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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. 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That document has been superseded by the Facility Pollution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 Louisville performed an assessment

at a plant that manufactures automotive lighting equipment and

accessories. Plastic, metal, glass, and composite-component

products are assembled by the plant. Raw materials include

coils of metal, paint, solvents, oils, coolants, light bulbs, glass

and mirrors, plastic resins, wiring, and wire terminals. Plant

operations include plastic injection molding, metal pressing and

punching, painting, and assembly. The team’s report, detailing

findings and recommendations, indicated that a significant

amount of waste is generated through the stripping of paint

hooks and parts and that the greatest cost savings could be

achieved by installing a plastic media blasting paint stripper.

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

Risk Reduction Engineering Laboratory, the Science Center

has established three WMACs. This assessment was done by

engineering faculty and students at the University of Louisville’s

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.

Pollution Prevention Assessment for a Manufacturer of Automotive

Lighting Equipment and Accessories

ENVIRONMENTAL

RESEARCH BRIEF

Marvin Fleischman*, Brian Couch*, Alan Handmaker*,

and Gwen P. Looby

E AP

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/012 August 1995

* University of Louisville, Department of Chemical Engineering

** University City Science Center, Philadelphia, PA
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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

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

This plant produces automotive products, including lamps, mirrors, flashers and switches, wiring systems, and emergency

warning equipment.

Manufacturing Process

Numerous plastic, metal, glass, and composite-component products are assembled by the plant. Operations include plastic

injection molding, metal pressing and punching, painting, and

assembly. Raw materials used by the plant include coils of

metal, paint, solvents, oils, coolants, light bulbs, glass and

mirrors, plastic resins, wiring, and wire terminals. The various

production operations used by the plant are described in the

following sections.

Metal Working Operations

In the metal working area, several single-station and two multistation metal presses perform blanking, drawing, bending,

punching, or breaking of metal sheets or tubing. A small amount

of tapping of pressed and cast metals is also done. Drawing

oils, cutting lubricant, and rust-proofing compounds may be

applied automatically or manually prior to metal working. As a

result of the necessary lubrication, parts must be washed

before they are painted, used in assembly, or packaged and

sold.

Wire Harness Fabrication

Wiring is cut to appropriate lengths and the plastic insulation

surrounding the wires is stripped off at each end of the wiring

prior to terminating or molding. Workers attach terminals to the

wires for assembly. In the shuttle molding process, some of the

wires are bundled together and the terminals are placed in a

mold into which PVC is injected. A junction block that provides

sealed, plug-in connection ports for other wires is thus formed.

Plastic Injection Molding

Various thermoplastics, including nylons, acrylics, polycarbonates, polypropylenes, and acrylic-butadiene-styrene, are processed according to customer specifications. Plastic pellets are

transferred pneumatically from storage boxes to heated driers

above the injection-molding presses. The pellets are melted in

a screw injection molder and injected into the mold. Sprues

and runners from the finished parts are reground and returned

to the hopper above the press, when possible.

Metal Painting

Several different solvent-based paints are used for painting

metal parts. In general, the painting campaigns for metal parts

last between a half-hour and several days.

Metal parts that are to be painted are first placed on an

overhead conveying system that carries them through a sixstage pretreatment system to remove oils from metal working

and to undergo surface preparation by chemical treatment. The

six stages are an aqueous alkaline cleaner, a rinse, an iron

phosphate-phosphoric acid chemical conversion coating for

rust prevention and paint adhesion enhancement, another rinse,

a chromating seal, and a final rinse.

After the six-stage treatment, the parts pass through a compressed air blow-off and air-knife, and then enter a drying

oven. The parts are allowed to cool and then are sent to the

first paint booth and then through a second booth where the

other side is painted. The majority of the paint overspray in

these two booths is collected in a waterfall. The parts are

allowed to air dry for a short time and then enter a hand-spray

touch-up booth.

The painted metal parts then go through the direct-fired oven,

are allowed to air cool, and are removed from the hangers.

Parts are placed in boxes and stored for later use in assembly

operations. Some painted parts are put in final packaging for

shipment from the warehouse.

Plastic Painting

The plastic parts painting operation consists of five separate

paint lines which are usually cleaned out daily.

Solvent-based acrylics, lacquers, and two-component urethanes

and epoxies are used in plastic painting. Preparation of plastic

parts for painting is not needed because the parts are clean

when received for painting.

Assembly

A variety of assembly operations, including fastening, crimping,

terminating, boring, drilling, reaming, and stapling, are performed in the assembly lines for a variety of products. Assembly operations may be automated or manual.

In a typical assembly operation, parts are unpacked from

various storage containers and placed on a conveyor belt.

Smaller parts are attached to the main housing as the part

moves down the line. Assembly may consist of attaching a wire

harness or other subassembly to the main housing. Bonding is

done using various techniques such as hot melting, sonic

welding, hot-knife welding, and mechanical bonding. Lamps

are soldered to wires or conductors. Brazing is used for bonding terminals to a lamp in a specific product assembly line.

