Application Guide: Friction Brake System ProductsBACKGROUNDBrake systems (disc or drum) work to directly oppose a vehicle’s tendency to move. Friction materials in brake systems include clutch facings, linings, blocks, and disc pads. These are typically made from a mix of fibers, fillers, lubricants, resins and abrasives. Historically, fibers from asbestos were used due to superior reinforcement and heat resistance properties. In recent years, this mineral has been replaced by less hazardous alternatives such as wollastonite, mineral wool and glass fibers.Important goals in friction systems include noise control, improved rotor and drum wear, vibration control, and product life improvement.EXPECTED OBSERVATIONSOverall wear improvement with low noise, low vibration, and acceptable friction stability are achieved when reinforcing fillers are utilized.In some systems, melting of milled glass may be a concern. The suggested replacements are wollastonite or mineral wool or a combination.Selection of appropriate surface treatments can improve wettability and bonding.COMMENTARYFriction material formulations are complex and performance can vary. Each application should be carefully examined and selection should be based on formulation and prototype definition and performance.