Exploration of Triboprocesses in Reduced-Scale and Full-Scale Disc Brake Performance Test

Brake pad testing has attracted increasing scientific attention in recent years, particularly in focus of the upcoming EURO 7 regulation, which will introduce for the first time limits on PM10 emissions from tires and brakes. This study aims to compare the friction behavior determined using a Pin on Disc setup with that obtained from an inertia dynamometer test setup. For this purpose, a conventional low metallic brake pad material was tested with a ductile cast iron rotor. The test procedure was based on selected sections of the SAE J2522 standard (AK Master). The scaling method applied to the Pin on Disc system, as presented in this study, enables the calculation of deceleration based on the energy per contact area. After the Burnish section, the Pin on Disc setup systematically achieved a higher mean coefficient of friction of approximately 2 to 6% across the Speed/Pressure Sensitivity sections, with a larger offset of about 14% above 160 km/h. Meanwhile, the average coefficient of friction for the dynamometer test generally declined with speed, but on the Pin on Disc setup it only decreased up to 120 km/h. The coefficient of friction in Pin on Disc tests also decreased as pressure increased. SEM and EDX analysis showed the formation of bright primary metallic plateaus and darker, oxidized secondary plateaus. The disc tracks exhibited carbon- and oxygen-enriched tribological layers.