Metal Cleaning: Washing Long Aluminum Skin Panels

Large, aluminum door panels can be difficult pieceschange, for easy maintenance. The nozzles and
to clean. Used in many applications, including theheaders are customized to optimize the coverage
construction of the United States Army'sof parts as well.
Hummer vehicle as a skin to be placed over theAfter the wash stage but before the rinse stage,
armor plate frame, these panels need to bea blow off feature is installed that was not
cleaned quickly and efficiently. This article willpresent on the previous machine. Using a stripping
serve as an example of how one manufacturerair knife system running at 25 horsepower and
was able to replace an outdated and inefficientdelivering up to 600 cfm of air, the parts will be
washing system with one that cleans morestripped of excess or puddles of water before
effectively and the steps that went along withbeing sent to rinsing. This stage helps to prevent
the transformation.the cleaner from being carried over to the rinse
The original washer had a load/unload stage of 5',tank from the wash tank, thereby making the
a wash stage of 16', and a spray length of 12'.rinsing stage more effective. There will always be
The overall dimensions of the machine measuredwash water rinsed off into the rinse tank, but
out to 7' W x 8'H x 76'L. The machine had acarrying the water on the part and dumping it into
600-gallon washer tank, a 5,000,000 BTU/hrthe rinse tank makes the rinse tank just another
heater size and design, and a pump size ofpart of the wash tank and diminishes efficiency
481GPM running at 15 PSI. By decreasing some ofand efficacy.
these measurements and using a more efficientAfter a rinse stage that removes any left over
design, the overall design of the washer will becontaminant or cleaner, the parts will move along
reduced and operating costs will be lowered, alonginto the final blow off stage. High velocity
with an increase in production and quality.regenerative blowers will be used to strip the
First, the loading and unloading stages of theexcess water from the parts. The air manifolds,
machine will be increased from the original 5' to 8'.which utilize air knives with directional nozzles that
By adding three to these stages the operators willcreate a curtain of air, will be mounted parallel to
have the benefit of increased safety whilethe spray headers. The blow off stage is further
maneuvering the larger panels. The wash stageenhanced by the addition of a heated blow-off for
will be reduced, from 16' to 12'. The smaller length2 of the blowers. These heated blowers will be
will make it easier to clean the tanks, as well asadjustable up to 200 degrees and enhance flash
keeping the gas burner immersion tube to adrying. With the increased PSI and more efficient
minimal dimension. Still, the 12' length will allow a 10'air knives used in the blow off stage, the length
panel to drain before moving on to the nextwill be decreased from 24' down to just 12'. By
stage in the process. Once loaded, the parts willincreasing the power of the blow off stage and
move through the system in one of twoeffectively concentrating it, length is reduced in
separate lanes, which are both driven by a single,half and keeps the footprint of the machine small.
common drive motor. The lanes will consist of flatAdditional monetary savings will be made when
wire belts on a roller bed, driven by the motor atthe heater used in the machine is replaced. In the
approximately 8 feet per minute. Adjustable guideold machine, a 5,000,000 BTU/hour heater was
rails in the tall lane will allow the machine to handleused. This was necessary in order to maintain a
3 different widths of the panels.steady temperature using a 500 gallon per minute
Spray length will be reduced from 12' to 8'. Bypump flow. In the new design, a 3,000,000 BTU
decreasing the pump size, from 500 gallons perhour system is installed. This results in 2 million
minute to 300 gpm, but running at a higher PSI,less BTUs expended per hour of use and
40 instead of 15, the spray length can be reduceddecreases monthly energy costs.
without a drop in wash quality. Since the washerFinally, by using two lanes for washing and
tank has been increased from 600 to 1000, thespeeding up the conveyor, the washer and
pump must be size appropriately. Tank volumetherefore the heater only need to operate 8
cannot be less than 3 times the total pumphours per day. This is 2 times less than the 20
volume or else you can possibly run the pumphours the old machine was operating. Using the
dry. In the previous configuration, the tank wasnewest technology available, the burner operates
600 gallons and the pump was running at 481at a higher efficiency rate as well, further reducing
GPM, which is not the correct ratio. A 1000-galloncosts.
tank and 300GPM pump is more appropriate. TheThe overhaul of this particular wash process
increase in PSI makes up for the decrease inillustrates how new technology and an
gallon per minute flow and spray bar impingementexperienced vendor can help a manufacturer save
time. Also, by installing a larger tank, the timemoney and increase productivity. With the
before the tank becomes saturated with soil andadvances made in washing technology and design,
stamping lubricant is increased, thereby decreasingit is worthwhile for any company to investigate
the amount of time that production must bewhether they could benefit from a change in
stalled in order to clean the machine.process. In this example, the footprint of the
In terms of maintenance, the spray stages willmachine was significantly reduced while efficiency
also be easier. The pump will be a vertical barrelwas increased and operating costs were
mount pump, which can be removed withoutdecreased.
draining the tank. The spray nozzles are quick