Minimum Quantity - Near Dry (Mist) Lubrication


MQL eliminates large quantities of water and oil-based coolants and replaces them with a small quantity of lubricant mixed with air. This air-oil stream is precisely metered and delivered to the cutting tool's edge. The philosophy behind MQL is based on a simple principle – more is not always better; use only what's needed for the application.


Manufacturers applying MQL are reaping many sustainable benefits. Their workers are safer, with both short and long-term benefits. They are no longer exposed to the toxicity, bacteria, and fungi risks that come with traditional “wet” machining. The small amount of oil used for MQL is generally based on vegetables or esters, which are less harmful to humans. Our environment is cleaner because there are no used cutting fluids that must be disposed of according to stringent regulations. Oil and other wastes present significant disposal impacts and implications to our environment. While legislation and regulation specify mitigation to the environment, enforcement of this legislation is challenging, expensive, and difficult.

In addition, metal chips produced during MQL machining are nearly dry, and much cleaner than chips produced with conventional approaches. Near-dry chips are easier to recycle and more valuable as a recycled material.


Most manufacturers still associate sustainability with higher costs. However, when we break down the investment and operating expenses of “wet” manufacturing systems, just how much these conventional systems cost becomes much easier to understand. Transferring, recycling, and pressurizing coolant results in significant costs for coolant supply, filtration, and mist collection equipment. Operating “wet” equipment produces increased and on-going lifecycle costs in the form of energy consumption, chemical maintenance, water make-up, disposal of used cutting fluids, and then starting the cycle of waste/recovery all over again by replenishing consumed fluids.

The cost-inflating factors of conventional flood lubrication are done away with when MQL is used. This results in:

• Reduction of metalworking fluid quantities in use

• Decrease in the work required for monitoring and metalworking fluid maintenance

• No need to prepare and dispose of used metalworking fluids

• Decrease in the work required for cleaning the processed pieces and easy recycling of the nearly dry chips due to less oil soiling.

Lubricant is supplied by means of a minimum quantity lubrication system (MQL system).Application of a targeted supply of lubricant directly at the point of use lubricates the contact surfaces between tool, work piece and chip. The lubricant is either applied from outside as an aerosol using compressed air or it is “shot” at the tool in the form of droplets.

Another possibility is internal lubricant feed through the rotating machine tool spindle and the inner channels of the tool. The illustration below shows the basic differences between external and internal feed.