Sources and scope for this page: Industry convention — no single governing standard (conventional usage, definitions vary between sources), covering the definition of minimum quantity lubrication (mql). No independent source check is recorded for this page: the content rests on the sources listed and on the working shown on the page. How sources, methods and updates are recorded.
Definition
MQL uses millilitres per hour where flood cooling uses litres per minute. The benefit is not just cost: no flood coolant means no coolant disposal, no mist, and no thermal shock from sudden cooling, which is what causes thermal cracking in carbide.
Its limits are real. It does not remove heat, so it suits operations where most heat leaves with the chip — aluminium, cast iron, and high-speed machining — and struggles in deep-hole or low-speed work where heat builds up.
Common misuse
Assuming MQL will replace flood coolant everywhere. It is a lubrication strategy, not a cooling one.