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Mixing coolant
and dispensing it to CNC machines had become a cumbersome and
labor intensive operation at Symmetry Polyvac (Manchester,
NH), a leading worldwide manufacturer of sterilizable plastic
and metal cases for surgical instruments. Because of the necessity
to avoid any possibility of contamination of the instrument cases
by coolant concentrate or mixtures, Polyvac management imposed
strict guidlines for handling coolant. The coolant concentrate
as received in 5 gallon pails is kept in a designated area on
spill containment pallets. To prepare the coolant/water mixture
for the machines, a jet mixer was used to meter coolant concentrate
and mix it with water from a hose to fill 5 gallon pails on containment
pallets. The pail filling procedure resulted in frequent spills
which, although contained, increased the volume of the shop’s
hazardous waste. The 5 gallon pails of coolant mixture were then
hand-carried and added as required to the sumps of the machines.
Because the Polyvac shop floor is quite spread out, carrying the
5 gallon pails required significant unproductive labor and was
physically demanding for the CNC operators. In addition, the inevitable
small spills on the floor required immediate time consuming cleanup
and disposal procedures.
Since the
coolant mixing and handling procedure which had been used by Polyvac
is also used with minor variations in the majority of shops, Gary
Hannifin, Shop Supervisor, thought that Polyvac had to live with
the less than desirable process. Then the salesman from Keller
Products, Inc. advised him of a convenient coolant mixing and
dispensing device, the CPD-101, newly developed by Keller.
With the CPD-101, a shop can accurately prepare 30 gallon batches
of coolant at any desired concentration, wheel the portable unit
onto the floor, and pump the coolant mixture to each sump as required,
without hand-carrying pails or running hoses across the shop floor.
The CPD-101 contains a calibrated 35 gallon translucent plastic
drum and a self-priming air-operated diaphragm pump, mounted on
a drum dolly. First, the drum is filled by hose with 30 gallons
of water through a fitting which has an automatic shutoff to allow
unattended filling. The desired volume of coolant concentrate
is then poured into the calibrated jug provided. For example,
if a 2% solution in 30 gallons is desired, 0.6 gallons of coolant
is added to the jug. A 1/4” compressed air line is then attached
to the pump, the water in the drum is recirculated at high flow
rate, and the coolant concentrate is drawn into the recirculating
water by the self-priming pump and thoroughly mixed. The compressed
air line at the mixing station is then disconnected, and the unit
is wheeled to a sump which is to be filled or topped off. An air
line at that machine is connected, and the desired quantity of
coolant mixture is added to the sump. The CPD-101 is then moved
to another sump, and the simple procedure is repeated.
As soon as
he heard the description of the CPD-101 by the Keller salesman,
Gary Hannifin ordered one. He and Ryan Depalmenary, Supervisor
CNC, quickly determined that the performance of the CPD-101 met
all their expectations. The spills in the containment area at
the coolant preparation station were eliminated, and there are
no floor spills in transit to the machines. The labor for coolant
preparation and dispensing is now a small fraction of the previous
usage. A bonus advantage of the CPD-101 is that different coolant
mixture concentrations can be prepared with no change in the operating
procedures, while with the jet mixer changing concentrations requires
changing metering orifices, a procedure which is prone to operator
error. The ability to change makeup coolant concentrations conveniently
is important because coolant concentration in the sumps tends
to increase with time as a result of evaporation of some water,
and therefore the makeup coolant should be at a lower concentration
than the initial charge in order to restore the initial concentration
in the sumps.
When asked
his evaluation of the CPD-101, Dean Martineau, responsible for
CNC setup and operation, says, “The CPD-101 is great! No
more floods in the containment area, no spills on the floor, and
I personally very much appreciate not having to haul 5 gallon
pails of coolant around the shop. This is a very nice product.”
Polyvac management agreed and soon purchased a second CPD-101
for another coolant makeup station.
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