Quarterly Mags: 2005 3rd

Contents

Thermoforming

®

Q U A R T E R L Y

TECHNICAL SECTION

Lead Technical Article:

Enhanced TPO Thermoforming Using High Melt Strength Polyolefin Elastomers …. 10

Industry Practice:

Collaborative and Methodical Development Reduces Time From Concept to
Production ……………………………………………………………………………………………………..15

Industry Practice:

Proper Colleting and Collet Maintenance in CNC Routing of Plastic ……………………. 16

Industry Practice:

History of Thermoforming – Part I………………………………………………………………………19

Thermoforming 101:

Understanding How a Sheet Stretches ……………………………………………………………….. 22

Book Review:

The Evolution of Plastics in America (As Seen Through the National Plastics
Expositions) ……………………………………………………………………………………………………24

DIVISION ACTIVITIES

Chairman’s Corner …………………………………………………………Inside Front Cover
Membership Memo: It’s Conference Time Again! ……………………………………. 2
New Members ……………………………………………………………………………………….. 3
Thermoformer of the Year 2006 Nomination Form …………………………………. 7
Milwaukee Board Meeting Schedule ………………………………………………………. 8
Council Report …………………………………………………………………………………….. 26
Membership Application ……………………………………………………………………… 33
Index of Sponsors ………………………………………………………………………………… 36
Board of Directors List…………………………………………………….Inside Back Cover

These sponsors enable us to publish Thermoforming
QUARTERLY

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Lower cycle rates • Lower reject rates
Greater heater life • Greater oven uniformity

Don’t be fooled by claims of outrageous energy
savings. Ask your heater supplier to provide
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Ask for Solar Products on your next new machine
purchase or for that old machine retrofit.

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Fax (973) 835-7856

228 Wanaque Ave., Pompton Lake, NJ 07442 www.solarproducts.com

A NOTE TO
PROSPECTIVE
AUTHORS

TFQ is an “equal opportunity”
publisher! You will note that we have
several categories of technical articles,
ranging from the super-high tech
(sometimes with equations!), to
industry practice articles, to book
reviews, how to articles, tutorial
articles, and so on. Got an article that
doesn’t seem to fit in these categories?
Send it to Jim Throne, Technical Editor,
anyway. He’ll fit it in! He promises. [By
the way, if you are submitting an
article, Jim would appreciate it on
CD-ROM in DOC format. All graphs
and photos should be black and white
and of sufficient size and contrast to
be scannable. Thanks.]

Thermoforming

®

QUARTERLY

A JOURNAL PUBLISHED EACH CALENDAR
QUARTER BY THE THERMOFORMING DIVISION
OF THE SOCIETY OF PLASTICS ENGINEERS

Editor

Gwen Mathis

(706) 235-9298 • Fax (706) 295-4276
gmathis224@aol.com
Technical Editor

Dr. James Throne

Sherwood Technologies, Inc.
1797 Santa Barbara Drive
Dunedin, FL 34698-3347
1-800-273-6370 • Fax (727) 734-5081
throne@foamandform.com
jthrone@tampabay.rr.com

Sponsorships

Laura Pichon

(815) 678-2131 Ext. 624
Fax (815) 678-4248
lpichon@extechplastics.com
Thermoforming Quarterly® is published four times annually
as an informational and educational bulletin
to the members of the Society of Plastics
Engineers, Thermoforming Division, and the
thermoforming industry. The name, “Thermoforming
Quarterly®” and its logotype, are registered trademarks
of the Thermoforming Division of the Society
of Plastics Engineers, Inc. No part of this publication
may be reproduced in any form or by any means
without prior written permission of the publisher,
copyright holder. Opinions of the authors are their
own, and the publishers cannot be held responsible
for opinions or representations of any unsolicited
material. Printed in the U.S.A.

Thermoforming Quarterly® is registered in the US
Patent and Trademark Office (Registration no.
2,229,747).

1
Thermoforming
QUARTERLY

MEMBERSHIP MEMO

It’s Conference
Time Again!

BY MIKE SIROTNAK, MEMBERSHIP CHAIRMAN

gram will be cutting edge with a

T
T
he last time our conference

port a group of doctors and

focus on new technology in our in

was held in the beautiful

nurses to visit Sri Lanka to aid

dustry. Walt Walker and Ed Probst city of Milwaukee, our country

in the Tsunami relief. Make sure

have searched high and low to bringwas still reeling from the dev

to read the article in this issue

you all that is new. The exhibit floor astating attacks of 9/11. I will

for complete details. It’s another

will be bigger and better than ever. never forget having to drive

example of the good works your

Try to make a point of spending as from New Jersey to Milwaukee,

membership provides. Scholar

much time as possible on the exdue
to the massive airport clos

ships, educational equipment

hibit floor. The exhibitors

ings, wondering what the

are the backbone of these

future would hold. Now

conferences. Joe Peters has

four years later, it’s hard

MEMBERSHIP REPORT

put together a very diverse

not to think back on that

as of 6/15/05

Parts Competition. Make

time and reflect on how

sure to stop by and see what
remarkably how much Primary Paid …………………..1,229 your competitors are up to.
has stayed the same. I am

much has changed and

This year we are offering

Secondary Paid ………………….447

four plant tours including

bers for their continued Total Membership …………..1,726 topnotch processors, Prent
support and I am confi

very proud of our mem-

Corp. and Profile Plastics.
Goal as of 6/30/2005 ………2,000 You have to respect those

dent that our division
will achieve all of its

business leaders that allow
the public to visit their facilities.
Steve Murrill and Walt Walker are

goals.

grants, disaster relief donations,

Just a reminder! The reprints

educational DVD’s, Thermo

two examples of our industry’s best.

of our very first DVD “What is

forming Quarterly, technical con-
Four years ago, Milwaukee did

Thermoforming?” have arrived

ference and the only industry
not see our best. Let’s make sure

and are available. Please feel free

specific trade show … all possible
this conference changes that. See

to contact any of the Board

because of your continued support.
you on the exhibit floor.

members to request additional

I urge you to continue to help
God Bless America!

copies or visit our website,

recruit new members.

www.thermoformingdivision.com,

This year’s conference should be

for more information.

very exciting. Hometown boy, Bob

Recently the Thermoforming

Porsche, has put together an excit-

Division donated money to sup

ing conference. The technical pro-

Thermoforming
QUARTERLY 2

To Our New Members

Philip Allgood
MEI
Smyrna,

Georgia

Jeff Bostic

Three Four
Solutions
LLC

Bammamish,
Washington

James L.
Cameron

Barron &
Rowson Ply
Ltd.

Australia

Euclide

Ceccchin
Omega Tool Ltd.
Warren,

Michigna

Ray Collins

Anchor Plastics
Machinery
Ltd.

United
Kingdom

Don Gerhardt
Ingersoll Rand
Clemmons,

North
Carolina

Sheila Greer
Benver State
Plastics

Drain, Oregon

Kenneth Herold
Rotocast
Technologies
Akron, Ohio

Don Hexamer
Tri City
Packaging
Waterloo,
Canada

Ken A. Hopkins
Allen, Texas

Daniel W. King
Copley, Ohio

Young Soo Ko
Borealls
Polymers Co.
Finland

Fernando Lemos
Jay Packaging
Group
Warwick, Rhode
Island

John Luscombe

Integrated
Composite
Technologies

Montezuma,
Georgia

Charles Mans

Azimuth
Custom
Extrusions
LLC

Evansville,
Indiana

Gary Mantyla
Plast-Labs, Inc.
Lansing,

Michigan

Dick Marr
Genpak LLC
Holyoke,

Massachusetts

Mark McKaig
Genpak LLC
Montgomery,

Alabama

William Moore
Ballwin,
Missouri

John Mosher
The Boxboro
Group
Boxboro,
Massachusetts

Charles A.
Munson

American Pipe
& Plastics,
Inc.

Binghampton,
New York

Trevor
Nickerson
PCF/Jamestown
Plastics
Mayville, New
York

Fred Ollarsaba
Tempe, Arizona

Thomas Schein

All About
Packaging,
Inc.

Appleton,
Wisconsin

Shankara
Shettym

Concept
Management
Company

St. Simons
Island,
Georgia

Ryan Snow Charles Tutty Keith
All About CJK Woodward
Packaging, Manufacturing CJK
Inc. LLC Manufacturing
Appleton, Rochester, New LLC
Wisconsin York Rochester, New
Harinder S. Tim Tutty
York
Tamber CJK Jim Zubersky
Tambar Manufacturing TPI
Consultants LLC White Bear
Mississauga, Rochester, New Lake,
Ontario -York Minnesota
Canada

WHY JOIN?

It has never been more important to
be a member of your professional
society than now, in the current
climate of change and volatility in the
plastics industry. Now, more than ever,
the information you access and the
personal networks you create can and
will directly impact your future and
your career.

Active membership in SPE:

• keeps you current
• keeps you informed
• keeps you connected
The question really isn’t
“why join?” but …

WHY NOT?

3
Thermoforming
QUARTERLY

THERMOFORMING

QUARTERLY … A WINNER!

At the recent Antec in Boston,
the Thermoforming Quarterly
again won First Place in the
Division’s Newsletter Contest.
Roger Kipp, Division Chairman,
is shown presenting the award
to the Thermoforming Quarterly
Editor Gwen Mathis.

