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 (image) and (image), respectively.