Machinability Study on Finish Turning of AISI H13 Hot Working Die Tool Steel With Cubic Boron Nitride (CBN) Cutting Tool Inserts Using Response Surface Methodology (RSM)

Finish turning of hardened die tool steel offers an economical alternative to grinding process. This study investigated the effects of machining parameters including workpiece hardness in a range of 45-55 HRC on cutting forces (F (c) & F (t) ), surface roughness (R (a) ) and cutting edge temperature (T) in finish turning of AISIH13 die tool steel with CBN inserts. Workpiece material AISIH13 has been selected on the basis of its wide applications in die making industries in the range of hardness 45-60 HRC. A central composite design has been used for the design of experimentation, and by using response surface methodology, a mathematical model has been developed. This study reported that the cutting forces are primarily influenced by the hardness of workpiece material. The work material hardness, feed rate and depth of cut are also statistically significant on cutting forces. Also, cutting forces increases, with the increase in workpiece hardness, feed and depth of cut, whereas the cutting speed has least impact on cutting forces. In fact, increase in hardness of work material resulted in better surface roughness as well as increase in tool tip temperature. Furthermore, optimum parameters are obtained through multi-response optimization technique using desirability function approach. The novelty aspect of the present study is that it contributes to practical industrial application of finish turning for the die and mold makers to select the optimum cutting conditions in a range of hardness of 45-55 HRC.