These sponsors enable us to publish Thermoforming
QUARTERLY

In Memory of
James E.
Gilham

ThermoformingQUARTERLY 4

O
O
n April 27, 2005, James
E. Gilham of Marlton,
New Jersey passed away at
the age of 78. He was the
beloved husband for 50
years to the late Doris E.
(nee Homan). Loving father
of Harold S. Gilham
and his wife Lisa of
Southampton, NJ; Deborah
Cherico and her husband
John of St. Louis Park, MN;
Robin Zerillo and her husband
John of Medford, NJ;
Lorrie Fabrizio and her
husband Joseph of West
Chester, PA; and 14 grandchildren.
Dear brother of
Mimi Leisy, Betty Danley,
Tom Gilham and Butch
Gilham. A service honoring
his life was held at St.
Andrew’s Methodist
Church with interment in
Locustwood Memorial
Park, Cherry Hill, NJ. Contributions
in his memory
may be made to the Lupus
Foundation of South Jersey,
1873 Rt. 70 East, Cherry
Hill, NJ 08003. ¦

PENN STATE-ERIE ROOMMATES RECEIVE
2005 THERMOFORMING SCHOLARSHIPS

Ken Griep, Chairman of Student Affairs, is pleased to announce the winners of the following scholarships.
These scholarships will be presented during the annual Thermoforming Conference in Milwaukee.

JOHN GRIEP MEMORIAL
$5,000.00 SCHOLARSHIP

TRAVIS HUNTER
PENN STATE – ERIE

T
T
ravis Hunter is a Senior at Penn State-Erie majoring
in Plastics Engineering Technology. He
has had extensive experience with the
thermoforming process and is currently completing
a project that tests the thermoformability of four
different polymers (HDPE, LDPE, PP and PET)
with additives. In an earlier project, he used an
epoxy compound to form a mold of a product that
is already on the market and tested the permeability
properties of the thermoformed polymer. Travis
had an internship at Emerson Appliance Controls
where he was able to design a new mold. The Manager
of Engineering at Emerson indicated that
Travis and his partner, Joshua Sindlinger, were the
best interns he’d worked with in his 35 years with
the company. ¦

SEGEN MEMORIAL
$5,000.00 SCHOLARSHIP

JOSHUA SINDLINGER
PENN STATE – ERIE

J
J
oshua Sindlinger is a Senior at Penn State-Erie
majoring in Plastics Engineering Technology. He
has had extensive experience with the
thermoforming process and is currently completing
a project that tests the thermoformability of four
different polymers (HDPE, LDPE, PP and PET)
with additives. Josh partnered with his PS-E roommate
Travis Hunter at Emerson Appliance Controls.
Josh also worked for Holbrook Tool as an injection
molding machine operator in the summer of 2000.
Upon graduation, he hopes to become a process
engineer and then work his way up the corporate
ladder. ¦

These sponsors enable us to publish Thermoforming
QUARTERLY

5ThermoformingQUARTERLY

THERMOFORMER OF THE YEAR
CRITERIA FOR 2006

E
E
very year The SPE Thermoforming
Division selects a individual
who has made a outstanding
contribution to our industry and
awards them the Thermoformer of
the Year award.

The award in the past has gone
to industry pioneers like Bo Stratton
and Sam Shapiro, who were among
the first to found thermoforming
companies and develop our industry.
We have included machine designers
and builders Gaylord Brown
and Robert Butzko and toolmaker
John Greip, individuals who helped
develop the equipment and mold
ideas we all use today. We have
also honored engineers like Lew
Blanchard and Stephen Sweig, who
developed and patented new methods
of thermoforming. Additionally,
we have featured educators like Bill
McConnell, Jim Throne and
Herman R. Osmers, who have both
spread the word and were key figures
in founding the Thermoforming
Division.

We’re looking for more individuals
like these and we’re turning to
the Thermoforming community to
find them. Requirements would include
several of the following:

.Founder or Owner of a
Thermoforming Company
.Patents Developed
.Is currently active in or recently
retired from the Thermoforming
Industry
.Is a Processor – or capable of
processing
.Someone who developed new
markets for or started a new trend
or style of Thermoforming
.Significant contributions to the
work of the Thermoforming Division
Board of Directors
.Has made a significant educational
contribution to the
Thermoforming Industry.
If you would like to bring someone
who meets some or all of these
requirements to the attention of the
Thermoforming Division, please fill
out a nomination form and a oneto
two-page biography and forward
it to:

Thermoforming Division Awards

Committee

% Productive Plastics, Inc.

Hal Gilham

103 West Park Drive

Mt. Laurel, NJ 08045

Tel: 856-778-4300

Fax: 856-234-3310

Email:
halg@productiveplastics.com

You can also find the form and see all the past
winners at www.thermoformingdivision.com in
the Thermoformer of the Year section.

You can submit nominations and bios at any time
but please keep in mind our deadline for
submissions is no later than December 1st of
each year, so nominations received after that
time will go forward to the next year.

These sponsors enable us to publish Thermoforming
QUARTERLY

Thermoforming
QUARTERLY 6

Thermoformers of the Year …

THERMOFORMER OF
THE YEAR 2006

1982

William K. McConnell, Jr.
McConnell Company

1983

E. Bowman Stratton, Jr.
Auto-Vac Corp.
1984

Gaylord Brown

Brown Machine

1985

Robert L. Butzko

Thermtrol Corp.

1986

George Wiss
Plastofilm Industries

1987

Dr. Herman R. Osmers

Educator & Consultant

1988

Robert Kittridge
Fabri-Kal Corporation

1989

Jack Pregont
Prent Corporation

1990

Ripley W. Gage

Gage Industries

1991

Stanley Rosen
Mold Systems Corp.

1992

Samuel Shapiro
Maryland Cup
Sweetheart Plastics

1993

John Grundy
Profile Plastics

1994

R. Lewis Blanchard
Dow Chemical
1995

James L. Blin
Triangle Plastics

1996

John Griep
Portage Casting & Mold

1997

John S. Hopple, Hopple Plastics

1998

Lyle Shuert, Shuert Industries

1999

Art Buckel
McConnell Company

2000

Dr. James Throne
Sherwood Technologies

2001

Joseph Pregont, Prent Corp.

2002

Stephen Sweig, Profile Plastics

2003

William Benjamin,
Benjamin Mfg.

2004

Presented at the September 2006 Thermoforming Conference in Nashville, Tennessee

The Awards Committee is now accepting nominations for the 2006
THERMOFORMER OF THE YEAR. Please help us by identifying worthy candidates.
This prestigious honor will be awarded to a member of our industry that has made
a significant contribution to the Thermoforming Industry in a Technical, Educational,
or Management aspect of Thermoforming. Nominees will be evaluated
and voted on by the Thermoforming Board of Directors at the Winter 2006 meeting.
The deadline for submitting nominations is December 1st, 2005. Please complete
the form below and include all biographical information.

Person Nominated: _______________________________________ Title: _____________________
Firm or Institution: _________________________________________________________________
Street Address: _____________________________ City, State, Zip: ________________________
Telephone: _________________ Fax: _________________________ E-mail: _________________

Biographical Information:

•
Nominee’s Experience in the Thermoforming Industry.
•
Nominee’s Education (include degrees, year granted, name and location of
university)
•
Prior corporate or academic affiliations (include company and/or institutions,
title, and approximate dates of affiliations)
•
Professional society affiliations
•
Professional honors and awards.
•
Publications and patents (please attach list).
•
Evaluation of the effect of this individual’s achievement on technology and
progress of the plastics industry. (To support nomination, attach substantial
documentation of these achievements.)
•
Other significant accomplishments in the field of plastics.
•
Professional achievements in plastics (summarize specific achievements upon
which this nomination is based on a separate sheet).
Individual Submitting Nomination: _______________________ Title: _____________________
Firm or Institution: _________________________________________________________________
Address: ____________________________________ City, State, Zip: ________________________
Phone: ____________________ Fax: _________________________ E-mail: _________________

Signature: ______________________________________ Date: ____________________
(ALL NOMINATIONS MUST BE SIGNED)

Please submit all nominations to: Hal Gilham,
Productive Plastics, 103 West Park Drive
Mt. Laurel, New Jersey 08045

Steve Hasselbach, CMI Plastics

7
Thermoforming
QUARTERLY

THERMOFORMING
DIVISION
BOARD MEETING
SCHEDULE

Hilton Milwaukee
City Centre
Milwaukee, Wisconsin

Wednesday, September 21, 2005

Executive Committee Arrive

Thursday, September 22, 2005

7:30 a.m. – 8:00 a.m. – Breakfast
8:00 a.m. – 5:00 p.m. – Executive
Committee Meeting, Presidential Suite
2432
12:00 noon – 1:00 p.m. – Lunch
1:00 p.m. – 2:00 p.m. – James Alongi,
Finance Chair, meets with Executive
Committee
2:30 p.m. – 4:00 p.m. – Technical Chairs
meet with Executive Committee, Room
2432
6:00 p.m. – 8:00 p.m. – Board Reception,
Presidential Suite 2432
Friday, September 23, 2005
HILTON HOTEL

