Table 1. Summary of Current Waste Generation

Annual Quantit Annual Waste
Waste Stream Generated ‘Source of Waste Waste Management Method Generated thd Management Cost”
Off-specification filler overwrap Filler machine in fett tip ‘Shipped to municipal landfill 4,730 $500
‘marker production
Empty dye containers Felt tip marker and Retumed to vendor for reuse 3,600 500
stamp pad production
Evaporated n-propyl alcohol Ink mixing in felt tip Evaporates to plant air 41,470 16,170
‘marker production
Excess plastic runners Injection molding in felt Ground; returned to supplier 16,600 1,960
"fp marker production for reprocessing
Unusable filler pieces Filler machine in felt tip ‘Shipped to municipal landfill 2,020 1,000
‘marker production
Hydraulic oil fiters Filtering of hydraulic oil from ‘Shipped offsite for incineration 170 2,280
mecarosaeatnn
Contaminated ink filters Ink mixing in felt tip marker ‘Shipped to municipal landfill 2,360 1,640
and stamp pad production :
Hydraulic oll/detergent solution Cleanup in felt tip marker ipped offsite for disposal 3,400 10,530
ee ‘and stamp pad production oP haterdous waste
Synthetic oil Air compressors ‘Shipped offsite for incineration 2410 8,620
Off-specification markers Felt tip marker production Donated to charitable organizations 56,250 90
Off-specification markers Felt tip marker production ‘Shipped to municipal landffil 508,250 830
‘Scrap packaging material Felt tip marker and stamp ‘Shipped to municipal landtit 560 500
‘pad production
Plastic ser Retumed to supplier for reprocessi 5,500 660
” “meting in felt ing Bolt to rarker suppl iid
and stamp pad production
Color-streaked marker Color consistency problems Ground; returned to supplier 185,140 19,690
‘components in felt tip marker production for reprocessing
Ink system wash water Cleanup in felt tip marker Treated onsite; sewered 106,240 50,630
‘production
Plastic pellets/hydraulic oil Spills in fott tip marker and ‘Shipped to municipal landfill 8,830 1,640
‘stamp pad production
Ink system wash solvent Cleanup in felt tip marker ‘Reused in black ink production 210 0
‘production
‘Scrap selt-inking stamp pads Improper curing of selt- Shipped oftsite for disposal as 21,830 95,540
inking pads” hazardous waste
Wash water ‘Stamp pad production Treated onsite; sewered 11,950 5,700
n-propyl alcohol wash-out {nk mixing in stamp ped ‘Shipped offsite for incineration 1,530 2,010
Evaporated n-propyl alcoho! Washout of ink mixer in Evaporates to plant air 380 150
stamp pad production
Unused inking mixture Selt-inking stamp pad ‘Shipped offsite for incineration 1,100 5,540
‘production
Empty solvent containers ‘Stamp pad production Retumed to vendor for reuse 900 500
‘Scrap cellophane overwrap Packaging of stamp pads ‘Shipped offsite to recycler 790 420
Off-specification plastic cases Injection molding of stamp ‘Retumed to supplier for 2,030 240
Pad cases reprocessing
Off-specification fett stamp pads ‘Stamp pad production ‘Shipped to municipal landiil 10,160 500
Contaminated plastic floor cover ipped offsite for disposal 50 630
pam herconing Suma paacn strat
Resins and powder dyes ‘Stamp pad production ‘Shipped offsite for incineration 50 560
Wash water Ink mixer in stamp pad Treated onsite; sewered 27,890 13,290
Production
Waste felt insorts Improper cutting during ‘Shipped to municipal landfil 3,750 500
stamp pad production
Waste foam inserts Poor ink transter during ‘Shipped to municipal landfilt 4,500 500
stamp pad production
Rubber cement residue Rubber cement production ‘Shipped to municipal landfill 380 500
Evaporated rubber solvent ‘Mixing of rubber cement Evaporates to plant air 15,600 9
esowater veatment sige Onsite WWTP ‘Accumulating onsite in drying pond NAT o
Includes waste treatment, disposal, and handling costs and applicable raw material costs.
' Waste is accumulating onsite; no waste was shippod oslo ceria tie pest joa

