The performance and oxidation stability of sustainable metalworking fluid derived from vegetable extracts

Throughout the world, the production, application, and disposal of metalworking fluid (MWF) must adhere to the requirements of nature and the environment. Plant-derived oils have been researched as the alternative to mineral-based cutting fluids as they are deemed to be more environmentally friendly and sustainable. This paper investigates different vegetable- and plant-derived oils in their pure state, as blends or as commercially available products within the industry, and measures their relative oxidation stability levels and their ability to perform as a lubricant. A set of standard techniques, such as pressure differential scanning calorimetry (PDSC), which measures the oxidation onset temperature and the oxidation induction time, four-ball tester, sliding resistance value (SRV), and micro tap methods, were utilized to analyse the tribological properties of the fluid. The results determined that the oxidation stability varies and is dependent on the chemical structure of the oil and its origins, and physiochemical processing during extraction and storage. In relation to oxidation stability being the sole limiting factor, the tribological performance of the oils was affected by their physical and chemical properties. It was apparent from the findings that the physical properties of the oil are also responsible for the low performance of the oil as a metal cutting fluid.