1

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 That document has been superseded by the Facility Pollution Prevention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

Colorado State University performed an assessment at a plant

that refurbishes large industrial crankshafts. Worn crankshafts

received by the plant are cleaned and stripped of chromium.

The crankshafts are inspected for defects, repaired as required, annealed, and straightened. Bearing surfaces are rough

ground, crankshaft journal surfaces are shot-peened, and the

crankshafts are cleaned. Then the crankshaft surfaces and

selected bearing surfaces are electrochemically plated with

chromium. Next, the crankshafts are baked, shot-peened again,

and fine ground to final specifications. The team’s report,

detailing findings and recommendations, indicated that the waste

stream generated in the greatest quantity is spent cutting fluid

from the grinding of crankshafts and that significant cost savings could be achieved by implementing a formal cutting fluid

management program.

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 Colorado State

University’s (Fort Collins) 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 Rebuilt Industrial Crankshafts

ENVIRONMENTAL

RESEARCH BRIEF

Harry W. Edwards*, Michael F. Kostrzewa*,

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-95/022 August 1995

* Colorado State University, Department of Mechanical Engineering ** University City Science Center, Philadelphia, PA
2

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 rebuilds large industrial crankshafts that are distributed regionally. Over 4,000 jobs are completed each year by

the plant during 2,210 hr/yr of operation.

Manufacturing Process

Worn crankshafts received by the plant are cleaned and

degreased in a heated caustic solution. Chromium plating is

then electrolytically stripped from the crankshafts in a caustic

solution. The chromium may also be removed mechanically

using large grinders.

Next, the crankshafts are inspected for cracks and flaws using

two different methods. One method entails applying a penetrating fluorescent dye solution and a visual inspection using a

UV-light. The second method involves the use of a solvent

containing fine, magnetic particles and application of a magnetic field which is distorted by any defects present.

Defects are repaired and worn metal is built up using arc

welding. Stresses are relieved in an annealing oven and a

hydraulic press is used to straighten the crankshafts as needed.

The bearing surfaces are then rough ground to desired factory

specifications.

Following grinding, the crankshafts are prepared for chromium

plating. The crankshaft journal surfaces are shot-peened to

relieve surface stresses, and the crankshafts are cleaned with

air-blown abrasive particles. Keyways are plugged with lead to

prevent plating of their surfaces and masking is applied as

needed to prevent plating of other surfaces. The crankshaft

surfaces and selected bearing surfaces are electrochemically

plated with chromium using heated chromic acid plating baths.

After plating, the crankshafts are baked to remove hydrogen

absorbed during plating, shot-peened again, and fine ground to

final specifications. A final magnetic particle inspection follows

grinding. The shafts are then dynamically balanced, polished,

and packaged and shipped to customers or added to inventory.

An abbreviated process flow diagram for the rebuilding of

crankshafts is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• All rinsing of crankshafts is done over process solution tanks

to reduce effluent to the sewer.

• Electrodialysis is used to maintain the chromium plating

baths, thereby extending bath life and reducing the need for

replacing the plating solutions.

• Lead anodes are melted and repoured to reduce the generation of waste lead.

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 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 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 opportunities, in most cases, result 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.

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 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.

• Replace the rented parts washers that use petroleum naphtha with alternative cleaning systems using a less hazardous

solvent.

• Develop a formal management plan for the maintenance of

the chromium plating solutions to increase bath life and

reduce waste generation. Special emphasis should be placed

on the maintenance and performance of the electrodialysis

equipment. Several measures are in place to maintain the

solutions, but procedures should be formalized.

• Investigate possible alternatives to the landfilling of chromium-contaminated soil and evaporator sludge stored onsite

pending identification of a suitable disposal method. Further

analysis requires sampling and quantitative analysis of the

chromium bearing wastes to determine the suitability of

recycling. Such procedures are beyond the scope of the

WMAC program.

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.
3

Figure 1. Process flow diagram for industrial crankshaft refurbishing.

Worn Crankshafts

Cleaning

Chemical

Stripping Inspection Welding

Shot-Peening Pre-Grinding Annealing

Abrasive

Cleaning

Chromium

Plating

Shot-Peening

Final

Grinding Inspection

Packaging Polishing Balancing

Refurbished

Crankshafts
4

Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

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

Waste caustic cleaning solution Initial cleaning of crankshafts Stored onsite pending determination of an

appropriate waste management method1 41,800 $2,1302

Waste stripping solution Chromium stripping of crankshafts Stored onsite pending determination of a

appropriate waste management method1 30,000 0

Evaporated penetrant/dye Inspection of crankshafts Evaporated to plant air 1,110 2802

Spent parts cleaning solvent Parts washer Removed by supplier; distilled offsite for

reuse or incinerated 1,810 1,250

Spent cutting fluid Grinding of crankshafts Filtered from grinding sludge; drained

through sand trap; sewered as industrial

wastewater 178,700 6,5602

Grinding sludge Grinding of crankshafts Shipped offsite for stabilization and burial

at a hazardous waste disposal facility 25,400 8,300

Waste hydraulic oil Routine maintenance of grinders Removed by oil recycler; blended to produce

industrial boiler fuel 2,350 60

Evaporator sludge Previous waste management Stored onsite pending determination of an

method for caustic wastes appropriate waste management method 13,600 0

Waste stripping solution Rework of plated crankshafts Stored onsite pending determination of an

appropriate waste management method1 10,000 0

Lead slag Preparation of anodes for plating Accumulated onsite 9,160 0

Waste caustic cleaning solution Cleaning of anodes Stored onsite pending determination of an

appropriate waste management method1 1,500 2,5002

1 Prior to the assessment, the caustic wastes were combined and placed in an evaporator. The evaporator was used to reduce the volume and weight of waste prior to disposal.

At the time of the assessment these wastes were being stored onsite. Filtration and the use of a sludge dryer were being considered as alternative waste management methods.

2 Includes applicable lost raw material value.
5

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)

Install a high pressure washer and filtration Waste caustic cleaning 26,500 63 $4,450 $910 0.2

system for the caustic solution used to solution

provide the initial crankshaft cleaning.

It is proposed that a small spray washer

be used to clean the crankshafts over the

caustic tank and a filtration system be

used to remove particulate matter from the

solution, thereby extending the life of the

solution.

Implement a formal cutting fluid manage- Spent cutting fluid 119,000 67 3,680 4,360 1.2

ment program for the grinders that use

aqueous cutting fluids. The program

should involve daily and regular maintenance, periodic cleaning, data gathering and tracking, and filtering of

particulate matter. A reduced volume

of waste grinding fluid will be generated

as a result of the program.

Filter the solvent used for magnetic in- Evaporated penetrant/dye 550 50 270 110 0.4

spection of the crankshafts in order to

increase its life. The solvent would be

pumped from the existing tank, filtered,

and returned.
6

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

National Risk Management Research Laoratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/022