coordinate measuring machines and systems

Coordinate Measuring Machines and SystemsSince John Bosch edited and published the first version of this book in 1995, the world of manufacturing and coordinate measuring machines CMMs a

Coordinate Measuring Machines and Systems

Since John Bosch edited and published the first version of this book in 1995,

the world of manufacturing and coordinate measuring machines (CMMs) and

coordinate measuring systems (CMSs) has changed considerably Completely

revised and updated to reflect the changes that have taken place in the last

sixteen years, Coordinate Measuring Machines and Systems, Second Edition

covers the evolution of measurements and the development of standards, the

use of CMMs, probing systems, algorithms and filters, performance and financial

evaluations, and accuracy

See What’s New in the Second Edition:

The book features two new editors, one from academia and one from a

metrology-intensive user industry, many new authors, and known experts

who have grown with the field since the last version Furnishing case studies

from a wide range of installations, the book details how CMMs can best be

applied to gain a competitive advantage in a variety of business settings

Second Edition

Coordinate Measuring Machines and Systems

Second Edition

A Series of Reference Books and Textbooks

SERIES EDITOR

Geoffrey Boothroyd

Boothroyd Dewhurst, Inc.

Wakefield, Rhode Island

1 Computers in Manufacturing, U Rembold, M Seth,

and J S Weinstein

2 Cold Rolling of Steel, William L Roberts

3 Strengthening of Ceramics: Treatments, Tests, and Design Applications,

Harry P Kirchner

4 Metal Forming: The Application of Limit Analysis, Betzalel Avitzur

5 Improving Productivity by Classification, Coding, and Data Base

Standardization: The Key to Maximizing CAD/CAM and Group

Technology, William F Hyde

6 Automatic Assembly, Geoffrey Boothroyd, Corrado Poli,

and Laurence E Murch

7 Manufacturing Engineering Processes, Leo Alting

8 Modern Ceramic Engineering: Properties, Processing, and Use

in Design, David W Richerson

9 Interface Technology for Computer-Controlled Manufacturing Processes,

Ulrich Rembold, Karl Armbruster, and Wolfgang Ülzmann

10 Hot Rolling of Steel, William L Roberts

11 Adhesives in Manufacturing, edited by Gerald L Schneberger

12 Understanding the Manufacturing Process: Key to Successful CAD/CAM

Implementation, Joseph Harrington, Jr.

