Wear of Electrical Contacts due to Small-amplitude Motion

Abstract

The "IBM wear model," which has previously been used to describe the wear of electrical contacts as a result of gross sliding motion, is used to describe contact wear in the case of small-amplitude sliding motion. This model was applied to a particular contact configuration on which a series of wear tests was performed. The empiricalresults of the tests are compared to the theoretical expressions and good agreement is found, thus indicatingthat the wear mechanism is essentially the same for both large-and small-amplitude slidingcontact. TheoryThe model used to describe the wear of electrical contacts under gross sliding conditions is known in technical literature as the "IBM wear model" [4][5][6][7]. In this model the wear in a sliding system is governed by one or the other of the following equations:where Q is the maximum cross-sectional area of the wear scar taken in a plane perpendicular to the sliding direction;T max is the maximum shear stress produced during sliding; W is the length of the apparent contact area taken in the direction of sliding; C is a constant dependent for a given system on the materials and lubricants used; and N is a measure of the amount of sliding. Specifically, N is the number of passes of sliding, where a pass is a distance of sliding equal to W.In this formulation of the wear process, the nature of the predominant wear mechanism determines which equation is to be applied to a given system. For a wear process in which the energy going into wear remains constant as wear progresses, Eq. (1) is the appropriate equation. Equation (2) applies to a system in which the