7:30 a.m. – 8:00 a.m. – Breakfast,
Kilbourn Room
8:00 a.m. – 10:00 a.m. – Materials
Committee, Miller Room
8:00 a.m. – 10:00 a.m. – Processing
Committee, Walker Room
8:00 a.m. – 10:00 a.m. – Machinery
Committee, Oak Room
10:00 a.m. – 12:00 noon – ALL OTHER
COMMITTEES, OAK ROOM
12:00 noon – 1:00 p.m. – Lunch,
Kilbourn Room
1:00 p.m. – 4:00 p.m. – BOARD OF
DIRECTORS’ MEETING, REGENCY
BALLROOM
5:00 p.m. – Bus departs from Hilton
Hotel to Wisconsin Club, Tailgate Party
and Brewers Baseball Game
Saturday, September 24, 2005

8:00 a.m. – 12:00 noon – Board Members
Assist in Parts Competition Setup
6:15 p.m. – Welcome Reception,
Convention Center Hall A, 3rd Floor
These sponsors enable us to publish Thermoforming
QUARTERLY

Thermoforming
QUARTERLY 8

These sponsors enable us to publish

These sponsors enable us to publish Thermoforming
QUARTERLY

Thermoforming

QUARTERLY

Visit the
SPE
website
at
www.4spe.org
9
Thermoforming
QUARTERLY

LEAD TECHNICAL ARTICLE

Enhanced TPO Thermoforming Using High
Melt Strength Polyolefin Elastomers1

BY K.L. WALTON, M.K. LAUGHNER, LAWRENCE J. EFFLER, E.S. GISLER,
DUPONT DOW ELASTOMERS LLC, GENEVA, SWITZERLAND

Abstract

Hard TPOs have grown rapidly in the automotive
industry because of their favorable cost/performance
characteristics and injection molding
processability. Other plastics processes are now either
currently used or under investigation. Processes
such as blow molding and thermoforming
offer the potential to manufacture large parts with
much lower tooling costs than injection molding.
However, it is well known that conventional
polypropylene exhibits poor melt strength. This
deficiency has limited its use in either large part
extrusion blow molding or thermoforming.

Recently, polypropylene producers have introduced
high melt strength polypropylene into the
market. These polypropylenes have much higher
melt strengths than conventional materials. They
are being promoted for used in hard thermoplastic
olefin (TPO) applications requiring high melt
strengths.

However, other components, particularly the impact
modifiers, can now play important roles in the
thermoforming characteristics of hard TPO compounds.
In a series of experiments, significant
changes in TPO Rheology were observed, depending
on the level and type of impact modifier used.
The characteristics of ethylene/alpha olefin copolymer
impact modifiers and their effect on hard TPO
thermoforming performance will be discussed.

Introduction

Propylene based compounds continue to successfully
replace engineering polymers in automotive
exterior and interior applications. The primary
driver for this substitution is raw material cost. A

1 This paper, presented at 2005 SPE ANTEC, Boston, has been
edited for publication in TFQ. Any errors or omissions are solely
the responsibility of the technical editor.

desire for lower conversion cost has led some Tier
I suppliers to examine methods of large part manufacturing
other than injection molding. For
example, it is possible to manufacture similar large
parts using either thermoforming or blow molding
that were formally reserved for injection molding.
The primary advantage of these conversion
processes is lower capital, including tooling costs.
On the other hand, it is well known that conventional
polypropylene exhibits poor melt strength
(1). The low melt strength stems from the lack of
melt strain hardening. This deficiency has limited
its use in blow molding. Thus, conventional
polypropylenes have very narrow processing windows
for most thermoforming and blow molding
applications.

Several approaches were attempted to improve
polypropylene (PP) melt strain hardening characteristics.
For example, high-pressure LDPE was
blended with PP at 15-20% (wt) to yield a PP composition
with some extrusion coating capability (2).
The LDPE has long chain branching (LCB), which
causes the polymer to exhibit melt strain hardening,
an important attribute in several processes. The
LDPE has some compatibility with the PP and thus
has an influence on the melt behavior. This blend
approach has also been extended to thermoforming
applications.

PP manufacturers are now offering alternatives
to conventional technology by providing products
with LCB incorporated into the polymer backbone.
The LCB structure causes the polymer to exhibit
melt strain hardening, an important attribute for
thermoforming. Numerous methods have been described
to incorporate LCBs into PPs (1, 3-5).

Constrained geometry catalyst (CGC) technology
utilizes a proprietary catalyst and solution process
based on transition metal chemistry, with titanium
being the most commonly used transition metal.
This catalyst technology enables the copolymeriza-

Thermoforming
QUARTERLY 10

tion of ethylene with different potential alpha olefin
comonomers. For example, DuPont Dow
Elastomer’s newest plant manufactures both ethylene/
1-octene and ethylene/1-butene copolymers
using this catalyst. These copolymers are widely
used as PP impact modifiers because of their elastomeric
nature, compatibility with PP, and pellet
form.

The combination of CGC catalyst and the solution
process allows the development of reactor conditions,
which can be tuned to produce ethylene
copolymers containing LCB 96). By judicious reactor
control, ethylene alpha olefins (EAOs) with differing
levels of LCB are produced (7).

This paper investigates the use of EAOs having
high and medium LCB levels in PP as impact modifiers.
The effects of these impact modifiers on PP
thermoforming characteristics are highlighted.

.

Experimental

Sample Preparation

The three EAO samples in this study were produced
in DuPont Dow’s commercial facilities using
CGC technologies. Three commercially
available PPs were examined. Selected properties
are shown in Table 1.

Blend compositions were melt compounded using
a Coperion ZSK25 corotating twin screw extruder.
The compounded pellets were extruded on

a 50 mm Killion extruder equipped with a 610 mm
wide EDI sheet die feeding a 600 mm wide Davis
Standard three-roll stack having chromed polished
rolls. The die gap was adjusted to yield a 1.1 mm
thick sheet. Roll speed was adjusted to minimize
orientation. Tables II – IV (see page 12) show the
compounded samples tested.

Thermoforming

The sheets were tested for thermoformability using
a Lamco thermoformer equipped with 12 individually
controlled quartz heaters, top and bottom.
And infrared pyrometer was positioned at the bottom
of the oven to monitor sheet surface temperature.
The average power setting was 40% for the
top and 55% for the bottom. Square sheets 56 cm x
56 cm were cut and clamped. After reaching the
desired temperature as measured by the oven pyrometer,
the sheet was indexed out of the oven,
surface temperature was measured via a hand-held
pyrometer, and the sheet was vacuum formed into
a 14.5 cm x 14.5 cm cavity mold with 2.4 cm depth.
The sheets were thermoformed over a temperature
range. The temperature at which complete part
thermoforming was achieved in the inside cavity
was called the “minimum temperature.” The temperature
at which the sheet formed a hole during
vacuum forming was called the “maximum temperature.”

(continued on next page)

Table I
Polymers Tested
Grade Type Comonomer Melt Melting Density
Viscosity Temp. (kg/m3)
dg/min (° C)

PP1 PP high LCB impact 1.8a 163 903
Copolym.
PP2 Clarified PP none 0.42a 164 905
homopolym.
PP3 PP homopolym. none 1.35a 165 905
EB1 EAO hi LCB butene 0.25b 93 901
EB2 EAO med LCB butene 0.28b 48 870
EO1 EAO med LCB octane 1.6b 93 897
ABS1 Extrusion grade terpolym. 1.2c N/A 1040

a = melt flow rate at 230°C, 2.16 kg. wt.
b = melt index at 190°C, 2.16 kg. wt.
c = melt index at 230°C, 10 kg. wt.
N/A = not applicable. ABS has no crystalline melting point

11
Thermoforming
QUARTERLY

(continued from previous page)

Table II

Simple Two-Component Blends

Compound PP1 PP2 EB1 EB2 EO1
1 100 0 0 0 0
2 0 100 0 0 0
3 90 0 10 0 0
4 90 0 0 10 0
5 90 0 0 0 10
6 0 90 10 0 0
7 0 90 0 10 0

Table III

Three-Component TPO Composition, [wt. %]

PP3 PP1 EB1
5050 0
850 15
0 70 30
0 100 0
0 85 15
700 30
3535 30
1000 0

Table IV

Fully-Formulated TPOs

Compound A B

Ingredient wt. % wt. %
PP3 48 44
PP1 812
EB1 24 24
Talc 20 20

Antioxidant 0.2 0.2

For selected samples, the thermoforming sheet
sag was measured as a function of index temperature.
A video capture technique was used to obtain
the data.

Physical Properties

Sheet hardness was measured according to
ASTM D2240. The tensile properties were determined
according to ASTM D638. Instrumented dart
impact was measured according to ASTM D3763.
Sheet tear strength was measured according to
ASTM D1004.

Rheological Measurements

Dynamic shear tests were conducted at 190, 210,
and 230°C on a Rheometrics dynamic spectrometer

model ARES, with a parallel plate fixture of 25 mm
and 2 mm cap setting. A 15% strain level was used
on all samples.

Results and Discussion

Rheological Characteristics

Figure 1 compares the tan deltas of the three PPs.
The relatively flat response of the tan delta curve
to frequency in Figure 1 infers that LCB is present
in PP1. As seen in Figure 2, the relative flatness of
the tan delta curve for EB1 infers a significantly
higher LCB level than either EB2 of EO1.

