Various conventional cutting fluids used for different machining processes are considered to be hazardous for the environment as well as human beings as they cause severe effects.
There are many commercially available cutting fluids that contain organic sulfur, chlorine, nitrite, etc that are harmful to the human body and environment. Toxicity of cutting fluids causes harm to the human body, machine tools working environment, etc.
The environmental pollution resulting from cutting fluid include the following two aspects
- Volatilization, the erratic leakage, spatter of cutting fluid during the cutting process lead to a drastic environmental deterioration and severely affect the safety of production.
- Mineral oil-based cutting fluid has poor biodegradability and will remain in water and soil for a long time, which causes contamination to lakes, rivers, oceans, and underground water, and hence aquatic life completely distracts.
- This has to lead the researchers to develop new cutting fluids/ new techniques that will overcome the disadvantages of conventional cutting fluids. In response to this, researchers have developed a new lubrication system called Minimum Quantity Lubrication (MQL).
What is MQL?
MQL stands for Minimum Quantity Lubrication. It is also known as NDM which stands for Near Dry Machining. As the name suggests, in the MQL system very low amount of lubricant oil is used for lubrication.
In the MQL system, lubricating oil used is 10,000 times less than the conventional lubricating system. From this, you will get that the use of lubricating oil used in the MQL system is reduced to too much low amount.
It is also called Near Dry Machining because the chips formed after the machining process contain a very much low amount of lubricating oil in them. Hence it reduces the recycling cost of the chips and also gives good quality of chips improving the surface finish of the workpiece.
In the MQL system, the interface between the tool and the workpiece is coated with high-quality lubricating oil which is delivered with high atomized spray. Hence during the machining process, the heat generated is mostly carried away by the chip formed increasing the tool life, surface finish, chip thickness, etc.
Various experiments were carried out to compare the study of Conventional lubrication systems and MQL. The results showed that the surface finish obtained by the use of the MQL system was comparatively better than the conventional lubricating system.
It also improved the tool life by using high-quality lubricating oil which reduced the cutting temperature during machining operations.
Advantages of MQL System :
- MQL system is an environmentally friendly lubricating system.
- The minimum volume of lubricating oil is used.
- Increased cutting speed.
- Improved chip evacuation.
- No disposal and recycling of lubricating oil are required.
- It is more efficient as compared to the conventional lubrication system.
- Most important, it is clean in operation, i.e., unlike the flooding type lubrication technique, this system maintains cleanliness in the workshop.