United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-94/018 September 1994
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer of
Electrical Rotating Devices
Richard J. Jendrucko*, Thomas N. Coleman*,
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ment has been superseded by the Facility Pollution Prevention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 several varieties of electrical rotating de-
vices. Metal stock is machined, cleaned, and surface-treated if
required. Laminations, which are used in rotor, stator, and
stepper assemblies, are manufactured in-house from strip stock.
Rotors, stators, and steppers are manufactured through a se-
ries of operations and are then assembled into the finished
devices. The team's report, detailing findings and recommen-
dations, indicated that spent solutions from the four-stage aque-
ous cleaner are the waste streams generated in the greatest
quantity and that significant cost savings could be achieved by
discontinuing the use of Freon™ vapor degreasing for precision
parts 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.
* University of Tennessee, Department of Engineering Science and Mechanics,
Knoxville, TN
** 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 the University of Tennessee WMAC.
The assessment teams have considerable direct experience
with process operations in manufacturing plants and also have
the knowledge and skills needed to minimize waste genera-
tion.
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.
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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
Several varieties of electrical rotating devices are manufac-
tured by this plant. It operates over 4,000 hr/yr to produce
more than 250,000 units annually.
Manufacturing Process
Carbon and stainless steel, aluminum, brass, and copper bar
stock, nickel strip stock, plastic powder, fiberglass pellets, and
powdered metal are the principal raw materials used in produc-
tion.
The various types of metal bar stock are machined into compo-
nent parts using automatic screw machines. Metal shafts that
are produced are sent to the four-stage aqueous cleaner con-
sisting of an alkaline wash tank, two rinse tanks, and a rust
inhibitor rinse tank for carbon steel parts. Other parts produced
by the screw-machines are machined further and then washed
in the four-stage cleaner. Stainless steel and aluminum parts
undergo surface treatment after cleaning.
Almost all of the stainless steel parts and all of the aluminum
parts undergo a protective surface treatment to prevent corro-
sion. The stainless steel parts are submerged in a passivating
bath, rinsed, dried, and cleaned in an ultrasonic vapor de-
greaser. Aluminum parts are submerged in a chromium dioxide
solution and rinsed.
Laminations, which are used individually in rotor assembly and
stacked and fixed together in stator and stepper assemblies,
are produced in the plant. Individual laminates are cut from
strip stock in a punch press and then washed in the four-stage
washer and heat-treated. The laminations are transferred indi-
vidually to the rotor assembly area or to spray painting, or are
stacked and held in place by shrink wrap or by welding. The
welded laminates are then sent to painting, and unwelded
stacks are transferred to the stator and stepper assembly area.
Injection molding machines are used to press plastic insulating
rings onto metal shafts and to press fiberglass pellets, plastic
powder, and powdered metal into various component parts.
The resulting parts are stored until needed for assembly.
In the rotor and stator assembly line, individual laminations are
pressed onto metal shafts. Magnet wire is machine-wound
onto the laminations and onto painted and unpainted laminate
stacks. An insulating coating is manually stripped from the end
of the contact wires using a stripping compound. Then, the
stripped wires are welded to a contact point. The wire coils are
impregnated with epoxy and oven-cured to fix the coils to the
laminations. The resulting rotors and stators are machined,
washed in the four-stage cleaner and in an ultrasonic vapor
degreaser, and transferred to final assembly.
For use in stepper assembly, laminate stacks are preheated in
an oven and powder-coated in a fluidized bed. The parts are
cured in an oven and, after manual removal of excess coating,
cleaned in an ultrasonic vapor degreaser. Magnet wire is wound
onto the laminate stacks. Insulating coating is manually stripped
from the end of the contact wires with a stripping compound
and the stripped wires are welded to a contact point. The wire
coils are impregnated with epoxy and oven-cured to fix the
coils to the laminations. The resulting steppers are machined,
washed in the four-stage aqueous cleaner and in an ultrasonic
vapor degreaser, and transferred to final assembly.
In the final assembly area, a bearing is inserted into a housing
at one end of the stator or stepper. The insulating ring end of
the rotor is inserted into a bearing plate. The rotors are matched
with stators and steppers and inserted into them. The bearing
plates are fastened, and a brushblock is fastened to ring
contacts on the rotors. The completed units are tested, the
motor housings are wiped clean and stamped with identifying
markings, and the finished parts are packaged and shipped.
The flow diagrams shown in Figures 1-7 depict the operations
used by this plant.
Existing Waste Management Practices
This plant already has implemented the following techniques to
manage and minimize its wastes:
• Distillation units are used to recover usable TF-Freon™ from
contaminated Freon™ in the plant's vapor degreasers.
• An in-drum waste compactor is used to reduce the volume
and disposal cost of paper towel waste.
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 treatment and disposal cost for each
waste stream identified 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 simple payback time are given in the table. The
quantities of waste currently generated by the plant and pos-
sible waste reduction depend on the production level of the
plant. All values should be considered in that context.
It should be noted that the economic savings of the minimiza-
tion opportunity, in most cases, results from the need for less
raw material and from reduced present and future costs asso-
ciated with waste treatment and disposal. Other savings not
quantifiable 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
implementing each waste minimization opportunity indepen-
dently and do not reflect duplication of savings that may result
when the opportunities are implemented in a package.
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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.
Metal bar
stock
Metal parts
to stock
Machining
Other
metal
parts
Metal shafts
4-stage
aqueous
cleaning
Lathing
Precision
grinding
Stainless
steel
parts
to stock
Ultrasonic
vapor
degreasing
Passivating
Stainless
steel
parts
Anodized
aluminum
parts to
stock
Chromium
anodizing
Aluminum
parts
Figure 1. Process flow diagram for machining and surface metal treatment.
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Contact
wires
Gold
rings
Metal
shafts from
stock
Assembly
Molded plastic
parts to
assembly
Fiberglass
pellets,
powdered
metal,
plastic
powder
T
Injection
molding
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trimming
Metal shafts
with insulating
ring to assembly
Figure 2. Process flow diagram for injection molding.
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strip stock
Cutting
4-stage
aqueous
cleaning
In
lar
Annealing
Individual
laminations
Welded
laminate
stacks
Laminate
stacks
Figure 3. Process flow diagram for laminate production.
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Individual
laminations
Shafts with
insulating
ring
Magnet
wire
Assembly
Coil
winding
Stripping
Painting
Soldering
Epoxy
impregnating
Ultrasonic
vapor
degreasing
4-stage
aqueous
cleaning
Precision
grinding
Curing
Rotors to assembly
Figure 4. Process flow diagram for rotor manufacture.
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Magnet
wire
Motor
housing
Laminate
stacks
Painting
Coil
winding
Painting
Stripping
Soldering
Assembly
4-stage
aqueous
cleaning
Precision
grinding
Curing
Epoxy
impregnating
Ultrasonic
vapor
degreasing
Stators to assembly
Figure 5. Process flow diagram for stator manufacture.
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inate
cks
^
Preheating
^
Powder
coating
^
Curing
Assembly
Coil
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vapor
degreasing
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Soldering
Assembly
^
Epoxy
impregnating
Ultrasonic
vapor
degreasing
4-stage
aqueous
cleaning
Precision
grinding
Curing
Steppers to assembly
Figure 6. Process flow diagram for stepper manufacture.
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Rotors
stators
steppers
Subassembly
Fastening
Testing
T
Finished motors shipped
Figure 7. Process flow diagram for motor assembly.
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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-94/018
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