Contents Thermoforming A NOTE TO PROSPECTIVEthermoformingdivision.com/wp-content/uploads/pdf... · 1 Thermoforming QUARTERLY Contents Thermoforming ® Q U A R T E R L Y A NOTE TO

1 Thermoforming QUARTERLY

Contents

Th e rmo f o rm i n g®

Q U A R T E R L Y

A NOTE TOPROSPECTIVE

AUTHORSTFQ is an “equal opportunity”publisher! You will note that we haveseveral categories of technical articles,ranging from the super-high tech(sometimes with equations!), toindustry practice articles, to bookreviews, how to articles, tutorialarticles, and so on. Got an article thatdoesn’t seem to fit in these categories?Send it to Jim Throne, Technical Editor,anyway. He’ll fit it in! He promises. [Bythe way, if you are submitting anarticle, Jim would appreciate it onCD-ROM in DOC format. All graphsand photos should be black and whiteand of sufficient size and contrast tobe scannable. Thanks.]

QUARTERLY

A JOURNAL PUBLISHED EACH CALENDARQUARTER BY THE THERMOFORMING DIVISION

OF THE SOCIETY OF PLASTICS ENGINEERS

EditorGwen Mathis

(706) 235-9298 • Fax (706) [email protected]

Technical EditorDr. James Throne

Sherwood Technologies, Inc.1797 Santa Barbara DriveDunedin, FL 34698-3347

1-800-273-6370 • Fax (727) [email protected]@tampabay.rr.com

SponsorshipsLaura Pichon

(815) 678-2131 Ext. 624Fax (815) 678-4248

[email protected] Quarterly® is published four times an-nually as an informational and educational bulletinto the members of the Society of PlasticsEngineers, Thermoforming Division, and thethermoforming industry. The name, “ThermoformingQuarterly®” and its logotype, are registered trade-marks of the Thermoforming Division of the Societyof Plastics Engineers, Inc. No part of this publicationmay be reproduced in any form or by any meanswithout prior written permission of the publisher,copyright holder. Opinions of the authors are theirown, and the publishers cannot be held responsiblefor opinions or representations of any unsolicitedmaterial. Printed in the U.S.A.

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

These sponsors enable us to publish Thermoforming QUARTERLY

TECHNICAL SECTION

Chairman’s Corner .................................................................. Inside Front CoverMembership: Strength in Numbers ................................................................... 2New Members ..................................................................................................... 32006 Scholarship Winners .................................................................................. 4Fall Board Meeting Schedule ............................................................................. 8Council Report .................................................................................................. 22Salute to Glenn Blackburn ............................................................................... 28Thermoforming With Style .............................................................................. 30Membership Application ................................................................................. 33Index of Sponsors ............................................................................................. 36Board of Directors List ............................................................. Inside Back Cover

Lead Technical Article:A Solution for Warpage in Polymeric Products by Plug-Assist Thermoforming .......... 9

Industry Practice:How Much Data is Enough? ........................................................................................... 14

Industry Practice:IR Scanning With Closed-Loop Feedback for Thin-Gauge Thermoforming ............... 16

Thermoforming 101:The Cutting Edge ............................................................................................................ 19

Book Review:Mathematical Modeling for Polymer Processing: Polymerization, Crystallization,

Manufacturing ............................................................................................................. 20

DIVISION ACTIVITIES

Thermoforming®

Thermoforming QUARTERLY 2

MEMBERSHIP

BY CONOR CARLIN, MEMBERSHIP CHAIRMAN

STRENGTH INNUMBERS

MEMBERSHIP REPORTas of 6/1/06

Primary Paid .......................1,704

Secondary Paid ......................541

Total Membership ..............2,245

Goal as of 6/30/2007 .........2,500

As the new membershipchairman, I would like

to recognize the efforts ofMike Sirotnak over the pastdecade. During Mike’stenure, the SPE Thermo-forming Division hasbecome one of the mostsuccessful divisionswithin SPE. Our grouphas steadily grownover the years and isrenowned for havingmembers from avariety of industries.In recent times, wehave expanded ourefforts to recruitmembers from ourburgeoning EuropeanDivision and also to fill ourranks with the brightestminds from universityprograms.

I joined the SPE Thermo-forming Division in 2000 andthrough every conference,meeting and seminar I haveattended, I am constantlyimpressed by the amount of

knowledge that is shared.From conference centers inNashville to congress halls inSalzburg, the wealth andbreadth of thermoformingskills and techniques ondisplay allows me to learnsomething new every time.

When you participate as anSPE member, you are joiningthe ranks of the experts.Polymer scientists, processengineers, old sales handsand company executives areall in attendance at theannual conference. There isno better place to take thepulse of our thermoformingindustry.

In addition to the benefitsyou receive as a member,you are also encouraged tocontribute. We receivetechnical articles fromuniversities in Europe aswell as industry practice

articles from seasonedformers. Your feed-back on the contentsof the ThermoformingQuarterly are impor-tant to the magazine’scontinued success.

It is my hope tobuild on the strongfoundation left byMike. Just looking at

the new members everyquarter is an inspiration aswe continue to welcomepeople from around thecountry and around theglobe. We are creating ourown worldwide networkand I am proud to be a partof it. I invite you to come andjoin us. ■


To Our New MembersJay AbbottDisplay Pack, Inc.Grand Rapids, MI

Phillip J. AskerVitasheet GroupUnited Kingdom

Donald E. BaileySun TechTuscaloosa, AL

Bruce BelhoffWhirlpool

CorporationBenton Harbor,

MI

Phillip M.Bertrand

Nike IHM, Inc.St. Charles, MO

Lamar A. BostSpartech PlasticsWarsaw, IN

Lou CalistroJetta CorporationEdmond, OK

Adam ClarkDisplay Pack, Inc.Grand Rapids, MI

Dakheel AlDakheel

Kuwait PackingMaterials Co.

Safat, Kuwait

Mike E. CarleyJSPNew Baltimore,

MI

Leon R. ColeGAFMCWayne, NJ

Randy CookCaro, MI

Olivier C.Coquerel

ABB Australia PtyLtd.

Victoria, Australia

ChandrakantDoshi

Rajoo EngineersLimited

Veraval, India

Duane DeJongDisplay PackGrand Rapids, MI

Fernando MouraDuarte

University ofMinho

Guimaraes,Portugal

John L. DurfeyDekalb, IL

Debra GilmourAmerican

StandardOntario, Canada

Thomas A. GoatesBaxter Health

CorporationMountain Home,

AZ

LaurenceGoddard

Bonar PlasticsOntario, Canada

Luke GrossMullinix

Packages, Inc.Fort Wayne, IN

Robert GuldiStryker

InstrumentsKalamazoo, MI

Paul HarrisTriEndaPortage, IN

Chris J. HendrykPlastic Package,

Inc.Sacramento, CA

Ming L. HoPactiv

CorporationCanandalgua, NY

Marcus HoldenEvans, CO

Daigo IshiyamaAmerican

StandardPiscataway, NJ

Timothy J.Jandrow

Tripod DataSystems

Corvallis, OR

Mark KishelArrowhead

PlasticsProducts

Eaton, IN

Randall K. LogaTek PackagingHuntley, IL

Dan P. LonghenryTennant CompanyGolden Valley,

MN

Jean ChristopheMercierDurand

MaquinariaEnvapac SA DeCV

Ed, Mexico

Pamela MarksSumitomo

Corporation ofAmerica

Houston, TX

John W. MeritonDuPont AustraliaRichmond,

Australia

Michael PastelakAAI CorporationHunt Valley, MD

Parimal K. PatelFremont, CA

Meng Y. PunTexchem

Polymerds SdnBhd.

Prai, Malaysia

Brenda S.Richmond

Printpack, Inc.Williamsburg, VA

Dennis ShimmellCorvac

CompositesBryon Center, MI

Tony StraubMercury MarineFond Du Lac, WI

Ron StarnesAltoAlbany, New

Zealand

Bayne UptonGE HealthcareWaukesha, WI

Cory S. WhiteGN Plastics Co.

Ltd.Chester, NS,

Canada

Bob WhitishPlastics Ingenuity,

Inc.Cross Plains, WI

Edward G. WolkHampel

CorporationGermantown, WI

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 membershipin SPE:

• keeps you current

• keeps you informed

• keeps you connected

The question really isn’t“why join?” but …

WHYNOT?


2006 SCHOLARSHIP WINNERSSEGAN MEMORIAL

SCHOLARSHIP

LUCUS D. STALLBAUMERPittsburg State University

Pittsburg, Kansas

Lucas Stallbaumerwill be a graduate stu-dent in Plastics Engi-neering Technology atPittsburg State Univer-sity this fall. A mem-ber of SPE, Lucas at-tended ANTEC 2004,the 2005 Thermo-forming Conference,

and was featured in a Plastics Engineer-ing magazine article on mentorship as aresult of his internship with Joe Peters,President of Universal Plastics. At Univer-sal Plastics, Lucas experienced all kindsof thermoforming applications and wascharged with designing a package withholes in the bottom so that it still containedphysical strength and durability. Aftergraduation, Lucas would like to work inthe automotive industry.

GRIEP MEMORIALSCHOLARSHIP

KIM C. ACINGERPittsburg State University

Pittsburg, Kansas

Kim Acinger willbe a senior at PittsburgState University work-ing toward a B.S. inPlastics EngineeringTechnology with a mi-nor in ManufacturingManagement. She hadan internship in thesummer of 2005 at

Nike IHM in St. Charles, MO working pri-marily in the thermoforming department,processing twin-sheet. She plans to returnto Nike this summer for a second intern-ship, doing project work in thermoforming.She also interned in 2004 at Sika Corp. ofGrandview, MO doing insert molding inthe injection molding division. Kim hasbeen a lab assistant at PSU since Fall 2005demonstrating thermoforming, extrusion,compression, injection and blow molding,as well as testing equipment such asInstron, Izod, DSC, and Melt Flow Index.She plans to pursue a career in the

thermoforming industry after graduationwhile simultaneously working on a Mas-ters of Business Administration.

