Methodology for characterizing brake friction material on high temperatures

The current work aims to describe a methodology to test brake friction materials through a braking tribometer, which is integrated by an electromagnetic induction heater. This technology allows to characterize the isolated effect of load and temperature on friction. Characteristics of the main machines and procedures for testing friction materials are evaluated, paying particular attention with regard to the effect of load and temperature on friction. Experimental methodology consisted of performing brakings under 3 levels of load and 4 levels of temperature. Results from the experiments show that coefficient of friction decreases considerably when temperature is higher than 300°C. It was also observed that the effect of load on friction varies according to the friction material evaluated. About the number of braking applications at each temperature level, it has been verified that at temperatures of 200°C, 300°C and 350°C, three braking are able to characterize the friction behavior. However, when temperature is 100°C, at least 10 brakings are required in order to obtain satisfactory results. The reason for that is due to the bedding-in and also recovery effect of friction, which occurs immediately after to the brake friction material to be subjected to high temperatures (300°C or higher)