Laser beam micro-milling (LBMM) of selected aerospace alloys

In micro-machining or micro-manufacturing, the accuracy of micro-feature size is a primary concern. It is possible to realize the exact sizes, but most of the time, undersize or oversize may achieve, especially when micro-machining is carried out by material removal processes based on thermal energies such as laser beam micro-milling (LBMM). This concern becomes more crucial if the objective is to generate an array of micro-features (e.g., micro-notches, micro-grooves, micro-channels, micro-holes, etc.) by laser beam machining. In this research, micro-channels have been fabricated in selected aerospace alloys including titanium alloy (Ti-6Al-4V), aluminum alloy (AA 2024), and nickel-based super alloy (Inconel 718) using Nd:YAG pulsed laser. Response surface methodology (RSM)-based mathematical models are developed for micro-channel sizes produced in each of the alloys in order to predict the corresponding micro-channel sizes in Ti-6Al-4V, AA 2024, and Inconel 718. Furthermore, the models are validated through various experimental confirmatory tests. The results reveal that the estimated errors between experimental micro-channel sizes and the anticipated sizes predicted from mathematical models have acceptable ranges. Finally, the optimized parametric combinations of involved laser parameters are proposed for optimum sizes of micro-channels to be machined in each of the tested material.