Performance analysis of new external chip breaker for efficient machining of Inconel 718 and optimization of the cutting parameters

Chip control issues are common problems in finishing, semi-finishing, and machining with variable depths of cut in the turning operations of ductile steels and super alloys. Most inserts have chip breaker geometry to control chips in the turning process. However, unbroken chips still cause obstacles for automation and production management in the machining of ductile materials. In this study, a new cutting tool holder with an external chip control system was designed to break continuous chips, and the effect of the holder was examined with respect to the efficient machining of Inconel 718. The efficiency of the developed chip breaking system was investigated relative to different feed rates, machining speeds, and cutting depth by using cementite carbide inserts under dry cutting conditions. The studies were performed based on the Taguchi L-16 design of experiments using a standard tool holder and a newly developed tool holder with a chip breaker. The surface quality, cutting force characteristics, temperature behaviors, and wear mechanisms of the inserts were measured to elucidate the influence of the chip breaking system on the machining process. Excellent chip breakability was achieved with respect to all the examined cutting parameters and chip morphologies. A remarkable improvement in tool wear was observed with the use of the chip breaker system for cutting parameters including a high machining speed, a low feed rate, and cutting depth combinations. Cutting forces and temperatures slightly decreased, and surface quality improved with increases in the cutting speed during external chip breaker-assisted turning of Inconel 718. The results indicated that the regression models of experimental responses were statistically significant.