Performance evaluation of TiN coated CBN inserts during hard turning of AISI 4340 steel with using Taguchi-Grey-Fuzzy approach

This Hard turning finds a broad range of applications in manufacturing industries. The high wear resistance
along with high dimensional accuracy is the primary attributes of the process. However, the critical setback
associated with hard turning is the high heat generation at the cutting zone. It lead to earlier tool wear rate
and causes the decrease in the machining performance. The cutting tool material plays a significant role in
deciding the performance of hard turning. Therefore in this research work, an attempt has been made to
investigate the performance of TiN coated CBN tools during machining of variable hardened AISI 4340
steel. The cutting speed, feed rate, workpiece hardness and cutting tools (uncoated CBN and TiN coated
CBN) were selected as process parameters during experimentation. The cutting force, chip-tool interface
temperature and material removal rate (MRR) was selected as performance parameters. The L-18 orthogonal
array from Taguchi approach was chosen to perform the experimental work. The grey relational technique
was used to optimize the process parameters. The results from the grey relational model were verified by
using fuzzy logic. The experimental results indicate that tool material and feed rate are the significant
process variables which influence the machining performance.