Procedure Improvements for Brake Burnish and Wear Testing

The commercial vehicle industry has seen regulations create new requirements over the last few years. Reductions to stopping distance, improvements to vehicle emissions, and the overall need for lighter weight vehicles has caused the commercial vehicle industry to look for new solutions to meet these needs. One such solution is light-weight aluminum metal matrix composite (MMC) brake drums. Aluminum MMC brake drums create the opportunity to reduce weight, lower brake temperatures, improve brake life cycle, and improve brake performance. During the evaluation of these aluminum MMC components it has been seen that existing procedures do not create accurate comparisons for this new material. Current procedures were designed and implemented for cast iron braking solutions. This paper will outline two procedures; FMVSS121 dynamometer burnishing and SAE J2115 wear performance testing, that do not allow direct comparisons from brake system to brake system to be made. These test procedures utilize initial brake temperatures (IBT) instead of duty cycle to compare performance. This paper will present an alternative procedure that utilizes duty cycle based on cast iron brake components. In other words this duty cycle allows the braking energy to become the controlling feature of the test and allows IBT to become a dependent variable. This duty cycle allows an effective comparison to be made between multiple brake systems. This paper will specifically compare cast iron brakes and aluminum MMC brakes, but comparisons can also be made with commercial vehicle rotor systems. Data will be presented that shows the comparable wear when multiple brake systems are subjected to the same duty cycle.