UHMW

UHMW (ultra-high molecular weight polyethylene) is a relatively soft, waxy plastic with some interesting properties for robot builders. Other grades of polyethylene have substantially different physical attributes.

UHMW may be a good candidate for many applications where Lexan would be considered.

UHMW is very light, weighing only 75% of what Lexan does.

Its tensile strength and yield strengths are both lower than that of Lexan. However, its impact resistance is literally off the charts. It won't crack under the stress of standard Izod impact testing. UHMW is more prone to deform under stress than Lexan will, but it generally will not crack.

UHMW has certain shape-memory properties. If dented, UHMW may over time return at least partially to its original shape.

It has a fairly low coefficient of friction. That's a fancy way of say it is slippery. It is also extremely resistant to wear. This makes it a popular material for use in food processing applications.

It also seems less prone to being chemically effected by Loctite like Lexan can be.

These properties may make it viable for use as armor, structural elements, or motor mounts in robots of various weight classes.

UHMW is available in various sizes and colors from McMaster Carr.