PAUL BERTSCHMEMORIAL SCHOLARSHIPS

Kurtis Schultz willbe a senior at WesternWashington Universitythis fall working to-ward a B.S. in PlasticsEngineering Technol-ogy. A member of thePhi Theta KappaHonor Society, Kurtisis also a SPE member

and was the recipient of a scholarship fromthe SPE Foundation last year. Kurtis heldan internship in the summer of 2004 atNorthwest Kayaks, where he used thethermoforming process for bulkheads,hatch covers, and protective nose coversfor kayaks. His senior project is to developa thermoformed kayak seat/support systemfor people who have restricted use of theirlower extremities (paraplegics, amputees,or those otherwise injured). Kurtis was alsoinstrumental in writing a grant proposal onbehalf of the WWU Engineering Technol-ogy Program for the ThermoformingEquipment Grant.

KURTIS J. SCHULTZWestern Washington University

Auburn, Washington

STEPHEN M. PROBERTUniversity of WashingtonWoodinville, Washington

Stephen Probertwill be a graduate stu-dent in MechanicalEngineering at theUniversity of Wash-ington this fall. Anhonors student, he isalso active in the UWKarate Club, the UWYacht Club and the

Campus Crusade for Christ. Stephen’s un-dergraduate research was a “cup project”– a successful attempt to thermoform amicrocellular foamed coffee cup from re-cycled bottles. The experience ofthermoforming a material that has not beencommercially thermoformed will now beincorporated into Stephen’s graduate re-search. His work at MicroGREEN Inc. in-

cluded modifying an old lab-scalethermoformer, developing lab protocolsand research objectives, and making thou-sands of test runs to develop the deep drawfoam sheet process. The University ofWashington plans to patent the process.

ADRIANE R. WILTSEPittsburg State University

Pittsburg, Kansas

Adriane Wiltse willbe a senior at Pitts-burgh State Universitythis fall, majoring inPlastics EngineeringTechnology with anemphasis in manufac-turing. Her interest inplastics was sparked,at age 11, by encour-

agement from a cousin who was graduat-ing from PSU as a plastics engineer.Adriane, too, decided to attend PSU whereshe is a member of Student GovernmentAssociation, University Ambassadors, andis currently serving as the president of SPEStudent Chapter at PSU. Adriane spoke atthe 2004 Thermoforming Conference andattended the 2005 Conference. She has alsoworked as a General Plastics laboratoryassistant, introducing freshman students tothe Plastics Engineering Technology pro-gram at the university. After graduation,Adriane hopes to work in thethermoforming industry.

JUSTIN J. DAMERONPittsburg State University

Pittsburg, Kansas

Justin Dameronwill be a senior atPittsburg State Univer-sity working toward aB.S. in Plastics Engi-neering Technology.He had an internship inthe summer of 2004 atCharloma, Inc. work-ing primarily with

thermoforming machines. An active mem-ber of the SPE Student Chapter at PSU,Justin attends many local Section meetingsand has participated in a large number ofplant tours to familiarize himself with allaspects of plastics processing. Justin’s fu-ture plans include marriage to a fellow PSUstudent this fall and a career in athermoforming or rotational molding pro-cessing plant upon graduation.


TK

ThyssenKrupp Materials NACopper and Brass Sales DivisionA ThyssenKrupp Services company

ThyssenKrupp Materials NA, Inc. — AIN Plastics, Copper and Brass Sales, Ken-Mac Metals, TMX Aerospace,ThyssenKrupp Steel Services, ThyssenKrupp Hearn, TKX Logistics

Or contact John Perryman at (248) 233-5725,

e-mail: [email protected]

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We will work with your machine shops so you can realize thetime and cost savings that will help you move ahead of thecompetition.

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6013-T651 Power Plate™ is distributed by:

These sponsors enable us to publish Thermoforming QUARTERLYNeed helpwith your

technical schoolor collegeexpenses?

If you or someone youknow is working towards

a career in the plasticindustry, let the SPEThermoforming Divisionhelp support those educationgoals.

Our mission is to facilitatethe advancement ofthermoforming technologiesthrough education, application,promotion, and research.Within this past year alone, ourorganization has awardedmultiple scholarships! Getinvolved and take advantage ofavailable support from yourplastic industry!

Start by completing theapplication forms atwww.thermoformingdivision.comor at www.4spe.com. Thedeadline for applications isJanuary 15th, 2007. ■


THERMOFORMER OF THE YEARCRITERIA FOR 2007

Every year The SPE Thermo-forming Division selects a indi-

vidual who has made a outstand-ing contribution to our industry andawards them the Thermoformer ofthe Year award.

The award in the past has goneto industry pioneers like Bo Strattonand Sam Shapiro, who were amongthe first to found thermoformingcompanies and develop our indus-try. We have included machine de-signers and builders Gaylord Brownand Robert Butzko and toolmakerJohn Greip, individuals who helpeddevelop the equipment and moldideas we all use today. We havealso honored engineers like LewBlanchard and Stephen Sweig, whodeveloped and patented new meth-ods of thermoforming. Additionally,we have featured educators like BillMcConnell, Jim Throne andHerman R. Osmers, who have bothspread the word and were key fig-ures in founding the ThermoformingDivision.

We’re looking for more individu-als like these and we’re turning tothe Thermoforming community tofind them. Requirements would in-clude several of the following:

➢Founder or Owner of aThermoforming Company

➢Patents Developed

➢ Is currently active in or recentlyretired from the ThermoformingIndustry

➢ Is a Processor – or capable ofprocessing

➢Someone who developed newmarkets for or started a newtrend or style of Thermoforming

➢Significant contributions to thework of the ThermoformingDivision Board of Directors

➢Has made a significant educa-tional contribution to theThermoforming Industry.

If you would like to bring some-one who meets some or all of theserequirements to the attention of theThermoforming Division, please fillout a nomination form and a one-to two-page biography and forwardit to:

Thermoforming Division AwardsCommittee% Productive Plastics, Inc.Hal Gilham103 West Park DriveMt. Laurel, NJ 08045Tel: 856-778-4300Fax: 856-234-3310Email:[email protected]


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.


THERMOFORMER OFTHE YEAR 2007

Presented at the September 2007 Thermoforming Conference in Cincinnati, Ohio

The Awards Committee is now accepting nominations for the 2007THERMOFORMER OF THE YEAR. Please help us by identifying worthy candidates.This prestigious honor will be awarded to a member of our industry that has madea significant contribution to the Thermoforming Industry in a Technical, Educa-tional, or Management aspect of Thermoforming. Nominees will be evaluatedand voted on by the Thermoforming Board of Directors at the Winter 2007 meet-ing. The deadline for submitting nominations is December 1st, 2006. Please com-plete 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 ofuniversity)

• Prior corporate or academic affiliations (include company and/or institu-tions, 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 andprogress of the plastics industry. (To support nomination, attach substan-tial documentation of these achievements.)

• Other significant accomplishments in the field of plastics.

• Professional achievements in plastics (summarize specific achievements uponwhich 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

Thermoformers of the Year …1982

William K. McConnell, Jr.McConnell Company

1983E. Bowman Stratton, Jr.

Auto-Vac Corp.

1984Gaylord Brown, Brown Machine

1985Robert L. ButzkoThermtrol Corp.

1986George Wiss, Plastofilm Industries

1987Dr. Herman R. OsmersEducator & Consultant

1988Robert Kittridge

Fabri-Kal Corporation

1989Jack Pregont, Prent Corporation

1990Ripley W. Gage, Gage Industries

1991Stanley Rosen

Mold Systems Corp.

1992Samuel ShapiroMaryland Cup

Sweetheart Plastics

1993John Grundy, Profile Plastics

1994R. Lewis Blanchard

Dow Chemical

1995James L. Blin, Triangle Plastics

1996John Griep

Portage Casting & Mold

1997John S. Hopple, Hopple Plastics

1998Lyle Shuert, Shuert Industries

1999Art Buckel, McConnell Company

2000Dr. James Throne

Sherwood Technologies

2001Joseph Pregont, Prent Corp.

2002Stephen Sweig, Profile Plastics

2003William Benjamin

Benjamin Mfg.

2004Steve Hasselbach, CMI Plastics

2005Manfred Jacob

Jacob Kunststofftechnik

2006Paul Alongi, MAAC Machinery


These sponsors enable us to publish Thermoforming QUARTERLYTHERMOFORMINGDIVISION

FALL BOARDMEETING SCHEDULESeptember 13th - 16th, 2006Renaissance Nashville Hotel

Nashville, TennesseeFOR RESERVATIONS: Call 615.255.8400Request SPE Thermoforming Rate of $143.00

Wednesday, September 13th, 2006Executive Committee Arrives

Thursday, September 14th, 20067:30 am – 8:00 am – Breakfast –

Executive Committee, BluegrassRoom

8:00 am – 9:00 am – Technical ChairsMeet with Executive Committee

12:00 pm – 12:30 p.m. – Lunch –Executive Committee

2:00 pm – James Alongi, FinanceCommittee Meet with ExecutiveCommittee

Friday, September 15th, 20069:00 am – 10:00 am – Machinery

Committee Meeting, Jazz Room9:00 am – 10:00 am – Materials

Committee Meeting, Classical Room9:00 am – 10:00 am – Processing

Committee Meeting, Belmont OneRoom

10:00 am – 4:00 pm – CommitteeMeetings, Belmont Three Room

BOARD ON THEIR OWN

Saturday, September 16th, 20067:30 am – 8:00 am – Breakfast – Board

of Directors, Music City Ballroom8:00 am – Noon – Board of Directors

Meeting, Music City Ballroom12:00 pm – 1:00 pm –Lunch Buffet,

Music City Ballroom Foyer6:00 pm – 8:00 pm – BOARD OF

DIRECTORS SPECIAL EVENT –“An Evening at the Blue Bird Cafe,”Music City Ballroom

Sunday, September 17th, 20066:15 pm – 6:30 pm – Ribbon Cutting

Opening Exhibits, ConventionCenter

6:30 pm – 8:30 pm – WelcomeReception, Exhibit Floor,Convention Center

September 18th, 19th & 20th, 200616th Annual Thermoforming Conference


LEAD TECHNICAL ARTICLE

A Solution for Warpage in Polymeric ProductsBy Plug-Assist Thermoforming1,2,3

BY H. HOSSEINI AND B. V. BERDYSHEVMOSCOW STATE UNIVERSITY OF ENVIRONMENTAL ENGINEERING, MOSCOW, RUSSIA

1 Paper was published in the 2006 ANTEC proceedings and waspresented at ANTEC on 8 May 2006.2 Paper retyped, partially rewritten, and edited by J. L.Throne,Technical Editor, who is solely responsible for any omis-sions, commissions and other blunders.3 Ed. Note: The mechanical deformation of plastic sheets, called“plug assist,” has been the subject of previous Tech Articles in thisQuarterly, at recent Thermoforming Conferences, and in a veryimportant paper being given at the upcoming 2006 Conference inNashville. The Editor believes that the approach given in this pa-per deserves further scrutiny by those examining the fundamen-tals of plug assist. (continued on next page)

