xvEPA
United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-95/015 August 1995
ENVIRONMENTAL
RESEARCH BRIEF
Pollution Prevention Assessment for a Manufacturer of
Combustion Engine Piston Rings
Richard J. Jendrucko*, Todd M. Thomas*, and
Gwen P. Looby"
Abstract
The U.S. Environmental Protection Agency (EPA) has funded
a pilot project to assist small and medium-size manufacturers
who want to minimize their generation of waste but who lack
the expertise to do so. In an effort to assist these manufactur-
ers Waste Minimization Assessment Centers (WMACs) were
established at selected universities and procedures were
adapted from the EPA Waste Minimization Opportunity As-
sessment Manual (EPA/625/7-88/003, July 1988). That docu-
ment has been superseded by the Facility Pollution Prevention
Guide (EPA/600/R-92/088, May 1992). The WMAC team at
the University of Tennessee performed an assessment at a
plant that manufactures piston rings. Steel and iron rings are
machined, chrome-plated or coated, machined again, cleaned,
and shipped to customers. The assessment team's report,
detailing findings and recommendations, indicated that waste-
water and wastewater treatment sludge are the waste streams
generated in greatest quantity and that the greatest cost sav-
ings could be achieved by modifying the method of masking
the rings prior to chrome plating.
This Research Brief was developed by the principal investiga-
tors and EPA's National Risk Management Research Labora-
tory, Cincinnati, OH, to announce key findings of an ongoing
research project that is fully documented in a separate report
of the same title available from University City Science Center.
Introduction
The amount of waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an
additional stress on the environment. One solution to the
"University of Tennessee, Department of Engineering Science and Mechanics.
"University City Science Center, Philadelphia, PA.
problem of waste generation is to reduce or eliminate the
waste at its source.
University City Science Center (Philadelphia, PA) has begun a
pilot project to assist small and medium-size manufacturers
who want to minimize their generation of waste but who lack
the in-house expertise to do so. Under agreement with EPA's
National Risk Management Research Laboratory, the Science
Center has established three WMACs. This assessment was
done by engineering faculty and students at the University of
Tennessee's (Knoxville) WMAC. The assessment teams have
considerable direct experience with process operations in manu-
facturing plants and also have the knowledge and skills needed
to minimize waste generation.
The pollution prevention opportunity assessments are done for
small and medium-size manufacturers at no out-of-pocket cost
to the client. To qualify for the assessment, each client must
fall within Standard Industrial Classification Code 20-39, have
gross annual sales not exceeding $75 million, employ no more
than 500 persons, and lack in-house expertise in pollution
prevention.
The potential benefits of the pilot project include minimization
of the amount of waste generated by manufacturers, and
reduction of waste treatment and disposal costs for participat-
ing plants. In addition, the project provides valuable experi-
ence for graduate and undergraduate students who participate
in the program, and a cleaner environment without more regu-
lations and higher costs for manufacturers.
Methodology of Assessments
The pollution prevention opportunity assessments require sev-
eral site visits to each client served. In general, the WMACs
follow the procedures outlined in the EPA Waste Minimization
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Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).
The WMAC staff locate the sources of waste in the plant and
identify the current disposal or treatment methods and their
associated costs. They then identify and analyze a variety of
ways to reduce or eliminate the waste. Specific measures to
achieve that goal are recommended and the essential support-
ing technological and economic information is developed. Fi-
nally, a confidential report that details the WMAC's findings
and recommendations (including cost savings, implementation
costs, and payback times) is prepared for each client.
Plant Background
This plant produces piston rings that are used in diesel en-
gines. Almost four million piston rings are produced by the
plant each year during 6,000 hr of production.
Manufacturing Process
Each of the major processes used by this plant—piston ring
machining and hard chrome electroplating—is described here
in detail.
Piston Ring Machining
The necessary raw materials, steel and ductile iron rings, are
received and stored until needed in production. To begin
production, approximately 100 rings are placed on a steel rod
for ease of processing. Next, the rings enter a sequential
machining line where they are blank-turned, bored, slot-milled,
and finish-turned. After these initial machining operations, the
rings are separated according to their final use as bottom-
rings, top-rings, or intermediate-rings, and further processed as
required.
Following these machining operations, approximately 95% of
the rings are prepared for chrome plating. First, those rings
are degreased to remove protective oils and machining resi-
due. Then the inside ring surfaces are masked using lacquer-
based paint film to prevent chrome plating on those surfaces.
After paint masking, the outer ring surfaces are grit blasted to
enhance chrome adhesion during plating. The final step is
removal of grit blast residue using a high-pressure spray-wash.
