Experimental investigation of various machining attributes and cost estimation during machining of hardened AISI 4340 steel with untreated and cryo treated cermet inserts

Now-a-days due to growing demand of high precision components to attain high performances, hardened steels with hardness above 45HRC have numerous applications in automotive gear, machine tool and die industry because of their superior characteristics (high thermal stability, high indentation resistance, high abrasiveness, low ductility and high value of hardness to modulus of elasticity ratio). For this, higher tool life of cutting inserts cryogenic treatment is considered as the most prominent method but no substantial researches have been found concerning the impact of cryogenic treatment on cermet inserts, especially in turning of hardened steels. Therefore, in the present experimental investigation, the comparative assessment of various responses such as cutting force, flank wear, crater wear, chip morphology and surface roughness were carried out during machining of hardened steel with both untreated and cryo-treated cermet inserts under dry cutting condition. Lastly, the input variables were optimized using Response Surface Methodology (RSM) to evaluate the tool life for the economic analysis. The experimental result demonstrated that the uncoated deep cryo-treated with tempered cermet insert delivered better results in comparison to other cermet inserts. According to cost analysis, uncoated and deep cryo-treated with tempered cermet insert was found to be the most cost saving among other cermet inserts at the optimum cutting condition.