Evaluation of Optimal Economic Life of Cemented Carbide Tool Turning AISI4340

Abstract

As turning operation proceeds on a lathe machine, it is required that sufficiently good surface quality be achieved if all the affecting parameters, including tool geometry are held constant. In this paper, the effect of tool geometry variation due to wear in the case of C6 cemented carbide tool on AISI 4340, was studied. Using surface roughness as yardstick for estimating the point beyond which the maximum economic utilization derivable from the tool is hampered, it was realized that each insert should be replaced after ten minutes of turning operation to retain their optimum usefulness. The tool wear parameters were found to be in linear relationship with the cutting time, while the average surface roughness was modelled nonlinearly using an exponential function. A fourth degree polynomial approximated the trend for the cutting force. Sharp deflections were observed on the surface roughness and cutting force graphs after the tenth minute. Generally for the entire cutting time, the measured cutting force increased by about 33% while the flank wear width and crater wear width increased by 170% and 56% respectively. Surface roughness also increased by about 130%.