Integrated Product Design and Manufacturing Using Geometric Dimensioning and Tolerancing (Manufacturing Engineering and Materials Processing) (v. 60)

327 Pages·2002·7.19 MB·English

by  Bob Campbell

Integrated Product Design
and Manufacturing Using
Geometric Dimensioning
and Tolerancing
Robert G. Campbell
William Rainey Harper College
Palatine, Illinois
Edward S. Roth
Productivity Services
Albuquerque, New Mexico
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
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Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
To my father, who believed as Ed Roth does that manufacturing is
both an interesting and honorable way to spend one’s life. And to my
mother, who worked all her life and made my engineering education
possible.
RGC
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
Foreword
In 1983, while working at Ford Motor Company, my colleagues and I had the
pleasure of meeting Ed Roth at one of his seminars. He opened our eyes to the
linkageneededforcommunicationtotakeplacebetweenProductandManufac-
turing Operations. This was done via an excellent geometric dimensioning and
tolerancing (GD&T) standard, ANSI Y14.5M-1982, and in a manner we had
neverseenbefore—notjusttheuseofGD&T,whichwehadalreadybeenusing
for 25 years, but how to effectively apply it. He also showed us the importance
of GD&T’s being interpreted correctly by manufacturing. The efficient applica-
tionofGD&Ttotheproductdevelopmentprocessenhancedproductivitytremen-
douslyandyieldedlong-termbenefits.TheANSIY14.5Mstandardwasthetool
neededtodefineandcommunicateaproductdefinitionthateveryonecouldread
andutilize.Asaresult,amassivetrainingprogramwasinitiatedatFordtoeffec-
tivelyapplyGD&Tthroughoutoperationsworldwide.Ihadthepleasureofwork-
ing closely with Ed Roth for many years and gleaned some of his expertise,
which made my engineering life easier and less stressful.
As a product design and manufacturing engineer, I often struggled with
communicating product definition, design intent, manufacturing, and quality re-
quirements. The drafting room had its protocols and standards for definition.
Designintentregardingfunctionalrequirementswasoftenoverlooked.Manufac-
turing utilized their expertise, past practices, and available facilities to produce
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
vi Foreword
the part. After the part was made, Quality verified that all drawing dimensions
had been achieved. Basically, each activity group operated independently with
only the drawing specifications as the common denominator.
Unfortunately,GD&Twasnotappliedeffectively.Alltoooften,Ireceived
a finished part that failed to meet functional requirements. If a part was ‘‘to
print,’’butstillfailedtoassemblewithitsmatingpart,thedrawingwasmodified
verbally to include specific functional criteria. Sometimes inspection gage re-
quirementsweredefined.Theknee-jerkreactionofmanyengineerswastotighten
tolerances. If this failed, a note was added stating, ‘‘Must Meet Functional Re-
quirements.’’Thepartsupplierwasheldaccountableforcharacteristicsthatwere
not clearly defined.
Thisbookdocumentsmethodologiesthatcanrevolutionizeengineeringand
manufacturing,providednoshortcutsaretaken.GD&Tbasedonanationalstan-
dardisthe‘‘language’’forcommunicatingproductspecifications,butteamwork
among the various functional activities involved with the product development
processmustbeachievedforeffective‘‘application’’toachieveoptimalbenefits.
This book provides various techniques to accomplish this feat. It is not a quick
fix, but a permanent fix for longstanding problems.
Several elements were essential to a viable program in GD&T at a large
corporation.
GD&T Standard. We had to adopt a common standard for dimensioning
andtolerancingandapplyitthroughoutEngineeringandManufacturing
Operations worldwide. This we did by endorsing ANSI Y14.5M-1982
totallyandsubsequentlyadoptingthe1994updateasthecorporatestan-
dard for GD&T.
Corporate Expertise. A task force, which eventually became a permanent
group, was established to gain GD&T expertise, develop training pro-
grams,andestablishacompanyfocalpointforconsultingandassistance
to line operations worldwide.
Local Expertise. Local operations needed GD&T experts to provide on-
going day-to-day guidance. Some of the local experts subsequently be-
came instructors in GD&T for their respective areas.
