This is not a demanding
environment, and the results were not unexpected.
Of
greater significance, though, was the behavior of the lubricant during
heat treating. The lubricant remains stable up to a fairly high
temperature, but when it decomposes it simply breaks down into carbon
dioxide and water vapor. It leaves no residue on the surface, and
produces no noxious outgassing.
Eliminating a production step
But before integrating the synthetic into its manufacturing
process, the wheel assembly plant conducted initial laboratory tests in
which the lubricant was applied to small steel coupons. These were
then raised to the same temperature as the heat treating process.
As expected, the lubricant simply vanished, leaving no residue on the
coupons.
The lubricant was then incorporated into the production
process, there by eliminating the step needed to remove the black
residue. The manufacturer sprayed a thin film of the lubricant
onto the assemblies after fabrication, which dissipates during heat
treating, and applied a thin film once more before shipment.
Shipping concerns
The completed wheel assemblies are shipped to the customer
by truck. However, the environment while shipping is very
different from that of the plant, and it is subject to dramatic seasonal
changes. The main concern was the presence of salt spray during
transit. Midwestern roads are frequently salted during winter. and
the salt tends to endure and create a highly corrosive aerosol that can
be very damaging to steel surfaces.
The lubricant manufacturer, having anticipated these
conditions during the development of TKO2, designed its
molecular structure to permit a very thin film to protect metals from salt
sprays, even at high temperatures. The scenario used as a rough
model during product development was the transoceanic shipment of
industrial equipment, in which transit times may be as long as three of
four months, and where exposure to salt and humidity is high.
Product testing
Santovac tested its new lubricant
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by using 2 x 2 in. (50 x
50 mm) coupons of mild steel that had been polished with 400 grade
sandpaper-- in other words, a surface that was extremely susceptible to
corrosion. The coupons were sprayed with a thin film and suspended
in a chamber in which they were rotated slowly to permit even
exposure. The chamber was heated to 212°F (100°C), and
water containing 5% salt by volume was continuously boiled at the base
of the chamber. The metal coupons, rotating at about the speed of
a second hand on a clock, received constant exposure to very hot
salt-laden vapor.
Because the water was actually at the boiling point, salt
was visibly deposited everywhere inside the chamber -- except on the
coupons. The test was continued for 150 hours, at the end of which
the surface of the coupons had not changed at all. There was no
rust or corrosion on the coupons __ nothing but the thin
film of lubricant. Because of the high temperature and the high
concentration of salt in the water, this test is the equivalent of about
1500 hours (about 9 weeks) of real-world exposure to a salt and humidity
environment.
We can contrast this by looking at the fate of other test
samples under the same conditions. The same mild steel coupons
with no protection at all will display visible corrosion after only 20
minutes of exposure. It is difficult to develop a lubricant that
will protect the coupons for even 1 hour under these test conditions,
yet some military applications require that a lubricant protect the
metal for 120 hours. And only a precisely designed lubricant will
endure for 150 hours.
The new lubricant was designed to be a lubricant and
protectant with a long lifetime, and to have several other useful
characteristics as well. In all, its development took three
years. It was designed to be biodegradable (which is why it
decomposes into CO2 and H2O), and it contains no
barium or other toxins. It contains no petroleum solvents __ and
one result is that it has no odor.
It was also designed to protect metal surfaces at both high
and low temperatures. You would naturally expect corrosion to be
most aggressive
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at high temperatures, but
that's not always the case. There are specific kinds of corrosion
that take place at low temperatures __ for example,
a lubricant turns solid, cracks, and permits atmospheric corrosion to
begin on the exposed metal. TKO2 was designed to
protect metals at temperatures down to -65°F (-54°C).
Passing the 120-hour salt vapor test meant the lubricant
successfully met the U.S. Army's tough requirements for lubrication of
small automatic rifles __ machine guns.
Cleaning and lubrication are vital in part because sand is likely to
find its way into moving parts, but also because sand, whether in a desert
or elsewhere, invariably contains a good deal of salt. The
standards that must be met are outlined in MIL-L-63460. One of the
characteristics that a lubricant in this application must have is the
ability to prevent burned gunpowder from adhering to metal
surfaces. TKO2 passed the separate gunpowder test
as well.
More recently, the lubricant has been adopted
by a Midwestern fabricator of steel and copper coils. This
manufacturer also needed protection from corrosion during transit, and
especially when shipment times were long. Spraying a thin film of
the lubricant completely eliminated rust and corrosion.
Conclusion
The development of a new product sometimes results in
benefits that no one could predict. It took three years to develop
this protecting lubricant, and the focus was on wear, lubricity, and its
long-lasting properties. In the real world, one of its most valuable features
has turned out to be its short-term performance in a
heat-treating environment. For
more information:
Sib Hamid
VP Technology
Santovac Fluids, Inc.
8 Governor Drive
St.
Charles, MO USA 63301-7311
Telephone: 636-723-0240
Fax: 636-723-4210
Send E-mail
shamid@santovac.com
Case History Page 1
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