Novel processing of micro-channels in micro-grinding with automated laser-assistance

Abstract Micro-structures are widely utilized in various fields such as optical, medical, defense, and aerospace. The accuracy and performance of micro-structures depend on fabrication methods, including conventional and non-conventional machining. High-quality micro-channel fabrication is challenging by conventional micro-grinding (CMG) which uses a micro-pencil grinding tool during micro-machining. However, in CMG, high-cutting forces act in the machining zone leading to tool deflection, tool failure, high temperature, and poor surface finish. The challenges of CMG can be overcome by using automated laser-assisted micro-grinding (LAMG), one of the modern micro-machining processes for fabricating high-quality, precise micro-channels. The novel processing of micro-channels in this work is through the in tandem use of LAMG and CMG. In this, the laser structuring is performed using LAMG followed by a micro-pencil grinding tool processing in a sequential manner on a same machine tool to achive high-quality parts and accuracy. This helps in fabrication of a micro-channel directly in one go without the need to remove the part to perform the two operations on two different machining setups, thereby reducing systematic fixturing errors which are significant when we are working at the micro-scale. This paper thus investigates the effect of various parameters viz. laser input energy densities and laser power on cutting forces and surface roughness on the tool as well as the work surface with two distinct scan patterns. In LAMG, at lower laser input energy density (pattern 1), the tangential and normal forces decreased by 10.3% and 20.5%, and surface roughness S a and S q reduced by 24% and 22% compared to CMG. Similarly, a normal force decreased by 20.5% in pattern 1 and 38% less in pattern 2. Still, the higher laser energy density (pattern 2) is unsuitable for structure due to an increase in S a and S q by 11% and 14.6%, respectively. Results have shown a maximum reduction in the normal and tangential force magnitude by 31 and 44% at 25 W compared to CMG. The work concludes that LAMG with novel laser assistance scan patterns has lower dynamic deflections resulting in better dimensional accuracy and surface finish compared to CMG with a lower tool.