13 Industrial Materials Science and Engineering, edited by

Lawrence E Murr

14 Lubricants and Lubrication in Metalworking Operations,

Elliot S Nachtman and Serope Kalpakjian

15 Manufacturing Engineering: An Introduction to the Basic Functions,

John P Tanner

16 Computer-Integrated Manufacturing Technology and Systems,

Ulrich Rembold, Christian Blume, and Ruediger Dillman

17 Connections in Electronic Assemblies, Anthony J Bilotta

18 Automation for Press Feed Operations: Applications and Economics,

Edward Walker

19 Nontraditional Manufacturing Processes, Gary F Benedict

20 Programmable Controllers for Factory Automation, David G Johnson

21 Printed Circuit Assembly Manufacturing, Fred W Kear

22 Manufacturing High Technology Handbook, edited by Donatas Tijunelis

and Keith E McKee

Management and Control, John Gaylord

24 Flat Processing of Steel, William L Roberts

25 Soldering for Electronic Assemblies, Leo P Lambert

26 Flexible Manufacturing Systems in Practice: Applications, Design,

and Simulation, Joseph Talavage and Roger G Hannam

27 Flexible Manufacturing Systems: Benefits for the Low Inventory

Factory, John E Lenz

28 Fundamentals of Machining and Machine Tools: Second Edition,

Geoffrey Boothroyd and Winston A Knight

29 Computer-Automated Process Planning for World-Class Manufacturing,

James Nolen

30 Steel-Rolling Technology: Theory and Practice, Vladimir B Ginzburg

31 Computer Integrated Electronics Manufacturing and Testing,

Jack Arabian

32 In-Process Measurement and Control, Stephan D Murphy

33 Assembly Line Design: Methodology and Applications, We-Min Chow

34 Robot Technology and Applications, edited by Ulrich Rembold

35 Mechanical Deburring and Surface Finishing Technology,

Alfred F Scheider

36 Manufacturing Engineering: An Introduction to the Basic Functions,

Second Edition, Revised and Expanded, John P Tanner

37 Assembly Automation and Product Design, Geoffrey Boothroyd

38 Hybrid Assemblies and Multichip Modules, Fred W Kear

39 High-Quality Steel Rolling: Theory and Practice, Vladimir B Ginzburg

40 Manufacturing Engineering Processes: Second Edition,

Revised and Expanded, Leo Alting

41 Metalworking Fluids, edited by Jerry P Byers

42 Coordinate Measuring Machines and Systems, edited by John A Bosch

43 Arc Welding Automation, Howard B Cary

44 Facilities Planning and Materials Handling: Methods and Requirements,

Vijay S Sheth

45 Continuous Flow Manufacturing: Quality in Design and Processes,

Pierre C Guerindon

46 Laser Materials Processing, edited by Leonard Migliore

47 Re-Engineering the Manufacturing System: Applying the Theory

of Constraints, Robert E Stein

48 Handbook of Manufacturing Engineering, edited by Jack M Walker

49 Metal Cutting Theory and Practice, David A Stephenson

and John S Agapiou

50 Manufacturing Process Design and Optimization, Robert F Rhyder

51 Statistical Process Control in Manufacturing Practice, Fred W Kear

52 Measurement of Geometric Tolerances in Manufacturing,

James D Meadows

53 Machining of Ceramics and Composites, edited by Said Jahanmir,

M Ramulu, and Philip Koshy

54 Introduction to Manufacturing Processes and Materials, Robert C Creese

55 Computer-Aided Fixture Design, Yiming (Kevin) Rong and

Yaoxiang (Stephens) Zhu

Revised and Expanded, Nello Zuech

57 Flat Rolling Fundamentals, Vladimir B Ginzburg and Robert Ballas

58 Product Design for Manufacture and Assembly:

Second Edition, Revised and Expanded, Geoffrey Boothroyd,

Peter Dewhurst, and Winston A Knight

59 Process Modeling in Composites Manufacturing, edited by

Suresh G Advani and E Murat Sozer

60 Integrated Product Design and Manufacturing Using Geometric

Dimensioning and Tolerancing, Robert Campbell

61 Handbook of Induction Heating, edited by Valery I Rudnev,

Don Loveless, Raymond Cook, and Micah Black

62 Re-Engineering the Manufacturing System: Applying the Theory

of Constraints, Second Edition, Robert Stein

63 Manufacturing: Design, Production, Automation, and Integration,

Beno Benhabib

64 Rod and Bar Rolling: Theory and Applications, Youngseog Lee

65 Metallurgical Design of Flat Rolled Steels, Vladimir B Ginzburg

66 Assembly Automation and Product Design: Second Edition,

Geoffrey Boothroyd

67 Roll Forming Handbook, edited by George T Halmos

68 Metal Cutting Theory and Practice: Second Edition,

David A Stephenson and John S Agapiou

69 Fundamentals of Machining and Machine Tools: Third Edition,

Geoffrey Boothroyd and Winston A Knight

70 Manufacturing Optimization Through Intelligent Techniques,

R Saravanan

71 Metalworking Fluids: Second Edition, Jerry P Byers

72 Handbook of Machining with Grinding Wheels, Ioan D Marinescu,

Mike Hitchiner, Eckart Uhlmann, Brian W Rowe, and Ichiro Inasaki

73 Handbook of Lapping and Polishing, Ioan D Marinescu,

Eckart Uhlmann, and Toshiro Doi

74 Product Design for Manufacture and Assembly, Third Edition,

Geoffrey Boothroyd, Peter Dewhurst, and Winston A Knight

75 Hot Deformation and Processing of Aluminum Alloys, Hugh J McQueen,

Michael E Kassner, Enrico Evangelista, and Stefano Spigarelli

76 Coordinate Measuring Machines and Systems, Second Edition,

edited by Robert J Hocken and Paulo H Pereira

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Coordinate Measuring Machines and Systems

Edited by

Robert J Hocken

& Paulo H Pereira

Second Edition

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Contents

Preface xiContributors xiii

Preface

Since.John.Bosch.edited.and.published.the.first.version.of.this.book.in.1995,.the.world.of.manufacturing.and.coordinate.measuring.machines.(CMMs).and.coordi-nate measuring systems (CMSs) has changed considerably Perhaps most signifi-cantly,.we.have.seen.a.large.volume.of.manufacturing.move.to.Asia,.particularly.the.People’s.Republic.of.China We.have.also.seen.enormous.growth.in.the.capability.of.what.were.once.called.microcomputers.and.the.incredible.strides.in.communication.through.the.multifaceted.ever-changing.marvel,.the.World.Wide.Web In.addition.to.that.the.proliferation.and.miniaturization.of.the.cell.phone,.personal.digital.assis-tants.of.all.sorts,.digital.books,.etc and.much.of.the.work.we.do.and.the.tools.we.do.it.with.would.have.seemed.quite.alien.a.decade.and.a.half.ago

