Friction Modifiers Optimization on Tribological Properties of Non-asbestos Organic (NAO) Brake Pad by DoE-Taguchi Method

Friction modifiers play an important role in modifying the friction performances on the brake pad material. This study aims to determine the optimal friction modifier composition for obtaining a high friction coefficient (CoF) stability and low wear with the Taguchi method. Taguchi's L8 orthogonal array consists of five factors, and two levels were used to design and perform the experiment. The tribological properties (CoF stability and wear) were tested using the JF160 Chase friction tester according to the SAE J661 standard. According to the S/N ratio and ANOVA analysis, the controllable factor of h-BN has a significant effect on CoF stability. While graphite and h-BN have a dominant influence on wear. Contribution of 4 vol.% h-BN, 4 vol.% MoS2, 4 vol.% Al2O3, 2 vol.% graphite, and 3 vol.% SiO2 is an optimal composition to obtain high CoF stability. Meanwhile, the contribution of graphite (8 vol.%), h-BN (2 vol.%), MoS2 (4 vol.%), Al2O3 (2 vol.%), and SiO2 (3 vol.%) can be an optimal composition on lower wear. The predictive value of CoF stability and wear on the optimal level, as made by the Taguchi method, is consistent with the confirmation test within a 95% confidence interval (CI).