Massive Training Program. A very energetic training program was
launchedandstillcontinuestoupgradeeveryone’sunderstanding,appli-
cation, and interpretation of GD&T. This included involving personnel
from Product, Design Services, Quality, Suppliers, Manufacturing Pro-
cessing,andTooling/GageDesigninjointtrainingsessions.Thiswasa
Ford first at that time (1983).
I previously referred to GD&T as a language. Consider ANSI Y14.5M-
1982thedictionary.Youcan’texpecttohandsomeoneanewWebster’sorOx-
fordEnglishdictionaryandexpecttocreateabest-sellingnovelwithouttraining.
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
Foreword vii
You must be able to master the language to create a novel, and even then not
everyone will have a best-seller. The same holds true for GD&T training and
skilllevels.Thefollowingfourlevelsofexpertiseshouldbeconsideredtoensure
correct application of GD&T.
Level One. Understand the “vocabulary.” All the symbols and the defini-
tions must be taught. These are the basics.
LevelTwo.Usageofthesymbolstoform‘‘grammaticallycorrectsentence
structure.’’Feature controlframesmustfollowstringentrules toensure
correct interpretations. Datum reference frames must be depicted and
used correctly. Typically this is referred to as correct syntax.
Level Three. The part definition must depict a ‘‘story,’’ which is design
intent.Mentally,thecalloutsmustdevelopacohesiveplanforwhatwill
happen ‘‘pictorially’’ when that part is inspected for acceptance. Will
thecalloutgivethedesiredrequirementformeetingdesignintent?This
is a very tough question. Metrology and measurement strategy are also
included for the design to be considered feasible.
LevelFour.Manufacturingpersonnelmustbeableto‘‘read’’thedrawing
callouts and clearly understand the requirements conveyed. They must
also be able to correctly apply that interpretation to select the required
metrology equipment. This is also a very difficult area which requires
a deep understanding of GD&T definitions. Subtle differences in data
measurement methods can totally change the result. For example, do
theyunderstandthedifferencebetweenmeasuringanaxisforparallelism
versus position on a CMM machine?
Inimplementingthistrainingthecommonquestionthatmustbeanswered
is ‘‘Who in your activity requires this knowledge?’’.
Allactivity teamsmust cooperateand communicate toachieve success.It
is truly a team effort. I applaud the efforts and expertise that went into creating
this book in which Bob Campbell and Ed Roth combine their vast experience.
If you read and apply its content carefully, you will enhance your product and
productivity capabilities exponentially.
Ed Boyer (Retired)
Manufacturing Engineer GD&T Specialist
Corporate Product and Manufacturing
Ford Motor Company
Bellaire, Michigan
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
Preface
While manufacturing firms search for a competitive edge, they frequently over-
look their most valuable asset, the product development process. When rushing
to apply the latest management techniques, it is easy to forget that the product
musteventuallybedefinedwithrealnumbers.Theproductdefinitionandmanu-
facturingplansthataretheresultsofthedevelopmentprocessaretangibleassets
as important to success as production facilities and finances.
Thisbookpresentsanalternativetothetraditionalmeansofdevelopingand
deliveringamanufacturedproduct.Itpresentsanintegratedproductdevelopment
processthatemphasizestheproductdefinitionusinggeometricdimensioningand
tolerancing (GD&T). The overarching theme of the book is the preponderant
influence the product definition has on the downstream phases of the product
cycle.Themajorityofthecoststructureislockedinbytheproductdesignsince
themanufacturingandinspectionmethodsarespecified—toagreaterdegreethan
recognized—by the endproduct specification.
Current product design techniques do not adequately recognize the con-
straintstheproductdefinitionimposesonmanufacturingandinspection.Asdis-
cussed in the first chapter, the product design is a script used throughout the
development process. An inadequate script will prevent the most elaborate pro-
duction plans from succeeding. For a manufactured product, the definition, in-
cludingspecificationofthemanufacturingandinspectionprocesses,isthescript.
