Evaluation of Machinability of Cu Matrix Composite Materials by Computer Numerical Control Milling under Cryogenic LN2 and Minimum Quantity Lubrication

This study focuses on the machinability properties of hybrid reinforced (Co-Mo) copper matrix composite materials. For this purpose, surface roughness (Ra), flank wear (Vb), and cutting temperature (Tc) analyses of hybrid composite materials were performed using CNC milling with dry, air, MQL (minimum amount of lubrication) and cryogenic LN2 cooling/lubrication supports. Two different cutting speeds (200-300 m/min) and two different feed rates (0.2-0.3 mm/rev) were used as cutting parameters. Taguchi L16 orthogonal array was chosen in the experimental design. In addition, chip morphologies of composites processed with different cooling/lubricating supports were examined. As a result, it was seen that the most effective factor on Ra, Vb and Tc levels was cooling/lubrication. A4B1C3D2 (reinforcement rate-level 4, cooling conditions-level 1, cutting speed-level: 3, feed rate-level: 2) equations for surface roughness, A3B1C4D2 (reinforcement rate-level 3, cooling conditions-level 1, cutting speed-level: 4, feed rate-level: 2) for flank wear and A3B1C4D2 (reinforcement rate-level 3, cooling conditions-level 1, cutting speed-level: 4, feed rate-level: 2) for cutting temperature were obtained. Compared to dry machining, approximately 88% improvement in surface roughness, approximately 72% improvement in flank wear and approximately 56% improvement in cutting speed was noted. It was determined that the chips obtained during the CNC milling experiments were of the desired type and size. The most suitable chip was cryo-LN2 type.