MQL: Lean and Green
While flood coolants have traditionally been used almost exclusively in machining operations, the concept of minimum-quantity lubrication has been steadily gaining momentum during the last several years. MQL, also known as near-dry machining, replaces flood coolant with a minute amount of high-efficiency lubricant applied precisely to the cutting tool/workpiece interface. The process has proven effective for machining all nonferrous metals and most grades of steel. The most common lubricants for this process are biodegradable vegetable oil derivatives, which, because of their polarity, are known for their extensive friction-reducing properties. Unlike mineral-based and synthetic fluids, vegetable based fluids are developed in the presence of oxygen, which causes them to organize and align better as they bond with the surface of metals, providing superior lubricity. These fluids, when properly applied, significantly reduce the friction and corresponding heat created when cut metal slides over the cutting tool before breaking off and becoming a chip. Reducing that friction not only extends tool life, but also eliminates the need for cooling the tool with flood coolant. Additionally, the amount of fluid used is often less than 8 oz. per shift, which is either consumed in the cut or remains as a light film on the part and chips.