A challenging study on compatibility or incompatibility of vegetable-based lubricant with human health

It has been estimated that over 85% of the cutting fluid used in machining industries is mineral-based which are potentially carcinogenic that over 70% of cutting fluid waste releases to the nature without any purification process. Knowing environmental concerns and increasing regulations over pollution, the request to use risk-free lubricant is irrefutable. Recently, many scholars recommended vegetable-based cutting fluid (VBCF) for replacing with mineral-based one (MBCF). The present work has tried to study the compatibility or incompatibility of VBCF with human health and provide a method for eliminating or reducing their potential risks. To achieve this goal, a study on one of the most known, destructive, and accessible microbes (Pseudomonas) in the workshop environment was performed. The results showed that Pseudomonas could multiply in solid and liquid mediums, and its colonies could quickly propagate in VBCF. Therefore, as a significant achievement in this study, unreinforced VBCF is not a suitable selection from a health point of view. Although these cutting fluids are introduced as a compatible lubricant with humans and the environment, bacteria and mold can multiply swiftly without apparent alterations. It was also observed that using nanoparticles like copper oxide (CuO) with a specific volume fraction (0.4%) could fight with the biofilm of Pseudomonas to destroy the colonies at the initial time of their formation, while silicon-oxide nanoparticles had no effect on control of microbial growth. Therefore, CuO-nanoparticles present antibacterial characteristics when they interact with microbes. As a result, CuO-nanoparticles are the good choice for replacing with harmful additive like formaldehyde biocides in MBCF. Scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX) analysis also studied the machinability attributes. The machining tests indicated that the VBCF reinforced with 0.4 wt% of CuO-nanoparticles also greatly impacts the control of tool wear mechanisms, especially products of adhesion wear like built-up edge and built-up layer, and surface quality compared to the conventional cutting fluid during the A286 superalloy machining.