Effects of cryogenic cooling by liquid nitrogen jet on machinability of steel by coated carbide insert

Abstract

Cryogenic cooling is a promising new technology in high production machining which economically addressed the current process environmental and health concern. High production and finish machining are inherently associated with generation of intense heat and cutting temperature at the cutting zone. Such high cutting temperature not only reduces tool life but also impairs the surface integrity of the job. So the temperat~re at the cutting tool interface is one of the important factors influencing the machining process while primarily dependent on the cutting speed and the work piece material properties as well as cutting tool properties. So, the benefits of cryogenic cooling are dependent on the process parameters and the tool geometry. Beneficial effects of proper cryogenic cooling on machining by uncoated carbide inserts and grinding by conventional wheels in terms of technological benefits and environment friendliness have already been established in number of previous investigations. Substantial cooling and favorable interactions at the chip-tool interface and work-tool interface as well as retention of tools-sharpness were reportedly found to be the main reasons behind these technological benefits of cryogenic machining. The present work deals with experimental investigation in the role of cryogenic cooling by liquid nitrogen jet on cutting temperature, chip formation mode, tool wear, surface finish and dimensional deviation in turning of AISI 8740 steel at industrial speed-feed combination by coated carbide insert which are widely used for high speed turning of plain carbon and low alloy steels.