The machinability of cast titanium and Ti–6Al–4V

This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti–6Al–4V alloy. Both CP Ti and Ti–6Al–4V were cast into magnesia molds. Two types of specimens (with α-case and without α-case) were made for CP Ti and Ti–6Al–4V. Machinability (n=5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15 000 or 30 000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15 000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co–Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with α-case and without α-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.