Patent ID: 8236742

Claim:
An oil-feeding type metal working method, comprising processing a metallic material using a metal working oil composition which comprises a base oil selected from the group consisting of natural fats, derivatives thereof and synthetic ester oils; and a phospholid, wherein the metal working is cutting, grinding, component, rolling, or press working and the metallic material is processed while supplying, by a compressed air, water drops covered with the metal working oil composition, wherein the metallic material is selected from the group consisting of cast iron, steel, and stainless steel, and wherein the step of supplying, by the compressed air, water drops covered with the metal working oil composition is generated by feeding 0.5 to 20 mL/hr of the metal working oil composition to a nozzle, feeding 500 to 2000 mL/hr of the water to the nozzle, and feeding 25 to 250 L/min of the air to the nozzle.