Investigation of Cooling Environments in Grinding EN 31 Steel

Abstract

Liquid nitrogen finds increased application as a coolant in various machining processes, due to its effectiveness in controlling the machining temperature and also in being a clean technology. EN31 is a difficult-to-cut material, and Sol-Gel (SG) alumina is a modern grinding wheel with self-sharpening characteristics. In this research, the influence of liquid nitrogen (LN₂) as a cryogenic coolant, and its delivery pressure in terms of grinding forces and surface roughness, were analyzed. The experiment was conducted with conventional Al₂O₃ (aluminium oxide) and SG grinding wheels. The liquid nitrogen coolant was supplied at 3, 4, and 5 bar pressure. The liquid nitrogen produces a reduction of 24% and 16% grinding forces over dry and wet grinding. The surface roughness reduced by a maximum of 43% and 26% over dry and wet grinding. The SG wheel delivers the maximum reduction in the grinding forces and surface roughness, compared to the Al₂O₃ wheel. The experimental results show that the increased delivery pressure of the liquid nitrogen produced a reduction of 4–8% in the grinding forces, and 3–8% in the surface roughness.

Keywords:

• Cryogenics
• Grinding
• Machining
• Steel
• Surface
• Temperature