Coolant and machining device utilizing same

Abstract

A coolant in a state of solution in which a water-soluble substance is dissolved is further included a sodium nitrite as additive by an amount of not less than 0.345 weight % for preventing crevice corrosion from causing particularly to a machining device such as machining center.

What is claimed is:  
     
         1 . A coolant in a state of solution in which a water-soluble substance is dissolved, wherein a sodium nitrite is added as additive by an amount of not less than 0.345 weight % for preventing crevice corrosion from causing.  
     
     
         2 . The coolant according to  claim 1 , wherein said water-soluble substance includes amine and inorganic salt.  
     
     
         3 . A coolant in a state of solution comprising 0.1 MNA 2 CO 3 , 0.01 MNaCl, 2 weight % of coolant solution, and a sodium nitrite added as additive by an amount of not less than 0.345 weight %.  
     
     
         4 . A coolant in a state of solution comprising 0.1 MNA 2 CO 3 , 0.01 MNaCl, 2 weight % of surface active agent, and a sodium nitrite added as additive by an amount of not less than 0.069 weight %.  
     
     
         5 . A machining device, wherein a structural member of the machining device is composed of a material which reacts with a coolant including a sodium nitrite as additive by an amount of not less than 0.345 weight % for preventing crevice corrosion from causing.  
     
     
         6 . The machining device according to  claim 3 , wherein said material constituting the structural member is a carbon steel for constituting the machine structure includes carbon of 0.07 to 0.61 weight %.