Fabrication of micro pin fins on inclined V-shaped microchannel walls via laser micromilling

• Published in: Advances in manufacturing Vol. 10; no. 2; pp. 220 - 234
• Main Authors: Deng, Da-Xiang, Zheng, Jian, Chen, Xiao-Long, Pi, Guang, Liu, Yong-Heng
• Format: Journal Article
• Language: English
• Published: Shanghai Shanghai University 2022; Springer Nature B.V
• Subjects: Control; Engineering; Fiber lasers; Heat sinks; Laser ablation; Laser outputs; Lasers; Machines; Manufacturing; Mechatronics; Microchannels; Nanotechnology and Microengineering; Pin fins; Process parameters; Processes; Robotics; Scanning; Micro pin fins; Laser micromilling; Laser ablation; Inclined walls; Microchannels
• ISSN: 2095-3127; 2195-3597
• DOI: 10.1007/s40436-021-00382-x

A laser-micromilling process was developed for fabricating micro pin fins on inclined V-shaped microchannel walls for enhanced microchannel heat sinks. A pulsed nanosecond fiber laser was utilized. The feasibility and mechanism of the formation of micro pin fins on inclined microchannel walls were investigated for a wide range of processing parameters. The effects of the laser output power, scanning speed, and line spacing on the surface morphologies and geometric sizes of the micro-pin fins were comprehensively examined, together with the material removal mechanisms. Micro pin fins with acute cone tips were readily formed on the V-shaped microchannel walls via the piling of recast layers and the downflow of re-solidified materials in the laser-ablation process. The pin-fin height exhibited an increasing trend when the scanning speed increased from 100 mm/s to 300 mm/s, and it decreased continuously when the line spacing increased from 5 μm to 20 μm. The optimal processing parameters for preparing micro pin fins on V-shaped microchannels were found to be a laser output power of 21 W, scanning speed of 100–300 mm/s, and line spacing of 2–5 μm. Moreover, the V-shaped microchannels with micro pin fins induced a 7%–538% boiling heat-transfer enhancement over their counterpart without micro pin fins.