A Beginner's Guide to Rigid Extrusion Design

(Including UPVC, ABS, PS, PC and Acrylic)

By keeping the profile as simple as possible, you keep both the tooling costs and the price per metre down to a minimum. The following points will hopefully help you towards this aim :-

1. Wherever possible, the profile needs to have an even wall thickness throughout. Large differences in thickness cause problems firstly with the tool design due to the flow of material and then production of the profile itself, which will cool at very different rates depending upon the thickness, causing bowing etc. Satisfactory production may eventually prove to be impossible.
2. It is of course possible to make extrusions with hollows (e.g. tubes), using vacuum calibration as part of the forming process. However, detail inside any hollows should be kept to a minimum as the process makes it very difficult to control any more than short nib type details. If internal detail is required, then the profile would need to be open at some point rather than tubular.
3. Plastic extrusions are often designed to fit with a mating part, maybe an injection moulding or a metal profile. Wherever possible, we will always request samples of such parts at the sampling stage, so that the “fit and function” can be tested. Sometimes drawing changes are discovered at this stage. We would also carry out such trials in a normal production run.
4. Length tolerances are subject to individual agreement depending upon many factors, including the size of profile and the material required. However, on a typical UPVC profile we would offer a length tolerance of + /- 1mm on a 500m length. If tight tolerances are required, then these can sometimes be achieved by cutting off line, with an additional cost. Generally, long bar lengths are cut with a plus tolerance (e.g. 3m + 25mm / - 0). The maximum length for rigid profiles is 6m, but depends upon the profile.
5. Choosing the right clear material for your application can be difficult, with several to choose from. Generally UPVC is the cheapest and is suitable for many applications. If good clarity is required, then the wall thickness should be kept to a minimum in any material. Acrylic, PS and PETG offer good very good clarity, but on the latter, we are restricted to fairly simple profiles. For strength and rigidity, choose polycarbonate. See our materials processed page for more details.

We hope that the above brief details will help you with your design, but please do not hesitate to contact us to discuss your specific requirements.

To enable us to quote accurately, please can you provide the following information wherever possible :-

1. Sketch / drawing or sample
2. Colour required
3. Material required (link to materials page)
4. Quantity required -- sample and bulk order
5. Length(s) required