The recent recall of Ducati and Triumph motorcycles had many automotive mechanics asking, “What is a sintered brake pad?” The story also had a lot of automotive engineers asking, “why are motorcycles using sintered brake pads?”
Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. According to many manufacturers, the process uses much higher temperatures and pressures when compared to the molding and bonding process used for the majority of passenger vehicle brake pads.
The sintering process also requires special ovens that are pressurized. Sintering bonds metallic particles or strands with other high-temperature ingredients. The process requires a lot of exact control of the mixture, temperature, and pressure to ensure the friction material is bonded to the backing plate since most resins or glues are destroyed by the sintering process.
The recent recall from Ducati and Triumph was caused because the sintering process and materials were not properly researched and controlled. This caused the friction material to be too porous and allow moisture to attack the bond to the backing plate.
Sinter brake pads are used for motorcycle and off-highway uses. These pads have excellent high- and low-temperature friction levels. But, they can be noisy. These pads typically have a copper colored backing plate. The sintering process requires a lot of copper to make a brake pad. Some sintered friction materials have up 30% copper by weight.
Motorcycle are exempt from the California and Washington State Better Brake Law that limits the copper and other environmentally damaging ingredients. If the law was applied to motorcycles, sintered brake pads would no longer be used by motorcycle manufacturers or sold by the aftermarket.