Cause of Worm-Tracking of Chrome Plated ABS Bumpers

Dr. Duane Priddy, Plastic Expert Group

The client manufactures chrome plated ABS bumpers for an automotive customer. They periodically experience bumpers with “worm tracking” on them as seen in the figure below. Our experts extensively analyzed a worm tracked bumper comparing areas where the chrome plating adhesion was good and compared areas where adhesion of the chrome plating was bad to identify the root cause of the problem. The results of the testing revealed that the problem was a tooling issue and was not related to the material. We subsequently worked with the client to eliminate the worm tracking problem.