Eco-efficiency solutions have been more and more proposed by researcher and industry around the world in latest years in order to become the manufacturing systems cleaner and greener. This action is related to the global warning about the generation of greenhouse gases (GHGs), like CO, as reported by Intergovernmental Panel on Climate Change (IPCC) . One of the most hazardous issue related to environmental risk in machining process is the application of metalworking fluids (MWFs), especially in grinding process in which MWFs are pivotal to control high generation of heat and avoid workpiece surface burns and microstructural changes. The minimum quantity lubrication (MQL) was broadly reported in the literature as a potential alternative lubri-cooling technique to the conventional technique (flood - F). However, the main drawback of MQL grinding is related to high generation of clogging phenomenon produced by the chips lodged on the grinding wheel active surface (GWAS) due to the low oil volume and consequently the low lubricating and cooling action. In order to propose improvements on MQL technique, increase its efficiency and viability and develop a potential greener lubri-cooling technique, this work aims to propose and evaluate the application of hybrid HMQL + WCJ technique combined oil and water at 1:5 oil-water in the AlO grinding process of AISI 4340 steel. This technique was compared to flood F and the pure PMQL + WCJ (pure oil) techniques. Both MQL techniques (hybrid and pure) employed at 30, 60 and 120 mL/h. The PMQL + WCJ technique produced the worst results irrespective of the flow rate. The HMQL + WCJ at 120 mL/h (highest flow rate) presented similar performance to the F technique in terms of surface roughness, microhardness, clogging behavior on GWAS, workpiece form deviation, grinding power, generation of CO during the process and acoustic emission (AE) and outperformance in terms of G ratio. This indicates the eco-efficient potential to be widely employed in manufacturing industry and mitigate the environmental impact and carbon footprint of hybrid MQL + WCJ technique.

中文翻译：

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混合环保MQL+WCJ技术在AISI 4340钢磨削中的应用，实现清洁绿色生产


近年来，世界各地的研究人员和工业界越来越多地提出生态效率解决方案，以使制造系统变得更清洁、更环保。这一行动与政府间气候变化专门委员会 (IPCC) 报告的有关二氧化碳等温室气体 (GHG) 产生的全球警告有关。机械加工过程中与环境风险相关的最危险的问题之一是金属加工液（MWF）的应用，特别是在磨削过程中，MWF对于控制高热量产生并避免工件表面烧伤和微观结构变化至关重要。文献中广泛报道了最小量润滑（MQL）作为传统技术（溢流 - F）的潜在替代润滑冷却技术。然而，MQL 磨削的主要缺点是，由于油量低，润滑和冷却作用低，碎屑滞留在砂轮有效表面 (GWAS) 上，容易产生堵塞现象。为了对 MQL 技术提出改进，提高其效率和可行性，并开发一种潜在的绿色润滑冷却技术，本工作旨在提出并评估油水比为 1:5 的混合 HMQL + WCJ 技术的应用AISI 4340 钢的 Al2O 磨削过程中。该技术与 F 驱和纯 PMQL + WCJ（纯油）技术进行了比较。两种 MQL 技术（混合和纯）均以 30、60 和 120 mL/h 的速度使用。无论流量如何，PMQL + WCJ 技术都会产生最差的结果。 HMQL + WCJ 在 120 mL/h（最高流量）下在表面粗糙度、显微硬度、GWAS 上的堵塞行为、工件形状偏差、磨削功率、加工过程中 CO 的产生和声发射方面表现出与 F 技术类似的性能(AE) 并在 G 比率方面表现出色。这表明混合 MQL + WCJ 技术具有广泛应用于制造业并减轻环境影响和碳足迹的生态效率潜力。