Experimental and numerical investigation on sustainable machining of Ti6Al4V using micro-pillar texture tools

Abstract

Continuous shearing of the chip under the condition of seizure at the tool-chip interface has been recognized as a significant source of heat input to the tool. This heat negatively affects the tool as it exhibits high plastic deformation of the sharp cutting edge under high compressive stresses, leading to tool wear. To diminish the severity of this condition, it seems necessary to decrease the chip-tool interface contact and enhance cutting fluid penetration and retention into this seizure zone. However, the use of cutting fluids in metal cutting is questioned due to environmental and biological impacts, encouraging the adoption of dry and near-dry machining to minimize these effects. However, dry machining accelerates tool wear, particularly in difficult-to-machine materials like Titanium and Nickel alloys. Approaches, such as rake surface texturing, address this challenge and promote sustainability in metal cutting. This work proposes a novel texture pattern fabricated on the rake face of tungsten carbide inserts using the Reverse micro electrical discharge machining process. A series of machining experiments under dry, compressed air, minimum quantity lubrication, and wet conditions revealed the potential of this micro-pillar textured tool to enhance its cutting performance. The textured tools can restrict the tool-chip contact area by disrupting the chip flow momentum and inducing tighter curling of the chips. Enhanced capillary suction through these developed texture patterns mitigates work material adhesion on the tool's rake face. The reduced heat input to the tool results in prolonged sharpness retention of the cutting edge, which controls flank wear and surface finish of the machined component. A theoretical estimation based on the minimum energy approach established the occurrence of the rate of total work done minima at a higher shear plane angle compared to a plain tool. A CFD-based numerical approach for inverse estimation of the tool tip temperature revealed the capability of textured tools to restrict the tool temperature, especially under dry condition. The same study further determines the effect of micro-pillar size on heat dissipation capability, revealing that smaller diameter, closed-spaced, and higher-depth textures perform better. It is expected that the knowledge gained from this fundamental study will lead to the development of advanced cutting tools.