Mechanical and Manufacturing Department, Faculty of Engineering, Mondragon Unibertsitatea, 20500, Mondragón, Spain.
Department of Industrial Engineering, School of Engineering, Universidad de los Andes, 111711, Bogotá, Colombia.
Sci Rep. 2021 Oct 25;11(1):20952. doi: 10.1038/s41598-021-00225-6.
Replacement of pollutant fluids with eco-friendly strategies in machining operations significantly contributes to protecting the environment, diminishing global warming, and ensuring a healthier workplace for employees. This study compares cryogenic coolants with conventional coolants in cylindrical plunge grinding using a Cubic Boron Nitride (CBN) wheel. Samples of 27MnCr5 steel used in the manufacture of automotive transmission components were ground using (i) Liquid Nitrogen (LN), (ii) a combination of LN + Minimum Quantity Lubrication (MQL), and (iii) a conventional coolant. The effects of the different cooling methods on the surface integrity of the ground surfaces were examined in terms of surface roughness, microstructural defects, microhardness profiles, and residual stresses. In general, surface roughness was similar for the tested cooling systems, even after grinding three subsequent surfaces in which the process stability was analyzed. Interestingly, the use of eco-friendly cryogenic systems induced fewer microstructural defects than conventional systems, and particularly, LN+MQL lead to more compressive surface residual stresses that would improve the in-service performance of components. These results show opportunities for replacing conventional pollutant systems with eco-friendly cryogenic strategies for refrigerating/lubricating grinding processes to reduce harmful effects on the environment and pose health risks to operators.
用环保策略替代加工操作中的污染液体，对保护环境、减少全球变暖以及确保员工更健康的工作场所有重要意义。本研究比较了在使用立方氮化硼（CBN）砂轮的圆柱形深磨中，低温冷却剂与传统冷却剂的性能。使用（i）液态氮（LN）、（ii）LN+最小量润滑（MQL）的组合和（iii）传统冷却剂对汽车传动部件制造中使用的 27MnCr5 钢样品进行了磨削。从表面粗糙度、微观结构缺陷、显微硬度分布和残余应力等方面考察了不同冷却方法对磨削表面表面完整性的影响。一般来说，即使在分析了工艺稳定性后磨削了三个后续表面，测试的冷却系统的表面粗糙度也相似。有趣的是，使用环保的低温系统会产生比传统系统更少的微观结构缺陷，特别是 LN+MQL 会导致更压应力的表面残余应力，从而提高零件的服役性能。这些结果表明，为了减少对环境的有害影响和对操作人员的健康风险，可以用环保的低温策略替代传统的污染性冷却系统来冷却/润滑磨削过程。
