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Designing to Improve Plastic Stiffness

When a plastic part needs a specific amount of stiffness, there are certain considerations that need to be made during the design phase. What the part will be subject to in terms of operating temperature, the level of load, whether this is constant or intermittent and finally the time under load. In this article, we will discuss how to add stiffness to your plastic parts.


How to improve plastic part stiffness



If you are unfamiliar with ribs, please read our previous article which explains what ribs are and how they are used in plastic injection moulding.

Adding ribs to the part design, will provide a stiffer part and reduce the cycle time and the amount of material required. As with many features, rib design guidelines have been developed through years, to understand these further, read this article. 


Rib Forms

Rib forms are used when the part requiring stiffness is to be loaded in different directions.



V-Grooves, as their name suggests are V-shaped indentations created within the part. V-Grooves are used when substantial part stiffness is required, yet not popular as they result in an irregular upper and lower surface. It is important to remember that V-Grooves need to be vertical to the bend in order to be successful.



Corrugation is a similar technique to V-Grooves and are typically straight indentations created within the part. Corrugation is the best option for achieving stiffness when the part is straight and loaded in the middle.


There are over 85 thousand types of injection moulding plastic materials, which are divided into six main categories:

  1. Polypropylene (PP)
  2. Acrylonitrile Butadiene Styrene (ABS)
  3. Polyamide (Nylon)
  4. High Density Polyethylene (HDPE)
  5. Polycarbonate (PC)
  6. ABS + PC Blend (mostly used for electronics enclosures)

 Stiffness, is the resistance to bending under stress and different materials have different properties and characteristics. Stiffness can also be increased by using glass fibres and when designing material selection is crucial to achieve good part stiffness. 

 Contact a member of our team today and discuss how designing to improve stiffness can be achieved for your plastic part.


Get in touch today and talk to the specialists, click here.

Our team will be more than happy to help, advise and quote for your requirements.

Looking for more information? Check out our blog, News & Views for useful articles, tips and tricks on plastic injection moulding.