Designing to Improve Plastic Stiffness
There are certain considerations to made when a plastic part needs a specific amount of stiffness. These can be made during the design phase by identifying what each part will be subject to in terms of operating temperature, the level of load and whether this is constant or intermittent,
We’ll be discussing how to add stiffness to your injection moulding parts:
Ribs – Adding ribs to the injection moulding part design will provide a stiffer part and reduce the cycle time and the amount of material required. Rib design guidelines have been developed over many years. To understand the designing further, you can read this article.
V-Grooves – As there name suggests, V-shaped grooves are indentations created within the injection moulding part. The V-Grooves are used when substantial part stiffness is required, although they are not popular as they can result in an irregular and lower surface. It is important to remember that V-Grooves need to be vertical to the bend in order to be successful.
Corrugation – This is a similar technique to V-Grooves. They are typically straight indentations created within the injection moulding part. This has been identified as the best option for achieving stiffness when the part is straight and loaded in the middle.
Material – There are over 85 thousand different types of injection moulding plastic materials. These have been divided into six main categories:
- Polypropylene (PP)
- Acrylonitrile Butadiene Styrene (ABS)
- Polyamide (Nylon)
- High Density Polyethylene (HDPE)
- Polycarbonate (PC)
- ABS + PC Blend (mostly used for electronics enclosures)
Stiffness is the resistance to bending under stress and different materials have different properties and characteristics. Injection moulding stiffness can also be increased by using glass fibres and when designing, material selection is vital to achieve good part stiffness.
For your injection moulding project, our team are happy to help discuss how designing can be utilised to create the best part for your requirements.