Abstract Minimum quantity lubrication (MQL) machining is an advanced near dry cutting technology in modern machining field. However, the cutting oil mist produced during the process of oil-based MQL affected the ambient air quality and endangered the health of employees. To avoid this drawback, a novel lubrication/cooling method called electrostatic minimum quantity lubrication (EMQL) which used SiO2 water-based nano-lubricant as cutting fluid was proposed. The charge mass ratio, surface tension and contact angle of SiO2 water-based nano-lubricant and vegetable oil with different charging voltages were compared, and the penetration performance of these two lubricants was analysed using capillary dynamics equation. The adsorption and deposition properties of oil mist produced by different lubrication methods were investigated, and revealed the adsorption and deposition mechanisms of the charged droplet. The influences of the charging voltage, flow rate, air pressure, spindle speed and cutting depth on PM10 and PM2.5 concentrations under different lubrication conditions were revealed. Finally, the milling performance of SiO2 water-based nano-lubricant EMQL of stainless steels was evaluated comparatively. The results showed that SiO2 water-based nano-lubricant presented better chargeability compared with vegetable oil, and thus displayed stronger penetrability, adsorption and deposition capacity. SiO2 water-based nano-lubricant EMQL with -4 kV showed the lowest oil mist concentration and similar machining performances compared with the vegetable oil MQL, and the concentration values were close to the standards set by the National Institute for Occupational Safety and Health (NOISH). The charged SiO2 water-based nano-lubricant droplets with excellent charging performance presented better adsorbability and penetrability, so that the charged droplets were prone to be electrostatic adsorbed in the machine tool and penetrated into the cutting region, which reduced the oil mist content in the machining environment and presented alternative cutting performance.

中文翻译：

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静电微量润滑-EMQL铣削中SiO2水基纳米润滑剂油雾浓度及加工特性

摘要 微量润滑（MQL）加工是现代机械加工领域一项先进的近干切削技术。然而，油基MQL过程中产生的切削油雾影响了环境空气质量，危及员工的健康。为了避免这个缺点，提出了一种称为静电最小量润滑（EMQL）的新型润滑/冷却方法，该方法使用SiO2水基纳米润滑剂作为切削液。比较了不同充电电压下SiO2水性纳米润滑剂与植物油的荷质比、表面张力和接触角，并利用毛细管动力学方程分析了这两种润滑剂的渗透性能。研究了不同润滑方式产生的油雾的吸附和沉积特性，并揭示了带电液滴的吸附和沉积机制。揭示了不同润滑条件下充电电压、流量、气压、主轴转速和切削深度对PM10和PM2.5浓度的影响。最后，对不锈钢的SiO2水基纳米润滑剂EMQL的铣削性能进行了比较评价。结果表明，与植物油相比，SiO2水基纳米润滑剂表现出更好的带电性，从而表现出更强的渗透性、吸附性和沉积性。与植物油 MQL 相比，-4 kV SiO2 水性纳米润滑剂 EMQL 显示出最低的油雾浓度和相似的加工性能，并且浓度值接近美国国家职业安全与健康研究所（NOISH）制定的标准。带电性能优异的SiO2水基纳米润滑液滴具有更好的吸附性和渗透性，使带电液滴在机床内容易被静电吸附并渗入切削区域，降低了切削液中的油雾含量。加工环境并呈现替代切削性能。