WEAR MECHANISM ANALYSIS OF COATED CARBIDE TOOLS IN HIGH-SPEED MILLING OF TI-6AL-4V ALLOY VIA CROSS-SECTION CHARACTERIZATION OF WORN CUTTING EDGE

摘要

Tool wear analysis is essential in high speed machining, especially in the intermittent cutting and milling processes. Analyses of tool wear mechanisms will be beneficial for proposing the suggestions in the tool design process how to enhance the tool material properties to improve the cutting performance and eventually tool life. Wear mechanisms of coated carbide tools in high-speed dry milling of Ti-6Al-4V were assessed by characterization of the cross-section of worn tool cutting edge utilizing scanning electron microscopy, and the element distribution of the worn tool surface was detected by using energy dispersive spectroscopy. Results show that flank wear, chipping and flaking of tool material on the rake face and/or at the nose of tools were the dominant failure modes. And synergistic interaction among coating delamination, erosion wear, adhesion, dissolution-diffusion wear, and thermal-mechanical fatigue wear were the main wear mechanisms analyzed from cross-sectional worn cutting edge. Erosion wear was identified in high speed milling of Titanium alloy and introduced into the wear mechanisms of metal cutting tools. The hydromechanics characteristic of the chips produced in high-speed machining should be responsible for erosion wear of cuttings tools.