Next, the assembly is tested by plugging it into an electric

outlet prior to final bonding and sealing. The part then undergoes final bonding with glue, is sealed with grease, and is

submerged in water for testing. In the mirror assembly opera-
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tions, glass is placed inside a painted rubber ring and is

crimped using a press or glued into housings.

An abbreviated process flow diagram depicting the manufacture of automotive lighting equipment is shown in Figure 1.

Existing Waste Management Practices

This plant already has taken the following steps to manage and

minimize its wastes:

• Some waste cardboard is baled and recycled.

• Scrap metal and plastic are collected and sold.

• A portion of the rejected plastic parts is reused.

• Shipping containers and packaging is reused, when possible.

• Unwanted pallets and skids are given away to a shelter

workhouse for rebuilding.

Plant personnel are currently evaluating the following options

for managing and minimizing plant wastes:

• Alternatives to caustic and methylene chloride paint stripping, such as plastic media blasting are being considered.

• The plant is considering participating in a local pallet and

packaging waste exchange.

• A central chiller is to be installed to replace portable chillers

that tend to generate waste oil emulsions from ethylene

glycol losses from connection and disconnection.

• The purchase of a softwood denailing/chipping machine is

being considered to provide materials from waste pallets

which may be useful elsewhere.

• The use of a laundry service for the cleaning and subsequent

reuse of rags is being considered.

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 waste management 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 payback

Assembly

Placement

of

Subassembly

on Part

Bonding

Testing

Sealing

Final

Assembly

Finished Parts to

Packaging and Shipping

Metal

Painting

Wire

Harness

Fabrication

Plastic

Painting

Metal

Working

Plastic

Molding

Incoming

Materials

Figure 1. Abbreviated process flow diagram for manufacture of automotive lighting equipment.
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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 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 would result when the opportunities are implemented in a

package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, several additional measures were considered. These measures were not analyzed completely because

of insufficient data, minimal savings, implementation difficulty,

or a projected lengthy payback. Since one or more of these

approaches to pollution prevention may, however, increase in

attractiveness with changing conditions in the plant, they were

brought to the plant’s attention for future consideration.

• Recover solvent from the cleaning of paint lines and guns

instead of spraying it into the water curtains and emitting it to

the atmosphere. Reuse the solvent if it is sufficiently clean or

dispose of the waste through the waste fuels program. This

opportunity would lead to reduced discharges to the POTW

and reduced fugitive emissions, stack emissions, and worker

exposure.

• Instead of landfilling waste pallets, grind the waste into wood

chips and mulch in cooperation with the local recycling

roundtable.

• Use dedicated dispensers for oil changeouts and dedicated

buckets for leaks from oil drums in the metal working area

instead of using unsegregated waste oil drums and buckets.

• Reuse packaging in cooperation with customers and suppliers to reduce the amount of packaging waste generated.

• Minimize the number of waste paint drums that must be

disposed of by purchasing paint in 330-gallon returnable

totes.

• Reduce evaporative losses from metal part painting pretreatment tanks by keeping lids closed.

• Use permanent washable filters in the paint booths instead of

disposable filters.

• Replace the current painting system for metal parts with one

that would generate less solvent-containing waste and fewer

air emissions. (The plant is in the process of implementing

this change.) Consider replacing the painting system for

plastic parts also.

• Investigate further opportunities for waste recycling.

• Replace hot caustic and methylene chloride with a nonhazardous solvent for stripping.

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. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.
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Table 1. Summary of Current Waste Generation

Waste Generated Source of Waste Waste Management Method Annual Quantity Annual Waste

Generated (lb/yr) Management Cost*

Scrap metal Metal working operations, rejected parts

and customer returns, other operations Segregated; sold to scrap dealer 732,000 $-27,330

Brazing waste Brazing/soldering operations in assembly area Shipped offsite to be fixed in concrete; landfilled 2,000 1,750

Brazing gloves Brazing/soldering operations in assembly area Incinerated offsite 400 1,000

Packaging waste Incoming shipments of raw materials Given away for refurbishing 52,500 0

(wooden pallets and skids)

Packaging waste (cardboard, Incoming shipments of raw materials Landfilled offsite 2,344,500 24,570

wooden pallets, fiber drums,

paper spools, pails)

Packaging waste (drums) Incoming shipments of raw materials Shipped offsite to be crushed for scrap 3,000 2,250

Packaging waste (drums) Incoming shipments of raw materials Returned to supplier 7,000 0

Waste absorbents Collection of liquid leaks in plant Shipped offsite to fuels program 50,200 42,350

Aqueous wastes Leaks from equipment, centrifugal separator, Shipped offsite as hazardous waste

metal plating, chromating to disposal facility 61,870 8,670

Aqueous wastes Metal parts painting pretreatment, paint Drained to POTW 251,400 20

booth water curtain

Oil wastes Oil changeouts, dispensing losses, drips, leaks Shipped offsite to fuels program 4,500 780