AbstractThe thermoforming process is one of the most popular techniques

in polymer process. The broad spectrum of applications is becauseof its high performance, simplicity, compactness, and relativelylow-cost equipment. The fundamental defect inherent inthermoforming technology is warpage of the products during theirapplications. This is particularly apparent when the products areused at high temperatures. The warpage defect is understood asthe process of non-uniform or heterogeneous change of thegeometric dimensions of product with time, resulting in a changeor distortion of their original form. The results of this work allowthermoformers to find the causes of this warpage and to ascertainthe processing conditions that give rise to this defect. This makesit possible to work out valid recommendations for the partial, andin some cases complete, elimination of warpage.

IntroductionPolymer processing production of all forms of polymeric articles

has found great application in chemical industries. Thethermoforming process is one of the most popular techniques inthis field. Thermoplastic sheet or film-forming techniques areapplied to various packaging applications such as medical devices,food containers, and pharmaceuticals [1-4]. The broad spectrumof thermoforming is because of its high performance, simplicity,compactness, and relatively low-cost equipment. These factorsmake it possible to produce complex, large-scale configurationsand free-form shapes. In thermoforming, a heated plastic sheet isstretched into a mold cavity by applying pressure, eventuallyassisted by direct mechanical loading [5,6]. When the sheet contactsthe cold surface of the mold, it is prevented from furtherdeformation. As a result, the forming sequence yields a thicknessvariation in the final part. In addition to wall thickness variation,

there is another problem that the thermoforming industry mustovercome. The sheet during inflation may have physical instabilitiessuch as sheet rupture and shrinkage that is exhibited in the finalproducts.

Another inherent fundamental processing defect in thethermoforming technology is part warpage that occurs during use.This is particularly apparent at high temperatures, Figure 1. Thewarpage defect is understood as the process of non-uniform orheterogeneous change of the geometric dimensions of product withtime, resulting in a change or distortion of their original form.Unfortunately, this problem has been overlooked or ignored inthermoforming literature [2].

Figure 1. The warpage of a polymeric product during its use.

The results of this work allow thermoformers to find the causesof this warpage and to ascertain the processing conditions that giverise to this defect. This makes it possible to work out validrecommendations for the partial, and in some cases complete,elimination of warpage.

Mathematical Description andRheological Model

An analysis of the results obtained shows that warpage is causedby relaxation of the residual or frozen-in stresses produced duringthe thermoforming process. Consider the after-effects of thedeformation process of a viscoelastic polymer that had beensubjected to the direct deforming influence of a fixed degree ofintensity under pure shear.

The kinematics of the direct deformational influence on apolymer has not been randomly chosen. It completely correspondsto the deformation kinematics of a polymeric product at the initial


t~Ttt

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stage of pre-stretching with a plug [1]. In this case, the kinetics ofthe development of general viscoelastic and elastic deformationsresulting from the direct deforming effect on the polymer is givenin the literature [1].

Assume that at a certain point in time, , the direct deformingeffect on the polymer is instantly removed by the removal of anyexternal effects on it. At that time, as a result of the deformation,certain levels of general viscoelastic and elastic deformations havebeen accumulated:

This condition corresponds to the free or unconstrained conditionof the polymer in the molded product. Now, in accordance withthe rheological model [1], for a polymer medium in theunconstrained condition, the relaxation process will occur at ratesthat relate to the reduction in the level of accumulated elasticdeformation. This is characterized by the following natural kineticconditions:

(1)

Where is the strain rate tensor and is the flow strain rate tensor.

The meaning of this condition is that in the absence of an externalinfluence on the polymer, the rates of deformation changes in thelatter are determined only by the typical rates of the relaxationprocesses themselves.

Applying this condition of the rheological model [1,7] to thekinematically determined process of deformation after-effects in aviscoelastic sheet or formed shape, the following system ofdifferential equations that describe the kinetics of the processionare obtained4:

(2a)

(2b)

Where , c is the Cauchy strain, is relaxationtime, � is the flexibility parameter of the molecular chain, �H is theHencky strain, �e

H is the elastic Hencky strain, �e and is the elasticstrain ratio.

The initial conditions for solving the system of equations

are determined by solving the deformation influenceson the polymer. From an analysis of these equations, it followsthat the elastic deformation, �e

H, accumulated during thedeformation sequence on the polymer, relaxes at a rate dependenton the removal of the mechanical field – in this case, the plug –from the polymeric sheet. This leads to the reduction in accumulatedgeneral deformations as given by the second equation5.

For rigid chain polymer, � ➝ 0, or for a low level of accumulated

elastic deformation, , the following solutions follow:

(3a)

(3b)

Now , the dimensionless time and is the dimension-

less time of plug-assist forming. Figure 2 represents the kinetics ofthe process of free relaxation of elastic deformations in aviscoelastic polymer resulting in the uniaxial process of changingits original dimensions6.

tt He

H ~,~ .

fee

e

4 Ed. Note: The analysis that follows implicitly assumes uniaxialdeformation and relaxation. For multiaxial deformation and relax-ation, the scalar Cauchy, Henky, and elastic Henky strain termsmust be replaced with the equivalent tensors.5 Ed. Note: Again, keep in mind that the authors appear to assumethat the mechanical deformation of the sheet with a plug is a uniaxialdeformation process.

2

0

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211 cceT

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tdeettt

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6 Ed. Note: Unfortunately, the labels for the curves on in this figureare obscured in the original paper. Those given in the figure cap-tion are those proposed by this Editor.

Figure 2. The kinetics of the process of free relaxation, t~ > 4, of elasticdeformations in viscoelastic polymers resulting in the process of chang-ing its original dimensions, t~ = 4. [Ed. note: It appears that the verticalscale is �, the top curve is �H, the second curve is �e

H, and the horizontalscale is t~ .]

Results and DiscussionAs shown above, the cause of molded part warpage during use

is the accumulation of elastic deformations in the polymer. Becausethe accumulated elastic deformations in the polymer are usuallynon-uniformly distributed throughout the formed part, therelaxation process occurs at different rates across the part. Thisresults in noticeably different rates of dimensional change indifferent regions of the part, that is, the warpage as evidenced bythe last set of equations above. On the basis of our analysis, wefind that the defect of warpage originates under the condition ofthe accumulation of heterogeneous elastic deformations in thepolymer during thermoforming, and it manifests itself through therelaxation process of these deformations.

The equations above show that warpage is essentially determinedby one of the fundamental rheological characteristics of polymers,the typical relaxation time, �0(T), which is temperature-dependent.Relaxation processes increase in rate, and, consequently, the rateof warpage increases with increasing polymer temperature.

Consider a quantitative characterization of the time-dependentwarpage. A coefficient of dimensional change, ku�, that integrally


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(continued on next page)

minimized. This means that the profile of the pre-stretched sheetshould be maximized to approximate the profile of the final product.

The Concept of Relaxation PauseUnlike the forming process, the mechanical plug pre-stretching

process can be regulated through control of the plug motion. Thisprovides an opportunity to organize, at the plug stage, the relaxationprocess of elastic deformations accumulated in the sheet becauseof the stretching action of the plug. The simplest of many possiblescenarios to achieve this is to create a relaxation pause betweenthe pre-stretching step and the vacuum forming step. During thispause, the accumulated elastic deformations can completely orpartially relax. The problem here is that during this pause, the pre-stretched sheet may cool too much, making the forming step of theprocess difficult or impossible. Consider the necessary duration ofthis pause that would allow realization of the relaxation process.

During the relaxation pause, a plug holds the stretched sheet.One of the kinematic conditions of this process, corresponding tothe absence of an external deforming influence, is:

(8) e = 0

Using this condition, from the rheological model for thekinematically determined process of the relaxation in a viscoelasticpolymeric medium [1], we obtain the following equation thatdescribes its kinetics:

(9a)

(9b)

Figure 4 presents the kinetics of change of elastic deformationsduring the relaxation pause in a sheet stretched with a plug7.

ttStSku ~~~

1

tS ~ ttS ~~

characterizes the relative change in the original dimension of theproduct is defined as:

(4)

Where and are the current and original area of thelateral surface of the distorted part, respectively.

Using well-known mathematical equations and the equationsgiven earlier, we obtain the following:

(5)

(6)

Where , and

, where rp is the plug radius, r3 isthe initial radius of the sheet, r and z are the horizontal and verticalaxes, respectively, and H is the depth of the deformed sheet. Thefunction, , is determined from solution of the set of earlierdifferential equations (2a and 2b).

Using equations (5) and (6) from equation (4), we obtain anexpression that describes the kinetics of warpage as shown in Figure3. If we now assign an allowable value of the coefficient ofdimensional change of the product, , with which the part isconsidered suitable for its use, the maximum permissible time ofits use is given as:

1~

~~0

0

~,~

03

0

0

0 ~~

~,1~2~r

rr

tr

p

H

rdr

etrbrtS

Figure 3. The kinetics of the warpage of PS at T=353K. Curve is fromequation (4) and the points are experimental data. [Ed. note: The verti-cal scale is ku� and the horizontal scale appears to be t~ .]

