Milling machinability analysis of GW63K rare-earth magnesium alloys based on the concept of clean cutting

GW63K rare-earth magnesium (Mg-RE) alloys have been widely used in various advanced industries for their excellent mechanical properties. However, the machinability of GW63K alloys under clean cutting conditions still needs to be better understood. The novelty of this paper lies in addressing the influences of varying cutting parameters on the milling responses of GW63K Mg-RE alloys as well as the underlying mechanisms. A full-factorial design of experiments was conducted under dry cutting and minimum quantity lubrication (MQL) conditions. A three-tooth milling cutter with a diameter of 12 mm was used during the investigation. The critical milling outputs involving cutting forces, machining temperatures, and surface quality attributes were carefully analyzed. The results indicate that the cutting force highly depends on the feed per tooth, and the cutting temperature is raised with the increased cutting speed and feed per tooth. The MQL is found capable of reducing the milling temperature by 10.8 °C on average compared with dry cutting. The MQL shows benefits in improving the cutting performances of tools and surface quality of Mg-RE alloys by reducing the tool-workpiece friction coefficient and enhancing the heat dissipation conditions of the chip contact surface. In addition, lower feed per tooth and higher cutting speeds under MQL conditions are suggested for the milling of Mg-RE alloys while ensuring processing efficiency.