Air-induced laser-assisted sequential micro-milling process for precise microchannel fabrication

Laser micromilling suffers from surface oxidation and spatter surrounding the machined zone. However, the micromilling process has drawbacks, including tool wear, high cutting forces, burr formation, and reduced tool life. To address these issues, this study proposes a novel hybrid method for fabricating 100 µm microchannels through an air-induced laser-assisted sequential micromilling (AILASMM) process, comprising laser milling followed by tool-based micromilling. To mitigate cutting forces, compressed air is introduced during laser machining to assist in effective material removal and to promote the formation of an oxidation layer, thereby reducing forces during the subsequent micromilling step. Results demonstrated that AILASMM significantly reduces (15–25%) the magnitude of the cutting forces with respect to conventional micromilling (CMM). In addition to that, the tool wear and burr formation were reduced (15–25%) in the former technique and produced a better surface finish. Milling at an increased feed rate increased the cutting forces. The burr size was also observed to increase (from 37 to 59 µm) as the feed rate increased (from 40 to 60 mm/min). AILASMM at a lower value of the spindle speed (20000 rpm), the surface finish improved to 0.6 µm, and the burr size was reduced to 20 µm. AILASMM produced small and fragmented chips, significantly reducing the tool's adhesion wear.