Objective Method for Crack Detection in Brake Friction Material 2019-01-2113

Friction material manufacturing is a complex process where numerous raw materials are mixed, pressed, and cured to make brake pads. It is important to have a consistent manufacturing process that can produce a brake pad that satisfies the vehicle braking requirements. A basic and critical requirement for any brake pad is structural integrity with no internal cracks. In this work a series of processing changes were made to intentionally produce internal cracks in the friction material. Various pad crack detection methods were studied, and their advantages and disadvantages are discussed in detail. One of the crack detection methods used an ultrasonic measuring instrument which gives objective data in the form of calculated modulus of elasticity and signal loss. The details of the machine and how the measurements are obtained are discussed. The modulus calculation is also described. Additionally, random pads with and without cracks were selected and checked using subjective and objective crack detection methods. The comparison analysis is discussed, and authors were able to show the difference between cracked and non-cracked pads using several methods. Conclusions and recommendations are made based on the data from these studies.