Performance of Non Asbestos Disc Brake Friction Material for Automotive Application - An Experimental Case Study

Friction stability and wear resistance are key factors in brake system design and performance. The paper deals with the experimental investigation of friction characteristics and wear of three commercially available NAO (non-asbestos organic) disc brake friction materials viz. Grade A, Grade B and Grade C for a sport utility vehicle. The composites were evaluated for various friction performance properties such as average coefficient of friction, performance at various speeds (8.34 m/s to 38.89 m/s) and pressures (2 MPa to 12 MPa), fade & recovery behavior. These friction and wear characteristics were determined using four wheeler inertia dynamometer. The physical properties such as density, hardness, heat swell, water swell, adhesive bond strength at room temperature and adhesive bond strength at 400°C were studied according to Indian Standards. In addition SEM-EDX (Scanning electron microscope with energy dispersive X-ray) analysis was carried out for finding ingredients and micro structural characterization of brake friction material. Finally the results are discussed and correlated to the observed friction phenomenon. The coefficient of friction was found to be highest for Grade B and lowest for Grade A and wear of Grade A was lower than that of grades B and C. It was observed that the coefficient of friction increases with increase in speed from 8.34 m/s to 22.23 m/s and then it continuously decreases for speed up to 38.89 m/s. The maximum coefficient of friction was observed at a speed of 22.23 m/s for all the grades viz. A, B and C.