Abstract: Minimum quantity lubrication (MQL) has been developed for decades as a viable alternative to flood lubrication. However, the surface energy of the micro-droplet produced by pneumatic atomization MQL gradually decreases; the penetration, adsorption and wetting properties of the jet are insufficient, and the drift and splash loss of the droplets are serious, increasing the pollution to the environment. Electrostatic atomization MQL is an effective way to solve the technical bottleneck and environmental pressure faced by industrial production applications. In this review, firstly, a systematic review of the key devices, empowerment principles and green atomization medium (nano-bio-lubricant) of electrostatic atomization MQL are presented. Subsequently, the influence mechanism of the atomization performance of the micro-droplets on the wetting performance of the cutting area is revealed, the excellent atomization performance of the electrostatic atomization is expounded from the perspective of the statics of the charged droplets, and the influence mechanism of different parameters on the atomization performance is analyzed by characterizing the charging performance of the atomization medium. Furtherly, based on the fatty acid molecular structure, viscosity and other physicochemical properties of nano-biolubricants, as well as the surface state of charged droplets, spatial multi-energy field, etc., the mechanism of electrostatic atomization MQL to improve droplet infiltration, wetting and film-forming properties was revealed, and its excellent performance in reducing tool wear and improving the quality of machined surface under turning, milling, grinding and other working conditions is reviewed. On this basis, it is considered that the excellent atomization characteristics of electrostatic atomization and the unique lubrication and heat transfer mechanism of nano-biolubricants can not only reduce the oil mist concentration in the machining environment, but also improve the machining performance of MQL. Specifically, compared with traditional MQL, PM2.5/PM10 is reduced by about 6.2%-68.3%, tool life is increased by about 48.1%-100%, and Ra is reduced by about 12.6%-39.3%. Finally, the future development trend is foreseen in the hope of providing technical support and theoretical reference for the carbon peaking and carbon neutrality transformation of manufacturing industry.

Key words: cutting, grinding, minimum quantity lubrication, nano-biolubricants, electrostatic atomization, sustainable manufacturing