Sustainable alternatives to mineral-based cutting fluids: Performance and environmental assessment of vegetable oils

The growing need for sustainable manufacturing has encouraged the use of eco-friendly alternatives to petroleum-based cutting fluids, which pose environmental and health risks due to poor biodegradability and high toxicity. This study evaluates the potential of sunflower, olive, and canola oils as green substitutes for mineral oil (Renolin CLP 150) in metal cutting applications. Tribological performance was analyzed through dynamic viscosity, wear scar diameter (WSD), and coefficient of friction (CoF), using a Physica MCR 301 rheometer (ISO 3219) and a four-ball tribotester (ASTM D4172, D5183). A comparative assessment integrating functionality (viscosity stability, friction, wear) and sustainability (biodegradability, safety, renewability, availability, toxicity, cost) was conducted. Mineral oil exhibited the best wear resistance (0.234 mm; 1.84%) but the highest CoF (0.0913) and lowest sustainability. Olive oil showed a good balance of functionality (WSD: 0.808 mm; CoF: 0.0620) and sustainability, while canola oil demonstrated the most balanced overall performance and eco-friendliness. Thus, canola oil is identified as the most promising green lubricant, with further optimization through additives or high-pressure MQL systems recommended for improved performance一