vvEPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-94/004 September 1994
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer
of Pliers and Wrenches
Harry W. Edwards*, Michael F. Kostrzewa*,
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ment has been superseded by the Facility Pollution Prevention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
Colorado State University performed an assessment at a plant
that manufactures pliers and wrenches. The products are manu-
factured from metal blanks that have been forged in another
plant. In the case of the pliers, the blanks are machined,
etched, primed, and assembled. The handles are then plastic
coated and the finished pliers are inspected, packaged, and
shipped. For wrench manufacture, the metal blanks are nickel-
and chromium-plated, inspected, and packaged. The team's
report, detailing findings and recommendations, indicated that
the greatest quantity of waste in this plant came from the
machining and plating operations. The greatest cost-saving
opportunity recommended to the plant involved the replace-
ment of 1,1,1-trichloroethane vapor degreasing with nonhaz-
ardous aqueous cleaning.
This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, 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, Phila-
delphia, PA.
* Colorado State University, Department of Mechanical Engineering,
Fort Collins, CO
" University City Science Center, Philadelphia, PA
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
problem of waste generation is to reduce or eliminate the
waste at its source.
University City Science Center 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 Risk Reduc-
tion Engineering Laboratory, the Science Center has estab-
lished three WMACs. This assessment was done by engineering
faculty and students at Colorado State University's (Fort Collins)
WMAC. The assessment teams have considerable direct ex-
perience with process operations in manufacturing plants and
also have the knowledge and skills needed to minimize waste
generation.
The waste minimization 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 waste minimiza-
tion.
The potential benefits of the pilot project include minimization
of the amount of waste generated by manufacturers and re-
duction of waste treatment and disposal costs for participating
plants. In addition, the project provides valuable experience for
graduate and undergraduate students who participate in the
program and a cleaner environment without more regulations
and higher costs for manufacturers.
^§3} Printed on Recycled Paper
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Methodology of Assessments
The waste minimization assessments require several site visits
to each client served. In general, the WMACs follow the proce-
dures outlined in the EPA Waste Minimization 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 supporting tech-
nological and economic information is developed. Finally, a
confidential report that details the WMAC's findings and recom-
mendations (including cost savings, implementation costs, and
payback times) is prepared for each client.
Plant Background :
The plant manufactures pliers (adjustable and needle-riose)
and wrenches that are distributed nationally. It operates 7,200
hr/yr to produce almost ten million pieces annually. i
Manufacturing Process
The principal raw materials used by this plant are metal b anks
that have been forged in another plant.
Piter Manufacture
In the production of adjustable pliers, the metal blanks are
trimmed and coined to dimension and straightened. Then, one
or two holes are pierced in each blank for the joint connection.
Next, arcs are cut into the blanks using broaches that also cut
teeth into the blanks. The plier handles are then ground using
vertical broaches. Heat treating, sandblasting, and polishing of
the blanks follow.
Brand names are etched on the single-hole blanks using jacid.
Then, those blanks are dipped in clear-coat primer that adts as
a sealant and provides corrosion protection. Primer is also
applied to double-hole blanks, but in this case, spray applica-
tion is used. '.
The finished halves are assembled using nuts, bolts,' and
washers. Plier handles are then dipped in molten plastic for
coating. The finished pliers are allowed to cool, inspected,
packaged, and shipped. ;
The processes used in needle-nose plier manufacture are
similar to those used in producing adjustable pliers. In this
case, however, the pliers are etched using a laser instead of
acid. In addition, vapor degreasing is required before plastic
coating. !
i
An abbreviated process flow diagram for plier manufacture is
shown in Figure 1. i
Wrench Manufacture
In the manufacture of wrenches, polished metal blank$ are
loaded into racks for processing. The racks are sent through
an automated plating machine for electroless nickel-plating and
electrolytic trivalent-chromium-plating. The plated wrenches are
then unloaded, inspected, and packaged. .
An abbreviated process flow diagram for wrench manufacturer
is shown in Figure 2.
Existing Waste Management Practices
This plant already has implemented the following techniques to
manage and minimize its wastes:
• Many of the machining operations require no cutting fluid and
therefore generate no waste cutting fluid.
• A cutting fluid reuse program has been developed and
implemented successfully.