The rings are then transported to the chrome-plating process.
The other 5% of the rings are prepared to receive a magne-
sium phosphate coating in a hot water wash for removal of
remaining machining debris and protective oils. The rings are
then dipped into the magnesium phosphate tank. After the
coating has dried the rings are dipped in rinse tanks for re-
moval of residual coating solution. Depending on their final
use, the coated rings undergo additional machining and grind-
ing. The rings are then cleaned in solvent, marked with
identification numbers, cleaned again, dipped in a rust preven-
tative, and shipped to customers.
Chrome Electroplating
The plant's plating line operation is semi-automated. Use of a
computer reduces human error and standardizes plating op-
erations.
A heated sulfuric acid etch is the first tank in the plating line.
The etch is used to enhance the ring's surface to facilitate
chrome adhesion. Following etching, the rings are rinsed and
placed in one of four heated chromic acid plating tanks. Resi-
dence time varies according to the type and thickness of
chrome deposit required.
Next, the rings are rinsed in a cold water rinse tank and then
with a high-pressure water spray. Masking paint on the inside
ring surfaces is removed by dipping the rings into a series of
tanks containing paint stripping agents and water rinses. The
rings are then dipped in a tank containing rust inhibitor solu-
tion. Inspection of the rings for proper chrome application is
done next. Unacceptable rings are stripped of chrome and
replated.
After chrome plating the rings are machined and ground as
needed. The rings are then cleaned in solvent, marked with
identification numbers, cleaned again, dipped in a rust preven-
tative, and shipped to customers.
An abbreviated process flow diagram for piston ring manufac-
ture is shown in Figure!
Existing Waste Management Practices
This plant already has implemented the following techniques to
manage and minimize its wastes.
• Personnel from the plant's parent corporation conduct a
waste assessment each year to specify waste reduction
measures for the facility.
• A local university performed a waste audit for the plant
several years ago.
• Waste cardboard is baled and sold.
• Sludge from the plant's general wastewater treatment sys-
tem is shipped to a facility for fuels blending.
• Sludge from the plant's chrome wastewater treatment sys-
tem is shipped to an outside firm for metals extraction.
Pollution Prevention Opportunities
The type of waste currently generated by the plant, the source
of the waste, the waste management method, the quantity of
the waste, and the annual treatment and disposal cost for each
waste stream identified are given in Table 1.
Table 2 shows the opportunities for pollution prevention that
the WMAC team recommended for the plant. The opportunity,
the type of waste, the possible waste reduction and associated
savings, and the implementation cost along with the simple
payback time are given in the table. The quantities of waste
currently generated by the plant and possible waste reduction
depend on the production level of the plant. All values should
be considered in that context.
It should be noted that, in most cases, the economic savings of
the minimization opportunities result from the need for less raw
material and from reduced present and future costs associated
with waste treatment and disposal. Other savings not quantifi-
able by this study include a wide variety of possible future
costs related to changing emissions standards, liability, and
employee health. It also should be noted that the savings
given for each opportunity reflect the savings achievable when
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implementing each opportunity independently and do not re-
flect duplication of savings that may result when the pollution
prevention opportunities are implemented in a package.
Additional Recommendations
In addition to the opportunities recommended and analyzed by
the WMAC team, several other measures were considered.
These measures were not analyzed completely because of
insufficient data, implementation difficulty, or a projected lengthy
payback. Since one or more of these approaches to waste
reduction may, however, increase in attractiveness with chang-
ing conditions in the plant, they were brought to the plant's
attention for future consideration.
• Install covers on all heated tanks to minimize evaporative
water losses and to conserve energy.
• Use aqueous cleaners instead of solvents forwashing piston
rings.
• Separate nonhazardous from hazardous wastewaterstreams
to reduce the volume of sludge from treatment that must be
considered hazardous and its associated costs.
This research brief summarizes a part of the work done under
Cooperative Agreement No. CR-819557 by the University City
Science Center under the sponsorship of the U.S. Environmen-
tal Protection Agency. The EPA Project Officer was Emma
Lou George.
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Precast Steel and
Iron Rings
I
Machining Operations
Blank Turning, Boring, Slot
Milling, Finish Turning
Heat Shape
Oven
Cam and
Finish Turning
Vapor
Degreasing
Chrome
Plating
Etching
Grit Blast
Cleaning
Paint
Masking
Machining
Magnesium
Phosphate
Dipping
Cleaning
Packaging
Piston Rings Shipped
to Customer
Figure 1. Abbreviated process flow diagram for piston ring manufacture.
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United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/S-95/015
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