A thermal model of drilling a titanium alloy (Ti-6Al-4V) under different cooling techniques

Abstract

The direct injection of coolants and lubricants in the drilling process lowers heat generation in the cutting zone; however, in the absence of a mechanism for positive heat dissipation, the heat from the cutting zone gets continuously accumulated. In this work, we propose novel applications of the following cooling techniques: (i) Ti-Cu as butt joint and (ii) heat sink bottom-channel cooling to improve heat dissipation. The higher thermal conductivity of copper in the Ti-Cu scheme and the flow of coolant in the heat sink in the bottom channel carry away the intense heat generated during drilling. Experiments were also performed using the cooling techniques to monitor thrust, torque, and temperature using an infrared (IR) camera. A numerical model of heat dissipation shows that temperature is reduced by 30% and 38% in heat sink-based cooling and Ti–Cu combinations, respectively, in comparison to dry drilling. The numerical temperature lies within ~1%–6% of the experimental values.