Study on the milling of cobalt-chromium (Co-Cr) alloy produced by wire arc additive manufacturing (WAAM)

Abstract: In recent years, Cobalt-chromium (Co-Cr) alloys have gained popularity especially in dental and orthopedic implants due to their exceptional properties related to bio compatibility. However, they have not been extensively studied. Wire arc additive manufacturing (WAAM) is a promising manufacturing technique, as it can produce parts with mechanical properties similar to wrought or cast materials. But the surface finish from WAAM produced components are questionable. Milling is widely used technique to improve the surface finish of WAAM produced component. Therefore, this work outlines the work carried out to suggest the best possible milling conditions and suitable tool inserts for milling WAAM’ed Co-Cr alloys. The WAAM’ed Co-Cr alloy is prepared by WAAM. The hardness of the alloy is found to be 783.5 HV. CVD coated inserts and PVD coated inserts have been used for machining. A cutting speed of 150 m/min, machining length of 100 mm and radial depth of cut (DoC) of 50 mm is initially set. Due to high hardness of the material the inserts could not machine in the set cutting conditions. Reducing the radial DoC and cutting speed are found to be safe to machine without causing tool damage. A combination of 50 m/min Cutting speed (Vc), 0.05 mm/z feed rate, 0.1 mm axial depth DoC, 5 mm radial depth of cut, and 50 mm machining length is recommended using PVD coated insert to produce better surface roughness (Ra = 0.0514 µm) and reduced tool insert flank wear (0.066 mm).