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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 manufacturers Waste Minimization Assessment Centers (WMACs) were

established at selected universities and procedures were

adapted from the EPA Waste Minimization Opportunity Assessment Manual (EPA/625/7-88/003, July 1988). That document has been superseded by the Facility Pollution Prevention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 outboard motors for water craft. Three

basic subunits received from other manufacturing plants undergo primarily painting and assembly operations in order to

produce the final product. The team’s report, detailing findings

and recommendations, indicated that paint overspray waste

and spent clean-up solvent are generated in large quantities

and that significant cost savings could be achieved by installing

robotic paint application equipment.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research Laboratory, 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 become 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 (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 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 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 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.

Methodology of Assessments

The pollution prevention opportunity assessments require several site visits to each client served. In general, the WMACs

follow the procedures outlined in the EPA Waste Minimization

Pollution Prevention Assessment for a Manufacturer of

Outboard Motors

ENVIRONMENTAL

RESEARCH BRIEF

Richard J. Jendrucko*, Thomas N. Coleman*, and

Gwen P. Looby**

* University of Tennessee, Department of Engineering Science and Mechanics

* University City Science Center, Philadelphia, PA

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/018 September 1995
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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 supporting technological and economic information is developed. Finally, 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

Approximately 140,000 finished water craft outboard motors

are manufactured by this plant, which is a final assembly

facility. It operates 2,000 hr/yr.

Manufacturing Process

Three basic subunits received from other manufacturing plants,

component parts, hardware, paint and primer, and decals are

used to produce the outboard motors. The production operations required can be classified as lower-unit subassembly,

power-head subassembly, motor cover subassembly, and final

assembly. Each of the production operations will be described

here.

Lower-unit Subassembly

The lower units, which are received in two parts, are bolted

together in this plant. First, the connection surface on each

part is polished and then a primer coating is applied. After

coating, the part surfaces are cleaned manually.

Lower-unit subassemblies are then sent through a five-stage

washer in preparation for painting. Following the final rinse of

the five-stage washer, water is removed from internal surfaces

and cavities with pressurized air. Masking is applied to protect

areas of the lower units that do not require painting and then

the subassemblies are conveyed through a dry-off oven for

further water removal.

Primer is applied in one of two primer spray booths where the

required coating is manually applied with electrostatic spray

guns. The subassemblies are then conveyed through a curing

oven. Next, the units are cleaned and conveyed through one of

the topcoat spray booths where the final cosmetic coating is

manually applied. The subassemblies are then conveyed

through a final curing oven.

The finished lower units are inspected for defects and any

rejected units are rewashed and repainted. Masking is manually removed from accepted parts, which are transferred to final

assembly.

Power-head Subassembly

Various types and sizes of power heads (internal combustion

engines) are received in almost ready-to-use condition. Various parts including carburetors, solenoids, and starters are

bolted onto the power head subassemblies using metal fasteners that have been dipped in a lubricant. The power-head

subassemblies are then transferred to the final assembly area.

Motor Cover Subassembly

Motor covers are received as unpainted fiberglass shells. The

shells are processed through a three-stage washer for grease

and dirt removal. Next, the clean motor covers are conveyed

through a spray paint booth where primer is manually applied

with high-volume low-pressure spray guns. The primer is then

cured in an oven.

Following primer curing, the covers are conveyed through one

of two spray booths where either a basecoat or a topcoat is

applied. The motor covers that receive basecoat paint are

conveyed through a flash-off tunnel, where some drying occurs, to one of two clearcoat paint booths where a clear finish

is applied over the basecoat.

Motor covers from the clearcoat booths and covers from

topcoating are conveyed through an oven for curing. The

completed motors are inspected for coating imperfections and

rejected covers are transferred to a sanding booth and then

back to the 3-stage washer for reprocessing. Accepted covers

are transferred to a motor cover detailing operation where

decals and molding are attached manually. The finished covers are transferred to final assembly.

Final Assembly

In final assembly, power heads are bolted onto lower units

which are then filled with gear-case oil. The assembled motors

are tested in water tanks. Units that fail testing are repaired

and retested. Accepted motors are degassed using compressed

air.

Finally, the motor covers are placed over the power-heads and

attached to the power units. The completed motors are then

spot-cleaned as needed and any required touch-up painting is

performed. Finished motors are packaged and shipped to

customers.

An abbreviated process flow diagram for outboard motor manufacture is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• Wet scrubber paint booths have been converted to a dry filter

system in order to eliminate the generation of a wastewater

stream containing hexavalent chromium.

