Enhanced Cutting Performance of Ti6Al4V Microchannels by a Micro Discrete Staggered Edge Milling Tool

Titanium alloy microchannel heat sinks provide an ideal solution for thermal management of high heat-flux devices. Nevertheless, the fabrication of titanium alloy microchannels in common micromilling method by conventional micromilling tools with continuous cutting edges were limited by the large cutting forces, poor surface qualities, and dimensional accuracy. To address the above issues, this work proposed a micro discrete staggered edge milling tool (DSEMT) with a diameter of 0.5 mm for the fabrication of Ti6Al4V microchannels. The continuous right-handed cutting edges of conventional helical micromilling tool (CHMT) were separated into multiple discrete right-handed and left-handed cutting edges for the DSEMT. The left-handed cutting edges of the DSEMT were designed to be of a spoon-shaped cross section with a positive rake angle. This design enhanced their sharpness of the tool and shifted the cutting mode from the traditional plowing process of conventional arc-shaped cutting edges to the shearing process of spoon-shaped ones. Benefiting from the reverse cutting effect of left-handed cutting edges and improved flow of cutting fluid and chip evacuation by the multiple interconnected flow areas, the DSEMT reduced cutting forces by up to 54% and decreased the bottom surface roughness by up to 44% and sidewall surface roughness by up to 50% compared to the CHMT. The burrs in Ti6Al4V microchannels and tool wear were mitigated considerably, and the dimensional accuracy of the microchannels was also improved by the DSEMT.