Abstract: The micro-capillary lubrication theory explained lubricant penetration into the tool-chip interface under the action of atmospheric pressure and capillary force without considering the electrokinetic effect caused by triboelectrification. The axial electric field generated by the electrical effect in the cutting contact zone was enough to trigger the electroosmotic flow of cutting fluid. Based on this, the effect of electroosmosis on the penetration mechanism of water-based cutting fluid was explored for the first time, and the effects of electroosmosis additives, capillary materials and axial electric field on the electroosmosis characteristics of cutting fluid were also revealed. The variation of self-excited axial electric field at both ends of capillary in cutting zone was investigated by measuring the emission intensity of charged particles. The results showed that the cutting fluid has electroosmosis effect in the cutting zone, which related to the property of workpiece material and the emission intensity of charged particle. Compared with pure deionized water and electroosmotic suppressant cutting fluid, the cutting force lubricated with electroosmotic promoter cutting fluid was reduced by 31.1% and 44.3% respectively when cutting AISI 304. Moreover, the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses on the tool edges using the above fluids showed a transfer from adhesive wear to micro breakage, which demonstrated that the electroosmosis effect has a positive relationship with the penetration of cutting fluid and the cutting performance. The results presented in this study are of great significance for understanding electroosmosis effect on the lubricant penetration mechanism to perfect the micro-capillary lubrication theory and provide reference for improving the efficiency of cutting fluid.

Key words: electrokinetic effect, electroosmotic flow, charged particle, water-based cutting fluid, cutting performance