Analysis of Chips Geometry and Parametric Optimization using Grey Relational Analysis (GRA) in Hot Turning of AISI 202

Hot turning is a method that assists in metal cutting by applying heat, especially useful for dealing with difficult-to-machine materials. Such challenging materials typically possess unique characteristics, including exceptional strength at high temperatures (referred to as hot strength), low ability to conduct heat, and a tendency to become harder during machining. As a result, machining these materials leads to increased cutting forces, higher specific power consumption, quicker tool wear, and compromised quality of the machined surface. To improve machining efficiency, one can utilize the concept of hot machining, which involves using an external heat source to heat the workpiece before machining. This preheated workpiece becomes softer, improving tool life, surface finish, and power consumption while facilitating the removal of material with less cutting effort and tool wear. To improve surface quality and the material removal rate (MRR), which is always desirable for any machining operation, AISI 202 steel which is widely used in the automotive, aerospace, and electrical machinery industries was subjected to a hot turning process in this research study. The effort focused on maximizing material removal rate and lowering surface roughness utilizing the GRA approach to assess the optimal process environment that may concurrently satisfy both quality and productivity objectives. Special focus was also given to chip geometry. The results indicate that temperature has the greatest influence on not only equivalent chip thickness but also surface roughness and MRR, followed by cutting speed and cutting depth.