Friction Characteristics of Textured Surface Created by Electrical Discharge Machining Under Lubrication

Abstract

Whirling Electrical Discharge Texturing (WEDT) was developed as a method of creating microstructures by a single-pulse discharge on the inner surface of a cylinder. In a previous study, a textured surface was successfully created on the inner surface of a cylinder, and it was clarified that the surface characteristics of the textured surface such as the texture-area ratio can be controlled by adjusting the texturing conditions. In this study, a new WEDT device was developed to create microstructures on the surface of a disc workpiece for the ball-on-disc or the pin-on-disc friction test. This paper describes texturing characteristics such as the texture-area ratio, crater depth and crater diameter on a disc workpiece surface and friction characteristics measured by the pin-on-disc friction test. From the results of texturing experiments, it was confirmed that the texture-area ratio can be controlled by adjusting the feed speed of the workpiece, and the diameter and depth of a crater do not depend on the feed speed. In the pin-on-disc friction test, the tip of a pin has a spherical shape with large spherical radius to prevent partial contact. As a result, the friction coefficients under the boundary lubrication condition and the mixed lubrication condition near the boundary lubrication condition were decreased by WEDT. It was confirmed that the textured surface created by WEDT is effective for reducing friction coefficient and an optimal texture-area ratio exists depending on the lubrication conditions.