Modeling and simulation of heat input in deep-hole drilling with twist drills and MQL

Former investigations on deep-hole drilling using twist drills and MQL indicated that the heat input into the workpiece results not only from the primary thermal load within the machining zone but also from the secondary heating at the borehole wall. In order to determine the primary heat flow into the machined part an experimental setup for drilling devoid of the influence of the borehole wall has been developed. The results show that the machining time is the major factor: the lower the machining time the lower the measured temperature within the workpiece. A finite-element-(FE)-based simulation in consideration of the material removal has been implemented and studied, regarding the process, the FE-mesh and the time discretisation. Based on the reliable parameter, obtained by the discretisation study, a simulation control loop is presented which allows the calculation of the rate of heat flow into the machined part. It is remarkable that due to the material removal the heat flow into the workpiece increases when machining with higher cutting speed and feed values, while the measured and simulated temperature decreases. (C) 2013 The Authors. Published by Elsevier B.V.