(7)

Where is determined from equation (4).It is now apparent from the above analysis that the use period of

a polymeric product under the given temperature conditions, withthe allowable coefficient of dimensional change, is essentiallydetermined by the elastic deformations, , accumulated inthe product during its formation. The smaller they are, the longerwill be the operational period of the product.

Therefore, it is apparent that the practical task is organizing theplug-assist thermoforming methods so that the total level of elasticdeformations – that is, the accumulated deformations during boththe plugging and the forming stages of the molding process – is

2

0

2 1

211 cceT

cdtdc

0dtd H

7 Ed. Note: Again, unfortunately the labels for the curves in thisfigure are obscured in the original paper. Again, those given in thefigure caption are those proposed by this Editor.

Figure 4. The kinetics of the relaxation process, t~ > 4, of elastic defor-mations in viscoelastic polymers during the relaxation pause, t~ � = 4.[Ed. note: It appears the vertical scale is �, the top curve is �H, the sec-ond surve is �e

H, and the horizontal scale is t~ .]

Comparing the differential equation systems (9a and 9b) and(2a and 2b), it is seen that the relaxation processes in polymersunder the conditions of limited and free after-effects vary only bytheir rates.


1~1~

1~1~

ln0*

0*

0

00 tc

tctctc

Ttpn

tc ~0*

1~~1

~~ln

21

20

0 rrrH

rp

pH

trr He

H ~,, 00 ,

tS ~

uk .

uk , t 0uk

111

111

ln21~,

~~

~,2

~,2

~~

~,2

~,2

0

0

0

0

0

tt

tr

tr

tt

tr

tr

He

eee

eee

tr

He

He

He

He

1~tH

ee


This is quite logical, considering that the limited conditions ofthe relaxation after-effects do not completely correspond to theremoved mechanical field, superimposed on the polymeric medium.This also slows the development of the relaxation process. Forrigid-chain polymers, � ➝ 0, or at a low to moderate level of

accumulated elastic deformation, , the analytical solu-tion of equations (9a and 9b) is:

(10a)

(10b)

The analysis of the equations obtained by numerical solution ofthe differential equations (9a and 9b) for common cases showsthat even in the most unfavorable conditions, � > 1 and c(t� ≈ 3),the accumulated elastic deformations are practically completelyrelaxed in a time period not exceeding approximately 9�0(T). Inthermoforming, most thermoplastic materials have typicalrelaxation times in the range of �0(T�) ≈ 0.2 to 0.5 seconds. Thus,even in the most unfavorable situations, the maximum timenecessary for the relaxation process would not exceed about 4.5seconds.

From [8], it was determined that for a Bi=0.04 and Fo=1.75,within this time frame, a polymer sheet with thickness of, forexample, 1.0 mm and a temperature of T=140°C, cools only about10°C. This time is not considered critical when comparing the timespent during the pre-stretching phase of the process.

For thinner sheets, the maximum duration of the relaxation pausewill obviously become critical. But this will occur only under thevery strict requirements concerning the quality of the final product,according to the admissible criterion of their distortion, viz,

. In less strict conditions, when some level of distortion is

admitted, as determined the value of , the time necessary for

the relaxation pause, is determined as follows:The minimum duration of the relaxation pause should be a value

that guarantees an infinitely large use time for a product with theallowable coefficient, . Nominally, considering equation (4),this is given as:

(11)

From the analysis of equation (6), the function is determinedby solving the differential equations (2a and 2b). Solving the

equations under different initial conditions, , will

always yield a solution that will satisfy the condition of equation(11). The results obtained in this work provide the followingexpressions for determining the initial conditions specified above:

constrtr HH00

~,

uktStS 1~~

It follows from these equations that the procedure of the equationsystems (2a and 2b) that satisfies equation (11) is reduced to asearch of the critical maximum value of the elastic deformation,

. This value should not be exceeded in a given section of the

stretched sheet at the end of the relaxation pause. This value mustsatisfy the condition in equation (11).

When this value is found, the duration of the necessary relaxationpause is determined by solving the differential equation (9a). Forthe special case given above, when the obtained value is substitutedas the current one, corresponding to the end of the relaxation pausein equation (10a), an expression is obtained that determines theoperational factors of the duration of the relaxation phase:

(13)

The level of elastic deformation in the sheet can also be reducedby decreasing the speed of the plug. This effect can be determineddirectly from the results in this work. However, in certain cases,the time of sheet stretching will exceed the sum of the time spentstretching at a normal plug speed and the relaxation pause. This isapparent because, in the plug-assist stage, a much greatermechanical force is imposed on the polymer than the effect of therelaxation pause. As a result, the rate of the relaxation step in theplug assist step will be less than that in the forming step.

Note also that the necessary time for the relaxation process duringthe relaxation pause can be reduced by raising the temperature ofthe sheet. This results in a reduction in the typical relaxation time.However, as noted earlier, the thermoforming operating range,Tg < T < Tm , limits the practical use of this option.

SummaryThe analysis conducted on the causes and conditions of warpage

in thermoformed products under specific applications has yielded:

• A method for calculation the operating conditions forforming products that would ensure operation of thefinal product with warpage not exceeding admissiblevalues.

• A method for calculating the maximum admissibleperiod for the use of polymeric products within whichthe warpage would not exceed allowable limits.

• Uneven strain recovery, caused by non-uniformorientation in the trim area is the major cause of long-term part distortion and warpage. In some cases, 24-hour annealing at mold temperature prior to trimmingcan reduce warping8.

AcknowledgmentsThis word was supported by the Laboratories of Moscow

State University of Environmental Engineering and MoscowState University of Chemical Engineering.4~

~~~1

1~

1~~

~~~1

1~

1~

21ln

21~,~

2

30

40

0

03

0

40

0

00 r

tbrtbtc

tcrtbr

tbtctc

trH

8 Ed. Note: The authors do not explicitly address this conclusion inthis paper.



References

1. H. Hosseini and B. V. Berdyshev, Structural Plastics2005, Society of Plastics Industry, Orlando, Florida.

2. J. K. Thoren, Thermoforming, Hanser Publishers,Munich, 1987.

3. J. K. Lee, T. L. Virkler, and C. E. Scott, Poly. Eng. Sci.,41, 2001, pg. 1830.

4. G. J. Nam, K. H. Ahn, and J. W. Lee, Poly. Eng. Sci.,40, 2000, pg. 2232.

5. Rush et al., U.S. Patent 5 641 524, 1997.

6. A. Wineman, Jnl. Non-Newt. Fluid Mech., 4, 1987, pg.249.

7. A. I. Leonov, Rheol. Acta., 15, 1976, pg. 85.

8. B. N. Udaev, Engineering Thermodynamics, in Russian,Moscow, 1988.

News from PennState, Erie, The Behrend College

SPE Grant Will Help Purchase Thermoformer

Students in Penn State Behrend’s plastics engineer-ing technology program will have access to the

latest thermoforming equipment, thanks to a grant fromthe Society of Plastics Engineers Foundation.

The Brookfield, Conn.-based foundation for thesupport of plastics and polymer education has awardedBehrend’s program a $10,000 matching grant for thepurchase of a Formech 660 vacuum forming machine.Vacuum forming is a technology that forms sheets ofplastic into a desired shape and is used to create prod-ucts that range from clamshell take-out food contain-ers to automotive body panels.

Penn StateBehrend will matchthe gift equally, andFormech, which isheadquartered inHarpenden, En-gland, has agreed toa discounted flatprice of $20,000 forthe 660, three re-ducing plates, andan optional coolingsystem.

The Formech 660 will be installed into the new160,000-square-foot Research and Economic Devel-opment Center (REDC) opening on campus in fall.

“We were very fortunate to get this grant from thethermoforming division of the SPE. This piece ofequipment will go a long way to improving the qualityof education our students will receive in the area ofthermoforming,” Brian Young, assistant professor ofEngineering, said. “I have several students who areinterested in starting research projects on this equip-

ment as soon as ithits the floor.”

In addition tobeing used by stu-dent researchers,the Formech 660will permit the col-lege the add a tech-nical elective inthermoforming,develop trainingseminars andapplied research

projects that support local industry, and enhance theemployment prospects of plastics engineering technol-ogy graduates by exposing them to a growingtechnology.

Penn State Erie’s plastics engineering technologyprogram boasts 100 percent job placement; more than300 inquiries were received in 2005 from companiesinterested in hiring the year’s 40 graduates.

Contact: Christine Palattela, 813.899.6063,[email protected]. ■

“We were very fortunate to get this grant fromthe thermoforming division of the SPE. This

piece of equipment will go a long way toimproving the quality of education our students

will receive in the area of thermoforming,”Brian Young, assistant professor of

Engineering, said. “I have several students whoare interested in starting research projects on

this equipment as soon as it hits the floor.”


How Much Data is Enough?1

INDUSTRY PRACTICE

BY RICHARD KNEBEL, CARL ZEISS IMT CORP., MINNEAPOLIS, MN

1 This article has been edited from an article appearing in Manu-facturing Engineering, November 2002, pg. 15. It is used withpermission of Society of Manufacturing Engineers, www.sme.org,and cannot be recopied without permission of the copyright holder.The Technical Editor is responsible for any rewriting, omissions, orerrors in transcription.

Coordinate Measuring Machines or CMMs come inmany types, but one important area of distinction is

the method of data acquisition.There are two basic types of CMMs – touch-trigger

probing and scanning. Today, the touch-trigger CMM ismost common. It measures features by contractingindividual points on the workpiece. The scanning probeSCMM uses a probe sensor that is, by itself, a smallmeasuring machine. Linked to the larger CMM withadvanced control technology, it continuously scans thecontour of the workpiece surface. Scanning CMMs cancollect hundreds or even thousands of independent pointsto define a part feature in the same time it takes touch-trigger probe CMMs to measure only four to eight points.

