CO2-Reduced Lubricants and Minimal Quantity Lubrication in Punching

Increasing environmental requirements demand more sustainable punching processes. This study investigates how minimal quantity lubrication (MQL) and CO₂-reduced, biodegradable lubricants can jointly lower the ecological footprint of metal forming without compromising tool life or productivity. In industrial practice, lubrication is typically applied via felt rollers using conventional oils, often in excessive quantities. This approach increases material consumption and cleaning effort. Although MQL is a mature technology, it is still rarely implemented in punching. To evaluate its potential, two lubrication conditions were examined: MQL with standard oil and MQL with a CO₂-reduced, biodegradable oil. Tool wear, particularly at the punch edge, served as the main performance indicator and was compared to both traditional felt-roller lubrication and an additional dry punching reference. Results show that MQL drastically reduces lubricant use while maintaining tool performance. Both oils achieved wear behaviour comparable to felt-roller lubrication, with the CO₂-reduced oil offering further ecological advantages through lower emissions and biodegradability. The dry reference exhibited accelerated wear and early tool failure, confirming the necessity of lubrication for process stability. A CO₂ balance illustrates the environmental benefit: replacing conventional lubrication with MQL and CO₂-reduced oils can significantly reduce the overall carbon footprint of punching operations. The improvement results from lower lubricant consumption and the reduced carbon intensity of biodegradable oils. The findings demonstrate that combining MQL systems with CO₂-reduced lubricants enables more sustainable punching by aligning environmental responsibility with industrial efficiency.