Comparison of the steel machining performance of new and reground cemented carbide drills

Abstract

The purpose of this study is to evaluate the performance of new and reground cemented carbide twist drills considering the variation in the form of regrinding applied to a drill after it reaches its wear limit. The following variables were taken into account: coating material (uncoated, TiAlN and AlCrN) and recoating routine after regrinding (no recoating, recoating over existing coating and recoating after removal of the existing coating). The performance evaluation parameters were tool life, thrust force and torque. The results indicated that the performance of reground drills was generally inferior than that of new drills. Among the coated drills, only TiAlN-coated drills that were stripped (removal of the existing coating), reground and recoated (application of a new TiAlN coating) reached performance values approaching those of new drills. In most of the tests, the uncoated drills produced higher thrust forces and torque, underwent higher wear and had shorter tool lives.