When choosing a CMM, it is common practice toobtain the machine’s measurement uncertainty from themanufacturer. The data are compared to part size andtolerances to determine the suitability of a particularCMM for a given application. There is, however, oncepotential shortcoming. Specifications for measurementuncertainty are made relative to traceable artifacts suchas gage blocks and ring gages.

One might ask, what’s wrong with that? It’s commonpractice to specify a system’s capability relative to knownartifacts. But it must be understood that these knownartifacts are produced to have nearly perfect form. Theyare actually gages that are used to measure the CMM’sperformance. The fact that they have near-perfect formmakes them a relatively easy target to measure using lowdata density.

In day-to-day use, CMMs must inspect imperfectlyformed features. This task is much more difficult thaninspecting artifacts with near-perfect form, becauseresults can vary significantly depending on where theCMM samples the feature.

Most people are aware of the need for high datadensity when evaluating form, but there is less awareness

of this need when evaluating location and size. It is easyto assume that if a particular feature has no specific formrequirement, data density is not an issue. But it isimportant, and especially so when form isn’t controlledseparately. Form deviation exists in all measured features,only the magnitude of deviation varies. When form isnot controlled separately through the use of a modifiersuch as circularity or roundness of a bore, then limits ofsize control the allowable form deviation.

Studies show that a minimum of 300 points arerequired to approach the correct result for form such ascircularity of a diameter in the 25 to 70 mm range. Onlyabove this level of data density will you begin to approach90% or more of the correct form value. Any method thatuses lots of data will see a more complete “picture” ofthe surface, and gain a better understanding of the truehigh-to-low variation. Low data density most likely willmiss this variation and has the potential to be somewhatmore repeatable.

In other words, if repeatability of form was theprimary objective, one could measure only four pointsand calculate, for example, flatness. In general, however,the benefit of high density data is obvious when lookingat the average results for many features.

You may have heard the saying “form followsfunction.” Ad agencies often use it to describe a productwith a very functional appearance. The inverse of thissaying, “function follows form,” is true in metrology.You cannot know the functional size and location withoutunderstanding the form of a feature.

When evaluating a CMM, consider the influence thatform has on size and location. It can be greater than anyerror inherent in the CMM. Select a system and methodthat can accurately measure production parts, not justperfect artifacts. If a CMM must pass a gage repeatabilityand reproducibility or GR&R study, high data density isthe best defense when challenged to repeat readings onimperfectly formed elements.

High data density also provides better functionalresults that lead to fewer problems in assembly, lowerwarranty costs, and improved overall productionprocesses. ■


These sponsors enable us to publish Thermoforming QUARTERLYTHERMOFORMING

DIVISION DVD’S

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The first DVD is titled:“WHAT EXACTLY IS

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This six-minute DVD introduces

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and heavy gauge cut sheet fed

aspects of thermoforming are

illustrated. It is for students,

industry and anyone who

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The second DVD is titled:“FORMING EDUCATIONAL

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This six-minute DVD discusses

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Both DVDs are free of charge andavailable from SPE through

Gail Bristol at phone number203-740-5447 or Gwen Mathis,

Thermoforming Division, atphone number 706-235-9298.


IR Scanning With Closed-Loop Feedbackfor Thin-Gauge Thermoforing1

INDUSTRY PRACTICE

BY C. P. CARLIN, SENCORP, INC., AND C. CASALE, LAND INSTRUMENTS


1 This article is based on a case-study using a Land InstrumentsLFP7 line scanner and a Sencorp Series 2500SD in-linethermoformer.

When Lexus introduced their slogan, “TheRelentless Pursuit of Perfection®,” they

made a simple and bold statement. They explicitlystated what most businesses strive to achieve –the reduction in errors. Whether it is a program ofcontinuous improvement or lean manufacturing,businesses today in North America understand thatin order to remain competitive, they must reachfor perfection. This is a principle that hasimplications for today’s thermoforming industry.

It has long been assumed that practice makesperfect. But what happens when outside factorsinfluence what you’ve been practicing? In aprocess filled with variables, it is not alwayspossible to have complete control. Inthermoforming, if we focus on just the material(and assume there is no in-house extrusion), wefind several factors that are outside the processor’scontrol. These factors include:

• Basic material type/properties,

• Thickness,

• Material storage, and

• Ambient room temperature.

If we focus on what the processor can control,the first stage of thermoforming is heating thesheet.

Oven temperature is both easy to control andeasy to define. Whether the heating elements arequartz, ceramic, or other, all machines are

equipped with a means of reading temperature.However, what is easily forgotten at this stage ofthe process is what really matters is the temperatureof the sheet. Infra-red sensors, pyrometers, andheat guns provide a limited reading of the sheet.The latest technology that allows for a morecomplete visualization of the sheet is an infra-redline scanner, Figure 1.

Figure 1.

When taken by itself, the line scanner providesa graphical image of an entire index length of thesheet, scanning through a window of less than oneinch or 25 mm, Figure 2.

When coupled with a powerful closed-loopsystem, this method of scanning becomes a seriousadvantage for the custom thermoformer. Theprocess now becomes more mathematical andrigorous, allowing the operator to analyze and



Figure 4.

Figure 2.

monitor sheet temperature in a way that waspreviously unavailable. By scanning up to onehundred lines per second, a line scanner providesone thousand data points per line, or one hundredthousand temperature points per second (100,000/sec), Figure 3.

point. The operator only has control of the heaterelements.

When the closed-loop system is integrated, thesituation changes dramatically. When setting up ajob, the operator can start the scanner and viewthe sheet temperature profile on the control systemscreen. Next, the tolerance range of the sheet isentered into the program so that if a change intemperature is detected, the closed-look systemwill determine whether a single zone or the entireoven needs to be adjusted. The operator also hascontrol of the number of indexes required beforemaking any change, Figure 4.

Figure 3.

Trial and error can be costly, especially whenusing expensive and complex materials. We arenot thermoforming ovens, we are thermoformingsheet. Scarp, returns, and downtime all cost money.If all three of these variables can be reduced and/or eliminated, the thermoformer is one step closerto perfection. ■

The current system of heating the sheet relieson operator skill and savoir faire. Assuming a newjob, the machine is set up and run until acceptableparts are formed. Then, the heater controls arecalibrated to a set-point and the operator is alertedif the oven temperature is above or below this



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Twin-SheetThermoforming?

“This method is commonlyused for making hollow

articles. Two pieces of sheetare placed between the top

and bottom dies of themould, and compressed air or

steam is blown in betweenthem until the plastic has

assumed the required shape.At the final stage of themoulding, extra pressuregiven to the edges of the

mould causes the superfluoussheet to be cut away, whilst

the effective edges fusetogether so that the finishedarticles are removed in onepiece. The die is ventilatedwith very fine air outlets soas to obviate airlocks with

the resulting faultymouldings. The sheets ofplastic are usually slightly

heated before being placed inthe die. If steam is used forblowing, a pressure of about

50 lbs. per sq. in. isemployed; if compressed air,

the approximately doublethat pressure is necessary.”

F. W. Kellaway andN. P. Meadway,

Introducing Plastics,The Scientific Book Club,

London, 1945.


The Cutting EdgeBY JIM THRONE, SHERWOOD TECHNOLOGIES, INC., DUNEDIN, FL

THERMOFORMING101

For those of you who came in late,we have been examining the various

aspects of part design. In this lesson, wefocus on the edge or periphery of the part.The first thing we need to realize is thatthe part we’ve just thermoformed is stillattached to the plastic that held it in theclamp frame while it was being formed.This is true whether the entire assembly,formed part and edge material, isremoved to a separate fixture or whetherthe formed part is punched from the trimmaterial immediately after forming.We’ve discussed trimming in earliertutorials. In this tutorial, we discuss thecharacteristics of the edge itself.

RegistrationTrimming devices need to trim the part

where the designer wanted it trimmed.This means that the trim line and the trimdevice must register. The accuracy ofregistration is a design issue. In heavygauge forming, it is impractical to ask atrim device to trim within thousandthsof the design trim line everywhere alongthe trim line. Heavy-gauge parts may befixtured between the time they areformed and the time they are trimmed.Fixturing allows for some residual stressrelaxation and often improves the trimregistry. In thin-gauge forming, the trimdevice should be able to trim very closeto the design trim line. Because manythin gauge parts are axisymmetric,meaning that the trim line is round,registration focuses on the degree ofovality of the formed trim line prior tothe trimming step. Thin-gauge parts areoften trimmed within minutes of beingformed. Certain polymers such aspolypropylene continue to crystallizeafter forming. As a result, the design trimline and the final part edge peripherallocation may be quite different.

Heavy-Gauge Cut EdgeThe nature of the final cut edge

depends strongly on the trimming device.In many robotic trimming steps, the edge

is rough-cut initially. This edge finishmay be adequate if the cut edge of thepart is completely hidden in the finalassembly. Polycarbonate skylights thatare edged in aluminum are examples.Often the product requires a smootheredge. For robotic trimming to achieve thedesired edge, the rough-cut edge isrouted a second time while the partremains on the trim fixture.

In some applications, the edge mustbe as smooth as the overall plasticsurface. Here are some ways of achievinga very smooth, even polished edge.

• Fine grit sanding followed byCrocus cloth or 1200-grit polishing

• The above method, followed bypumice polishing

• For certain plastics, a light wipewith a mild solvent will smooth trimcuts. Care must be taken tominimize the amount of solvent thatis absorbed into the polymer.

• Flame-polishing is popular withtransparent amorphous plastics suchas acrylics and polycarbonates.Flame-polishing is notrecommended with plastics such asPVC.

• Laser cutting. The laser is a high-intensity beam that cuts plastic bymelting and vaporizing it. The cutline is usually very smooth.

Thin-Gauge Cut EdgeThin-gauge trimming is substantially

simpler than heavy-gauge trimming.

