• FAQ.
    Section.
1. Abstract

1. History

1.1. Where does MQL come from and how long does it exist already?

Spray Lubrication Systems have already been used in the metal processing for a longer time. Thus, the predecessor of today’s Steidle unit Spraymat was already built around 1970. This technology prevailed from the beginning of the 90’s. The term “Minimum Quantity Lubrication” also has its origin in this period.

1.2. How long does Steidle already manufacture MQL?

The Steidle GmbH was established in 1979 and offered its first spraying system, the “VAPOR LUB” (predecessor of the Spraymat) around 1983. Until 1990, the programme was extended by the Lubrimat and the Pulsomat; followed by Sawfix, Toolmat, Centermat and Flowster until today.

2. Application area

2.1. For which type of processing is MQL suitable?

MQL can be used in almost all metal processing methods. For this purpose the chipping processes with the geometrically defined cutting edges are most suitable. But MQL can be used also in case of undefined cutting edges and chipless processing.

2.2. For which processing is it not possible to use MQL?

The overall conditions of the process are less decisive than the process, especially the available space: Is it possible to place the nozzle at the point of contact of tool/work piece or even to spray through the tool?

2.3. Which conditions are necessary to be able to use MQL?

For MQL an appropriate device, a suitable medium and compressed air are mainly necessary.

2.4. Up to which length-Ø ratio is it possible to work with an external lubrication in case of the MQL?

2.5 – 3 times the diameter can be taken as a rule of the thumb for the maximum drilling depth; sometimes more and sometimes less depending on the material feature. From this depth the tool has to be aerated in case of an external lubrication so that the lubricating film can be renewed.

2.5. Is it possible to spray through the spindle?

Yes, the so-called “internal lubrication” is possible, but it requires suitable MQL devices, which are distinguished from the equipment provided for the “external lubrication“.

2.6. Is it also possible to process wood with MQL?

Traditional, pure wood processing: Wood is mostly processed in dry state, since the lifetimes are also good without lubrication and the moisture would make the chips heavy and sticky, which in turn would make the suction difficult. In addition, the moisture would penetrate into the wooden work piece and soak it. All these are arguments against a wet processing. The layer applied by MQL would be very small so that it does mean any impairment but it also does not bring any great advantage.

 

Modern wood working: Wood workers (carpenters, furniture industry) are not “pure” wood workers any more for quite some time today. Machine requirements for coatings of chipboards, aluminium and plastic as deco or reinforcing materials and other composite materials are different than for pure wood.  Therefore modern wood working machines must be also appropriate for this purpose. – dry is not possible anymore. Cooling by refrigeration is excluded completely; only MQL remains as solution.

3. Advantages

3.1. Which advantages result using MQL?

With MQL, it is possible to make the lubricating process more efficiently. Only the quantity actually necessary is applied. A time-consuming and costly cleaning of chips and work piece are not needed. Similarly the machine and the surroundings remain dry, which improves the safety of the workplace. No emulsions must be maintained and disposed of any more. The lifetime normally increases.

3.2. Which lifetime is to be expected for flood cooling and/or dry processing?

An increase of the lifetime is certain compared to dry procession; at least the same lifetime is to be expected compared to closed-circuit cooling, and in many cases even a better lifetime.

3.3. Are my work pieces so dry after the processing with MQL that they can be further processed without washing?

This mainly depends on the medium used and the quantity applied. In most cases, the parts processed with MQL show a film of moisture at the direct processing areas maximum. In case of some media, these remaining quantities volatilise, and in others, they remain present. Whether this remaining quantity must be washed off or not depends on the requirements of the further processing. In any case, the quantity of foreign matters entering the washing bath is reduced, which extends its lifetime.

3.4. Is it also possible to blow away light chips with the spray air of the MQL?

Up to a certain grade, light chips can be removed by the spray air.

4. Conversion

4.1. Do I need special tools for MQL?

Mostly you can obtain good results with the present tools. However, sometimes the result can be optimised with the coated tools or tools specially manufactured for MQL, especially in case of tools for the internal lubrication.

4.2. Do I have to change the speed and feed rates / rpm’s?

Not initially. Only when problems with lifetime or temperature occur, a variation may be helpful. In most cases it is better to increase the feed rates instead of reducing them, as higher feed speeds can be obtained by the improved lubricating effect conducting more heat into the chip and reducing the manufacturing time.

4.3. How much time and effort are required to equip a machine with MQL?

This depends on the machine and the device. Simple systems such as Pulsomat or Spraymat are sometimes ready for use in 15 minutes. For more complex systems, the connection to the machine control and eventually the installation of the feed tubes and the installation of the nozzles are also added.

4.4. Do I have to rebuild/modify something at the machine to be able to use the MQL?

In many cases, the machine can be used further on without changes; however it depends on the equipment and the use of the machine.

5. MQL and health

5.1. Does MQL offer advantages or disadvantages compared to wet processing?

The German Accident Prevention and Insurance Associations for the Metal Industry expressly mention the MQL as a promising strategy of avoidance for skin protection. Employees at working places with MQL seldom have contact with lubricoolants, one of the main means causing skin diseases. In addition, there is a reduction in slip hazard, as the area around the machine remains cleaner.

5.2. Do the nozzles get misty?

The nozzles of the devices LubrimatSawfixPulsomat and Flowster are designed for a fogless spraying with the correct setting. In case of flat jet nozzles and the device Spraymat, a tendency to mist can be seen in some settings. The devices Toolmat and Centermat deliberately generate an aerosol for the internal lubrication through the spindle.

5.3. Is a suction system necessary for the MQL?

Our customers normally do not use any suction. But if the nozzles should mist deliberately, or the employees should work directly in the spraying area, or if the medium sprayed is dangerous to health, then a suction system is recommended.

5.4. I would like to install a suction system – can I buy it from you?

No. But we can establish a contact with suppliers for you.

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