Figure 1. Tan deltas versus frequency of the tested PPs.

Figure 2. Tan deltas of the tested elastomers in the melt state.

Thermoforming Comparison

Simple Two Component Blends: Figure 3 compares
the thermoforming window of PP2 alone and
blended at 10% (wt) with EB1, EB2, and EO1. As
seen, PP2 (unbranched homopolymer PP) exhibits
a very narrow thermoforming window. All of the
EAOs improve the PP2’s thermoforming window.
The widest thermoforming window is observed
with compound #3 containing 10% EB1. The sheet
of compound #4 exhibits localized thin spots during
thermoforming. It is apparent that the incorporation
of an EAO with high LCB levels significantly

Thermoforming
QUARTERLY 12

Figure 3. Effect of impact modifier on PP2 thermoforming window.

improves the thermoforming window of standard
PP homopolymers by 25°C.

Figure 4 compares the thermoforming window
of PP1 alone and blended at 10% (wt) EB1 and EB2.

Figure 4. Effect of impact modifier on PP1 thermoforming window.

Note that a much higher temperature is required
to thermoform the PP1-based compounds. Sheets
based on PP1 exhibit very little sag, indicating significantly
higher melt strength than PP2-based
sheets. However, little change in the breadth of the
thermoforming window is observed. Further, at
elevated temperature, hole formation readily occurs.
Also, during thermoforming, high levels of
sheet “nerve” are observed. No thermoforming
benefit is observed by adding EB1 to PP1. However,
by adding EB2 to PP1, the thermoforming
window increased by 30°C. With EB2 present, the
sheet deformed more readily at higher temperatures
with no rupture. Perhaps the addition of a
lower LCB EAO with reduced melt elasticity improves
the melt extensibility of a composition having
a branched PP.

Simple Three-Component Blends: It has been previously
reported that blends of branched PP with
standard PP homopolymers and a branched impact
modifier yielded compositions with optimum performance
for thermoforming (8). A Three-component
mixture design was formulated to determine

the effect of standard PP, branched PP, and
branched EB blends on thermoforming sheet sag.
The experimental compositions are shown in Table

III. ABS1 was used for benchmark comparison. Figure
5 compares the sheet sag verses temperature of
selected compounds from this study. A wide range
of sheet sag characteristics is seen for these compounds.
Figure 5. Three-component TPO thermoforming sage range.

As expected, standard PP3 alone sagged most.
On the other hand, pure PP3 exhibited low sag. The
lowest sag observed was with blends of PP1, PP3,
and EB1. The ABS1 sag characteristic is shown in
the the middle of the sag curves.

Fully Formulated TPOs: Based on the three component
results, two optimize TPO compounds were
evaluated and compared with ABS1. Table IV describes
these two TPO compounds. Figure 6 shows
the temperature-dependent sag characteristics of
these two compound. As seen, The sag characteristics
of both compounds match the ABS1 sheet sag
characteristics reasonably well, with the TPO B
compound having the better match of the two. The
sag characteristics and sag time of TPO B closely
matches that of ABS1 at 210°C.

Figure 6. Thermoforming sag comparison, TPO-A, TPO-B, and
ABS1.

(continued on next page)

13
Thermoforming
QUARTERLY

(continued from previous page)

Physical Properties

Figures 7 and 8 are radar plots comparing the effects
of adding 10% (wt) impact modifer on the physical
properties of PP. As shown in Figure 7, all impact
modifiers improve the impact strength of PP1 at 0°C.

Figure 7. Radar plot of PP2 properties with and without 10% (wt.)
impact modifier.

However, the low crystallinity EB2 is a more efficient
impact modifier. Because the refractive index of EB1
and EO1 matches that of PP2, sheets are quite clear.
As a result of the comonomer content, the crystal
structures of these two EAOs match the refractive
index of PP. On the other hand, the refractive index
of low crystallinity EB2 does not match those of other
EAOs. As a result, sheet based on EB2 is hazier. High
clarity impact-modified thermoformable TPOs may
prove useful in translucent applications or in parts
where color depth is important.

Figure 8 compares the effect of adding impact
modifier to PP1. The DSC melting point indicates that
the product is not a random copolymer. On the other
hand, the 0°C impact value of PP1 is higher than that
for a standard homopolymers. This suggests that it
contains an impact modifier. Additional modifier has
little effect on its impact strength. It is evident that
PP2 is not designed for transparent applications. The
haze of PP2 alone is quite high. It is likely that the
haze is partially the result of a low crystallinity im-

Figure 8. Radar plot of PP1 properties with and without 10% (wt.)
impact modifier.

pact modifier compounded into the PP during its
manufacture. Additional impact modifier had little
effect on haze.

Conclusions

The thermoforming characteristics of standard PPs
can be significantly improved with the addition of
newly developed LCB impact modifiers. Higher crystalline
impact modifiers match the refractive index
of PP and yield compositions with good clarity. Lower
crystalline impact modifiers yield optimum impact
modifications.

The branched PP examined in this study exhibited
a high level of melt strength, but low melt extensibility.
The addition of an impact modifier with low levels
of LCB improved the melt extensibility and
thermoforming window of this PP.

TPOs containing optimized levels of standard PP,
branched PP, and branched EAO yield
thermoforming sag characteristics similar to a
thermoforming grade ABS.

Acknowledgments

The authors thank Doug Waszneciak for his help
in manufacturing the sheets and thank the testing lab
personnel of DuPont Dow Elastomers for providing
physical property data on the various polymers and
formulated compounds.

References

1. Tau, L., et al, US Patent 6,593,005, assigned to The Dow
Chemical Company, July 2003.
2. Beren, J.R., Phillips, E.M., Reginister, L., and Travernier,
M., “Polyolefins for Extrusion Coating: Trends and Limitations,”
Presented at TPPI, Dusseldorf, 1995.
3. Weng, W., Hu, W., and Dekmezian, A.H., “Structure and
Property of Long Chain Branched Isotactic Polypropylene,”
Presented at 226th ACS National Meeting, New
York, 2003.
4. Oliver, D., Michel, J., Dupire, J., European Patent Application
EP 2002-77723, assigned to Atofina Research SA,
2002.
5. DeMaoi, V., and Dong, D., “The Effect of Chain on Melt
Strength of Polypropylene and Polyethylene,” presented
at SPE ANTEC, Toronto, 1997.
6. Laughner, M., Parikh, D., and Walton, K., “New Developments
in Metallocene Ethylene Elastomers for Automotive
Applications,” presented at the SPE Global
Polyolefins Conference, Houston, 2001.
7. Lai, S., et al., US Patent 5,272,236, assigned to The Dow
Chemical Company, 1993.2
8. DeMaio, V.V., Dong, D., and Gupta, A., “Using Branched
Polypropylene as a Melt Strength Modifier – Improvement
in Sheet Sag Resistance,” presented at SPE ANTEC,
Orlando, 2000. ¦
Thermoforming
QUARTERLY 14

INDUSTRY PRACTICE

Collaborative and Methodical Product Development
Reduces Time From Concept to Production

BY ERIC HAUSSERMAN, PREMIER MATERIAL CONCEPTS, FINDLAY, OHIO

T
T
he most effective product development initiative ensures
that all parties involved have input … from the
resin supplier, all the way through to the end-user since
so many factors must be taken into consideration when
deciding on a material or a finish.

First and foremost the function of the finished product
must be taken into account. How is the product going to
be installed? What elements is the product going to face?
What is the expectation as far as life of the product? These
could include: UV stability, chemical resistance, co-efficient
of friction, fire rating, etc. For example, PMC developed
a Thermo Plastic Elastomer (TPE) insert for a
household step stool. The design of this product covered
many of the factors mentioned above. A product was created
that achieved a high co-efficient of friction, so that
the user would not slip off the stool when in use. It also
was chemical resistant, as step stools are often used around
cleaning supplies. If not the insert could become easily
and quickly degraded.

Next we took into consideration the processes that the
material would go through as it was manufactured into a
finished product. What kind of temperature is the product
going to see in secondary processes? Is any pressure
going to be applied to the sheet in secondary processes?
Could the material be scratched as it goes through secondary
processes? These include: Thermoforming, die cutting,
lamination, injection molding, etc.

Consideration of these factors above was critical for this
project. First we discovered that the material would go
through a secondary die cutting operation. So the material
designed had a very clean trim permitting it to be die
cut very efficiently. Next the insert was to be placed inside
an injection mold. The material we developed withstood
a very high temperature, did not “bleed,” and
maintained a very crisp, clean edge, when the molten plastic
was shot behind it.

Creating this product was a very collaborative effort.
There was involvement from the resin supplier, the sheet
extruder, the die-cutter, the manufacturer of the footstool,
and of course feedback from potential end-users. The
product was developed, qualified, put through all of the
specified testing, and we were able to go from concept to
production in 45 days.

We also believe using a “Stage Gate” approach enhanced
our success. It made sure everyone knew the objectives,
whether we have met our objectives, and that the proper
resources were being allocated.

