Optimization of a Non Asbestos Semi Metallic Disc Brake Pad Formulation with Respect to Friction and Wear

A semi metallic friction formulation consisting of Zircosil, barites, Copper fiber, synthetic graphite, NBR (Nitrile Butadiene rubber), steel wool and Alkyl benzene modified phenolic resin with acceptable friction coefficient (μ) and low wear was developed using the Golden Section approach to search the optimal weight fraction of each ingredient in the formulations. The ingredients used in the formulation were divided into three groups: reinforcing fibers, fillers (space and functional type) and the binder resin. The weight fraction of each ingredient in the formulation was calculated by means of Wi = 0.618n in phase 1, Wj=Wi + Wixrm /WF and Wj=Wi + Wixrm/Wf in phase 2 and Wj=Wi + Wixrm/(WF+Wf) in phase 3. After doing 18 formulation experiments that performed using Chase Testing Machine, an optimized formulation (NA -17) with high μ and low wear was obtained. With this base, various formulations has been arrived by adding various commercial ingredients by considering fade and recovery property also and tested by reducing the costly items in the formulation. Finally a formulation is arrived and the tribological performances were tested following IS 2742 standards and compared with an O.E brake pad. It was found that the values of Normal μ, Hot μ and wear of the newly developed brake pad were close to the O.E brake pad.