• The cleaning process for small paint pots has been converted

from a simple solvent rinse to an automatic solvent spray

cleaning system in order to reduce the quantity of solvent

used.

• A crank-case oil waste stream has been eliminated by

collecting spills and drips and reusing them.

• Approximately 50% of raw material shipments are received

in reusable packaging.

• Cardboard packaging and office paper are recycled.

• Clearcoat paint application has been converted to robotic

paint application in order to achieve increased paint transfer

efficiency and improved coating appearance.

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.
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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 the economic savings of the opportunity, in most cases, results from the reduction in raw material

and from reduced present and future costs associated 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 that pollution prevention opportunity

only and do not reflect duplication of savings that may result

when the opportunities are implemented in a package.

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. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.
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2-part Lower Units

Bolt-up 5-Stage

Washer

Pre-paint

Preparation

Primer

Application

Topcoat

Application

Inspection

Completed

Lower Units

Power

Heads

Add-on

Parts

Bolt-on

Completed

Power Head

Units

Fiberglass

Motor Covers

3-Stage

Washer

Pre-paint

Preparation

Primer

Application

Basecoat &

Topcoat

Application

Clearcoat

Application

Completed Detailing Inspection

Motor Covers

Power

Hook-up

Testing

SpotCleaning

and

Touch-up

Head Finished

Product

Figure 1. Abbreviated process flow diagram for outboard motor production.
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Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Stream Generated Source of Waste Waste Management Method Generated (lb/yr) Management Cost1

Cardboard packaging material Incoming materials Baled; shipped offsite for recycle 500,000 $ -2,800

(net revenue received)

Waste chromate material Lower-unit bolt up, primer application Shipped offsite for disposal 67,530 115,530

Evaporated clean-up solvent Cleaning of subassemblies, paint and Evaporates to plant air 21,400 0

primer lines, and finished units

Rinse water Five-stage washer Sewered 11,765,250 2,100

Waste paint-related material Painting of subassemblies Shipped offsite for disposal 4,200 13,215

Evaporated paint carrier solvent Painting of subassemblies Evaporates to plant air 114,060 0

Spent clean-up solvent Cleaning of paint lines and equipment Shipped offsite for recycling 122,310 61,160

Spent air filters and paint arrestors Paint booths for subassemblies Incinerated onsite 117,630 19,740

Spent “wool grease” lubricant Lubrication of fasteners Shipped offsite for disposal 480 1,220

Evaporated water Three-stage washer Evaporates to plant air 1,120,500 0

Rinse water Three-stage washer Sewered 3,921,750 650

Gasoline/water Motor degreasing following testing Shipped offsite for use in fuels blending 5,400 2,280

Unused paint Painting of subassemblies Shipped offsite for disposal 2,860 3,270

Miscellaneous solid waste Various plant operations Shipped offsite to landfill 4,860,000 14,760

1Includes waste treatment, disposal, and handling costs.
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Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Reduced Quantity (lb/yr) Per Cent Savings Cost Payback (yr)

Convert all manual spray painting operations to Waste chromate material 16,640 25 $1,104,8001 $2,139,100 1.9

robotic paint application. Spent air filters and paint arrestors 85,340 73

Convert to electrostatic painting in topcoat spray Waste chromate material 17,530 26

booths and improve electrostatic painting in Spent air filters and paint arrestors 34,320 29 290,018 34,840 0.1

lower-unit primer booths.

Determine an optimum painting schedule to Spent clean-up solvent 48,500 40 34,580 15,000 0.4

reduce the quantity of waste solvent generated

as a result of color changes.

Use compressed air to blow topcoat and base- Spend clean-up solvent 24,250 20 27,350 2,570 0.1

coat paint remaining in individual paint gun

distribution lines back into recirculating

paint lines.

Recover spent clean-up solvent onsite using a Spent clean-up solvent 122,310 100 24,430 66,460 2.7

distillation unit. A small quantity of still bottoms

will be generated and shipped offsite as hazardous waste if this opportunity is implemented.

Replace air filters and paint arrestors on an Waste chromate material 4,754 7 21,164 0 0

“as-needed” basis only. Spent air filters and paint arrestors 23,526 20

Purchase coatings in 300-gal reusable totes Waste paint-related material 2,100 50 6,420 0 0

instead of 5-gal containers that are currently

disposed of as hazardous waste.

Reuse waste gasoline for subsequent Gasoline/water 5,400 100 1,220 0 0

motor tests.

1Includes labor cost savings.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/018