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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.
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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.
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2.
Area of application of the MQL
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.
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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?
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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.
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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.
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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“.
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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.
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3.
Advantages of the MQL
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.
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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.
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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.
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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.
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4.
Conversion to MQL
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.
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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.
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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.
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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.
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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.
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5.2.
Do the nozzles get misty?
The nozzles of the devices
Lubrimat,
Sawfix,
Pulsomat
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.
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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.
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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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