Stress Cracking of Wear Strips

A manufacturer of bacon slicing equipment was having environmental stress cracking problems on a polycarbonate wear strip. The existing design had a metal insert pressed into the body of the part, which created stress concentrations. The wear parts cracked when exposed to cleaning chemicals. These chemicals weakened the polycarbonate and caused part failure.

Temperature, concentration, duration, and mechanical load are important factors for the examination of chemical resistance

Curbell worked with the manufacturer to change the part from polycarbonate to PBT, which has superior chemical resistance and environmental stress crack resistance. The manufacturer also changed the threaded metal inserts to a design that created less stress on the part.