The following steps are an example of an effective Stage
Gate process:

1. Investigation/quote phase
a. Product criteria
b. Product design
c. Manufacturing process(s) design
d. Quotation
2. Sample/Prototype phase
a. List requirements
b. Sample run
c. Testing
d. Submission
e. Customer feedback
3. Approved product/proceed to production
a. Forecast
b. Finalization of manufacturing processes/
equipment
c. Vendor releases
d. Quality plan
4. Post Production analysis
a. Continuous improvement opportunities
b. Other product/market applications
Product development, and determining the right finish
for your thermoplastic product, is a very complex process.
If the proper steps are not followed, this can be a
very expensive and inefficient process. If you involve everyone,
follow the right steps, you can “get the right finish”
for your thermoplastic materials and reduce the
number of days necessary for the development of your
product.

***************************
Premier Material Concepts (PMC), is a custom manufacturer
of TPE, ABS, HIPS, PP and acrylics for thermoforming, POP
display material, converters and custom fabricators. PMC, a
division of Rowmark, Inc., serves diverse industries including
marine, industrial, aerospace, government, agriculture, automotive,
displays, signage, electrical and furniture. For additional
information about Premier Material Concepts (PMC)
visit their Worldwide Web at www.buypmc.com.

15
Thermoforming
QUARTERLY

INDUSTRY PRACTICE

Proper Colleting and Collet Maintenance
in CNC Routing of Plastic1,2

BY VAN NISER, ONSRUD CUTTER, LIBERTYVILLE, ILLINOIS

Introduction

Rigidity is a key factor in the routing of plastic
material. The problems associated with rigidity involve
the part as well as the machine. Parts must
be held solidly with established fixturing techniques,
and the machine must be appropriately
maintained to insure the cutting tool is following
the proper tool path in a rigid and concentric fashion.
One of the elements that aids in this whole
process lies in the area of proper colleting of the
router bit and the ongoing maintenance procedure
associated with router collets.

Types of Collets

The half-grip and full-grip collets are the two
basic types found in CNC routers. Half-grip collets
are identified by slits running from the bottom or
mouth of the collet toward the top for about 80%
of the collet length. These collets are often counterbored
at the top, so that the shank of the tool does
not contact the entire length of the collet. The force
holding the collet is primarily generated at the
mouth of the collet, and proves ideal in situations
where the shanks of the router tools are not long
enough to fill the entire collet, Figure 1.

The full-grip collet is identified by slits running
from both ends of the collet, which creates specific
collet sections. Full-grip type collets allow for
squeezing pressure to be exerted over the entire
length of the collet, Figure 2.

1This article appeared in Plastic Distributor & Fabricator, Nov/Dec
2004, and is reprinted with permission of David Whelan, Editor/
Publisher. For subscription information, please contact
www.plasticsmag.com. The article has been edited by TFQ Technical
Editor, who is responsible for any alteration in content or intent.

2 Although the article addresses plastic trimming issues, the information
is directly applicable to pattern makers and craftsmen working
in other materials such as wood.

Figure 1. Half-Grip Collets.

Figure 2. Full-Grip Collets.

Proper Colleting

The proper method of colleting a router bit in
the full grip collet is to fill at least 80% of the depth
of the collet. This allows the tool to be equally distributed
on all sections of the collet and provides
an environment where the tool runs in a true circle

Thermoforming
QUARTERLY 16

or concentrically. Without concentricity, the finish
of the plastic will be adversely affected and tool
failure can occur. There are situations where the
80% rule cannot be maintained because of inadequate
shank length or extreme reach problems.
Consequently, it becomes necessary to fill the void
in the top of the collet with a filler or collet life plug.
This is a practical solution to avoid collapsing of
the collet, which may result from not following the
80% rule, Figure 3.

Figure 3. Proper Tool Colleting.

In all router bits, there is an area known as the
flute fadeout section of the tool. This is formed
when the grinding wheel utilized in the manufacturing
of the tool exits the work piece. In order to
properly collet a router bit, the mouth or bottom of
the collet must contact the router bit slightly above
the flute fadeout. Over-colleting or allowing the
flute fadeout portion to extend inside the collet can
damage the collet. This is a common cause of tool
breakage, Figure 4.

Figure 4. Incorrect Tool Colleting.

Collet Maintenance

Router bits and collets are expected to operate
accurately in a work environment inundated with
heat and grime. Plastic chips formed by the cutting
action of the router bit carry with them resins
that migrate through the slits of the collets and adhere
to the inside of this closely toleranced mechanism.
The resin build-up usually concentrates
nearest the mouth of the collet. At this point, the
tool is no longer being equally gripped, causing a
loss in concentricity and tool run-out. Once again,
the lack of a router tool running in a true circle affects
the finish of the part and may cause the ultimate
demise of the tool, Figure 5.

Figure 5. Collet Examples.

Fortunately this problem is easily resolved by
cleaning the collets after every tool change. The procedure
involves the use of a non-abrasive brass tube
brush applied inside the collet in combination with
a cleaner such as Rust Free™. All surfaces inside and
outside the collet, inside the spindle taper, and
matching and mating surfaces of quick-change tool
holders, should be thoroughly cleaned and dried
before being reassembled. Also the collet nut should
be cleaned of resin and chip build-up and regularly
replaced to ensure the integrity of the whole collet
system, Figure 6.

Figure 6. Full-Grip Collets.

(continued on next page)

17
Thermoforming
QUARTERLY

(continued from previous page)

Collet Replacement

Collets are manufactured from spring steel and
regular usage causes a loss of elasticity. Therefore,
it becomes necessary to replace collets on a regular
interval as part of an ongoing maintenance program.
With diligent attention to proper collet maintenance,
the average collet should be replaced about
every 400-600 hours. Avoiding regular replacement
can lead to brittle collets, which may crack or break,
and cause permanent damage to the spindle. Re

placement of collets is a much more economical
alternative than replacing router bits or expensive
spindles.

Rigidity and concentricity are the key elements
in any routing application. The simple process of
properly colleting router tools, maintaining collets,
and replacing them at regular intervals will safeguard
the productivity of the operation and ensure
that the finish of plastic parts is not jeopardized.

For more information on this or other cutter
issues, contact Onsrud Cutter, 800 Liberty Drive,
Libertyville IL 60048, email: vniser@onsrud.com. ¦

Tsunami Relief – Thermoforming Style!

On December 26, 2004 at approximately 8:00 am rampant. The widespread devastation witnessed by
a magnitude 9.3 earthquake devastated the these workers cannot be put into words. PRN Interocean
floor off the coast of Northwest Sumatra. The national and my sister would like to thank the
resulting Tsunami traveled thousands of miles across Thermoforming Division for their $2,500 donation.
the Indian Ocean, taking the lives of nearly 300,000 The Thermoforming Division would like to thank
people in countries as far apart as Indonesia, the the volunteers at PRN International for actually do-
Maldives, Sri Lanka and Somalia. ing what most of us just talk about. We would like
Early in 2005, the Thermoforming Division started to think that in some tiny way, though PRN Internato
investigate a way we could help out. Our thoughts tional, D25 made a difference, Thermoforming Style.
were to find a truly unique way to make a differ~
By Mike Sirotnak, Solar Products ¦
ence. We looked into some of the more conventional
disaster relief funds, Unicef, Red Cross and
Worldvision. That is when I received a phone call
from my sister, Barbara McConachie, a registered
nurse who has made numerous relief trips to 3rd
world countries. Her group, PRN International, was
looking to send a small group of doctors and nurses
over to Sri Lanka to assist with the relief efforts. This
group was experienced in the most efficient way to
get in and get busy.
At our winter Board of Directors meeting in
Florida, I submitted a request for a donation to PRN
International. The request was unanimously approved.
On January 28th, 3 doctors and 5 nurses from
Bridgeport Hospital left New York for Sri Lanka.
Twenty-eight pieces of luggage filled with donated
antibiotics, vaccines, analgesics, skin ointments and
baby formula made the trip as well. Our volunteers
worked their way up the northern coast of Sri Lanka
(Ampara) and partnered up with healthcare providers
from around the world.
During their stay the PRN relief team treated over
200 people in 3 different refugee camps on a daily
basis; revisiting these same people every other day
trying to prevent a outbreak of Malaria and Cholera.
The physical injuries treated were pneumonia, diarrhea,
fevers, open wounds and cellulitis. The
physiological wounds were just as bad if not worse;
most of the people lost 3 out of 4 family members.
Depression and Post Traumatic Stress Syndrome is

Thermoforming
QUARTERLY 18

INDUSTRY PRACTICE

History of Thermoforming – Part I

BY STANLEY R. ROSEN, PLASTIMACH CORPORATION, LAS VEGAS, NEVADA

Thermoforming Pioneers 1930-1950

The development of modern machinery for the
thermoforming industry took place on the shoulders
of very perceptive pioneers during the years
1930-1950. These experimenters did not have the
modern tools or hindsight we now possess yet they
developed many of the processes we currently
employ. Information contained in this article was
abstracted from periodicals, patents, and conversations
with industry innovators. Some firms during
this period developed proprietary equipment
to thermoform their products and they are nameless
at this time.

A great deal of development effort pre-World War
II went into forming airplane acrylic canopies free
of flaws. E. L. Helwig of Rohm and Haas Company
in Philadelphia, an acrylic resin manufacturer, has
two patents using different techniques which when
modified can be used today.

