Optimisation of machining parameters in high-speed end milling of hardened AISI H13 die steel by integrating RSM and GA

This study explores the potential of high-speed hard-end milling as a cost-effective alternative to the time-consuming grinding process for Chromium-molybdenum steel (AISI H13), widely used in cold and hot work tooling. The research aims to optimize machining parameters for achieving desired surface roughness, comparable to grinding and polishing. Cutting depth (0.4 - 0.8 mm), feed rate (1 - 4 mu m per tooth), and cutting speed (80 - 140 m/min) were varied, and soybean oil replaced conventional lubricants. Employing Titanium Aluminum Nitride (TiAlN) coated end mills (3 mm diameter, 2 mu m coating thickness) and response surface method (RSM) with Design Expert software, the study aimed at reducing tool wear and enhancing surface quality through multi-criteria optimization. Surface roughness analysis led to a streamlined surface by lowering mass flow rate and increasing cutting speed. The optimization approach predicted an optimal surface roughness value of 0.217475 mu m at a cutting speed of 110 m/min, a feed rate of 1 mu m/tooth, and a cut depth of 0.4 mm using genetic algorithm (GA), closely aligned with RSM's ideal value of 0.215 mu m. Both values converge around the 0.4 mm cut thickness.