Experimental and numerical investigation on heat dissipation capability of micro-pillar textured cutting tools.

Abstract

In metal cutting, the extreme tool temperature restricts the material removal rate. To address this, it is crucial to adopt techniques that reduce heat input and enhance heat dissipation from the cutting tool inserts. Rake surface texturing, particularly with micro-pillars, is gaining popularity in this context. Direct measurement of the cutting tool temperature is exceptionally challenging, so a numerical approach is adopted in this work to inverse estimate the tool tip temperature based on the temperature measured at a distant location from the rake face. Stage I of the work involved the development of a circular micro-pillar array on tungsten carbide inserts using the Reverse Micro Electrical Discharge Machining (RµEDM) technique. Based on the discharge pulses recorded during RµEDM, the 110V-100 nF voltage-capacitance combination proved feasible for this operation. In Stage II, turning operations were performed on Ti6Al4V alloys under dry, compressed air, and wet conditions. The tool temperature measured at the distant location revealed a substantial temperature drop for textured tools. This is attributed to the reduced contact area at the interface, as observed from the rake morphology of the tools, and to the enhanced heat dissipation from the higher surface area of the developed textures, as revealed by the computational fluid dynamics-based numerical study in Stage III of the work. An array of closely spaced, small-diameter, and higher-depth micro-pillars beyond the tool-chip contact area could enhance heat dissipation from the cutting tools.