Mr. Shotaro Imai, ADVICS CO.,LTD., JAPAN

Mr. Katsuya Okayama, ADVICS CO.,LTD., JAPAN

Mr. Koji Sugimoto, ADVICS CO.,LTD., JAPAN

Ms. Noriko Matsunaga, ADVICS CO.,LTD., JAPAN

Brake wear debris and its contents have been matters of concern due to their impacts on the human body and the environment, which has led to many studies being done in the brake industry.

In North America, copper is a prime example of brake wear debris impacting the environment when it’s exhausted to the atmosphere. The regulation of copper content in brake pads for new cars has been enacted and has led to the development of copper free friction materials which are used in the market today.

In Europe, micro particles such as PM2.5 and PM10 contained in the brake wear debris, which are also called BPE (brake particle emissions), are considered to affect human health and air pollution. As regulatory activities have accelerated, so has the work towards establishing measuring methods of BPE.

As a brake supplier, fundamental research is necessary for understanding characteristics of BPE and reducing the amount of BPE for each type of friction material. As the first step of the research, BPE characteristics were investigated for various friction materials, such as Low Steel, Non Asbestos Organic, and Cu-Free Non Asbestos Organic. In addition, a hard coated rotor was also prototyped and investigated.

In this study, a brake corner for a compact passenger car was used for testing.

Particulate mass (PM2.5 and PM10) were obtained by a measurement system in accordance with JASO C470 (established in 2020). Also, the CPC (condensation particle counter) device was added to this system in order to measure the particulate number (PN) which was proposed in the WP29/GRPE/PMP/TF2 document.

As a result, there were significant differences in the amount of BPE among the friction materials tested. The results also show good correlation between the amount of BPE and wear mass of the pad and rotor. In addition, it is suggested that PM2.5 account for 9-18% of wear mass, PM10 for 31-43% in this test condition.