Investigation of machinability of aluminum-bronze alloys

Aluminum bronze alloys are widely used in industry thanks to their superior mechanical properties such as high strength and wear resistance. Especially in sectors requiring advanced technology such as aviation, space and defense industries, these alloys are frequently preferred. In this study, the machinability properties such as cutting forces, tool wear and surface roughness of Cupral 8 (CuAl14Fe4Mn2Co), a high performance plaster aluminum bronze, during turning operations were investigated. In the experimental studies, 2 different tip types were used. These inserts were named as Type 1 and Type 2. Type 1 refers to standard carbide finishing inserts with WNMG 431-TF code and Type 2 refers to cryogenic heat treated inserts with the same code. As cutting parameters, 5 different cutting speeds (280, 320, 400, 500 and 625 m/min), 3 different feed rates (0.2, 0.25 and 0.3 mm/rev) and constant depth of cut (2 mm) were used. A total of 30 experiments were performed by performing 2 passes of chip removal on the workpiece. In the machinability results, the best tool wear value was 84.19 μm at 400 m/min cutting speed and 0.25 mm/rev feed rate at Type 2 insert. The worst wear value was 360.45 μm at 625 m/min cutting speed and 0.3 mm/rev feed rate at Type 1 insert. The best surface roughness value was 0.59 μm at 400 m/min cutting speed and 0.2 mm/rev feed rate at Type 2 tips, while the worst surface roughness value was 3.28 μm at 400 m/min cutting speed and 0.3 mm/rev feed rate at Type 1 tips. The lowest cutting force was 625.56 N at 400 m/min cutting speed and 0.2 mm/rev feed rate at Type 2 inserts, while the highest cutting speed was 925.74 N at 625 m/min cutting speed and 0.3 mm/rev feed rate at Type 1 inserts. According to the experimental results, the best surface roughness values and the best cutting force values for both types of inserts were obtained from the experiments performed using cutting speeds of 400 m/min and feed rates of 0.2 mm/rev. In general, as the feed rates increased, surface roughness, tool wear and cutting force values also increased. Key Words: Aluminum bronze, CNC turning, Cryogenic heat treatment, Surface roughness, Tool wear, Cutting force