5



United States

Environmental Protection Agency

Center for Environmental Research Information
Cincinnati, OH 45268

Official Business
Penalty for Private Use
$300

EPA/600/S-94/013

BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35



Layering Dyes —_p» Injection <——_ pollots
nd rs 9
Felt
asphalt t Mixing
Over. 7] if Dimethylphthalate
co wrapping dyes
Cotton Pouring resins
cloth i into
trays
Insertion of if
pad into
case
Oven
V s
Ink if
ad injection
Water- ;
based Air
ink if cooling
Labeling, y
J Ly) Pomuenny le —
case
fs sh Pad base
© customers t material
Labeling,
wrapping,
packaging
Salt-inking stamp pads

ing to customers

Figure 2. Abbreviated process flow diagram for stamp pad production.


Table 2, Summary of Recommended Waste Minimization Opportunities

Annual Waste Reduction
Net Annual Impleme "
Minimization Opportunity Waste Stream Reduced Quantity (ib) Per Cent Savings Con rent ,
in)
Segregate scrap plastic from Excess plastic runners 9,340 56 $5,100' $0 I ;
injection molding by color and Plastic scrap 3,090 56 immediate
reuse in subsequent production Color-streaked marker 61,930 38
runs, components
Modify the seltinking stamp Scrap seltinking stamp pads ——*19,650 90 20,050! 0 immedi
‘pad production process to re- immediate
duce pad thickness by one-half
So that individual pads with surface
defects can be combined to
produce one pad with an acceptable
visible top surface,
Improve maintenance of injection ‘Hydraulic oi/detergent 2,980 70 7,370 17,400 24
‘molding machines to reduc i
leaking of hydraulc ol
Fiter and reuse synthetic oil Synthetic oi! 2170 90 7,450! ,
removed from ait compressors. . ° inmechate

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

aati


United States
Environmental Protection
Agency

Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268

Research and Development

EPA/600/S-94/013 _ September 1994

EPA

ENVIRONMENTAL

RESEARCH BRIEF

Waste Minimization Assessment for a Manufacturer
of Felt Tip Markers, Stamp Pads, and Rubber Cement

Richard J. Jendrucko*, Todd M. Thomas’,
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 the
University of Tennessee performed an assessment at a plant
that manufactures felt tip markers, stamp pads, and rubber
cement. Plastic components for the markers are formed in
injection molding machines. A porous filler is inserted into the
marker case and ink is injected into it. The endplug, nib, and
cap are added to the marker, which is then labeled and pack-
aged. The first step in stamp pad production is the injection
molding of plastic double-hinged stamp pad cases. Three types
of stamp pads are manufactured: felt, foam, and self-inking.
The pads are prepared and inserted into the cases. Rubber
cement is manufactured by mixing synthetic rubber strips and
solvent. The team's report, detailing findings and recommenda-
tions, indicated that a large quantity of scrap plastic is gener-
ated by the injection molding of markers and stamp pad cases,
and that significant cost savings could be achieved by segre-
gating scrap plastic and reusing it in subsequent production
runs.

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

* University of Tennessee, Department of Engineering Science and Mechanics
** University City Science Center, Philadelphia, PA

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 be-
come 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 Tennes-
see 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 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
reduction of waste treatment and disposal costs for participat-
ing plants. In addition, the project provides valuable experi-
ence for graduate and undergraduate students who participate

& Printed on Recycled Paper

>> >



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.

Additional Recommendations

In addition to the opportunities recommended and analyzed by
the WMAC team, several additional measures were consid-
ered. 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 waste reduction may, however, increase in
attractiveness with changing conditions in the plant, they were
brought to the plant's attention for future consideration.

Line the ink mixing tanks with Teflon inserts to minimize the
amount of residual ink adhering to tank walls after mixing and
draining in order to reduce the amount of washout waste
generated during clean-up.

Reduce the scrap rate in the automated felt tip marker
assembly line by improving the scheduling of production runs
and maintenance of the line.

Utilize reusable, washable ink filters to recover resins and
dye pigments collected during filtration following ink mixing
and use them in production of black ink.

+ Modify the solvent-based ink mixing tanks to minimize sol-
vent evaporative losses.

Purchase a sludge dryer to reduce the weight of the waste-
water treatment sludge in order to reduce disposal costs.

