Experimental and Statistical Study of Surface Roughness in CNC Slot Milling of AL 7075 Alloy Using Full and Fractional Factorial Design

This work deals with comparing the fractional and full factorial design of experiments on evaluating surface roughness characteristics during slot milling of Al 7075 alloy. Mean surface roughness (Ra) was selected as the response parameter. Cutting variables (cutting speed, feed rate, axial depth of cut) were the input parameters, each having three levels. The input parameters were assigned to an L27 orthogonal array to determine the experiments. Thereby, the L27 OA was split into three L9 sub-arrays where each held the "orthogonality property". Several statistical tools indicate that the fractional factorial approach is just as suitable as the full factorial design of experiments for analyzing machining (milling) results of aluminum alloys.