&EPA
                         United States
                         Environmental Protection
                         Agency
                                    Risk Reduction
                                    Engineering Laboratory
                                    Cincinnati, OH 45268
                         Research and Development
                                    EPA/600/S-94/009   September 1994
ENVIRONMENTAL
RESEARCH   BRIEF
                 Waste Minimization Assessment for a Manufacturer
                                    of Surgical Implants

                              Harry W. Edwards*, Michael F-. Kostrzewa*,
                                       and Gwen P. Looby**
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 manufactur-
ers, Waste Minimization Assessment Centers (WMACs) were
established at selected  universities,  and procedures were
adapted from the EPA Waste Minimization Opportunity As-
sessment Manual (EPA/625/7-88/003, July 1988). That docu-
ment has been superseded by the Facility Pollution Prevention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 manufactures surgical implants from stainless  steel and
titanium stock. The metal stock is machined,  vibratory pol-
ished, electropolished, passivated, inspected, and shipped. The
team's report, detailing findings  and recommendations,  indi-
cated that wastewater and waste cutting fluid are the wastes
generated in  the greatest quantities and that significant cost
savings would result from implementing a formal cutting fluid
management plan.

This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, 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, Phila-
delphia, PA.


Introduction
The amount  of  waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an

* Colorado State University, Department of Mechanical Engineering, Fort Collins,
  CO
" University City Science Center, Philadelphia, PA
                        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 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 Reduc-
                        tion Engineering Laboratory, the Science  Center has estab-
                        lished 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 ex-
                        perience with process operations in manufacturing plants and
                        also have the knowledge and skills needed to  minimize waste
                        generation.

                        The waste minimization 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 waste minimiza-
                        tion.

                        The potential benefits of the pilot project include minimization
                        of the amount of waste generated by manufacturers and re-
                        duction 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 waste minimization assessments require several site visits
                        to each client served. In general, the WMACs follow the proce-

                                                 &SS Printed on Recycled Paper

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dures outlined  In  the  EPA Waste Minimization Opportunity
Assessment Manual (EPMG25/7-B8/Q03, 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 tech-
nological and  economic Information is developed. Finally,  a
confidential report that details the WMAC's findings and recom-
mendations (including cost savings, implementation costs, and
payback times) is prepared for each client.


Plant Background
This plant manufactures surgical implants. Nearly four million
parts are produced each year during 4,160 hr of operation.


Manufacturing Process
Fasteners and  plates are manufactured from  stainless steel
and titanium sheets, rectangles, and round stock.

The first step in the plate manufacturing process is the sanding
and cutting to size of stainless steel stock. Computer numeri-
cally-controlled  (CMC) mills are used to mill the  sides of the
plate, and another mill finishes the top and  bottom of the plate.
Lathes,  drills, broaches, and additional mills  are used for fur-
ther machining operations. Then the parts are placed in one of
several  vibratory  polishers that utilize aluminum  oxide chips
and water for additional finishing. Sand blasting may be used
in place of vibratory polishing for some parts. The final finishing
step is electropolishing,  which uses an alkaline cleaner, a hot
water rinse, a  cold water rinse, a phosphoric acid solution,  a
hot water rinse and hold, an electropolishing solution, and  a
datonlzed water rinse. After the part dries, a logo and serial
number are etched chemically onto its surface. Finally,  the
parts are passivated (made less reactive) in a nitric acid solu-
tion, inspected, boxed, and shipped.

Fasteners are  manufactured in a  separate area of the plant.
Cylindrical metal blanks  are cut and  machined to form a screw
head on one end. Centerless grinders are used to shape the
head and reduce the outside diameter. Threads are cut into the
blanks using mills. The fasteners are polished in the vibratory
polishers, electropolished, and passivated. The finished prod-
ucts are inspected, packaged, and shipped.

An abbreviated process flow diagram for surgical implant manu-
facture is shown in Figure 1.


Existing Waste Management Practices
This plant already has implemented the following techniques to
manage and minimize its wastes:

  * An aqueous, citric-based cleaner has replaced solvents used
    for cleaning machined plates prior to polishing.

  • Water meters have been installed on  all aqueous waste
    streams that are discharged to the treatment unit, to monitor
    and control water usage.

  • Scrap metal is shipped offsite for recycling.

  • Centrifuges have been installed on many of the machines
    used in fastener fabrication to separate metal chips from the
    oil-based cutting fluid, extending the fluid's life and reducing
    waste generation.
        Fastener
        fabrication
                                Plate
                              fabrication
                       Stainless steel
                         titanium
Passivation



1

Inspection


Etching
*
Passivation
                      Parts shipped
                      to customers
Figure 1.
Abbreviated process flow diagram for surgical implant
manufacture.
Waste Minimization 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 waste minimization that the
WMAC team recommended for the plant. The minimization
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 pos-
sible 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 minimiza-
tion opportunity,  in most cases, results from the  need for less
raw material and from reduced present and future costs asso-
ciated 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
implementing each  waste minimization opportunity  indepen-
dently 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-814903 by the University City
Science Center under the sponsorship of the U.S. Environmen-
tal  Protection Agency.  The EPA Project  Officer was Emma
Lou George.

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Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268

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