Improved tool life in heat-pipe assisted drilling operations

This paper focuses on the feasibility and effectiveness of heat-pipe cooling in drilling operations. The basic idea is to embed a heat-pipe at the center of the tool with the evaporator close to the tool-tip, and the condenser at the end of the tool. Consequently, the heat generated at the tool-chip interface can be removed by convection heat transfer. To achieve this, a combination of numerical analyses and experimental measurements was used under three different cooling conditions, e.g., dry drilling, fluid cooling and heat-pipe cooling. The thermal characteristics of the drills were predicted using a numerical calculation with Fast Finite Element (FFE) plus solvers, whilst flank wear is considered as the criterion for tool failure and the wear was measured using a Hisomet II Toolmaker's microscope. Tool life was also evaluated based on the foregoing tool wear morphology under each condition. The evidences obtained from the experimental study and finite element analyses were compared. The results demonstrate that heat-pipe assisted cooling in drilling processes can effectively perform thermal management comparable to the fluid cooling used pervasively in the manufacturing industry, extending the tool life of the drill.