Performance evaluation & action mechanism analysis of extreme pressure additives used for oil-based cutting fluids

Although it is unexpected, pure mineral oils or machinery oils are still widely used as cutting fluids in many cases and areas. In this paper, the performance of extreme pressure (EP) additives, including Chlorinated Paraffin, Acid phosphate, and ZnDDP, was evaluated with the index of material removal ability and specimen hardness drop by the use of grinding test method. A micro-structure model of specimen surface layer under wet grinding conditions was proposed, which could be used for explaining the boundary lubrication mechanism of cutting fluids. The characteristic was revealed that organizational structure and shearing strength of specimen surface layer at wet grinding conditions descended along the out normal line direction of the specimen surface. Based on experimental research, high-performance oil-based cutting fluids were developed and tested in several machine-building factories. The fluids one also expected to be applied in the processing of natural rock materials, during which the friction between diamond tools and rock is the main barrier to increase processing efficiency.