Performance of alloyed uncoated and CVD-coated carbide tools in dry milling of titanium alloy Ti-6242S

Many researchers believe that alloyed cemented carbide (W–Ti/Ta)C–Co is not suitable for machining of titanium alloys. However, the result of study reported in this paper shows that the alloyed carbide tools, i.e. alloyed uncoated carbide (W–Ti/Ta/Nb)C–Co and alloyed CVD-coated carbide (W–Ti/Ta/Nb)C–Co + (TiC + Ti/CN + /TiN), have good possibility to use in end milling of titanium alloy Ti-6242S even under extreme dry (green) cutting condition. It is probably due to the grain size of tools’ substrate and geometry (off-center ball end mill) and the class of titanium alloy Ti-6242S (α–β). From series of machining trials on the range of cutting speed, Vc between 100 and 125 m/min, fz 0.15–0.20 mm/tooth, aa 2–2.5 mm and ar 8.8 mm using factorial 23 with four center points and three replications, it can be concluded that the best performance of the tools is at Vc of 100–110 m/min, fz 0.15–0.185 mm/tooth and aa 2–2.25 mm where tool life is ranging from T of 5–15 min. Moreover, when those collected data through the trials are analysed using multiple linear regression method, the performance of both alloyed carbide tools can be represented by modified Taylor equations (TVc0.30fz0.89aa0.84=74.851) and (TVc0.28fz0.35aa0.57=156.192), respectively.