Carbon-Fiber Reinforced Paper-Based Friction Material: Study on Friction Stability as a Function of Operating Variables

Carbon-fiber-reinforced paper-based friction material (CFRPF), as a new type of wet friction material for automatic transmission, was prepared by a paper-making process. The frictional response of CFRPF is highly complex under a set of dynamically variable operating conditions. To better understand the effect of operating factors (braking pressure, rotating speed, oil temperature, and oil flow rate) on friction stability of the material, tests were carried out using a single ingredient experiment and the Taguchi method. Experimental results show that the braking stability and the dynamic friction coefficient (μd) decrease as braking pressure, rotating speed, oil temperature, and oil flow rate increase. The influence of braking pressure on μd is largest among the four operating factors. μd declines gradually during the first 3000 repeated braking cycles and changes very little subsequently due to the surface topography change in friction material.