Nevertheless, the trim edge charac-teristics can be quite important to thecustomer. There are three major issueswith the cut edges of thin-gauge parts:

• Trim dust and fibers, known asangel hair and fuzz.

• Microcracks that can grow into theformed part as it is flexed

• Jagged edges that can cut or abradethe user

Edge and surface contamination areoften the results of problems in thetrimming step. But not always. It is verydifficult to trim polystyrene withoutgenerating very tenacious trim dust. It isoften difficult to trim polypropylene prPET without generating fibers and fuzz.Adding antistatic agents to PS, either asan additive that is compounded into thepolymer or as a topical coat to the sheetprior to forming, helps the trim dustproblem. If fuzz and fibers areobjectionable to the customer, they areoften minimized by passing the containeredges through a hot air knife. The heatshrivels the fibers to microscopic size.

Microcracks and jagged edges can alsobe “healed” by heating the edges withhot air. One approach is to collect andnest a stacked, counted number of partsand pass the stack though a hot air tunnelprior to packaging or boxing forshipment. ■

Keywords: registration, flame polishing,laser cutting, trim dust, microcracks


BOOK REVIEW

V. Capasso, Ed., MathematicalModeling for Polymer Processing:Polymerization, Crystallization,Manufacturing, Springer Verlag,Berlin, 2003, 74.85 euro ($94),320+xiv pages, 90 figures, in English.

All right, let’s get the bellyachingout of the way first. “Oh, Jeez,

another technical book!” “Who theheck reads all this stuff, anyway?”“Why can’t this guy review apractical book, like ‘Thermoformingfor Dummies’?” Okay, are you done?Can I proceed? Thank you! (After all,this is my column, not yours!)

This is a technical book. Jam-packed with equations, most of whichappeal only to people of the ilk1 ofthe particular author(s). The titleintrigues – Mathematical Modelingin Manufacturing! Wow! If we canmathematically model, maybe wecan predict. And if we can predict,maybe we can eliminate many trial-and-error steps as we bring a newpolymer/product to production. So,let’s see what’s between the covers.

First off, the book is a translationof an edited collection of mostlyEuropean papers. The translationseems to flow well. In certain cases,the equation jumps2 omit criticalintermediate steps. In at least onecase, the authors tacitly make a major,very questionable assumptionbetween equations which thereviewer believes calls into questiontheir conclusions.

There are seven chapters. There aremany references to earlier, lesscomplex efforts. The first chapterconsiders the math of polymerization.

The next three chapters focus oncrystallite nucleation and the next twoon the mechanisms of crystallization.The last section, 44 pages long, isentitled “Manufacturing,” andconsists of one chapter, entitled“Modeling of Industrial Processes forPolymer Melts: Extrusion andInjection Molding.” Yep, you’reright! Nothing on thermoforming!“So,” you ask. “Why the heck are youreviewing this thing, anyway?” Well,don’t get your britches in a bunch justyet. Let’s keep in mind that some ofthe most challenging polymericmaterials that we deal with arecrystalline in nature – polyethylene,polypropylene, TPO, PET …Typically, we form these materials intheir amorphous, melt state. And thenwe wait for them to crystallize … Or,with PET, maybe not. So chapters 2through 6 form a basis forunderstanding the variouscrystallization mechanisms. (Yes,Virginia, there are manymechanisms!)

The early chapters focus onvariations in Gibbsian cluster theory.In short, how many molecules needto collect in a given region before acrystallite forms? How do they getthere? And why? There’s a nicesection by the late A. Ziabicki,considered the father of moderncrystallization theory, on the freeenergy of aggregation and … Oh …You’re not following along, are you?

Well … Let’s see. Are youinterested in the theoretical reasonswhy crystallization ceases for manypolymers? No? Figgers. How aboutmechanisms that promote purespherulitic crystallization rather thanshish-kebabs? You know, thedifference between quiescent3 crystalgrowth and shear-induced crystalgrowth? Not that, either?

Okay, then. Let’s jump right to themanufacturing chapter. As I said,

there’s nothing in here onthermoforming. If you want to learnabout the parameters that affect thecooling rate of your just-formed-and-still-sitting-on-the-mold waiting-to-be-crystalline-eventually part, you’llneed to read the chapters you justskipped over. On the other hand, ifyou want to know what kinds ofissues face your sheet supplier, youmight want to listen up (or in thiscase, read up)! Unfortunately, theauthors theoretically address only oneextrusion processing issue – flowinstability, often called ‘meltfracture.’ (The astute4 and well-educated reader should have learnedsome of this arithmetic some timeago.) The authors add an additionalterm to the traditional KBK-Zconstitutive model to handle a newly-defined effect the authors describe as‘spurt.’ (Your reviewer is notcomfortable replacing the traditional‘stick-slip’ concept with the authors’‘Newtonian, latency, and spurtphases,’ though.)

Again, this is a collection ofmathematical treatises that isobviously not bedtime reading. Andit is not a book that will engenderheated debate on the Conferencefloor. Nevertheless, many of us dealdaily with semicrystalline polymersand we should have at least get awarm, fuzzy feeling that there areunderlying theories that describe whyour polymers behave the way they do.(And not necessarily the way we wantthem to do!)

Because the book title purports todiscuss the theory of processing (butdoesn’t) and because the workfocuses extensively on crystallizationkinetics but fails to apply same tosheet extrusion, this reviewer givesit only one-and-a-half books out offive.

~ Jim Throne

1 Ilk = type or kind.2 An ‘equation jump’ means that the textgoes between two equations with littleexplanation. Typically authors resort to thephrase, “therefore, …”3 Quiescent = quiet, still, tranquil, notmoving.4 Astute = discerning.


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THERMOFORMINGDIVISIONTO FUND

THESPE STRETCH

AWARD

The Thermoforming

Division Board agreed to

fund a program to

reward SPE Student

Chapters who win the

STRETCH Award. The

STRETCH stands for

“Students Reaching

Excellence Through

Chapters.” Application

forms are on the SPE

website: www.4spe.org.

The total amount is

$5,000 and will be split

among the Student

Chapters who win the

STRETCH Award with a

$500 limit per Chapter.

Students lead busy lives

and we hope to motivate

them to complete all the

requirements of the

STRETCH Award.

If they do that, they are

truly an active chapter!


BY LOLA CARERE, COUNCILOR

Council Report …

Charlotte, North Carolina

This summary is intended tohelp you review the high-

lights of the Council Meetingsheld in Charlotte on May 7th,2006.

ANTECRegistration at ANTEC was

2,063 (including registrants in theseminars). A total of 206 registrantsattended 24 Society seminars.

Incoming President Tim Womer’sSPE mantra is “Are You In? (Inter-nationally Networked).”

From the Council FloorEach of the Society’s officers and

vice presidents provided a brief up-date on their recent activities andliaison work.

• Senior Vice President VickiFlaris reviewed the InternationalAwards, Fellows, Honored ServiceMember, and the other SPE awardprograms and noted that the processhas been completed for 2006. Dr.Flaris also encouraged the submis-sion of names of additional candi-dates for the coming year.

• Kishor Mehta provided an up-date on the Constitution and BylawsCommittee (newly renamed goingforward as the Bylaws and PolicyCommittee) and the work on the re-vision to Bylaws and dissolution ofthe Constitution. He reviewed the

success of the recent vote on the dis-solution. The motion to dissolve theexisting SPE Constitution passed byan overwhelming majority: 4,808for, 153 against. Therefore, effectiveMonday, April 10th, the new Bylawspreviously approved by Councilbecame the official governing docu-ment for the Society.

• Dr. Roger Corneliussen gave anupdate on the Sections Committeemeeting. Issues discussed and pur-sued included regionalization andSection revitalization. Dr.Corneliussen recognized past ChairsBarbara Arnold-Feret and AlanArduini as well as Vice Chair HelenBasso.

• Bill Arendt provided an updateon the activities and plans for theDivisions Committee. Goals includerevamping/expansion of the Speak-ers List, sponsoring new Divisions/SIGs, and supporting Sectionsthrough MiniTecs.

• John Szymankiewicz providedan update on ANTEC and theANTEC Operating Committee. Theupdate included some details on thepreparation for and results to dateon ANTEC 2006 in Charlotte, NC.

• Jon Ratzlaff provided an updatefrom the International Committeeon the work with headquarters andlocal Sections to grow globally. Mr.Ratzlaff gave details on the plan(s)to grow individual Sections/areas/

regions. Mr. Ratzlaff also indicatedthat the International Committee ispublishing a semi-annual newslet-ter with additional details and sum-maries of activities throughout theworld. Mr. Ratzlaff reminded thegroup of the Spanish-language se-ries for one set of seminars at NPE,formation of the India AdvisoryBoard, and network expansion withlocal Sections in Mexico and theAsia/Pacific rim area.

Governance RestructuringPrior Past President Donna Davis

presented data and progress on theprocess for reviewing the currentgovernance structure. Ms. Davis re-viewed the mission statement of theSociety and the philosophy the teamhas adopted in reviewing and evalu-ating potential changes to the cur-rent governance structure.

New ChartersA Student Chapter was estab-

lished at the University of Houston.

Awards and RecognitionsIn addition to the recognition of

the retiring administration, theMichael Cappelletti ExcellenceAward was given to Hector Dilan.(Note: The James Toner ServiceExcellence Award was awarded atthe Brookfield headquarters on May19th, 2006 to two recipients thisyear: Yetty Pauwels and DorisThoren.)



Outgoing President Len Czubathanked his Executive Committeefor their hard work. Incoming Presi-dent Tim Womer introduced hisExecutive Committee. New Execu-tive Committee Vice Presidents are:Barbara Arnold-Feret, Ken Braney,Dan Cykana and Bill O’Connell.Paul Anderson is the 2006-2007Secretary and John Szymankiewiczis the 2006-2007 Treasurer.

Contributions and DonationsIt is with grateful appreciation

that the Society would like to ac-knowledge the following contribu-tions and donations by its Sectionsand Divisions:

• Bartlesville-Tulsa Section –Vivek Rohatgi presented a check for$1,000 to SPE.

