Inhibiting Agents
Case Studies
Washington Scientific Industries (WSI) is a precision machining company that had been using TCA vapor
degreasers at 20 work stations. Initially one aqueous cleaning system using a mild alkaline detergent with a rust
inhibitor sprayed at high-pressure was put into service. This unit replaced one vapor degreaser that required the
purchase of 1,000 gallons of TCA annually and generated 200 gallons of waste. The cost was $7,000 and the first
year's savings were $6,500. Subsequently, other workstations have been switched to high-pressure aqueous
cleaning.
DeWahl, Karl, and Donna Peterson. 1992. Waste Reduction in Solvent Cleaning; Process Changes Versus
Recycling, Pollution Prevention Review, Winter: 74.
A Connecticut manufacturer of precision steel components needed to eliminate the use of two 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. 1991. Solvent Waste Reduction Through Process Substitution, presented at the Environmental
Technology Expo '91, Chicago, Illinois.
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.
Dayton Rogers Manufacturing Company, Minneapolis, MN, is a short-run metal stamping company founded in
1929. Dayton Rogers had been using a vapor degreaser to remove oil-based lubricants from metal parts prior to
deburring. Currently, Dayton Rogers is using a vibratory tumbler with aqueous cleaning solution to clean and
deburr 75% of its manufactured parts simultaneously. The remainder of the deburring is done with a wet sander
that also cleans and deburrs simultaneously. Switching to a water-based lubricant facilitated cleaning. The aqueous
cleaning solution has a neutral pH and contains rust inhibitors when needed for steel parts. All of the parts are air
dried after deburring. Dayton Rogers has eliminated the annual purchase of 1,100 gallons of 1,1,1-trichloroethane
(TCA). Capital cost was $9,000 for a wet sander and sheet-metal drier. NET SAVINGS: $36,000 PER YEAR IN
OPERATING COSTS.
Replacement of Vapor Degreasing Operation with Debuuring Process for Cleaning Metal Parts, Case Study,
Minnesota Technical Assistance (MnTAP), Minneapolis, MN.
SAAB, a Swedish automobile manufacturer, uses a high-pressure cold water spray to clean aluminum engine
cylinder heads after machining. No detergent additives are used to aid cleaning. The water does contain a small
amount of corrosion inhibitor. The water is filtered and reused. The water is pressurized to 4,000 psig and exits
the nozzles at 500 mph. The cleaning system produces one clean, dry cylinder head every 48 sec.
Cold Water Cleans Machined Parts, Tooling & Production, pp. 38-39, June 1989.
Briggs and Stratton, a small engine manufacturer, changed from a solvent degreaser to an aqueous cleaning
system. Though a reclamation system was used for the solvent degreaser, fugitive emissions of trichloroethylene
(TCE) and methyl chloroform were unavoidable. The aqueous system includes a rust inhibitor to prevent
corrosion of the engine parts. A heater was added to the cleaning tank to facilitate degreasing. A rinse station and
air drying station were also added. Changing to an aqueous system cost approximately $10,000. The payback
period was 3 months. Oily waste is separated from the wash and rinse water and used as a fuel. The wastewater is
then sent to sewer.
Wisconsin Department of Natural Resources. Case Study: Briggs and Stratton; Replacing Chlorinated Solvents
with Aqueous Detergent for Parts Cleaning. PUBL-SW-162 92. Hazardous Waste Minimization Program (SW/3),
Madison, WI.
The Eaton Corporation of Spencer, Iowa, produces hydrostatic transmissions for heavy- and light-duty offroad
use. Four large vapor degreasers required the purchase of 25,000 gallons of TCA annually. They could not find a
suitable aqueous alternative for cleaning the oil-based lapping compound that was a major contaminant. Switching
to a water-miscible lapping compound solved this problem. Eaton now uses a low-pressure spray cleaner for many
of its parts. Cleaners and inhibitors are constantly being evaluated as new chemistries emerge. One Eaton
representative estimates that chlorinated solvent use has been reduced by 99% since 1987.
Alternatives to Solvents (Degreasing for the '90s, Solid and Hazardous Waste Education Center, University of
Wisconsin-Extension, Madison, WI.
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