STUDY OF ADVANCED FRICTION MATERIAL FOR THE AUTOMOTIVE INDUSTRY

Manufacturing/casting defects and the corroding nature of grey cast iron require the attention of researchers to search for a better alternative to grey cast iron rotors. The increasing demand and market of electric, hybrid vehicles draw the attention of scientists and car manufacturers to conduct more research to find suitable and sustainable braking material that can overcome the issues related to grey cast iron rotors brakes. A modern alternative for grey cast iron rotors may be 3D-printed stainless steel rotors. The promising future of 3D printing technology has propelled the manufacturing industry into a new era of customized fabrication. Thus, choosing 3D printing technology which can automate the manufacturing of rotors could be a good alternative to address the manufacturing defects related to grey cast iron rotors. Also, with a paradigm shift with regenerative braking, there is a need for a lightweight, non-corroding brake that can replace regular cast iron rotors. The goal of this research is to address the friction performance of the brake system with an NAO commercial pad and laboratory 3D-printed stainless steel brake rotor. The friction testing was conducted using a scaled-down ISO/SAE J2522 procedure on a benchtop friction tester (Brucker UMT) equipped with an environmental chamber controlling temperature. The relative humidity was kept at a constant value of 50%. Scaled-down samples were manufactured from commercially available NAO brake pads with a diameter of 13 mm were rubbed against rotors with a diameter of 90 mm. The friction and wear mechanisms were studied by analyzing the surfaces of tested pads and rotors using scanning electron microscopy in secondary and backscattered electron modes (SEM, Quanta FEG 450 by FEI). The results showed that a more stable and smooth friction layer was formed on stainless steel rotors (Ra=1.2 m). This was responsible for a very stable and high friction level detected in systems with 3D printed rotors (average ~ 0.4 0.1). Wear of the 3D printed rotor was measured after completion of the entire procedure and was extremely low (avg 0.28 g). However, the wear of NAO pad was high (avg 0.9 g). Noise generated during section 4.5 speed/ pressure sensitivity of SAEJ2522 for the stainless-steel rotor was high with a maximum noise level of 108 dBA. A further study of friction performance of 3D printed stainless-steel rotors is recommended to better understand its suitability for its commercial applications