This research brief summarizes 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.


in the program, and a cleaner environment without more regu-
lations 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-
dures 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 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
The plant produces several varieties of felt tip markers, stamp

pads, and rubber cement. It operates 6,120 hr/yr to produce >
2x 10° Ib/yr of product.

Manufacturing Process

Polypropylene, polystyrene, and polyethylene pellets, liquid and
powdered dyes, and solvents for ink mixing are the principal
taw materials used for making markers and stamp pads. Rub-
ber strips and solvents are the major raw materials required for
rubber cement manufacture,

Felt Tip Marker Production

In order to manutacture felt tip markers, polypropylene and
polystyrene pellets are placed in a hopper and mixed with
colored pellets. The pellet mixtures are metered into injection
molding machines in which the three parts of the marker are
formed (the case, cap, and endplug).

The filler, a porous ink reservoir that is to be inserted into the
marker case, is produced in a parallel operation. Cellulose
acetate or polyester fiber is fed into a machine that stretches
and relaxes the material. Next, cellophane is wrapped around
the filler piece, and a long cylindrical form is automatically cut
into individual pieces.

In a third parallel operation, solvent or water is mixed with
appropriate dyes to make marker ink.

During final assembly of markers, the fillers are inserted into
the molded cases, the inks are needle-injected into the fillers,
and the molded endplugs are attached. The next step is the
attaching of nibs (small pieces of felt that wick the ink from the
filler) in the tip of the marker body. Molded caps are snapped
into place, labels are applied to the markers, and the finished
products are packaged.

An abbreviated process flow diagram for felt tip marker produc-
tion is shown in figure 1.

Stamp Pad Production

Three types of stamp pads are manufactured by the plant: felt,
foam, and self-inking. Polystyrene pellets and black and grey

dyes are mixed together and metered into injection molding
machines where double-hinged stamp pad cases are formed.
Felt pads are made by layering and cutting felt and asphalt
sheets. A cloth overwrap is added and then the entire pad is
inserted into a molded case. Water-based ink is injected into
the pad and the finished stamp pad is labeled, packaged in
cellophane, boxed, and shipped. For foam stamp pad produc-
tion, pre-cut foam pieces are dipped in water-based ink and
passed through a wringer machine to remove excess ink. The
pad is inserted into a molded case, which is labeled, packaged
in cellophane, boxed, and shipped. Self-inking stamp pads are
manufactured by first blending dimethy! phthalate, powdered
dyes, and PVC resins in a covered tank. The mixture is poured
into individual trays, which are conveyed through a natural gas-
firad oven for curing and then air-cooled. A pad base material
is placed in the bottom of a case and the ink-impregnated pad
is placed on top. The assembled pads are labeled, wrapped in
cellophane, boxed, and shipped.

An abbreviated process flow diagram for stamp pad production
is shown in figure 2.

Rubber Cement Production

To produce rubber cement, synthetic rubber strips and rubber
solvent are mixed together in a tank and stored in a storage
tank. The contents of the storage tank are pumped to a filler
machine where the rubber cement is pumped into individual
bottles traveling on a conveyor. The filled bottles are capped,
packaged, and shipped to customers.

Existing Waste Management Practices

This plant already has implemented the following techniques to
manage and minimize its wastes.

+ Waste cardboard is baled and sold to a recycler.

* Plastic waste from the injection molding machinesis reground
and sold to an outside firm for reprocessing after which it is
returned to the plant for reuse.

Hydraulic oil from the injection molding machines is filtered to
extend its useful lite.

Liquid hazardous waste streams are segregated by primary
component.

+ Attempts have been made in the past to recycle dimethy|
phthalate. However, recycling has been discontinued be-
cause of varying product quality and employee health con-
cers.

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


Polypropylene pallets Solvent, liquid dyes

polystyrene pellets powdered dyes
7 Color pellets ant:foam Resins 7
Mixing Mixing
Y Y
Injection .
molding oon Fitering
polyester Cellophane
y y :
Cases i
caps ‘Stretching/relaxing Ink i
endplugs cellophane
overwrapping
|
’ |
Fillers i
Nibs ——r Assembly
Labels >
Markers shipped
to customers

Figure 1. Abbreviated procass flow diagram for felt tip marker production.