High performance cold forging oil for stainless steel has been developed to realize the galling prevention property superior to those of present commercial oils and low corrosiveness against ferrous materials. The effect of extreme pressure additives on the galling prevention has been investigated using the tapered plug penetration method. As a result, sample oils containing a Cl-type additive (stearic acid trichloride) and P-type additives (phosphoric acid and oleyl acid phosphate) were found to exhibit an excellent galling prevention property due to the synergistic effect of both types of additives. It was discovered that adding zinc phosphate into the oil suppressed the corrosiveness of the oil without reducing the galling prevention property. The target of the development has been satisfactorily accomplished by the composition of the additives including stearic acid trichloride, phosphoric acid, oleyl acid phosphate and zinc phosphate. The developed oil showed excellent performance in practical cold forging tests. The production line using the developed oil has brought enormous benefits to the cost, productivity and production environment.
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