Oil wastes Skimming of paint pretreatment wash tank Drained to POTW 6,230 10

and stainless steel wash tank

Oil wastes Hydraulic oil leaks from turbines, compressors, Shipped offsite as hazardous 6,610 1,250

and hydraulic presses waste to disposal facility

Oily rags Cleaning Landfilled offsite 5,200 70

Plastic waste (contaminated Bonding operations Ground; sold to recycler 20,000 -600

and rejected composite parts) (net revenue rec’d)

Plastic waste Customer returns Ground; sold to recycler or landfilled offsite 11,500 not available

Plastic waste (insulation, Stripping and terminating operations, wire harness Landfilled offsite 13,420 730

cable scrap, foam) operations, injection molding, and assembly

Solvent waste Paint line and paint gun cleaning, paint equipment Shipped offsite to be used as fuel 35,640 11,210

and fixture cleaning, paint stripping

Evaporated solvent Fugitive and stack emissions Evaporates to atmosphere 17,010 0

Solvent waste Paint stripping and parts washing Shipped offsite for recovery 18,720 20,800

Paint waste (obsolete paint, Metal and plastics paint spray booths Shipped offsite to be used as fuel 57,270 37,650

overspray, plastic sheet,

paint solids, filters)

Paint waste (water/paint) Plastics paint spray booth Incinerated offsite 11,690 14,500
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Table 1. (continued)

Waste Generated Source of Waste Waste Management Method Annual Quantity Annual Waste

Generated (lb/yr) Management Cost*

Paint waste (paint overstocks) Plastics parts painting Returned to supplier for reworking 1,000 $2,250

Paint waste (stripper solids) Metal parts painting Shipped offsite as hazardous waste to disposal facility 2,200 1,000

Grease Assembly operations Landfilled offsite 1,440 20

Ink waste Label printing Shipped offsite to be used as fuel 375 60

Miscellaneous solid waste Various operations Landfilled offsite 722,180 18,780

*

Includes waste disposal costs.

 It is estimated that an additional $119,000/yr is spent on waste management costs such as labor, administration, and record keeping.

Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

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

Replace the hot caustic and Solvent waste shipped offsite 1,320 7 $48,850 $10,800 0.2

methylene chloride strippers used for recovery

for stripping paint hooks and paint- Solvent waste shipped offsite 6,000 10

ed parts with a plastic media blast- to be used as fuel

ing paint stripper. Implementation Evaporated solvent 40 0.2

of this opportunity will lead to the Paint waste (stripper solids) 2,200 100

generation of a nonhazardous

waste stream of paint chips and

spent plastic media.

Replace existing VMF naphtha Solvent waste shipped offsite 17,400 93 14,050 4,150 0.3

parts washers with environ- for recovery

mentally preferred solvent

washers. Purchase three new

parts washers to replace the

three washers leased by the plant.

Replace the VMF naphtha in all

five washers with the preferred

solvent.

Replace the existing VMF naphtha Solvent waste shipped offsite 17,400 93 11,510 0 0

parts washing service with one for recovery

that uses petroleum naphtha. The

recommended service offers a program in which spent mineral spirits

are used directly in asphalt manufacturing.

Use wringable reusable absorbents Waste absorbents 10,040 20 21,260 6,270 0.3

and a manual wringer in the metal

working and injection molding areas

for pick-up of oil from spills.
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Table 2. (continued)

Annual Waste Reduction

Net Annual Implementation Simple

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

Contract with a new waste collection Solid waste 0 —- $2,040 $170 0.1

service that recovers recyclables

from the trash. The generation of

solid waste at the plant site will

not be reduced, but the quantity

of waste landfilled will be reduced.

Purchase and install cardboard Packaging waste (cardboard) 0 —- 18,060 14,600 0.8

balers to permit baling of the scrap

cardboard from the plant. Cardboard recovered from the solid

waste can be sold as scrap. Implementation of this opportunity

will not reduce the generation of

solid waste at the plant site, but it

will reduce the quantity of waste

landfilled.

Improve the segregation of scrap Scrap metal 0 —- 4,710 6,450 1.4

metal that is sold to the scrap metal

dealer in order to increase the

revenue the plant receives.

Implementation of this opportunity will not lead to reduced waste

generation at the plant.

Sell all pallets which cannot be reused Packaging waste (wooden pallets) 0 —- 1,750 0 0

by the plant to a pallet broker/rebuilder.

Implementation of this opportunity will

reduce the amount of pallets being

landfilled.

Place the waste material from the Plastic waste (foam) 0 —- 690 0 0

gaskets used in the assembly area

on a waste exchange. Implementation of this opportunity will reduce

the quantity of solid waste landfilled.

Use paint pigs in the tank containing Paint waste (water/paint) 4,470 38 6,890 0 0

recirculated water from the lacquer

line to absorb the paint overspray.

The saturated pigs can be disposed

of through a fuels program and the

water can continue to be incinerated,

but less frequently.
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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-95/012