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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 That document has been superseded by the Facility Pollution Prevention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 piston rings. Steel and iron rings are

machined, chrome-plated or coated, machined again, cleaned,

and shipped to customers. The assessment team’s report,

detailing findings and recommendations, indicated that wastewater and wastewater treatment sludge are the waste streams

generated in greatest quantity and that the greatest cost savings could be achieved by modifying the method of masking

the rings prior to chrome plating.

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 (Knoxville) 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

Combustion Engine Piston Rings

ENVIRONMENTAL

RESEARCH BRIEF

Richard J. Jendrucko*, Todd M. Thomas*, 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-95/015 August 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

This plant produces piston rings that are used in diesel engines. Almost four million piston rings are produced by the

plant each year during 6,000 hr of production.

Manufacturing Process

Each of the major processes used by this plant—piston ring

machining and hard chrome electroplating—is described here

in detail.

Piston Ring Machining

The necessary raw materials, steel and ductile iron rings, are

received and stored until needed in production. To begin

production, approximately 100 rings are placed on a steel rod

for ease of processing. Next, the rings enter a sequential

machining line where they are blank-turned, bored, slot-milled,

and finish-turned. After these initial machining operations, the

rings are separated according to their final use as bottomrings, top-rings, or intermediate-rings, and further processed as

required.

Following these machining operations, approximately 95% of

the rings are prepared for chrome plating. First, those rings

are degreased to remove protective oils and machining residue. Then the inside ring surfaces are masked using lacquerbased paint film to prevent chrome plating on those surfaces.

After paint masking, the outer ring surfaces are grit blasted to

enhance chrome adhesion during plating. The final step is

removal of grit blast residue using a high-pressure spray-wash.

The rings are then transported to the chrome-plating process.

The other 5% of the rings are prepared to receive a magnesium phosphate coating in a hot water wash for removal of

remaining machining debris and protective oils. The rings are

then dipped into the magnesium phosphate tank. After the

coating has dried the rings are dipped in rinse tanks for removal of residual coating solution. Depending on their final

use, the coated rings undergo additional machining and grinding. The rings are then cleaned in solvent, marked with

identification numbers, cleaned again, dipped in a rust preventative, and shipped to customers.

Chrome Electroplating

The plant’s plating line operation is semi-automated. Use of a

computer reduces human error and standardizes plating operations.

A heated sulfuric acid etch is the first tank in the plating line.

The etch is used to enhance the ring’s surface to facilitate

chrome adhesion. Following etching, the rings are rinsed and

placed in one of four heated chromic acid plating tanks. Residence time varies according to the type and thickness of

chrome deposit required.

Next, the rings are rinsed in a cold water rinse tank and then

with a high-pressure water spray. Masking paint on the inside

ring surfaces is removed by dipping the rings into a series of

tanks containing paint stripping agents and water rinses. The

rings are then dipped in a tank containing rust inhibitor solution. Inspection of the rings for proper chrome application is

done next. Unacceptable rings are stripped of chrome and

replated.

After chrome plating the rings are machined and ground as

needed. The rings are then cleaned in solvent, marked with

identification numbers, cleaned again, dipped in a rust preventative, and shipped to customers.

An abbreviated process flow diagram for piston ring manufacture is shown in Figure1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• Personnel from the plant’s parent corporation conduct a

waste assessment each year to specify waste reduction

measures for the facility.

• A local university performed a waste audit for the plant

several years ago.

• Waste cardboard is baled and sold.

• Sludge from the plant’s general wastewater treatment system is shipped to a facility for fuels blending.

• Sludge from the plant’s chrome wastewater treatment system is shipped to an outside firm for metals extraction.

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.

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, in most cases, the economic savings of

the minimization opportunities result from the need for less 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 the savings achievable when
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implementing each opportunity independently and do not reflect duplication of savings that may result when the pollution

prevention opportunities are implemented in a package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, several other measures were considered.

