Experimental Studies in Deep Hole Drilling of Ti-6Al-4V with Twist Drills

Due to the attractive material properties such as high specific strength and very good corrosion resistance, titanium and its alloys are frequently used in the aerospace, automotive and chemical industries. However, the low thermal conductivity leads to high thermomechanical tool loads during machining, making an optimal cooling lubricant supply to the cutting edge essential. For an optimized design of the tools a realistic simulation is necessary. Since the viscosity of deep hole drilling oils is strongly temperature dependent, it plays a significant role in the comprehensive simulation of the process. In this study the thermomechanical tool loads on TiAlN-coated helical deep hole drills during machining of the titanium alloy Ti-6Al-4V (Grade 5) are investigated and will serve as input for a three-dimensional finite element method (FEM) chip formation simulation focusing on the temperature distribution. The experimental investigations are carried out with successively varying process parameters of cutting speed, feed rate and cooling lubricant pressure. The knowledge gained in this study is of fundamental importance, as it serves as the basis for the future development of a fluid-structure interaction (FSI) simulation in order to be able to take the temperature influence on the cooling lubricant flow into account.