Machining parameters and distortion analyses in end milling of AA2050 and AA7050

The machining of high-strength-low-density materials such as AA2050-T84 and AA7050-T7451 has become one of the most important focuses in the development of the aerospace industry. AA7050-T7451 that shows good fatigue resistance with low cost is one of the materials used in the wing box, skin panels, spars, and other structural parts. However, after the World War II, the low-density requirement is the critical option in choosing materials for the industry. AA2050-T84 is a relatively new alloy, which has high strength and low density. One of the important problems encountered in the machining processes is the distortion of the workpiece. So, to reduce distortion ratio according to the selecting cutting parameters is exclusively crucial. Distortion analyses of AA2050-T84 and AA7050-T7451 are investigated due to the mathematical model with the cutting parameters. Cutting parameters include feed rate, spindle speed, and depth of cuts which directly affect the machining distortion, were studied by using the tap test and the Box-Behnken experimental design method. Spindle speed of 7992.5 rpm and 10,070 rpm, 5 mm axial and 0.5 mm radial depth of cuts, and 0.15 mm/min were found to be the optimum cutting parameters with using a 20 mm diameter, 0.5 mm radius, 2-flutes carbide endmill at 5-axis Mazak milling center. Relying on the found parameters, cutting speed, material removal rate, and spending time were calculated for mass production terminology. According to these calculation parameters, optimum spindle speed, feed rate, and depth of cuts were found. In addition, with these parameters, on the machined parts, geometric dimensioning and tolerance data such as perpendicularity, parallelism, and flatness were examined, and the distortion values of the workpiece were obtained. According to the processes, depth of cuts has little effects; spindle speed and feed rate have the most significant effect on distortion of workpieces. Improvements have been observed on workpieces; thus, this approach is useful in suitable cutting parameters for the machining of AA2050-T84 and AA7050-T7451.