These measures were not analyzed completely because of

insufficient data, 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.

• Install covers on all heated tanks to minimize evaporative

water losses and to conserve energy.

• Use aqueous cleaners instead of solvents for washing piston

rings.

• Separate nonhazardous from hazardous wastewater streams

to reduce the volume of sludge from treatment that must be

considered hazardous and its associated costs.

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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Figure 1. Abbreviated process flow diagram for piston ring manufacture.

Precast Steel and

Iron Rings

Machining Operations

Blank Turning, Boring, Slot

Milling, Finish Turning

Heat Shape

Oven

Cam and

Finish Turning

Vapor

Degreasing

Paint

Masking

Grit Blast

Cleaning

Chrome Etching Plating

Machining Magnesium

Phosphate

Dipping

Cleaning

Packaging

Piston Rings Shipped

to Customer
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Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

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

Packaging materials Incoming materials Shipped offsite to landfill 1,620,000 $18,240

Off-specification piston rings Machining Sold to recycler 18,750 1,260

Scrap metal shavings and Machining Shipped offsite to landfill 750,000 10,380

grinding residue

Spent 1,1,1-trichloroethane Vapor degreasing Regenerated offsite 33,630 9,240

Evaporated 1,1,1-trichloroethane Vapor degreasing Evaporates to plant air 17,410 0

Waste masking paint Masking of piston rings prior to plating Shipped offsite to landfill 400 2,625

Evaporated paint thinner Masking of piston rings prior to plating Evaporates to plant air 7,580 0

Grit-blast sludge Grit-blast cleaning of piston rings Shipped offsite to landfill 41,700 6,710

Spent naphtha Cleaning of piston rings Regenerated offsite 98,600 29,260

Evaporated naphtha Cleaning of piston rings Evaporates to plant air 74,520 0

Spent chrome plating solution Plating of piston rings Shipped offsite for disposal 32,500 8,220

Spent scrubber filters Chrome exhaust scrubbers Shipped offsite for disposal 600 5,770

General plant wastewater Machining Pretreated in general wastewater 1,037,500 4,700

treatment system; treated in chrome

wastewater treatment system;

sewered

General plant wastewater sludge General plant wastewater treatment Shipped offsite to landfill 273,900 40,500

system

Wastewater Grit-blast cleaning, magnesium Treated in chrome wastewater 14,111,250 63,850

phosphate coating, etching, stripping, treatment system; sewered

rinsing

Chrome wastewater sludge Chrome wastewater treatment system Dried; shipped offsite for metals recovery 75,120 40,520

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 Stream Reduced Quantity (lb/yr) Percent Savings Cost Payback (yr)

Use plastic sleeves instead of Waste masking paint 400 100 $214,2301 $0 0

masking paint to prevent chrome Wastewater from stripping 2,768,120 20

plating of piston ring inner perimeters.

Replace 1,1,1-trichloroethane Spent 1,1,1-trichloroethane 16,820 50 10,5601 15,000 1.4

vapor degreasing with a high

pressure hot water spray system for removal of machining

residues prior to plating. A

small additional quantity of

wastewater will be generated

if this opportunity is implemented.

Purchase a solvent distillation Spent 1,1,1-trichloroethane 33,630 100 26,560 35,000 1.3

unit to regenerate spent sol- Spent naphtha 98,600 100

vents onsite instead of shipping them offsite for regeneration. A small quantity of still

bottoms will be generated and

shipped offsite if this opportunity is implemented.

Utilize all of the three existing N/A2 —- —- 20,310 0 0

cold water rinse tanks to completely remove chromic acid

from piston rings, thus eliminating the need for manual

spray rinsing.

1Total annual savings have been reduced by an annual operating cost required for implementation. 2This WMO achieves no waste reduction but leads to significant operating cost savings.
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United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

Official Business

Penalty for Private Use

$300

EPA/600/S-95/015