Evaluation of AL ₂ O ₃ , Graphite and Sulphide Effects on MU Behavior in Different Humidity Environments Through Combined Mixture-Environmental DOE

The friction performance of a Disc Brake Pad is even more required to present stable mu behavior in various environmental conditions such as different temperature and humidity. Interaction between compositional variables (raw materials) and environmental conditions cannot be revealed by a simplistic approach without taking into account their mutual interactions. Thereby is necessary a "crossed" design able to combine mixture components with environmental factors. This paper reports the mu behavior of a commercial Brake Pad Formulation in two different environmental conditions (winter condition, e.g., low humidity, and summer condition, e.g., high humidity) through a Combined Design of Experiment. The design was defined by the variation of three mixture components (Al₂O₃, Graphite and Sulfides) of the Brake Pad Formula according to a Response Surface Method (RSM). The μ behavior has been evaluated on a full-scale dynamometric bench test (AK-Master) with climatic control. The DoE output reports the effect of 7 different compositions at 2 levels of humidity and temperature on the friction performance at different speed, pressure and temperature conditions. Moreover a Physical and Chemical characterization of the 7 different composition brake pads has also been reported.