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| WGI Inc. is justifiably
proud of its spotless new manufacturing facilty. |
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| WGI Inc (Southwick, MA), founded in 1942,
is a high-precision machine shop specializing in OEM and repair
parts for aerospace industry customers, such as General Electric,
Pratt & Whitney, and Lockheed Martin. WGI's success in
satisfying the demanding requirements of these customers can
be judged by the fact that WGI recently expanded into a new
manufacturing facility which has double the area of the older
facility. The new facility, which operates with two shifts,
is equipped with a number of new CNCs, plus grinders and manual
machines, organized as flexible manufacturing cells. In addition
to greatly increasing manufacturing capacity, the new facility
provided WGI the opportunity to improve the working environment
for its skilled machinists, an important consideration for
the family-owned company.
One problem with the working environment
in the old building was the persistent high concentration
of tramp oil which accumulated in the coolant in the sumps
of all the machines. If tramp oil builds up in the coolant,
the resulting shop odor, smoke generation, and potential
for operator dermatitis quickly undermines all efforts to
keep a clean shop and maintain an optimum working environment.
In addition to the detrimental effect on shop conditions,
tramp oil in the sumps reduces machine operating efficiency
by causing excessive tool wear and––most important
for WGI––requiring frequent machine setting adjustments
to achieve the tight tolerances specified by their customers.
When the machine tools were ordered for
the new facility, WGI specified to the distributor that
each machine should be equipped with a tramp oil separator.
The tramp oil pump/separator selected by the machine tool
distributor and supplied with the first delivery of machine
tools is an inclined plate separator, which relies on the
density difference between the oil and coolant to cause
the oil to rise to the top of a large settling tank. There
is a strainer prior to the pump, but no filter to separate
finer solids. WGI immediately discovered problems with the
new tramp oil separators. Because a long residence time
in the settling tank is required to split the oil, the recirculation
rate of coolant through the separator was not sufficient
to remove tramp oil at the rate at which it was being generated.
In addition, because there is no filter in the system,
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The Model #255 separator
keeps a sump at WGI relatively free of tramp oil even if
a large quantity of oil enters the sump. Note the dark layer
of oil in the separator tank.
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| A Keller compact floating
inlet device can access a sump in a space as narrow as 3”
and automatically compensates for changes in sump liquid level. |
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| there was an alarming buildup of suspended
solids in the coolant, raising concerns that the solids would
adversely affect tool life and parts finish.
After WGI had tried to work with the gravity
separators for several weeks, the salesman for Keller Products,
Inc. (Lexington, MA) demonstrated the Keller Model #255
Filter/Separator to Jim Chaffee, Supervisor of the Lathe
Department. The Model #255 contains a high capacity bag
filter as a prefilter, a 100 gallon per hour air-operated
pump, and an oil separator tank with Keller permanent plastic
separator elements, mounted in a compact aluminum frame.
Suspended chips are removed from the sump by the bag filter,
which also protects the pump from damage by solids. The
tramp oil is split from the coolant by the Keller separator
elements at high efficiency, even at the 100 gallon per
hour coolant recirculation rate. The oil layer collected
in the separator tank can be drained into a waste oil container
by opening the oil drain valve occasionally, usually once
per day. No other operator attention is required. Keller
supplies three different types of inlet devices designed
to draw oily coolant from the surface of the sump while
avoiding intake of air, which can interfere with splitting
oil from coolant in the separator. The compact floating
inlet device selected by WGI automatically compensates for
changes in sump level over a range of 5" and fits into
an area only 3" wide.
WGI purchased one Model #255 to run as a
test unit. Jim Chaffee immediately found that the combination
of the bag filter, the high efficiency oil separator elements,
and the 100 gallon per hour recirculation rate of the Model
#255 cleaned tramp oil and floating chips from a sump in
a few hours. After the one month test period, WGI purchased
an additional six units and converted the entire shop to
Keller Model #255 separators. Jim Chaffee says, "The
Keller separators help us run our shop at target efficiency
and provide our operators with the clean working conditions
that they deserve."
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