• Color & Appearance Division– Returned its $2,684 rebate pay-ment for the 1st and 2nd quarters.

• Detroit Section – Tom Powerspresented a check for $35,519 to theSPE Foundation for the Robert G.Dailey Scholarship, HurricaneKatrina Relief, International Awardfor Education, International EssayAward, and conferencing proceeds.

• Electrical and Electronic Divi-sion – Amod Ogale presented acheck for $946 to SPE, represent-ing the Division’s rebate from SPEfor 2006.

• Extrusion Division – Presenteda check for $2,500 to the SPE Foun-dation Scholarship Fund.

• Mid-Michigan Section – KenKerouac presented a check for $500to the SPE Foundation for the Rob-ert Cramer Scholarship Fund.

• Plastics Environmental Division– Dennis Denton presented a checkfor $13,000 from their GPEC pro-ceeds.

• South Texas Section – Prior PastPresident Donna Davis presented acheck for $6,663 to SPE represent-ing new membership fees collectedat the Polyolefins Conference.

• Tex-La-Gulf Section – RickWagner presented a check for$32,308 to the SPE Foundation tobegin a fund to provide scholarshipand relief to victims of hurricanesKatrina, Rita, and Wilma. The con-tribution to the Foundation repre-sents the entirety of the Tex-La-GulfSection’s budget.

• Thermoset Division – PaidTopCon profits of $2,572. The Ther-moset Division also returned its2006 rebate check to SPE earlier thisyear.

• TPM&F Division – Sal Montepresented a check for $5,000 to theSPE Foundation.

• Vinyl Division – Presented acheck for $1,000 to the SPE Foun-dation Scholarship Fund and a checkfor $1,000 for the Student AuthorTravel Fund. ■


DVD or Video Series & Companion Volume

Based on Bill McConnell’sSeminar and Workshop Series Heavy & Thin Gauge Thermoforming Methods, Materials, Production, Tooling, Mold/Product Design Vacuum and Compressed Air Systems, Best Practices, Heating of Film and Sheet & Heating System Requirements Filmed at four plant locations200-page Companion Volume parallels video program and includes useful tables, charts and checklists The only Thermoforming Training in the marketplace

Ten Fundamentals ofTHERMOFORMINGby SPE and Bill McConnell (#0190)

www.4spe.orgemail: [email protected]


Dr. Peter Mooney, renowed economist on global developments in the plastics industry,displays his allegiance to the Thermoforming Division.



Help SponsorThermoforming®

Q U A R T E R L Y

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**Please note the increase in sponsorshiprates. This is the first increase since the

inception of the Thermoforming Quarterlyin 1981. We appreciate your continued

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Questions?Please Contact:Laura PichonEx-Tech Plastics

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We Appreciate Your Support!

From The EditorThermoforming Quarterlywelcomes letters from itsreaders. All letters are subjectto editing for clarity and spaceand must be signed. Send to:Mail Bag, ThermoformingQuarterly, P. O. Box 471,Lindale, Georgia 30147-1027,fax 706/295-4276 or e-mail to:[email protected].


These sponsors enable us to publish Thermoforming QUARTERLYThese sponsors enable us to publish

ThermoformingQUARTERLY

“FORMING EDUCATIONAL OPPORTUNITIES:GRANTS AND SCHOLARSHIPS OFFERED BYTHE SOCIETY OF PLASTICS ENGINEERS –

THERMOFORMING DIVISION”The Thermoforming Division of SPE has produced a new

six-minute DVD for educators.

The DVD discusses the 13 matching equipment grants of up to $10,000and how to apply for the grant. The 20 scholarships to college students

are discussed and information is provided as how to apply for ascholarship. The Thermoforming Division of SPE has contributed over

$150,000 in equipment grants and scholarships as of this date.

The DVD is free of charge and available from SPE throughGail Bristol at 203-740-5447 or Gwen Mathis,

Thermoforming Division, at 706-235-9298.


Forming

Thermoformers, have

you discovered a

forming tip that you

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A time saver?

Or a cost saver?

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The Thermoforming Division Salutes aPioneer Thermoformer … Glenn Blackburn

Most of Glenn Blackburn’s life wasdedicated to the Thermoforming

Industry. His life ambition was to be aveterinarian like his Dad. While Glenn wasonly able to achieve an 8th grade educationin a one-room school house before goingto war, he enlisted in the army with hopesof receiving veterinarian training. Hishopes were dashed when horses were notused during World War II. As a StaffSergeant in the First Calvary Division ofthe Army, he served in Australia, NewGuinea, The Admiralty Islands, ThePhilippines and Japan. He was a liberatorof the Japanese- held prison camp at theUniversity of Santo-Thomas in Manila.Fighting malaria that he had contractedfrom the war made it difficult to work fora period of time after the war. Uponreturning to the United States, he workedand received training as a chemicalbacteriologist. Working with groups incompanies such as BF Goodrich,Doebeckman and Dow Chemical, heassisted in the development of a plastic filmthat would be used to enhance thelongevity and storage of prepackagedcheese. Mr. Blackburn also worked on thedevelopment of equipment to cut, slice andvacuum pack cheese precisely. Mr.Blackburn obtained many patents duringhis work. He received 13 claims, allowingthe laminating and gluing of a mass ofcartons all at one time by means of steamand vacuum under precise timing andcontrol. After two years of developmentwork, many pieces of equipment becameavailable to the prepackaging industry.Some of the equipment was tested and putto use in the sliced bacon department ofArmour and Company. Mr. Blackburntotally developed and directed the use ofthis equipment, which was the first toproduce marketable sliced bacon with astairstep appearance.

During the 1950s, Mr. Blackburn wasrecognized and awarded the responsibilityto manage the operations of a small plasticprocessing company in Portage,Wisconsin. Only a few types ofthermoplastic existed during those days.Working long days and nights, he learnedfast and gained an education in plasticprocessing through trial and error. Thechallenge was immense with the companyoperating at a loss. One year later the

company was profitable and after years theplant grew to sales of $12 million. Thisplant was Portage Plastics, later becomingPortage Industries and finally SpartechPlastics Portage facility. He hired manypeople from outside of the plastics industry,all of which became successful in theextrusion, thermoforming and compressionmolding industries.

In 1966, Mr. Blackburn was offered anopportunity to become one-third partner ina small company in Winter Haven, Florida.His goal was to build machinery andthermoformed plastic field boxes for thecitrus industry. The company also did handlay-up of fiberglass for many differentproducts. With little or no money, 10 yearssoon slipped away as Mr. Blackburndeveloped a full line of containers foragricultural use in harvesting and materialhandling. During this time the companywas reorganized several times as it tried tofind new markets in the South. WinterHaven Plastics was dissolved in 1975 asMr. Blackburn left his partners and formedArtec Plastics, Rebel Plastics andBlackburn Industries. All of thesecompanies carried on the agricultural lineof formed containers while developing newmarkets. Mr. Blackburn was one of the firstto develop a low profile wheeled refusecontainer for municipal garbage pickupand installed this system into many citiesin the U.S. and as far away as Brisbane,Australia. As Blackburn Industries grew,the name was changed to Progress PlasticsInc. Progress Plastics grew to be the largestcustom thermoforming company in theSoutheast U.S. with 9 Rotarythermoformers, several CNC routers, 13compression molding presses and severalrotational molding machines. PPI hadmany reputable customers who choseProgress Plastics because of the highquality standards and immaculate plant thatMr. Blackburn demanded. His businessalways had a competitiveness that wasfueled by ingenuity. Mr. Blackburnstrongly believed in structured training ofhis employees. A five-year plan putemphasis on specific training each year inareas such as Safety, Quality, Efficiencyand Communications. Training took placecontinuously for skills in thermoformingand other manufacturing methods. Mr.Blackburn believed in sharing techniques,

technology and systems with customers aswell as competitors. The doors of ProgressPlastics were opened several times forseminars and tours for customers,competitors and the local SPE chapter. Mr.Blackburn was one of the founders of theCentral Florida Chapter of SPE andencouraged his employees and others tojoin.

Since the sale of Progress Plastics toTriangle Plastics, Mr. Blackburn has beenenjoying an active retirement. He spendsa lot of his time in his local communityhelping neighbors with home and gardenprojects. He has returned to the PhilippinesIslands twice to visit WWII sites. Hefrequently travels and speaks at Veteransof Foreign War meetings. He has workedon his life memoirs from childhood daysthrough WWII. As one of the mostknowledgeable in the ThermoformingIndustry, he is not wasting that talent either.Besides producing oil paintings and otherarts and crafts with his wife Eunice, he stillfinds time to consult and help startupcompanies as well as establishedthermoforming companies. Glenn hasalways been respected for coming up witha way to thermoform something whenothers said it had to be done by anotherprocess. He is often called upon for hisideas in part, tool or process design. Itwasn’t until after his retirement and in 2001that Mr. Blackburn was awarded a HighSchool Diploma at a graduation ceremonyfor WWII Veterans.

Glenn’s three children – Dennis, Wandaand Wendy – all live close to his centralFlorida home.

Mr. Glenn Blackburn



American ThermoformingMachinery LLC

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PresidentDanny Blasch989.345.5394

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�

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Some of Glenn Blackburn’sAccomplishments:

1. Developed a process for vacuumpackaging and sealing of cartons of foodproducts in stacks.

2. Worked with development of packagingfilms, Dow Chemicals (Saran Wrap),Doebeckman (Cellophane), B.F. Goodrich(Polyfilm).

3. Developed tooling and procedures formanufacturing a 5 gal. plastic pail liner.The material was .060 HDPE and a fourcavity female mold with plug assist wasused in this difficult project.

4. After other companies failed, Mr.Blackburn developed tooling and processto thermoform the 18” x 18” x 32”McDonald’s waste receptacle using afemale mold.

5. Developed a method for impregnatinganti-static solution onto HDPE extrudedsheet prior to vacuum forming. Thismaterial was used to form several milliontrays for Johnson & Johnson andsurpassed the required static decay factors.

