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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 That document has been superseded by the Facility Pollution Prevention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 various types of metal fasteners for

automobiles, furniture, and appliances. Products are manufactured from steel, brass, copper, and aluminum wire and rod

stock in two production lines—large part production and small

part production. In large part production, header machines

press wire stock into specific product shapes which are washed,

machined, and in some cases heat-treated and polished. Small

parts are manufactured from wire and rod stock in a series of

machining operations, then washed, heat treated and polished,

before shipment to an outside firm for surface finishing. The

team’s report, detailing findings and recommendations indicated that a large amount of plant oil waste is shipped off-site

for fuels blending and a significant quantity of oily sludge waste

is shipped offsite for disposal as non-hazardous waste. Large

cost savings can be achieved by the plant through the use of

alternative methods of removing metal chips from parts, thereby

reducing intermediate washings.

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’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 experiPollution Prevention Assessment for a Manufacturer of

Metal Fasteners

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-95/016 August 1995
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ence 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

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

The plant produces various types of metal fasteners for automobiles, furniture, and appliances. It operates 6,000 hr/yr to

produce over 100 million parts annually.

Manufacturing Process

The plant’s products are manufactured from steel, brass, copper, and aluminum wire and rod stock in two production lines—

large part production and small part production.

In the large part production line, wire stock is fed automatically

into header machines in which it is pressed into specific product shapes. The formed parts are transported to a four-stage

aqueous parts washer where residual machining oils and metal

chips are removed. Then the cleaned parts undergo a series

of secondary machining operations including drilling, roll threading, and turning. Parts are rewashed during secondary machining in order to remove metal chips that could interfere with

subsequent machining steps. After machining is complete, the

parts are sent to auditing for inspection or to the heat treatment

area which includes a single-stage wash, a high temperature

heat-treat oven, an oil quench, and a draw furnace for stress

relief. Heat treated parts are polished in a vibratory finisher.

Finally, finished parts are inspected for defects, packaged, and

shipped to customers.

Small parts are manufactured from wire and rod stock in a

series of machining operations. The stock is drawn and sized

and fed into header machines where specific parts are formed.

The formed parts are cleaned in a two-stage drum washer

where residual lubricant and metal chips are removed. A series

of secondary operations, including drilling, tapping, and trimming specific to the product being manufactured, completes

the required machining.

After most secondary operations, parts are rewashed in the

two-stage drum washer to remove metal chips that could interfere in subsequent machining steps. Then, parts are heattreated onsite, sent to an outside company for surface finishing, or sent to auditing. Heat-treated parts are polished to

remove scale and sent to an outside company for surface

finishing. Finally, completed parts are inspected, packaged,

and shipped to customers.

An abbreviated process flow diagram for this plant is shown in

Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• An ultrafiltration unit is used to treat oil wastewater onsite.

Treated water is reused.

• Water is separated from waste oil in order to make the oil

usable for fuels blending offsite.

• A water evaporator is being installed to evaporate excess

wastewater that currently is shipped offsite for treatment.

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,

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 financial savings of the opportunity,

in most cases, results 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

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 pollution

prevention opportunity reflect the savings achievable when

implementing each opportunity independently and do not reflect duplication of savings that would result when the opportunities are implemented in a package.

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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LARGE PARTS

SMALL PARTS

Wire Stock

Wire and Rod Stock

Headers

4-Stage Washing

Secondary Machining

4-Stage Washing

Heat Treating

Vibratory

Finishing

Auditing

Drawing and Sizing

Headers

2-Stage Washing

Secondary Machining

2-Stage Washing

Heat Treating

Polishing

Shipped Offsite for

Surface Finishing

and Returned

Auditing

Parts Packaged and

Shipped to Customers

Parts Packaged and

Shipped to Customers Figure 1. Abbreviated process flow diagram for metal fasteners manufacture.

Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Generated Source of Waste Waste Management Method Generated (lb/yr) Management Cost*

Petroleum naphtha Machine part cleaning Shipped offsite for recycling 9,930 $17,663

Oily sludge Header clean-out Shipped offsite as

nonhazardous waste 50,000 27,473

Miscellaneous solid waste General plant operation Shipped offsite to landfill 500,000 10,100

Waste Oil Machine clean-out and

wastewater treatment Shipped offsite for fuels blending 82,000 17,250

Scrap metal Scraps and rejected parts

from all operations Shipped offsite for recycling Not available 6,500

Waste water Various processes Shipped offsite for treatment 448,200 42,600

* Includes waste treatment, disposal, and handling cost, and applicable raw material 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) Percent Savings Cost Payback (yr)

Discontinue intermediate washing Wastewater 224,100 50 $19,1731 $5,820 0.3

between machining operations. As

an alternative, install lubricant baths

for dipping of parts for metal chip

removal.

Discontinue intermediate washing Wastewater 224,100 50 19,1731 2,020 0.1

between machining operations.

As an alternative, use compressed

air to blow off metal chips.

Eliminate the use of petroleum Petroleum naphtha 9,930 100 15,663 0 Immediate

naphtha for machine part cleaning.

Instead, use the 4-stage washer

for machine part cleaning. No

additional expense/waste is expected because of the low volume

of machine parts that require

washing.

Replace disposable paper towels Miscellaneous solid 25,000 5 11,5791 5,400 0.5

with cloth rags that can be waste

laundered onsite and reused.

Construct collection troughs around Miscellaneous solid 32,000 6 8,424 2,000 0.2

leaky machines to reduce use of ab- waste

sorbent “socks” for containment of

leaks.

Utilize a cartridge filtration unit to Waste oil 26,782 33 6,6931 1,500 0.2

remove dirt and metal fines from

waste oil so that it can be reused

onsite as lubricating oil in the headers.

1 Total annual savings have been reduced by an annual operating cost required for implementation.

EPA/600/S-95/016

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Penalty for Private Use

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United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

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