Surface Finish Requirements of Spacer Plates for Paper Friction Applications

Paper type friction materials can be used to provide higher dynamic coefficient and better engagement characteristics in wet application, but the softer structure of these products necessitates care for the surface condition of the mating spacer plate if optimum durability is to be obtained. This report covers methods of studying surfaces and relating the observed finish to durability obtained under special dynamometer test conditions. A variety of surface preparations have been investigated including rolled, tumbled, ground, and sanded finishes. Friction material durability was studied as a function of mating plate preparation, roughness, surface profile, and hardness. Relative sensitivity to mating surface of various paper friction formulations is provided. Acknowledging the limitations of the present state-of-the-art, an attempt is made to define spacer requirements for use with these types of friction materials.