Figure 1. Helwig’s patent, filed on 11-27-1938, illustrates
the forming of a canopy from a pre-heated
sheet of acrylic forming which utilizes a hot fluid
under variable pressure. The mold was water
cooled so that sheet surface facing the cavity would
chill and be hard enough to avoid being marred
against the mold surface. The inner surface sheet
would be free of blemishes since its contact is with
the hot fluid. This process is similar to a modified
method used today where air pressure forms sheet
against a temperature- controlled mold producing
high quality parts.

Ed. Note I: The philosopher Santayana said, “Those who cannot
remember the past are destined to repeat it.” Stan Rosen is undertaking
a prodigious project – identifying the pioneers who laid the
foundations of the industry we know so well. Although shaping of
sheet extends back to pre-history – oil-heated and shaped tortoise
shell and steam-heated and shaped wood, Stan begins the journey
in the 1930s. We hope you enjoy the trip!

Ed. Note II: Each year since 1982, the SPE Thermoforming Division
has honored a leader in the thermoforming field. Bow Stratton
was the 1983 Thermoformer of the Year. Bob Butzko was the 1985
Thermoformer of the Year. And Stan Rosen, the author of this article
was the 1991 Thermoformer of the Year. Stan can be reached
at thermoipp@earthlink.net.

Figure 1. H. E. Helwig of Rohm and Haas Corp. filed for a patent 1127-
1936 using hot oil pressure for forming acrylic.

Figure 2. Helwig patent filed, on 8-28-1942, describes
a male snap-back technique using an ovenheated
acrylic sheet which is clamped to the device
with quick-acting clamps or bolts. Figures 2-1 and
2-2 exhibit the use of vacuum to pre-stretch the hot
sheet and allowing atmospheric pressure to force
the cooling plastic to the male cavity. Figures 2-3
and 2-4 show air pressure creating a bubble of hot
plastic which, after the air is exhausted from the

Figure 2. H. E. Helwig filed for a patent 8-28-1942 using snapback
forming.

(continued on next page)

19
Thermoforming
QUARTERLY

(continued from previous page)

chamber, the cooling sheet then conforms to the
cavity. The expansion of the surface of the hot sheet
before forming is used to assist in producing uniform
wall thickness on the finished part. This process
appears to be the first patent in which a male
cavity is used in thermoforming.

Figure 3. R. E. Leary of Dupont Corp., patent filed
12-27-1940, illustrates vacuum forming using two
methods of controlling a radiant heat source to
achieve a uniform wall thickness.

Figure 3. R. E. Leary of DuPont Corp. filed for a patent 12-27-1940
for a vacuum forming apparatus.

1. This heater assembly can be raised or lowered
relative to the plastic sheet line. Moving a heat
source away from or toward the sheet is a powerful
method of heat control. The distance of a radiant
source to its receptor is not a linear function
and a small movement can create big differences
in temperature distribution across a sheet surface.
2. Each lamp in the heater assembly is individually
controlled so that the heating pattern can be
zoned to promote a uniform temperature distribution
across the sheet. This patent suggests the use
of radiant heating at the forming site rather than
preheating the sheets in an oven and later transporting
them to a mold.
Figure 4. J. J. Braund, patent filed on 2-17-1936,
is not a plastics fabricating patent but it has an interesting
concept. Braund in the early 1930s started
to develop a process to produce inexpensive three-

Figure 4. J. J. Braund filed for a patent 2-17-1936 for a relief map
duplicating machine.

dimensional relief maps for the U.S. Coast and Geological
Survey. A relief map sheet is distortion
printed with each color referring to a specific elevation.
When formed, the map might use green
for sea level at the sheet line and white for the tips
of the mountains in the deepest part of the mold.
This technique locates a pre-printed sheet of ductile
metal facing a female mold mounted above the
blank. The back face of the sheet is sealed to a shallow
box and the whole assembly is locked in a powerful
clamp frame. Hydraulic oil under pressure is

Figure 5. J. T. Braund filed for a patent 9-24-1946 for a relief mat
vacuum former using convection heat..

Thermoforming
QUARTERLY 20

pumped into the box, forcing the metal sheet to flow
into the mold. If the date of the above patent was
1946 instead of 1936, Braund could have chosen to
substitute a plastic sheet instead of metal and might
have used air instead of oil pressure.

Figure 5. J. J. Braund filed a patent on 9-24-1946,
which describes a system for vacuum forming plastic
relief maps similar to his earlier 1936 metal forming
methods. This sheet heating system is analogous
to R. E. Leary’s oven, except the heater provides
convection heat transfer rather than radiant
heating. The top fan creates an air flow through the

Figure 6. F. E. Wiley of Plax Corp. filed for a patent 6-1-1944 for a
method of deep drawing plastic sheets.

bank of heat lamps which increases the air temperature
within the hood and heats the plastic to forming
temperature. Braund claims this method creates
a very uniform sheet temperature for accurate
registration of pre-printed sheet to vacuum forming
mold.

Figure 6. F. E. Wiley of Plax Corp., Hartford, Connecticut,
filed for a patent on 6-1-1944. It is concerned
with forming techniques which produce a
uniform wall thickness on deep drawn parts. This
system is a three-step process in which the sheet is
pre-heated, and in the second operation it is drawn
to a shallow depth in a female cavity. A third operation
draws the sheet to the deeper finished size
on the male cavity. The heating medium is steam,
which raises the sheet to forming temperature in
all the steps and the clamp which holds the pre

heated sheet frame is moved manually from step
to step. Wiley has developed four similar variations
of this technique. (Only one is illustrated as
follows:)

Figure 6-1 is a steam heating chamber. In Figure
6-2, a shallow female mold and sheet is pressureformed
using steam and its wall thickness is at a
minimum at (20a) and thickest at (20b). In Figure
6-3, the sheet is steam-reheated with male cavity

(31) lying in the shallow form to prevent distortion.
When the sheet reaches forming temperature
the steam is exhausted and the cavity (31) is extended
to final depth while atmospheric air pressure
forces the sheet against the cavity. The male
cavity draws material from the upper side wall
(20d) and very little from the tip (20a) which results
in a fairly uniform product, Figure 6-4. ¦
References

J. H. DuBois, Plastics History USA, Cahners Publishing
Co., Inc., 1972.
J. J. Braund, US Patent 2,066,555, filed 2-17-1936.
E. L. Helwig, US Patent 2,142,445, filed 11-27-1936.
C. B. Strauch, US Patent 2,229,613, filed 11-22-1938.
R. E. Leary, US Patent 2,377,946, filed 12-27-1940.
G. W. Borkland, US Patent 2,347,806, filed 10-2-1941.
E. L. Helwig, US Patent 2,365,637, filed 8-28-1942.
F. E. Wiley, US Patent 2,468,697, filed 6-1-1944.
J. J. Braund, US Patent 2,493,439, filed 9-24-1946.
G. W. Borkland, US Patent 2,559,705, filed 7-8-1947.
Phone conversation with Jim Phohl, Plaxall Corp., Long
Island City, NY, Dec. 2004.
Phone conversation with Steve Hasselbach, CMI Plastics
Corp., Cranbury, NJ, Dec. 2004.
SPI (NPE now), archives from Hagley Museum and
Library, Wilmington, DE, for exhibitors 1950, 1952.
Modern Plastics and Modern Plastics Magazine, issues
1950-1953.
Army Map Service, Relief Map Division, Corps. of Engineers,
Washington, DC.

PART II WILL FOLLOW

IN THE NEXT

THERMOFORMING

QUARTERLY

21
Thermoforming
QUARTERLY

Understanding How a Sheet Stretches1

BY JIM THRONE, SHERWOOD TECHNOLOGIES, INC., DUNEDIN, FL

W
W
e began our discussion of
part design by reviewing
why we might not want to quote
on a job. But let’s suppose that we
did quote on the job. And we got it.
Now what?

Forming into a Mold v.
Forming onto a Mold

In the not-so-politically-correct
jargon of the day, if we form into a
mold cavity, the mold is called a
“female cavity.” A better PC2 phrase
is “negative mold.” If we form onto
a mold, the mold is called a “male
mold.” The proper PC phrase is
“positive mold.” Is there a difference
in forming “into” v. forming
“onto”? Of course. Let’s consider
for the moment, forming a very
simple truncated cone. If we use a
mold cavity, the sheet first drapes
into the open cavity, then stretches
into the cavity with the sheet progressively
laying on the mold surface.
Keep in mind that the sheet
that contacts the mold surface usually
doesn’t stretch any further. As
a result, the sheet that is free of the
mold becomes thinner and thinner
as it is stretched to the bottom of
the mold. The wall of the resulting
part is thickest at the rim and thinnest
at the bottom. The thinnest region
of the part is in the corner
where the wall meets the bottom.
We can show arithmetically that if

1 This is the third in a series that focuses
on part design.
2 PC. Politically correct.

3 We discuss draw ratio in the next lesson.
4 By “positive surface,” we mean that surface
that the customer considers to be the
more important one. Usually the surface
against the mold is considered the positive
surface, but not always.

5 Efficacious: Producing or capable of producing
a desired effect.

THERMOFORMING
101
the wall makes a 60-degree angle
with the horizontal rim, the wall
thickness decreases linearly from
the rim to the corner. If the wall
makes a 90-degree angle [think
soup can], the wall thickness decreases
exponentially.

