Influence of an Oxygen-Free Atmosphere on Process Forces and Workpiece Quality during the Surface Grinding of Ti-6Al-4V

Abstract

Most manufacturing processes, such as grinding, are usually conducted in a standard air atmosphere. The oxygen within this atmosphere leads to oxidation effects on tools and workpieces when machining metal components. This is primarily a factor in the processing of titanium due to its high affinity for oxygen. The oxidation of the surface increases tool wear and reduces surface quality. Hence, this paper investigates the influence of the atmosphere on process forces and workpiece quality when grinding titanium (Ti6Al4V) with metal-bonded diamond grinding tools. To generate oxygen-free conditions in production processes, a novel approach allows an atmosphere with a very low oxygen partial pressure. Using a silane gas, which reacts with oxygen, the oxygen partial pressure, pO2, can be reduced below 10−12 mbar, equal to the oxygen partial pressure in an extremely high vacuum (XHV). The results show a significant influence of the atmosphere on the process forces. When grinding in XHV-adequate conditions, the grinding forces are reduced by 16% in the tangential direction and 50% in the normal direction on average, while the quality of the ground titanium surfaces is consistent (both atmospheres: Rz = 13–21 µm). Phase analysis via XRD revealed a distinct amount of titanium nitride (TiN) on the ground surfaces independently of the atmospheric conditions.