Novel instrumentation for evaluating stone impact wear of automotive paint systems

Abstract Stone impact damage to painted automotive exteriors is an area of significant concern both to the automobile manufacturer and the paint supplier. Damage occurs by stones that are either launched by rear tires of heavy-duty trucks or stones dropped from moving gravel trucks. Stone impact can result in removal of one or more paint layers and in some cases can lead to delamination at the metal–polymer boundary. Removal of paint layers (referred to as chipping) is a cosmetic issue while delamination at the metal–polymer interface can lead to corrosion. Various methods have been described in the literature for rapid assessment of stone impact durability. These methods are associated with one or more drawbacks. These include: (A) being phenomenologically inappropriate; (B) not associated with quantitative metrics; (C) inadequate control of relevant parameters and (D) not being reproducible. This paper describes novel second generation instrumentation for precise and quantitative assessment of impact durability. This device overcomes many of the drawbacks associated with conventional methods. A statistically designed experiment to assess impact durability is also described.