- 20 -
951-170-218-EN
Version 06
EN
3. Overview, functional description
3. Overview, functional description
3.1 Principle of minimal quantity
lubrication
See Figure 2
Minimal quantity lubrication (MQL) involves
total-loss lubrication, i.e., the lubricant is
almost completely consumed during ma-
chining so treatment of the lubricant is not
required.
The actual lubrication is performed at the
friction point between the tool and in the
channels for chip removal. The lubricating
effect is achieved by an aerosol, i.e., droplets
of lubricant finely dispersed in an air flow.
Minimal quantity lubrication provides for ef-
fective lubrication of cutting processes using
very small amounts of lubricant. The ardu-
ous task of cleaning and disposing of large
amounts of lubricant and cooling lubricant is
greatly simplified or eliminated.
3.2 Principle of aerosol action
See Figure 2
Aerosol is a mixture of air and lubricant in
which air assumes transport of the lubri-
cant.
In terms of the size and distribution of lubri-
cant droplets created, the SKF MQL system
described here generates a very homoge-
neous aerosol with a droplet size of approx.
0.5 µm.
The lubricant droplets are very light due
to their small size, which in turn results in
a very low moment of inertia. These small
droplets of lubricant can be transported over
long stretches through lines and deflections
without being deposited.
Transport of the aerosol through rotating
spindles and tools is thus unproblematic for
the MQL systems even at very high rota-
tional speeds, since the effect of centrifugal
force on the oil droplets is very small.
3.3 General function and design
See Figure 2
All SKF minimal quantity lubrication systems
of the DigitalSuper series are identical in
their basic design and function.
Using compressed air, the aerosol produced
in the lubricant reservoir is transported via
one or several connected aerosol line(s) to
the transfer point on the machine tool.
The volumetric flow of the aerosol and the
composition of the mixture are adjusted by
a lubricant and air valve system according to
the operator’s specifications.
The formation of aerosol requires a pres-
sure difference between the inlet pressure
and the internal reservoir pressure.
No further aerosol is generated if the pres-
sures equalize.
During operation, the pressure difference
between the inlet air pressure and the in-
ternal reservoir pressure is determined and
monitored. The compressed air supply is
shut off to reestablish the required pressure
difference if the pressure difference drops
