Optimization of Machining Parameters for Al-Li Alloy to Enhance Surface Smoothness Using the Taguchi Method

Al-Li alloys offer a 20% weight reduction compared to conventional high-strength aluminum alloys, while exhibiting superior wear resistance and damage tolerance. Despite their low density, these alloys demonstrate exceptional yield strength and overall mechanical performance. As a result, Al-Li alloys are poised to become the preferred material for aerospace and defense applications, replacing other materials soon. To enhance applications in advanced manufacturing processes, this research tries to predict and optimize surface hardness and roughness based on several machining factors, such as feed rate, depth of cut, and cutting speed. The Al-Li alloy 2099 (94.309% Al and 5.691% Li) was machined using a Hartford CNC machine, the Omnis VMC 1270. A 16 mm Widia ALUFLASH series 3AN9 flat carbide cutting tool was paired with Sol XL coolant in a 1:20 water solution. The machining parameters included spindle speeds of 3000 to 6000 rpm, feed rates of 150 to 450 mm/min, and cutting depths of 0.1 to 0.2 mm. The study identified optimal machining conditions for Al-Li alloy 2099, achieving surface hardness and roughness improvements under 6000 rpm spindle speed, 150 mm/min feed rate, and 0.1 mm cutting depth. These conditions can help reduce costs and experimental time in aerospace applications. Major Findings: The feed rate most significantly influences surface roughness, followed by depth of cut and spindle speed. Optimal parameters were identified as a spindle speed of 6000 rpm, a feed rate of 150 mm/min, and a depth of cut of 0.1 mm. Increased feed rates adversely impact surface finish. Both feed rate and depth of cut are essential for improving milling efficiency and surface quality.