Electrical Discharge Texturing of Cutting Tools

Abstract

<p>During metal removal operations, friction occurs at the interface between the rake face of the cutting tool and the chip. Tool rake face friction adversely influences the chip formation process and consumes about 25% of the total cutting energy. Friction in cutting can be controlled and reduced by introducing a lubricant into the tool-chip interface, however the effectiveness of this is a function of the cutting speed and uncut chip thickness, among other factors. Lubricant penetration was determined in the 1970's to be a result of capillary action through channels resulting in part from the roughness of the tool rake face and the mating chip face. Recent investigations have looked at increasing the penetration and effectiveness of lubrication by engineering the tool surface to promote and retain lubricants by introducing a texture on the tool rake face.</p> <p>This thesis details methods used for surface engineering the rake face of cutting tools focusing on the novel application of electrical discharge machining (EDM) to obtain the desired texture, with a view to facilitating lubricant penetration and retention. A significant enhancement in machining performance consequent to such tool face texturing is demonstrated. The functionality of such surfaces is discussed as well as the texturing process, application areas and limitations.</p>