Change in Time of the Value of Dry and Lubricated Friction Coefficients for Surfaces Generated by Different Processing Methods

Abstract

The surfaces of the mechanical parts involved in friction processes are made using different processing methods. Each of these processing methods leads to a certain profile of the asperities of the generated surfaces. When such surfaces are subjected to friction processes, it is possible to produce a change in time in the magnitude of the friction coefficient. For experimental research, the outer cylindrical surfaces of some steel test samples were generated using various machining methods such as turning, grinding, ball and diamond burnishing, and vibroburnishing. Later, using a device adapted to a lathe, experimental tests were carried out following the time variation of the value of the friction coefficient under conditions of dry friction and lubricated friction, respectively. The results of the experimental tests were processed mathematically, being determined by empirical mathematical models that highlight the influence of the final processing methods of the surface, the presence of the lubricant, and the test duration on the variation of the friction coefficient. It was found that first, there is an increase over time in the values of the friction coefficient, and then the values of this coefficient stabilize at certain values. The increase in the coefficient of friction until reaching the stabilization value takes place in a proportion of approximately 148–305%.