Abstract
Aluminum and its alloys are growingly used in various applications including micro-channel heat exchangers and heat sinks to facilitate heat transfer though micro-fluidic flows. Micro-channels with precise control over geometrical features are very important in order to design micro-fluidic flow dynamics and its characteristics. In this research, Nd:YAG laser beam micro-milling has been utilized to produce micro-channels in aluminum alloy (AA 2024) having cross-sectional size of 400 x 200 mu m(2). The objective was to control the material removal rate (MRR) of the process in order to get the micro-channels' geometries (width, depth and taperness of sidewalls) close to the designed geometries. In this context, parametric effects of predominant laser parameters on the process performance have been categorically studied. Quadratic mathematical models have further been developed to estimate the MRR and each geometrical aspect of microchannels over different levels of laser parameters. Additionally, multi-objective optimization has been performed to get an optimized set of laser parameters generating the accurate machining geometries with appropriate material removal per laser scan. Finally, the models and optimization results were validated through confirmatory experimental tests. The results reveal that the precised micro-channel geometries can be obtained through laser beam micro-milling by selecting the appropriate combination of laser parameters (lamp current intensity of 84.48 %, laser pulse frequency of 35.70 kHz and laser scanning speed of 300 mm/s) that can collectively remove a required amount of material thickness per laser scan.