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
x Preface
Ifthefirmistosucceedindeliveringaneconomicallyviableproduct,bothprod-
uct and process must be fully defined prior to implementing production.
Whilemanyproductshaveattributesthatareintangible,mostproductshave
anidealgeometricformthatmustbetranslatedintophysicalreality.Themethods
presented in this book are necessary to create the functional (i.e., physical) ele-
mentsofpartgeometryandleadtoefficientandeconomicalproduction.Further-
more,thesemethodsprovidethisinformationinatimelymanner,enhancingthe
likelihoodofsuccess.Themethodologiesdescribedinthisbookaccomplishthis
by considering the variation encountered in the production process. Doing this
earlyinthedevelopmentcycleallowspredictionoftheeffectsthatvariationwill
haveon productfunctionand manufacturing efficiency.Designs canthen be al-
teredtoremovesensitivitytospecificsourcesofvariation.Ataminimum,knowl-
edgeofthisvariationwillquantifyelementsofriskinthedesignsothatintelligent
business decisions can be made.
Thebookemphasizesaproductdefinitionthatprovidesdetaileddesigns—
the numbers—allowing technical solutions based on objective methods rather
thanonvisceralresponses.‘‘Gettingtothenumbers’’requiresbothateamstruc-
tureandacommonlanguage(GD&T)withwhich theteammembersmaycom-
municate.This languageisnecessaryfromanengineeringstandpoint toprovide
the dimensions used in achieving part function. It also allows the budgeting of
variationamongthevariouscomponentscomprisingtheassembly.Thelanguage
and the methodology tie together the design and manufacturing processes, for-
mally eliminating the artificial barriers that segregated these functional areas in
the past.
The key to understanding the book’s structured design techniques is the
knowledgethatalltheinformationthatthesetechniquesgeneratewilleventually
be identified and documented for a successful product. The greatest economic
benefits will be achieved if the information is identified and documented early
in thedesigncycle—bothaccomplishedusingGD&T.Thepremiseofthebook
isthatthishappensonlythroughtheuseofthestructureddesignmethodologies
and GD&T. If the information is generated by trial and error during the latter
stages of the cycle, the price is high in terms of lost market opportunities and
avoidable expenses.
Becausetheproductdefinitionaffectstheentireproductdevelopmentcycle,
thebookisdirectedtowarddesign,manufacturing,andqualityassuranceperson-
nel involved with product and process design. It provides a set of structured
methodologies that can be used in developing specific product, manufacturing,
andinspectiondesignsthattaketheproductfromthedesigner’svirtualworldof
perfectionandintothephysicalworldofvariation.Thecommonthreadthatruns
throughoutthebookistheuseofgeometrictolerancingbasedonASMEY14.5M
and equivalent ISO standards.
An additional audience for the book is to be found in the engineering
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
Preface xi
schoolsofuniversities.Thecurrentuniversityenvironmentusuallytreatstheen-
gineering graphicscourse asa dead-endvehicle; concepts initially developedin
the first graphics course are not integrated into subsequent courses. This book
providesaninstructionalframeworkwithwhichtoexpandgraphicsconceptsinto
advanced undergraduate or graduate courses. The book’s emphasis on product
definitionwiththeoverarchingfocusonvariationenhancesastudent’sabilityto
create an interpretable and producible product definition. Once mastered, this
material ultimately makes the student more valuable to an employer.
The book is composed of five major parts. For individuals with adequate
knowledgeofbothGD&Tandmanufacturing,manyofthechapterscanberead
separately.Chapters1through3setthestageandprovidethefoundationconcepts
thatsupporttheintegratedproductdevelopmentsystem.Someofthisinformation
isinothersourcesbutisnotplacedwithinthecontextofaproductdevelopment
systemordescribedinsufficientlyconciseformtoshowtheconnectionbetween
part geometry and the development cycle.
Once the stage is set, Chapters 4 through 6 provide the structured design
techniquesusedinassemblingaproducibledefinitionoftheproduct.Thisisthe
crucialelementofthebook.Theinformationgeneratedbythesetechniquesgoes
beyondthecurrentnorminproductdesign.Thisinformationprovidesrecognition
of thephysicalformoftheproductand accountsforvariationinherentinactual
components.Thetechniquesleaddesignersthroughthevariousphasesofproduct
development,refiningthedesignswithgeometriccontrolsandenhancingproduc-
ibility.
