family of polymers often chosen for their hardness and/or optical clarity
- Nylon – a strong and lightweight thermoplastic often produced as a fiber
- ABS – Acrylonitrile butadiene styrene is an engineering thermoplastic with good toughness and impact resistance
- Polycarbonate – a clear thermoplastic with good impact resistance
- Polyacrylate – a form of synthetic rubber with good high temperature performance
Manufacturing Processes
At C-Plex we carry out vacuum forming, thermoforming and reaction injection molding (RIM). These processes are ideal for producing automotive components in a wide range of shapes, sizes and quantities. We can also machine plastics, both to trim and finish molded parts and to produce complex geometries as one-offs and in small quantities.
Thermoforming and vacuum forming are closely related. Both are used to produce plastic shapes from sheet material.
In thermoforming the sheet is heated and then pressed between two halves of a mold. In vacuum forming there’s only a single mold half and the sheet material is pulled down over it by vacuum.
Hollow forms are possible with these processes. One approach is to bring two halves together after molding, another is to blow air between two sheets clamped inside a mold tool.
A big advantage of thermo and vacuum forming is that the mold tools are far less expensive than those for injection molding. What’s more, it’s possible to produce much bigger parts than is practical by injection molding. (Alternatively, many small parts can be molded from one sheet in a single cycle.)
Thermo and vacuum forming are usually performed on thermoplastics like HDPE, ABS and acrylics.
The RIM process is used for making large plastic shapes in thermoset materials. It entails mixing two polymer components and then pouring or pumping them into a 3-dimensional mold. In this sense it’s a little like injection molding but with less expensive tooling, (because the pressures are much lower,) and the ability to make very large shapes.
Automotive Applications of Polymers
Vehicle manufacturers strive to maximize the amount of plastic used in every car, truck and SUV because it reduces weight. Unless there’s a need for high strength, high temperature resistance or optical clarity it’s very likely an automotive component will be made from one of the polymers discussed above.
Another major benefit of plastic molding is that it helps reduce piece count. Molding a part as a single piece rather than assembling it from smaller components saves time and money and improves quality by eliminating tolerance stack up issues.
External uses of polymers on vehicles include:
- Wheel covers
- Mud flaps
- Bed liners
- Headlamp covers
- Grilles
- Surround trim pieces
In addition, a growing number of body panels are being produced as single piece moldings rather than by using metal or joining smaller parts. Front and rear bumpers are prime examples.
Inside the vehicle polymers are everywhere. Applications range from seat cushions (poylurethane foam) to tray liners, door panels, glove box doors and inners and even the steering wheel.
Underhood applications present some particular challenges. High temperatures and potentially corrosive liquids are the biggest. However, lower thermal conductivity gives polymers an additional advantage over metals in some situations. Polymer applications in this part of the vehicle include:
- Fluid reservoirs
- Valve covers
- Intake ducting
- Battery housings
- Fuse boxes
Producing Automotive Components in Polymer Materials
Without extensive use of polymers, modern vehicles would be far heavier than they are now, and probably a lot more expensive. C-Plex uses thermo and vacuum forming processes as well as RIM to produce large and small parts for automotive and other customers. Our formal quality management system ensures high levels of consistency, whether the need is for prototype quantities or high volume production. Contact us to learn how we can meet the needs of automotive customers.
