ANALYSIS OF SURFACE ROUGHNESS IN HARD TURNING BY USING TAGUCHI METHOD

Hard turning is defined as the turning of hardened ferrous metals with Rockwell-C hardness ratings ranging from 45 to 70. Hard turning has the potential to reduce production costs by replacing more costly and less agile grinding operations on hard materials especially in finishing processes (Konig et al., 1990). PCBN tools tend to be damaged more severely than conventional cutting tools of mild turning under vibrations because of their relatively brittle property. In addition, the finishing process, which is often involved with hard turning, has a much smaller tolerance of surface precision than other machining processes. This paper is focused on hard turning of 20 MnCr5 Steel. The purpose of this paper is to analyze optimum cutting conditions to get lowest surface roughness in turning of 20 MnCr5 Steel.Taguchi method has been used for this. An orthogonal array, the signal to noise ratio and analysis of variance (ANOVA) are employed toinvestigate the cutting characteristics. The results indicate that feed rate has significant role to play in producing lower surface roughness followed by cutting speed. The cutting insert used is ceramic based TNGA 160404 .