Chapters 7 and 8 introduce ideas and concerns associated with product
verification. The order of presentation highlights the organization of the design
cycle into phases that initially design the product, create the inspection system,
andfinallydesignthemanufacturingprocess.Thebook’sphilosophyisthatthis
orderforcesrecognitionofmanufacturingreality.Oncecreatedinthefirstphase
of development, the design should not be released into production if adequate
verificationprocessescannotbedefined.Ifitcannotbeverified,theproductdefi-
nitionisinadequate,inflatingcostsandpossiblyleadingtoaninabilitytomanu-
facture.
Chapters9through12extendtheseideasintothefunctionaldesignofgag-
ing,fixturing,andinspectionprocesses.Sufficientexamplesareprovidedtodem-
onstratedetail-leveldesigntechniquesandtoshowhowtheyaredrivenbyearlier
designphases.Engineersanddesignerswilllearnhowtheirproductdesigncon-
strains tooling and gaging designs. Once recognized, these constraints can be
turned to ouradvantage, allowing the physicalproduct to be realized inan eco-
nomicallyefficientmanner.Ifdoneproperly,developmentcostsandengineering
changesaresubstantiallyreducedascomparedwithtraditionaldesignprocesses
in which variation is not directly anticipated.
The last two chapters, 13 and 14, consolidate the concepts into an actual
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
xii Preface
case study and discuss implementation. The feasibility and power of the ideas
aredemonstratedbythecasestudy,whichservestovalidatetheiruse.Inaddition,
with widespread interest in ISO 9001 compliance and certification in GD&T
(ASME Y14.5.2), these chapters illustrate how structured product development
basedonGD&Tcreatesanauditableprocessthataddsvaluetothedevelopment
cycle. Furthermore, it ensures that the benefits of this process are captured and
documented, becoming a major asset and competitive weapon.
Notetothereader:figuresinthebookusedtoillustrateengineeringdraw-
ings(hardcopyorCAD)arenotintendedtobecomplete.Ontypicalengineering
drawings, the data density can be so intense that it is difficult to illustrate key
ideaswithoutforcingthereadertospendaninordinateamountoftimedecoding
the drawing. Only after this task is accomplished does the reader arrive at the
pointwheretherealconceptisapparent.Toavoiddiscouragingpeople,thedraw-
ingshavebeensimplifiedorabbreviatedtoapointsufficienttoillustratetheidea
but not to pass muster with the checker—if such a person still exists.
Also,itshouldbeacknowledgedthattheterm‘‘drawing’’isusedtocover
a variety of forms of engineering communication. We live in a world of mixed
media where a drawing can be either a hard copy or in some electronic format;
it is also increasingly likely that the product description may exist only in the
formofathree-dimensionalmodelwithannotationattachedinoneofamultitude
of ways.
Iwouldliketotakethisopportunityto thanksomeoftheindividualswho
madethisbookpossible.Inparticular,Igainedimportanttechnicalinsightsfrom
Al Neumann of Technical Consultants, Inc., who also serves on the ASME
Y14.5Msubcommittee.Inaddition,SylviaGurneydeservesthanksforherefforts
over the years that it has taken to bring the book to completion and for her aid
in getting the manuscript ready to publish. I would be remiss if I did not thank
Barbara Mathieu and Rita Lazazzaro of Marcel Dekker, Inc., for their guidance
andpatienceinbringingthisbooktofruition.Inaddition,withthedifficultythat
normally attends reading technical books, the copy editor, Kristen Cassereau,
shouldberecognizedfortheclarityshehasaddedtothebook.Finally,andmost
importantly, I thank my coauthor, Ed Roth, who provided the core of this book
throughhisearlierworksandwhohascontinuedhiseffortstoexposethebenefits
of GD&T to the design and manufacturing world.
Robert G. Campbell
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.