Now consider using a truncated
cone male mold. The sheet first
touches the mold at the bottom of
the part being formed. As the mold
pushes into the sheet, the sheet
stretches between the clamp and
the bottom of the mold. If the sheet
doesn’t touch the sides of the mold
until the mold is completely immersed
in the sheet, the sheet thickness
is usually quite uniform. If the
sheet progressively touches the
sides of the mold as the mold is being
pushed into the sheet, the wall
of the resulting part will be thickest
at the bottom and thinnest at the
rim.

Does it make a difference
whether we form into a cavity or
over a mold? If part performance
is important, probably not, if the
part draw ratio3 is very low [think
picnic plate or aircraft engine
cover]. As the draw ratio increases,
however, the thinnest sections of
the part begin to control the performance
of the part. Several other factors
can influence our decision,
such as:

• Is it easier to prestretch the
sheet when forming into a cavity
or over a mold?
• Is it easier to machine a cavity
or a male mold?
• Is the rim thickness important,
as in the case of thin-gauge containers?
• And does the customer need
the inside or the outside of the
part to be the positive surface4?
Usually – but not always – mechanical
plugs are more effective in
stretching sheet into a cavity, female
molds are easier to fabricate
than male molds, and rim thickness
is better controlled with female
molds. We’ll revisit some of these
factors later.

Forming “Up” v. Forming
“Down”

What does this mean? If the mold
is placed above the sheet, the mold
is immersed in the sheet and the
part is formed up onto or into the
tool. If the mold is placed below the
sheet, the sheet sags into or onto the
mold and the part is formed down
onto or into the tool. Why is this an
issue? In thin-gauge thermo-forming,
forming up has advantages
with female molds. Gravity helps
when releasing parts from multicavity
tooling. And the parts are
properly oriented for in-line trimming.
Having said that, keep in
mind that it is easier to mechanically
prestretch the sheet into fe-

Thermoforming
QUARTERLY 22

male cavities if the molds are below
the sheet.

Although the mold weight may
prevent mounting the mold over
the sheet in heavy-gauge forming,
there are some advantages here too.
For example, when a male mold is
mounted over the sheet plane,
sheet sag acts to prestretch the sheet
prior to the mold immersion. The
sheet is formed down for most
heavy-gauge forming into female
molds. Again, sheet sag acts to
prestretch the sheet prior to forming.
And certainly, it is easier to activate
and maintain mechanical
plugs if they reside above the sheet
rather than below.

Mating Parts

It should be apparent that the
part side against the mold maintains
a more accurate dimension
than the other side. The mold side
is chosen whenever the part is to
mate with another dimensioned
part. For example, for an integrallid
container to be liquid tight, the
outside of one half must mate with
the inside of the other. This may
require that one half is formed into
a female mold while the other is
formed on a male tool.

An Observation

When quoting on a job, it is always
advisable to keep in mind the
capability of your equipment to
form the part in the most efficacious5
and least costly manner. If
you can’t form up, don’t quote on
a job that is best produced in this
fashion. The more tortuous the path
to perfect parts, the greater the degree
of difficulty. And surely the
greater the chance for quality
issues. ¦

Keywords: positive mold, male
mold, negative mold, female mold,
draw ratio, forming up, forming
down, sag

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ThermoformingQUARTERLY 24

BOOK REVIEW

G. L. Beall, The Evolution of Plastics
in America (As Seen Through the
National Plastics Expositions), Plastics
Historical Society Occasional Paper
No. 1, 1 Carlton House Terrace,
London SW1Y 5DB, United Kingdom,
26 pdf pages when printed,
sales@plastiquarian.com, ~$18.00.
I
I
t is fitting that Beall’s latest effort
(1) is on the history of plastics as
viewed from the exhibits seen at
NPEs and (2) is on a plastic CD-
ROM. It is also appropriate that in
this issue, we feature the first part of
Stan Rosen’s review of the history of
thermoforming in the Industrial
Practice column. The first NPE was
sponsored solely by SPI and was
held in New York City in 1946. The
public was invited to the inaugural
Exposition and the public came –
87,000 – an attendance record that
was not surpassed until 2000! Of
course, after the first NPE, the conferences
were ostensibly closed to all
but members of the plastics industry.

Even though the public viewed
plastics as wondrous things in 1946,
it seemed that the industry did not
really begin to believe in itself until
the late 1970s. Attendance appeared
to plateau below 40,000 during the
intervening years. The attendance in
1982, for example, was only 41,000.
Attendees in those intervening years
would have seen the shift from cellulosics
and phenolics to polyolefins
and urethanes, from a dominance of
custom molders to the dominance of
material suppliers and major machinery
builders, from just over a billion
pounds of plastic consumed a
year to more than 40 billion pounds
of the stuff. The attendees would
have seen a 42-pound compression
molded television cabinet,
Monsanto’s plastic “House of the Future,”
the newly-invented screw in

1 The reviewer spent many months working
on both of these projects, saw them
exhibited at NPE, and then watched the
first fail FDA trials and the second fail economically.

jection molding machine, the blowmolded
plastic milk bottle, the nitrile
barrier carbonated beverage bottle,
Coors molding-with-rotation (MWR)
beer can1, the Weyerhauser 714 composite
can1, pink flamingos, and the
following litany of new plastics –
LLDPE, rigid PVC, PP, EVA, ABS,
mPPO (Noryl), continuous cast
acrylic, ionomers, PPS, and PET. And
if you were a collector, you would
have tried to take home hula hoops,
swimming pool noodles, and PP garden
chairs, among other attractive
give-aways.

This is a fascinating trip down
memory lane for many of us. Beall’s
first show was in 1958 in Chicago;
mine was in 1966 in New York City.
And I’m sure that both he and I have
made the effort to go to every one
since. I, like Beall, remember both the
excitement of the new ideas and the
glitz and glamour of the exhibits.
Gone are the days when exhibitors
attracted us to their booths with
comely lasses in very short skirts, or
tickets to local shows (particularly in
NYC), or fancy gentlemen’s afterhours
clubs where libations
abounded.

Sometimes in the grim reality of today,
we need to reflect on another
time – not as intense, not as throatcutting
– when new ideas were not
kept as secrets but were touted as
representing the genius of our industry,
daring the competition to better
them.

Take time to seek out this CD-
ROM. It’s worth the time and effort.
And if you weren’t around for this
era, read it and pretend you were.
Five books out of five.

~ Jim Throne

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Roger Fox David A. J. Morgese
(630) 653-2200
www.foxmor.com
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25ThermoformingQUARTERLY

Council Report …
Atlanta, Georgia

BY STEVE HASSELBACH, COUNCILOR

ANTEC
Registration at ANTEC was 2,658 (including
participants in the seminars.)
A total of 168 registrants attended 19
Society seminars.

Incoming President Len Czuba’s
SPE mantra is “Connect, Collaborate,
Compete!”

From the Council Floor – Rebates:

The Council discussed the disposition
of rebates and accepted the proposal
drafted by a special subcommittee
chaired by Bill O’Connell. Most
changes to the rebates will take effect
in 2007 with the one exception that rebates
in 2006, while based on the prior
system, will be paid quarterly.

The main differences between the
old and new systems are as follows:

• Budgeting total rebate dollars – For
example, if Council budgets rebates at
$350,000 and the actual calculation
comes to $315,000, every group would
receive 111% of their calculated rebate.
Likewise if rebates are budgeted at
$350,000 and the actual calculation
comes to $390,000, every group would
receive 90% of their rebates. Furthermore,
rebates will be paid quarterly in
the same year they’re budgeted. This
provides Council and SPE with a
couple of important advantages. First,
spreading the rebate payments out
helps with cash flow management.
Second, paying them as part of a budget
in the same year allows Council to
make decisions about rebates closer to
the time actual rebates will be paid,
helping with balancing the budget. In
the event there are catastrophic difficulties,
Council has the flexibility to
reduce the total rebate amount as it
also reduces spending in other areas.
Likewise, in times of plenty, Council
would have the flexibility to distribute
more funds to SPE groups.
• Paying rebates quarterly – As mentioned
above, this helps tremendously
with cash management and will be initiated
in 2006 (so rebate payments in
2006 will be based strictly on the old
calculation which is based on membership
as of 12/31/05, and will be distributed
quarterly).
• Making the 3 changes to the calculation
– These are some minor “common
sense” changes that do not greatly
change the individual amounts. The
changes are too detailed to present
here, but please refer to the proposals
sent to you prior to the Council meeting
if you want to review them. Again,
these changes will not be implemented
until 2007.
• Paying rebates only for dues paying
members – In the past, folks who paid
no dues (unemployed members, distinguished
members, etc.) were still
included in the rebate calculations. The
pool of these folks is small, especially
when distributed across all of our
groups.
• Dropping the rebate for the seldomcollected
initiation fee – SPE’s initiation
fee is more often dropped as part
of a promotional incentive for new
members. Since SPE does not collect
these funds, the new system will take
the small amount that was being distributed
to groups out of the calculation.
Again, no individual group is
going to be materially affected by this
change.
• Tiering Division rebates – Under the
old system, Division rebates were not
tiered the way Section rebates were.
This makes the two systems more parallel.
• Having performance criteria for rebates
– This is not entirely new. The
current system requires a Board of Directors
and the submission of the required
financial statements. The three
items below are new, and the idea here
is to monitor how groups are serving
members, and give the Sections/Divisions
Committees a heads up on any
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Thermoforming
QUARTERLY 26

group that is failing to provide these
basic requirements so we can work together
to get things on track.

