Hybrid laser and micro milling methods for higher depth microchannel fabrication

The performance of microchannels is dependent on the geometry, dimensions and surface quality. The most widely used methods for manufacturing microchannels are laser micro-milling (LMM), conventional micro-milling (CMM), micro-forming, and chemical etching. The main challenges in manufacturing microchannels with LMM are non-uniform dimensions, tapering effect, and low aspect ratio. In addition to that, tool wear and burrs formation on the top surface of channels are common challenges in conventional micro milling (CMM) techniques. In the present study, Hybrid micro milling techniques have been proposed to manufacture the better quality of micro-channels. The proposed methods include the application of laser and conventional micro milling in two approaches; laser pre-channel micro milling (LPCMM) and laser assisted sequential micro milling (LASMM). In the LPCMM approach, a pre-channel was fabricated by LMM followed by CMM, whereas in LASMM, the material was removed layer by layer by LMM followed by CMM. The proposed methods were compared with CMM considering cutting forces, surface finish, top burrs, tool morphology and flank wear as responses. As compared to CMM, results revealed that the hybrid methodologies mean down burr width decreased by 75 % and 20 %; mean up burr width reduced by 81 % and 20 %; and cutting force decreased by 24 % and 60 % in LASMM and LPCMM, respectively. However, surface roughness (Sa) increased by 7.5 % and 32 % in LASMM and LPCMM, respectively, because of the thermal effect of the laser beam on the fabricated channels.