EFFECTS OF CRYOGENIC COOLING BY LIQUID-NITROGEN JET ON FORCES, TEMPERATURE AND SURFACE RESIDUAL-STRESSES IN GRINDING STEELS

Grinding is a widely employed finishing process for different materials such as metals, ceramics, glass, carbides, rocks, etc. to achieve good geometrical (form) and dimensional accuracy with acceptable surface finish and surface integrity. However, it is inherently characterized by high specific energy requirements, unlike other conventional machining processes such as turning, milling, etc., which lead to a high grinding zone temperature and poor surface integrity. Many methods have been investigated to control this high grinding zone temperature, but all have their shortfalls, both technological and environmental, in exchange for controlling the grinding zone temperature. This paper briefly discusses the results obtained with regard to grinding forces, specific energy, grinding zone temperature and surface residual stress when using cryogenic cooling and compares them to the results from dry grinding and grinding with soluble oil. Cryogenic cooling seems to have the edge over other coolants in terms of controlling the temperature, residual stresses and grinding forces, and it is also environment friendly.