Effect of Cutting Parameters on Surface Finish, Tool-Chip Interface Temperature and Machining Time in turning of OHNS O1 grade Hardened Tool Steel under Near Dry Machining Condition

The importance of temperature prediction for the machining processes has been well recognized in the machining research due to its effects on tool wear and its constraints on the productivity. It is well observed that particularly the rate of wear is greatly dependent on the tool–chip interface temperature. Most of the heat generated during the machining flows into the tool causing severe thermal stresses on the cutting tool accelerates tool fatigue and failures due to fracture, wear or chipping. Furthermore, if the temperature exceeds the crystal binding limits, the tool rapidly wears due to accelerated loss of bindings between the crystals in the tool material. Heat has critical influence on machining; to some extent, it can increase tool wear and then reduce tool life due to thermal deformation. Near dry machining is the goal of today’s metal cutting industry that tirelessly endeavors to reduce machining costs and impact from chemicals in the environment. In Hard turning, high amount of heat is generated at the tool-chip interface which not only increase the tool wear but also deteriorates the job quality in terms of surface finish. This study deals with turning round bars of 25 mm diameter of Oil Hardening Non-Shrinking Die Steel (OHNS – AISI O1 grade) hardened to 53-57 HRC by TNMG 160404 MT TT5080 insert under Near Dry Machining (NDM) condition. For this purpose MQL set-up was manufactured and machining was carried out at three levels of Cutting Speed (vc), Feed Rate (f), and Depth of cut (ap). To investigate the performance, Surface Roughness (Ra), Tool-chip interface temperature and Machining time (tc) was selected as output responses. Full factorial (3k) DOE was employed and 27 experiments were analyzed by using Response Surface Methodology (RSM) and regression equations were developed. ANOVA was used to find out the significant parameters. Feed rate was found to be the most influential factor in increasing the surface roughness and decreasing machining time, whereas Depth of cut is the most influential factor in increasing the avg tool-chip interface temperature.