On surface damage of polymer coated sheet metals during forming

Prepaint sheet metals are widely used in building construction, packaging, appliance, transportation and automotive industries. Due to tooling contact, damage of polymer coating can occur during sheet metal forming processes. This paper presents an investigation of surface damage of polyvinylidene flouride (PVDF) and polypropylene (PP) coatings in various forming conditions. Strip drawing experiments were conducted to test coatings subjected to bending under tension with sliding contact. The experimental results and numerical simulations suggest that coating damage is commonly caused by low coating strength, high contact pressure, and poor lubrication. The presented experimental approach can be used to facilitate tooling design and lubricant selection in forming prepaint sheet metals.