Immersion
Case Studies
Crown Equipment Corporation in New Bremen, Ohio, manufactures lifting equipment and has production
facilities worldwide. Crown-New Bremen started investigating aqueous cleaning in the mid-80s. A major portion
of their cleaning was done with TCA, either in cold tanks or vapor degreasers. After investigating various
alternatives, Crown-New Bremen first replaced the TCA in the cold cleaning tanks with aqueous solutions.
Satisfied that aqueous cleaning was as good or better than TCA for cold cleaning, Crown turned its attention to
the two large TCA vapor degreasers. In restructuring their entire cleaning process(es) Crown was able to eliminate
some of the interim parts cleaning completely. The remainder of the parts fell into two categories: small parts
which needed cleaning and deburring; and larger parts of various sizes which needed cleaning only. The smaller
parts are now cleaned and deburred in one operation which consists of a vibratory cleaner with an aqueous
cleaning solution. The larger parts are immersed in a heated, agitated, alkaline cleaning solution. After an initial
rinse, some parts receive an additional rinse in a rust inhibitor. All parts are then dried with forced air. Crown has
eliminated the annual purchase of 17,000 gallons of TCA.
Alternatives to Solvents Degreasing for the '90s, Solid and Hazardous Waste Education Center, University of
Wisconsin-Extension, Madison, WI.
Digital Equipment Corporation (DEC) has replaced CFC cleaning systems at its Colorado Springs, Colorado and
Kaufbeuren, Bavaria, Germany facilities. The alkaline aqueous system it installed at these locations consists of
one cleaning, three rinsing, and two drying stations. The cleaning station consists of a heated ultrasonic tank
filled with an alkaline detergent-surfactant. Cleaning is followed by a rough spray rinse, immersion in a high
purity water ultrasonic tank, and finally a spray rinse with high purity water. Drying is accomplished in two
stages. First, excess water is blown off the parts using pressurized clean, dry air. Infrared radiation then heats the
parts surface to 160 F to speed up evaporative drying. The system incorporates a water purification and
reclamation system. Waste water is nonhazardous and can be sent directly to sewer, provided the parts being
cleaned contain no hazardous contaminant. The aqueous system surpasses the CFC system in removing
particulates and is at least equal to the CFC system in overall efficiency.
Vosper, Fred C. and Vickers, David J. Developing Precision Aqueous Cleaning of Hard-Disk Electromechanical
Components, Microcontamination, 10(10): 31-34, 1992.
American Etching and Manufacturing in Pacoima,CA manufactures precision sheet metal parts, solar cell wafers,
and satellite dish components from stainless steel and nickel. Photoresist coatings and cleaners are now
water-based as opposed to solvent based. Alkaline aqueous cleaners are also replacing methanol, reducing the
flammability of the waste generated. American Etching reduced its waste from 683 tons in 1988 to 548 tons in 1989.
American Etching and Manufacturing, Case Studies in Waste Minimization, Government Institutes, Inc.,
Rockville, MD, October 1991.
The Marine Corps Air Station Naval Aviation Depot, Cherry Point, NC, is responsible for the complete
maintenance/rebuilding of naval aircraft. In 1990 the depot used 8000 gallons of CFC-113 and 15,600 gallons of
1,1,1-trichloroethane. By the end of 1992 CFC-113 usage had been reduced to 500 gallons annually and TCA
usage had been cut to about 4800 gallons annually. The replacements included: soap bubbles for leak checks;
aqueous power washers for electronics, motor, and engine shop use; terpene cleaners for hand wiping; steam
cleaning or wet sodium bicarbonate blasting for soil and carbon removal; and plastic media blasting for paint
removal.
Fennell, Mary Beth and Roberts, James Mark/Naval Aviation Depot, Hazardous Minimization-Saving Time,
Money , and the Environment, proceeding of the Aerospace Symposium, January 1993, Lake Buena Vista,
Florida, pp 39-46.
A Connecticut manufacturer of precision steel components needed to eliminate the use of two
1,1,1-trichloroethane (TCA) vapor degreasers. The degreasers were centrally located and used to clean parts at
various stages of the production process. After evaluating the cleaning needs of the factory, several changes were
made. Cleaning was eliminated for parts that were in transit from one machining process to the next. Cleaning
was decentralized, allowing alternate methods for a department's specific needs to be developed. Aqueous methods
were substituted for the TCA vapor degreasers in 95% of the cleaning applications. Several systems were
developed using emulsifying alkaline solutions, nonemulsifying alkaline solutions, rust inhibitors, ultrasonics, and
immersion cleaning. Some of the clients of this manufacturer required lubricants that could not be removed by
aqueous chemistries. A small TCA degreaser was kept for this fraction (5%) of "special" cleaning.
Elliott, Bradley T. (Capsule Environmental Engineering). 1991. Solvent Waste Reduction Through Process
Substitution. Presented at the Environmental Technology Expo '91, Chicago, Illinois, April.
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