Machinability and Surface Quality During Milling CFRP Laminates Under Dry and Supercritical CO2-Based Cryogenic Conditions

Carbon fiber-reinforced polymer (CFRP) composites have been widely used in the aerospace industry due to their excellent mechanical properties. CFRP machining is still a challenging task for manufacturers due to its high temperature-sensitivity and poor machinability. Cryogenic machining is believed to be an effective and eco-friendly way to solve the aforementioned problem. This work primarily compared the machinability and machined surface quality of CFRP laminates under dry and supercritical CO2 (scCO2)-based cryogenic conditions. A series of tests were carried out under different cutting conditions, in which the feed rate, cutting speed, and cooling method were considered. To reveal the material removal mechanisms under different cooling conditions, the tribology and micro-hardness tests were innovatively carried out under different temperatures. The obtained results show that the scCO2-based cooling method is suitable for machining CFRP materials. Under cryogenic cutting conditions, the machined surface quality is considerably improved despite that the cutting force presents higher magnitudes compared to those under dry cutting. The improvement of surface quality under cryogenic cooling method is attributed to avoidance the degradation of material properties caused by high temperatures during dry cutting.