The effect of different cooling techniques on machining performance in milling of Ti6Al4V alloy

Titanium and its alloys continue to perform excellently in many technical applications requiring superior in-service performance, such as those in the aerospace, biomedical, and nuclear sectors. This is because of their low weight, high hot strength and hardness, and improved fracture and corrosion resistance. However, the bulk of these alloys are still made using traditional machining methods and are widely known for being difficult-to-machine materials. Because of the high compressive pressures on the cutting edge, their high hot strength and hardness promote plastic deformation of the cutting tool, resulting in premature tool failure. Titanium alloys' exceptionally poor thermal conductivity prevents heat generated during machining from being dispersed, resulting in high localised temperatures that can easily exceed 1000 oC at the tool-chip contact. Coolants/lubricants such as coolants, minimum quantity lubricant (MQL), and cryogen are routinely used to lower this temperature. However, alternative coolants/lubricants are needed because traditional coolers and MQL are not environmentally friendly and have high costs. In this study, a cryogen-assisted hybrid cooling/lubrication system is proposed by using the coolant and MQL at a minimum in the milling process. As a result of the experiment, it was seen that hybrid machining increased tool life by 25%, and direct use of cryogen on surface roughness was not beneficial. Furthermore, hybrid processing was shown to be superior to other approaches in terms of surface quality, burr development, and temperature. As a result; The remarkable improvement in tool life with hybrid cooling/lubrication strategies increases the industrial application possibilities of this cooling/lubrication technique. Keywords: Titanium and alloy, Hybrid machining, Chip Morphology