Analysis of the Thermal Impact on Gamma Titanium Aluminide by Grinding with Internal Coolant Supply Based on Experimental Investigation and Transient Thermal Simulation

Gamma titanium aluminide as an intermetallic alloy is considered to be one of the materials which can substitute nickel based super-alloys in high duty applications e.g. in turbines of aircrafts. In this respect the grindability of γ-TiAl alloys is of high importance despite of the restrictions due to the alloy's thermal and metallurgical characteristics. High temperatures in the grinding zone effect the formation of micro cracks during the grinding operation. A more efficient cooling by an internal cooling supply can be seen as a suitable approach to tackle this obstacle. Thus the coolant flow is directly induced into the grinding zone through the abrasive. This kind of lubrication allows the reduction of the flow rate and a more effective cooling of the temperature sensitive materials, respectively. In order to investigate the effects of an internal coolant supply experimental investigations has been performed and the thermal impact on the workpiece has been detected by measurement. A newly designed measuring device based on a thermocouple, which is mounted on a ball screw, enables the automated adjustment in the workpiece according to the actual depth of cut. The results of these investigations are used as boundary conditions for a transient thermal simulation. Based on the finite element model the real grinding zone temperature can be calculated with respect to the influences of the heat transfer rate and the thermal inertia of the thermocouple as well as of the workpiece material