Less Wait, More Do: Why MQL is Right for You
Why MQL? Minimum quantity lubrication (MQL) is just what the name implies: A means of reducing the heat generated when cutting metal that uses a very small (minimum) amount of a fluid (more specifically, a lubricant) to reduce the friction between the cutting tool and the workpiece. The exact amount for “minimum” varies depending on who you ask: The German DIN specification puts it up to 50 mL/h of lubricant (1.7 oz/h) and, in exceptional cases, up to 150 mL/h (5 oz/h). Other studies cap it at 500 mL/h (17 oz/h). The amount is somewhat subjective and depends greatly on the materials, processes, and the tools used in the specific application. Some materials have more natural lubricity than others, some processes are better able to get the fluid to the right place, and bigger tools need more lubricant than smaller ones. But as a general rule of thumb, 5 mL/h to 80 mL/h (0.2 oz/h to 2.5 oz/h) on tools less than 40 mm (1.57 in) diameter seems to keep the chips dry and gives good results. No matter where you fall in this range, it is much less than the 30,000 mL/h to 60,000 mL/h (8 gal/h to 16 gal/h) typically used with flood coolants!