6. Developed 7 thermoforming companies:Portage Plastics, Haines Industries, WinterHaven Plastics, Artec Plastics, RebelPlastics, Blackburn Industries, andProgress Plastics.

7. Set up 2 different companies withequipment which included over 26compression molding presses, blenders,extruders and other machining equipmentto manufacture fiberglass flower pots aswell as low- and high-voltage electricalhousings. ■


Thermoformingwith StyleTechnology

advances haveincreaseddesigners’flexibility.

This is an example of a pressure-formedgrille that demonstrates the design flex-ibility that can now be achieved withthermoformed parts.

Designers who think that injec-tion molding is the only way

to fabricate stylish plastic parts arebehind the times and need to take asecond look at thermoforming.While it’s true that thermoformingis ideal for large, flat parts, thecapabilities of the process extendmuch farther, due to many technol-ogy innovations and the availabil-ity of new sheet materials.

“There’s a huge amount of edu-cation that needs to take placeamong designers,” says RichardFreeman, president of Freetech Plas-tics, Fremont, California. “I thinkwe are just scratching the surface ofits potential.”

Freetech Plastics has been aleader in stretching the design lim-its of thermoforming and in devel-oping an approach that’s becomeknown as the West Coast Style ofthermoforming.

The West Coast Style concen-trates on more dramatic shapes withsweeping curves, deeper draws,larger undercuts, and the use of ribstructures. Because this approach re-lies on painting after forming, iteliminates the need to mold in tex-ture and color, a need that can re-

strict part design to a more conser-vative style.

A number of designers have al-ready gotten the message and areworking with Freetech to providetheir customers with creative con-cepts. For example, Lunar Design,Palo Alto, California, has won fivedesign awards from ID Magazinefor projects on which Freetechthermoforms the enclosures. FrogDesign, Sunnyvale, California, andZiba Design, Portland, Oregon, havealso each won a design award usingparts formed at Freetech.

“For the most part, we can du-plicate any part design that you cando with injection molding,” Free-man says. “We’ve never turnedaway a customer because the partshape was too complex.”

Thermoforming also gives de-signers the freedom to use signifi-cantly fewer parts, notes Freeman,and new techniques are allowingthem to do things they couldn’t dobefore. For example, Freetech canperform insert forming, which itdoes to produce the Xenogen enclo-sure (see photo on next page).

“For structural purposes, we in-serted some machined corner blocks

and formed the material aroundthem,” Freeman says.

Such secondary machining is afrequent means of executing com-plex part designs. For example, eventhough the thermoforming processcan only mold precise features onone side, additional structural sup-port and part nesting type featurescan still be added to the back sideby bonding machined parts afterforming. Vent openings on parts canbe achieved by designing in deepdrawn rib structures, then machin-ing the openings off the backside.

Freeman also refutes the myththat thermoformed parts cannotachieve the same level of aestheticquality of injected molded parts.

“We not only can achieve injec-tion molding standards, we often ex-ceed them,” Freeman notes. “AClass A finished, molded-in-texture,thermoformed part generally looksbetter than an injected molded partbecause we don’t have their issueswith swirls, sink marks, weld lines,gate marks, etc. On cars, plasticbumpers and plastic lower side pan-els are typically thermoformed be-cause we can consistently achieve


Life Measurement’s Pea Pod air displace-ment plethysmograph assesses infantbody composition. The top part of themachine enclosure is pressure formed byFreetech Plastics.

Xenogen Ivis 200Laboratory Imaging Systemalso uses enclosure partspressure formed at FreetechPlastics.

Credence Kalos XW Testhead usespressure formed enclosure parts thatillustrate the curvaceous aestheticrepresentative of the West Coast style ofthermoforming.

the Class A finish on a big partwhere injection molding night not.”

Depending on a particular partdesign and size, thermoforming canoften match, or even exceed, theproductivity of injection molding byusing inline or rotary machines.

“With a rotary machine and afour-up tool, we can get four shotsa minute,” Freeman says. “You can-not get four shots a minute on largeparts with injection molding.”

So when should someone usethermoforming instead of injectionmolding? There’s not one simple an-swer. Volume plays a huge role,given the difference in tooling costs.Lower volumes favor thermo-forming, since thermoforming tool-ing costs are only 10 percent to 15percent the cost of injection mold-ing tooling.

Part complexity and shape arebig factors, since they affect tool-ing costs. And, of course, size is im-portant. Very large parts favorthermoforming, while very smallparts favor injection molding, wheremulti-cavity tooling can be used. Formedium sized parts, all the factorsmust be considered together: com-plexity, size, and volume.

Material choices also affect thedecision making process, since notall engineering resins are availablein the extruded sheet form that isused by thermoforming machines.

However, resin suppliers con-tinue to roll out new thermo-formable materials every year.

Available materials al-ready include the olefins,ABS, polycarbonate, ny-lons, polyphenylene sul-fide (PPS), and thermo-plastic elastomerssuch asDuPont’s Hytrel. Lastyear, DuPont also intro-duced a thermoformableversion of its Delrin acetal.

Freetech Plastics wasthe first company to dem-onstrate the feasibility ofthermoformed Delrin,which DuPont is aiming at

the medical equipment segment be-cause of the material’s high chemi-cal resistance.

Conventional thermoformingmethods have long provided partsfor commercial appliances such asrefrigeration and vending machines,but the new techniques have alsoallowed thermoforming to provideinnovative solutions in segmentssuch as medical equipment, labora-tory equipment, fitness equipment,business machines, and lawn andgarden equipment. Some manufac-turers of consumer electronics haveeven turned to thermoforming forthe large housings used inprojectiontelevion sets.Such parts were typi-cally injection molded in the past.

Thermoforming may not be thebest route for every application, butit should definitely be looked at firston large parts.

“The process has been too oftenoverlooked in the past,” Freemansays. “But it’s a process that design-ers need to be aware of and keep intheir tool kit.” ■

Reprinted withpermission from

Appliance Design magazine,copyright 2004.


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CMS North America, Inc.Grand Rapids, MI800.225.5267 Fax: 616.698.9730

®

[email protected]


SOLVE COST & PERFORMANCE PROBLEMS� Over 40 specialized grades

satisfy highest performanceto lowest cost applications:– Aircraft– Mass transit– Building products– Weatherable– Conductive/ESD– Multi-purpose

� 10 Surface Textures

� Thickness from 0.028”to0.500”

� Certified Fire Ratings:– UL Std. 94 V-0 and 5V– UL 746C for signage– FAR 25.853(a) and (d)– Class 1/A– MVSS 302– ASTM E-662/E-162

� Broad Color Selection:– 34 Standard colors– 2000+ Custom colors– Granite patterns– Fluorescent colors– Woodgrain patterns

Kleerdex Company, LLC6685 Low StreetBloomsburg, PA 17815 USATel: 1.800.325.3133Fax: 1.800.452.0155E-mail: [email protected]

ISO 9001:2000 andISO 14001 CERTIFIED

INDEX OF SPONSORS


ADVANCED VENTURES INTECHNOLOGY, INC. ................. 15

ALLEN EXTRUDERS .................... 34

AMERICAN CATALYTICTECHNOLOGIES....................... 26

AMERICAN THERMOFORMINGMACHINERY ............................. 29

ALTUGLAS INTERNATIONAL ....... 21

BROWN MACHINE ....................... 27

CMS NORTH AMERICA ................ 35

CMT MATERIALS, INC. ................. 34

KYDEX .......................................... 36

LANXESS ...................................... 15

LYLE .............................................. 18

MAAC MACHINERY ........................ 1

McCLARIN PLASTICS................... 34

McCONNELL CO. .......................... 26

MODERN MACHINERY ................ 35

ONSRUD CUTTER........................ 25

PLASTICS CONCEPTS................. 26

PLASTIMACH................................ 27

PORTAGE CASTING & MOLD,INC. ............................................ 26

PREMIER MATERIAL CONCEPTS. 29

PRIMEX PLASTICS ....................... 34

PROCESSING TECHNOLOGIES .. 34

PRODUCTIVE PLASTICS, INC. .... 26

PRODUCTO CORPORATION ....... 34

PROFILE PLASTICS ..................... 26

RAY PRODUCTS, INC. .................. 35

RAYTEK ........................................ 24

ROBOTIC PRODUCTIONTECHNOLOGY .......................... 23

RTP ............................................... 27

SELECT PLASTICS....................... 35

SENCORP ..................................... 36

SOLAR PRODUCTS ..................... 35

STANDEX ENGRAVING GROUP .. 35

STOPOL INC. ................................ 21

TEMPCO ELECTRIC ....................... 8

THERMWOOD CORP. ...... Inside BackCover

TOOLING TECHNOLOGY, LLC ....... 8

TPS ............................................... 35

ULTRA-METRIC TOOL CO. ........... 32

WECO PRODUCTS ...................... 15

WELEX, INC. ................................. 18

XALOY .......................................... 35

ZED INDUSTRIES ......................... 34

COPPER AND BRASS DIVISION .... 5

EDWARD D. SEGEN & CO. .......... 32

EXTREME ADHESIVES ................ 29

FOXMOR GROUP ......................... 34

FUTURE MOLD CORP. ................. 35

GN PLASTICS ............................... 25

IRWIN RESEARCH &DEVELOPMENT .......................... 6

JRM INTERNATIONAL .................... 5

KIEFEL TECHNOLOGY................. 29W

e build machines that build business

Sencorp thermoformers deliver repeatable, quality production parts at high cycle speeds. Available options include closed loop thermal imaging sheet scanning, adjustable shut height, deep draw, quick changeovermaster tooling and robotic part removal systems. Sencorp thermoformers provide you with a competitive edge over your competition.

ThermoformersBlister Sealers Laboratory SealersSpecial Machines Clamshell Sealers

400 Kidds Hill Road—Hyannis, MA 02601—USAP: 508-771-9400 F: 508-790-0002 E: sales@sencorp -inc.com www.sencorp -inc.com

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