Machinability Study Using Chip Thickness Ratio on Difficult to Cut Metals by CBN Cutting Tool

Abstract

Machinability is the one of the criteria in determining the life of the cutting tool. In this experiment, hard and difficult to cut materials like hard AISI 440 C stainless steel and hard SCM 440 alloy steels were discussed. However, machinability of the material is considered to be poor due to its inherent characteristics. The machinability studies on AISI 440 C stainless steel and SCM 440 alloy steels had not been carried out by researchers. Machinability indices used in such cases have the characteristics such as cutting force, surface roughness, tool wear etc. In the case of high-speed machining of said materials machinability indices such as chip thickness (RC), shear angle (Ф), surface integrity, and chip analysis are of prime importance. Most of the researchers have not given due consideration to these vital machinability indices necessary for understanding of high-speed cutting of said materials. In this work, an experimental investigation was carried out to understand the behavior of difficult to cut materials, when machined with Cubic Boron Nitride (CBN) insert tool. The results and analysis of this work indicated that the above-mentioned machinability indices are important and necessary to assess the machinability of said materials effectively. The operating parameters used were cutting velocity 100, 125, 150, 175 and 200 m/min with feed rate of 0.10, 0.20 and 0.30 mm rev-1 with constant depth of cut of 1.0 mm. The length of turning was 150 mm and 300 mm. Machinability of both materials and tool was evaluated in terms of roughness, flank wear, cutting force, chip thickness ratio and shear angle.