The regulation of brake pad particulate in the upcoming Euro 7 standard offers several new challenges to the friction industry. These challenges are being addressed by the industry in many ways. Two of the major approaches are moving towards high performance friction materials and using coated rotors. The high-performance friction material must be compliant not only to Euro 7 but also to high-performance friction standards. On the other side, coating the rotor can lead to lower emissions but can also affect friction performance and NVH (Noise Vibration and Harshness) properties. This means that with a coated rotor the brake pad also needs to be adapted to fit this new paradigm. In this regard, mineral fibres-based NAO brake pads can play a positive role in reducing emissions and improving NVH properties of the rotor-pad couple. The study conducted a series of laboratory tests using a brake dynamometer to study the friction performance, emissions and noise properties of rotor-pad couples. Several non-steel NAO formulations having mineral fibres were used for this investigation. SAE J2521 and SAE J2522 were used to evaluate the friction and noise performance of the system. Furthermore, Krauss wear test was used to evaluate the wear properties. Coated rotors having a commercial coating and cast iron rotors were used in this investigation. Cast iron rotor used as reference since it was the base material used for the coatings. In this investigation, initial work has been done to study the effect of mineral fibres in non-steel NAO. This work presents a new combination of non-steel brake pads and rotor with a commercial coating. These insights can be useful for reducing emissions while maintaining friction performance. This study shows promising results for the rotor pad combination of a coated rotor with non-steel friction material. It shows the capability of mineral fibres to facilitate in improving the emission, NVH and friction properties when used in conjunction with coated rotors. This works highlights the complexity related to the change in the rotor. It shows that brake pad formulations need to adapt for the coated rotors to keep the required friction properties.
Dr. Adnan Sarfraz, Development Manager Automotive, LAPINUS; Ms. Desiré Tegels, Laboratory Engineer, LAPINUS