Wear Behaviour of PCBN, PCD, Binderless PCBN and Cemented Carbide Cutting Inserts When Machining Ti-6Al-4V in an Oxygen-Free Atmosphere

Abstract

One approach to overcome the difficulties in machining titanium can be the selection of a suitable cutting material. However, influences of the chemical tool wear under machining atmosphere has not been considered jet. In this work the tribochemical wear resistance of uncoated carbide tools, polycrystalline cubic boron nitride (PCBN) tools polycrystalline binderless CBN tools, and polycrystalline diamond (PCD) tools is investigated under different atmospheric conditions cutting Ti-6Al-4V. Air, pure argon and silane-doped argon are used to determine the influence of oxygen contents on tool wear. It was found that oxidation and adhesion behaviour were influenced by oxygen content. Up to 33% increase in tool live were obtained with uncoated carbide- and the PCBN tools with high CBN content. The reduced oxidation also affects PCBN tool behaviour. During machining under oxygen-free conditions increased adhesion of Ti-6Al-4V occurs. The increased wear behaviour for binderless PCBN tools lead to significantly reduced tool life.