Brake Linings are a combination of Friction Material. Prior to the mid-1970s, the most common friction materials in use for normal duty were termed organics. These friction materials usually contained about 30 – 40 % wt of organic components and were asbestos base. After mid-1970s, the introduction of front wheel drive vehicles brought about the widespread usage of a new class of friction materials called semi-metallics, also called semi-mets and carbon- metallic. Because of the allegedly adverse health effects associated with asbestos fibers, a second new class of friction materials called Non Asbestos Organics (NAOs) came out. In the case of automotive friction materials, the Coefficient of friction is usually found to decrease with increasing unit pressure and sliding speed at a given temperature. For a fixed amount of braking, the amount of wear of automotive friction material tends to remain fairly constant or increase slightly with respect to brake temperature, but once the temperature reaches >200°C , the wear increases exponentially with increasing temperature because of thermal degradation of organic components and other chemical changes.
At MK in Brake Linings, glass fibers, ceramic fibers, acrylic fibers and cellulose fibers are being used in replacement of asbestos as they are more thermally resistant than asbestos.
The methods for producing most friction materials are concerned with the placement of the reinforcement strand or wire within the matrix using some sort of winding operation. Cermet materials are manufactured using the powder metallurgy technique.
The manufactured friction materials are characterized by various chemical, physical and mechanical tests in addition to friction and wear testings.The properties like hardness, specific gravity, strength etc. are measured. The much attention has been placed on noise vibration characteristics. The friction materials are evaluated in the laboratory for a variety of tests.The full brake dynamometer reflects the actual performance of the friction material. Numerous test procedures are followed for the same.
At MK (VB Group), in four wheeler Brake Liners structural integrity of friction material is attended through a blend of mineral fibers, acrylic and glass fibers. This material is ideally suited for brake system in commercial vehicles. This material has excellent heat stability and is gentle on mating surface. It is consistent in performance at variable temperatures having dependable Coefficient Of friction. It has smoother braking and long service life. The testing is carried out in our labs and also on roads on fully instrumented vehicles