There are many different types of plastic available for enclosures. The plastic type and thickness you decide to use will depend on many factors including the design, manufacturing method, budget, and usage.
There are a few aspects you may want to take into consideration when selecting the plastic for your next enclosure project. They include:
Generally, more brittle types with low impact resistance are avoided for enclosures (for example amorphous grades like PS, PSU, SAN) as they tend to lack overall toughness. We find that ABS is a popular choice as it’s highly impact resistant. HIPs are also popular and known for their impact resistance which remains good also in low temperatures.
The effect of temperature on the enclosure
Depending on where and how the enclosure is to be used, temperature may be important when selecting a material. At elevated temperatures plastic tends to have a higher impact resistance (to a limit), but when it is lowered, plastic tend to turn stiffer. As the modulus of the material is increased, some toughness is lost. Amorphous plastics do this gradually but semi-crystalline materials might turn from ductile to brittle very suddenly as the temperature goes below their Tg. Each plastic material has its own characteristics so best check suitability.
Resistance against fatigue also needs to ba taken into consideration. Some plastic products might withstand single shocks well, but fail with repeated impact, even with smaller energy level. Amorphous materials are considered more sensitive to impact fatigue than semi-crystalline, as is the case with normal fatigue.
Reinforcements can be tricky when it comes to impact resistance. Whilst the increased strength from reinforcing plastic is a benefit, high stiffness can reduce toughness.
The geometry can affect impact resistance depending on the material selected. A compromise in material impact resistance does not necessarily mean loss of ductility for your product, however, while even the toughest material fails if the product is not properly designed so do ask advice from your designer.
If you would like to discuss any aspect of plastic enclosure material choices raised in this article please contact us or call us on 01280 845530.