Experimental investigations on cryogenic cooling by liquid nitrogen in the end milling of hardened steel

• Published in: Cryogenics (Guildford) 2011-09, Vol.51 (9), p.509-515
• Main Authors: Ravi, S., Pradeep Kumar, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chromium molybdenum vanadium steels; Cooling; Cryogenic cooling; Cryogenics; Cutting temperature; Cutting tools; Cutting wear; Die steels; Drying; End milling; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Hardened tool steel; Hot work tool steels; LN 2 machining; Machining; Refrigerating engineering. Cryogenics. Food conservation; Tool wear
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2011.06.006

► Investigated the machinability of LN 2 cooling on AISI H13 hardened tool steel. ► LN 2 machining provides lower tool wear, surface roughness and cutting forces. ► Better cooling and lubrication effect through reduction in the cutting temperature. ► The reduction in the cutting temperature is substantial at a lower cutting speeds. ► Smaller serrated teeth are produced indicating that lower shearing forces. Milling of hardened steel generates excessive heat during the chip formation process, which increases the temperature of cutting tool and accelerates tool wear. Application of conventional cutting fluid in milling process may not effectively control the heat generation also it has inherent health and environmental problems. To minimize health hazard and environmental problems caused by using conventional cutting fluid, a cryogenic cooling set up is developed to cool tool–chip interface using liquid nitrogen (LN 2). This paper presents results on the effect of LN 2 as a coolant on machinability of hardened AISI H13 tool steel for varying cutting speed in the range of 75–125 m/min during end milling with PVD TiAlN coated carbide inserts at a constant feed rate. The results show that machining with LN 2 lowers cutting temperature, tool flank wear, surface roughness and cutting forces as compared with dry and wet machining. With LN 2 cooling, it has been found that the cutting temperature was reduced by 57–60% and 37–42%; the tool flank wear was reduced by 29–34% and 10–12%; the surface roughness was decreased by 33–40% and 25–29% compared to dry and wet machining. The cutting forces also decreased moderately compared to dry and wet machining. This can be attributed to the fact that LN 2 machining provides better cooling and lubrication through substantial reduction in the cutting zone temperature.