A Study on Relationship Between Disc Thickness Variation and Casting Material Properties

A disc rotor is one of the friction pair in a brake system, but its behavior as friction material is seldom studied. The authors had found that some used discs in the field with large DTV wore locally at the same angular position on both the in-board and out-board friction surfaces. This phenomenon suggests that these discs have non-uniformity in the casting material properties such as the graphite structure and/or matrix. To identify the relationship between local wear and casting material properties, a design of experiment (DOE) is performed. Surrogate discs with non-uniform material properties are intentionally cast and tested on a chip-on-disc type friction tester. Local wear is reproduced and it is found that circumferential non-uniformity in the casting material has some correlation with disc local wear. The local wear depth also depends on the friction materials and gray cast iron grades.