Some investigations in hard turning of AISI 4340 alloy steel in different cutting environments by CBN insert

摘要

Generally, hard turning requires large quantity of coolants and lubricants. In the present study, minimal quantity lubrication (MQL) is used for cooling in turning of hardened alloy steel AISI 4340 (45 HRC) with CBN insert of MT KB 5625 grade. The effect of MQL environment on surface roughness, cutting force components is studied and compared with dry and wet environments. The experiments were conducted using Taguchi L_(18) (2~1 × 3~7) mixed orthogonal array. Analysis of variance (ANOVA) of the experimental results shows that depths of cut and cutting environment have statistically 95% significant effect on the cutting force components. The cutting environment is statistically significant at more than 95% confidence level on the surface roughness value (Ra). The surface finish, Ra value for dry and wet turning were 0.49 μm and 0.47 μm, respectively and whereas in MQL turning it is 0.36 μm. It was also observed that tightly coiled chips were formed and can be handled easily during MQL. The study indicates that MQL technique can be environment friendly and form a viable alternative to conventional wet turning.