Performance study of uncoated and AlTiN-coated tungsten carbide tools in micromilling of Ti6Al4V using nano-MQL

Nowadays, micromilling is often employed to fabricate precise and miniaturized complex shapes for biomedical, thermal, and aerospace enterprises. However, it shows very poor machinability for difficult to cut titanium alloys in micromilling. The utilization of CuO nanofluids in a minimal quantity lubrication (MQL) environment with uncoated and AlTiN-coated WC micro-end-mills has been investigated in this study to improve machining performance in the micromilling of Ti6Al4V titanium alloy. Before micromilling operations, tribological tests were performed to determine the friction characteristics of uncoated and AlTiN-coated WC surfaces with Ti6Al4V alloy counterparts at different cutting environments. The highest friction coefficient was observed with an uncoated WC surface in a dry condition. At the same time, 0.25 vol% CuO nanofluids with AlTiN-coated WC samples show minimum friction coefficient and excellent wear track surface. The micromilling experiments at MQL condition were conducted by uncoated and AlTiN-coated WC micro-mill under deionized water and deionized water-based CuO nanofluids at 0.25 vol% and 1 vol% concentration. Due to the low coefficient of friction and better lubrication/cooling, CuO nanofluids and AlTiN-coated micro-tools demonstrate a significant reduction in cutting forces, surface roughness, and top burr height. FFT diagrams illustrate the spindle and tooth-passing frequency amplitude in micromilling, which shows lower amplitude in the nanofluids MQL condition.