Effects of Milling Methods on Cutting Performance of Wood–Plastic Composites Based on Principal Component Analysis

In the industrial machining of wood–plastic composites, optimization of cutting parameters is key to improving workpiece machinability. To explore the influence of different milling methods of straight-tooth milling, helical milling, and tapered milling on the machinability of wood–plastic composite, a milling experiment was performed. Cutting force, cutting temperature, and surface roughness were selected as evaluative factors. Based on experimental results, principal component analysis was used to analyze the significance of each factor’s contribution and to assess different milling methods of wood–plastic composite for different needs. By calculating the total score from principal component analysis, the optimized cutting mode was determined to be straight-tooth milling, with feed per tooth of 0.2 mm and cutting depth of 0.5 mm. Milling methods in order of decreasing cutting force were helical milling > straight-tooth milling > tapered milling. Milling methods in order of decreasing cutting temperature were helical milling > tapered milling > straight-tooth milling. In terms of the tradeoff between surface quality and processing efficiency, tapered milling is suitable for finishing, considering the machining quality, while helical milling is suitable for roughing, considering the machining efficiency. One of the contributions of this study is to link three separate milling study systems (straight-tooth milling, helical milling, and tapered milling) into one system.