–
No rebates for sections and divisions
whose council seat has been
declared vacant by Council (nonattendance
for 3 consecutive
Council meetings)
–
Requiring communication with
members (demonstrate regular
communications to members)
–
Having a plan (helps to demonstrate
that activities are ongoing)
For a full copy of the proposal, go to
the SPE Leadership page at: http://
www.4spe.org/communities/leadership/
0505/materials.php.

New Charters

The Council approved the charter of
the Flexible Packaging Division. Two
new SIG’s were presented to Council:
Nanotechnology and Micromolding. A
student chapter was established at the
University of Mississippi.

Awards & Recognitions

In addition to the recognition of the
retiring administration, two additional
awards were given out. The Michael
Cappelletti Excellence Award was
given to Bill O’Connell and the James
Toner Service Excellence Award was
given to Tobi Gebauer.

Outgoing President Karen Winkler
thanked her Executive Committee for
their hard work. Incoming President
Len Czuba introduced his Executive
Committee. New Executive Committee
Vice-Presidents are: Russell
Broome, Héctor Dilán, Lance Neward,
and William Smith. Paul Anderson is
the 2005-2006 Treasurer and John
Szymankiewicz is the 2005-2006 Secretary.

Presentations

Composites Division – $1,500 Harold
Giles Scholarship; $1,000 Foundation
Scholarship program

Mold Making & Mold Design – $1,000
Student Author Travel Fund

Detroit Section – $2,000 Essay contest;
$2,500 International Education Award
in honor of Fred Schwab

$5,000 Robert Dailey Scholarship

Color & Appearance Division – $1,000
Donation to the SPE Foundation

¦

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ThermoformingQUARTERLY 28

September 24-27, 2005
GET READY TO
SOAR AT THE
15th Annual
Thermoforming
Conference
Midwest Airlines Convention
Center
Milwaukee, Wisconsin
We need
your
continued
support
and
your
efforts
on
membership
recruitment!!

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Help Sponsor

Thermoforming®

Q U A R T E R L Y

ONE YR. SPONSORSHIPS

**Please note the increase in sponsorship
rates. This is the first increase since the
inception of the Thermoforming Quarterly
in 1981. We appreciate your continued
support of our award winning publication.

Patron – $625

(Includes 2.25″ x 1.25″ notice)

Benefactor – $2,000

(Includes 4.75″ x 3″ notice)

Questions?

Please Contact:

Laura Pichon

Ex-Tech Plastics
815/678-2131 Ext. 624
lpichon@extechplastics.com

We Appreciate Your Support!

From The Editor

Thermoforming Quarterly

welcomes letters from its
readers. All letters are subject
to editing for clarity and space
and must be signed. Send to:
Mail Bag, Thermoforming
Quarterly, P. O. Box 471,
Lindale, Georgia 30147-1027,
fax 706/295-4276 or e-mail to:
gmathis224@aol.com.

29
Thermoforming
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Thermoforming
QUARTERLY 30

Thermoformers, have
you discovered a
forming tip that you
are willing to share
with your fellow
formers?
A time saver?
Or a cost saver?
Or something that
will save wear and
tear on your machine?
Or your employees?
Then the

TIPS

column
is for you!

Just send Jim Throne a fax at
727-734-5081, outlining your
tip in less than a couple
hundred words. You can
include drawings, sketches,
whatever. Thanks!

31ThermoformingQUARTERLY

YOU ASKED

WE
LISTENED

Due to the many surveys requesting
that we change
the dates of the annual
Thermoforming Conference,
the Board has listened
and beginning in

Sunday,
September 17
through
Wednesday,
September 20,
2006

2006, we are pleased to an-
nounce the new dates.
Renaissance Nashville
Hotel & Nashville
Convention Center

General Chairman:
Martin Stephenson
Placon Corporation
Phone: 608-275-7215
E-Mail:
mstep@placon.com

Technical Chairman:
Mike Lowery
Premier Plastics
Phone: 414-423-5940 Ext. 102
E-Mail:
mikel@lowerytech.com

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MEMBERSHIPAPPLICATION
®
MEMBERSHIPAPPLICATION
®
33
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TIM WELDON
General Manager
(989) 793-8881
Fax (989) 793-8888
Email: timweldon@millermold.com
ThermoformingQUARTERLY 341305 Lincoln Avenue, Holland, MI 49423
PH (800) 833-1305 / FX (800) 832-5536
www.allenx.com
ABS ABSFR PCABS
HIPS HIPSFR GELOY
CENTREX LURAN NORYL
SOLARKOTE
A Tradition of Excellence Since 1970
When it comes to answering your
need for quality thermoform tooling,
you can’t find a better source
than Producto.

• Complete turnkey service
• Tooling machined and assembled
with precision
• Deliveries to suit your schedules
• Mold beds up to 70″ x 120″
• Engineering design using the latest
CAD systems and programming
technologies
• Gun drilling services and
Temperature Control Plates
• Adjustable Pressure Boxes
• Die sets, punches and dies, springs,
pins & bushings and a full line of
quality accessory items
Producto Corporation

800 Union Ave., Bridgeport, CT 06607

(203) 367-8675
FAX: (203) 368-2597

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PRODUCTS / INC
plastics………
RAY
™
The Experts in
Thermoforming
1700 Chablis Avenue
Ontario, CA 91761
909/390-9906
800/423-7859
FAX 909/390-9896
www.rayplastics.com
Brian Ray
CUSTOM CUT SHEET & ROLL FED MACHINERY
OVEN, CONTROL & INDEX RETROFIT KITS
PATENTED ADJUSTABLE CLAMP FRAMES
3031 GUERNSEY ROAD, BEAVERTON, MI
PH: 989-435-9071 FAX: 989-435-3940
Email: info@modernmachineinc.com
President
brianr@rayplastics.com
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MACHINING
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CMS NORTH AMERICA, INC.
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800.225.5267
Visit us on the web at:
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www.cms.it
or email us at
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Standex Engraving Group
5901 Lewis Rd.
Sandston, VA 23150

Ph: 804/236-3065

Fax: 804/226-3462

35
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INDEX OF SPONSORS

ADVANCED VENTURES IN

TECHNOLOGY, INC. …………….. 26
ALLEN EXTRUDERS ……………….. 34
AMERICAN CATALYTIC

TECHNOLOGIES ……………………. 8
ARISTECH ACRYLICS ……………… 23
ALTUGLAS INTERNATIONAL ……. 24
BROWN MACHINE ………………….. 31
CMS NORTH AMERICA ……………. 35
CMT MATERIALS, INC. …………….. 34
EDWARD D. SEGEN & CO. ………. 32

ENSINGER/PENN FIBRE ………….. 28
FILTRONA EXTRUSION ……………. 25
FOXMOR GROUP ……………………. 25
FUTURE MOLD CORP. …………….. 35
GEISS THERMOFORMING ……….. 30
GN PLASTICS …………………………. 27
IRWIN RESEARCH &

DEVELOPMENT …………………….. 6
JRM INTERNATIONAL ……………… 23
KIEFEL TECHNOLOGY …………….. 28
KYDEX …………………………………… 36

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ThermoformingQUARTERLY 36

LAND INSTRUMENTS ……………….. 9

LANXESS ……………………………….. 27
LYLE ………………………………………… 5
MAAC MACHINERY …………………. 35
McCLARIN PLASTICS………………. 34
McCONNELL CO. ………………………. 9
MILLER MOLD CO. ………………….. 34
MODERN MACHINERY ……………. 35
NEW CASTLE INDUSTRIES ……… 29
ONSRUD CUTTER …………………… 27
PLASTICS CONCEPTS ………………. 4
PLASTIMACH ………………………….. 31
PORTAGE CASTING & MOLD,

INC……………………………………….. 9
PREMIER MATERIAL CONCEPTS . 9
PRIMEX PLASTICS ………………….. 34
PROCESSING TECHNOLOGIES .. 34
PRODUCTIVE PLASTICS, INC. …… 9
PRODUCTO CORPORATION ……. 34
PROFILE PLASTICS ………………….. 9
PROTHERM ……………………………. 25
RAY PRODUCTS, INC………………. 35
RTP ……………………………………….. 31
SELECT PLASTICS………………….. 34
SENCORP ………………………………. 36
SOLAR PRODUCTS ………………….. 1
SPARTECH PLASTICS …………….. 35
STANDEX ENGRAVING GROUP .. 35
STOPOL INC. ………………………….. 24
TEMPCO ELECTRIC ………………….. 8
THERMWOOD CORP…….Inside Back

Cover
TOOLING TECHNOLOGIES,

LLC …………………………………….. 23
TPS ……………………………………….. 35
ULTRA-METRIC TOOL CO. ……….. 32
WALTON PLASTICS…………………. 29
WECO PRODUCTS …………………. 25
WELEX, INC. …………………………… 29
ZED INDUSTRIES ……………………. 34

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