Investigation of the effect on surface roughness of the turning of processing hard material by statistical method

Hot machining is applied in order to facilitate the machinability of the hard machining engineering materials. The aim is to heat the workpiece by a heater before removing the chip, thus it is easier to be machined and reduced strength. Cryogenic process is applied to increase the service life through the occurring changes at the inner structure of the material. This process is a method of material cooling under a degree of room temperature. In this study, the experiments were carried out with the cryogenic process appling cutting tools in the combinations of different cutting speed and feed rate. American Iron And Steel Institute (AISI) 4340 alloy steel and Ti6Al4V titanium alloy were determined as materials to be machined. In this study, it is aimed to investigate the effects of the hot turning of the hard machining engineering materials on the surface roughness and cutting tools mechanism. In addition, the effects of the cryogenic and the hot turning processes on the machinability were investigated. It was found that, during the turning of AISI 4340 alloy steel, the surface roughness decreases with increasing spindle speed and decreasing feed rate of cutting tool. Additionally, the surface roughness decreases with increasing pre-heat temperature until the degree of 650 °C. In the process of turning of Ti6Al4V titanium alloy the surface roughness decreases with decresing spindle speed and increasing feed rate of cutting tool. Moreover, the surface roughness decreases with increasing pre-heat temperature until 450 °C. The surface roughness was increased at 650 °C.