Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying (NCES) Using Different Types of Vegetable Oils as Base Fluids of External Fluid

Abstract The current study of minimum quantity lubrication (MQL) concentrates on its performance improvement. By contrast with nanofluid MQL and electrostatic atomization (EA), the proposed nanofluid composite electrostatic spraying (NCES) can enhance the performance of MQL more comprehensively. However, it is largely influenced by the base fluid of external fluid. In this paper, the lubrication property and machining performance of NCES with different types of vegetable oils (castor, palm, soybean, rapeseed, and LB2000 oil) as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids. The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances. The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid, NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7% and 7.6%-26.5%, respectively. The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2% and 3.6%-11.2% lower than those for NCES with other vegetable oils as the base fluids of external fluid, respectively. When LB2000/multi-walled carbon nanotube (MWCNT) water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1, NCES showed the best milling performance. This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.