• Waste oil is separated from waste cutting fluid and reblended
off-site for use as industrial boiler fuel.
• 1,1,1-trichloroethane has replaced perchloroethylene as the
degreasing agent, thereby reducing slightly the toxicity of the
solvent used for cleaning the pliers.
• The plant plans to replace the spray priming system with a dip
priming system that will generate less waste.
• An acid purification unit (APU) has been installed in conjunc-
tion with the nitric acid rack stripper in the plating area. The
APU removes dissolved nickel from the acid so that the bath
can be regenerated without being dumped.
• Nickel plating solution is filtered and reused. Drag-out tanks
are used in the plating line to reduce nickel drag-out into the
rinse streams.
• Liquid nitrogen instead of solvent is used to remove plastic
coating from rejected pliers.
• Whenever possible, waste plastic coating, instead of being
disposed of, is returned to the manufacturer. Cross-contami-
nation of coatings is minimized.
• Flow reducers have been installed on the rinses in the plating
line.
Waste Minimization 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 waste management costs are given
in Table 1.
Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the plant. The minimization
opportunity, the type of waste, the possible waste reduction
and associated savings, and the implementation cost along
with the 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 the financial savings of the minimization
opportunities result from the need for less raw material and
from reduced present and future costs associated with waste
management. Other savings not quantifiable by this study in-
clude a wide variety of possible future costs related to chang-
ing emissions standards, liability, and employee health. It also
should be noted that the savings given for each opportunity
reflect the savings achievable when implementing each waste
minimization opportunity independently and do not reflect du-
plication of savings that would result when the opportunities
are implemented in a package.
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Blanks
Waste cutting fluid
recycled on-site
Spent solvent
recycled on-site
Plastic coating
+
Inspection,
packaging,
shipping
k.
Waste
incinerated
off-site
Solid-joint and
adjustable pliers
Figure 1. Abbreviated process flow diagram forplier manufacture.
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Blanks
Loading
Plating
• Cleaning
• Electroless nickel plating
- Electrolytic chromium plating
Unloading
Inspection
Packaging
Wrenches
Figure 2. Abbreviated process flow diagram for wrench manufacture.
Waste alkaline and acidic
solutions to batch treatment
Nickel-bearing rinses and
chromium-bearing rinses
toWWTP
Rack stripping
Rejected parts
stripping
Waste to acid
purification unit
Additional Recommendations
In addition to the opportunities recommended and analyzed by
the WMAC team, two additional measures were considered.
These measures were not completely analyzed because of
insufficient data, minimal savings, implementation difficulty, or
a projected lengthy payback. Since one or more of these
approaches to waste reduction may, however, increase in
attractiveness with changing conditions in the plant, they were
brought to the plant's attention for future consideration.
• Remove chromium and nickel from rejected parts using an
electro-soap cleaner instead of the currently used stripper.
• Electrowin nickel from the effluent of the acid purification unit
in order to reduce the amount of nickel discharged to the on-
site waste water treatment system that eventually ends up as
metal hydroxide sludge.
This research brief summarizes a part of the work done under
Cooperative Agreement No. CR-814903 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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Tsblo 2. Summary of Recommended Waste Minimization Opportunities
Minimization Opportunity
Annual Waste Reduction
Waste Stream Reduced Quantity (Ib) Percent
Net Annual
Savings
Implementation
Cost
Simple
Payback (yr)
Replace 1,1,1-trichIoroethanB
vapor degreasing with an
aqueous cleaning system.
Nonhazardous liquid waste
witt be generated during
periodic replacement of the
cleaner arid associated
rinses if this opportunity is
Implemented.'
Spent 1,1,1-trichloroethane 520 100
Still bottoms 520 100
Evaporated
1,1,1-trichloroethane 44,360 100
$21,280
$60,490
2.8
Replace the cutting fluid
currently used in the
broaches with a vegetable-
OS based spray coolant system.
When used properly, the pro-
posed oil is consumed com-
ptBtety during cutting.
Spent cutting fluid
Reusable cutting fluid
227,000
40,000
22
22
5,680
11,000
1.9
It was estimated that a total of 77,000 Ib/yr of waste nonhazardous cleaning solution and rinse water will be
generated if this opportunity is implemented.
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United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/S-94/004
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