So, what has changed in Coordinate Measuring Machines and Systems? First.

and.foremost,.it.is.helpful.to.remind.ourselves.that.the.basic.physics.of.the.machines.has.not.changed.at.all A.good.deal.of.this.book,.therefore,.deals.with.topics.that.have.not.changed.in.essence.but.have.just.become.more.deeply.understood In.other.areas,.software.as.an.example,.the.expectations.of.the.user.for.operator.interfaces,.ease of use, algorithms, speed, communications, and computational capabilities.have expanded.remarkably Further,.some.types.of.machines,.particularly.the.non-Cartesian CMMs, have expanded in market share and increased in accuracy and.utility We.have.also.seen.big.changes.in.probing.systems,.called.accessory.elements.in.this.text,.and.the.number.of.points.they.can.deliver.to.ever.more.sophisticated.software New applications have multiplied and pressures to improve machine performance.have.continued.to.increase The.concept.of.uncertainty.has.been better.defined.and.is.now.widely.used It.has.been.an.interesting.and.exciting.16.years.In.addition.to.two.new.editors,.one.from.academia.and.one.from.a.metrology-intensive user industry, this book has many new authors and a known cadre of.experts.who.have.grown.with.the.field.since.the.last.version Many.of.them.the.reader.will.recognize.from.the.literature.on.metrology,.machine,.and.software.standards.development,.and.their.activities.in.technical.societies We,.the.editors,.are.confident.that.we.have.assembled.a.first-rate.team.and.believe.that.this.book.will.be.a.valuable.resource.for.students,.practitioners,.and.researchers Our.authors.come.from.around.the.world,.and.we.intend.that.this.book.will.play.an.important.part.in.the.global.economy.of.manufacturing

Contributors

Dean E Beutel.has.responsibility.for.global.manufacturing.process.execution.for.

ment.of.manufacturing.processes.internationally Dean.joined.Caterpillar.in.1978.as.a.sweeper,.and.has.performed.a.variety.of.manufacturing.and.quality.engineering.functions.for.over.33.years He.obtained.his.certification.as.a.journeyman.machin-ist.in.1984,.as.well.as.his.bachelor’s.degree.from.Bradley.University.in.production.operations.the.same.year He.was.certified.as.a.quality.engineer.by.the.ASQ.in.1987.and.maintains.this.certification

Caterpillar.Inc His.organization.supports.development,.maintenance,.and.improve-John A Bosch.is.the.chairman.and.CEO.of.Commander.Aero,.Inc Mr Bosch.joined.

the.U.S Air.Force.as.an.aircraft.maintenance.officer.immediately.after.graduating.from Penn State with an engineering degree in 1951 and then spent 28 years at.General.Electric.with.assignments.in.engineering.and.general.management.before.joining.Sheffield.as.president,.a.position.he.held.from.1982.to.1993 Mr Bosch.was.a.research.associate.at.the.National.Institute.of.Standards.and.Technology.(NIST).and.consultant,.advance.measurement.technology.for.Giddings.&.Lewis Mr Bosch.has.authored.a.number.of.technical.and.business.publications.and.served.on.the.board.of.directors.of.Leland.Electrosystems.and.Shaw.Aero.Devices,.Inc

James B Bryan.is.an.independent.consultant.in.precision.engineering Mr Bryan.

retired.in.1985.from.the.Lawrence.Livermore.National.Laboratory.after.30.years.of.service.in.metrology He.is.the.recipient.of.the.1977.Society.of.Manufacturing.Engineers.International.Medal.for.Research.in.Manufacturing,.an.honorary.member.of.the.American.Society.of.Precision.Engineering,.a.member.of.CIRP.since.1964,.a.charter.member.of.ANSI/ASME.Committee.B89.on.Dimensional.Metrology,.and.the.first.chairman.of.B89.6.2.Temperature.and.Humidity.Environment.for.Dimensional

Measurement Mr Bryan was selected by Fortune magazine as one of its heroes.

of the year in 2000, received a Lifetime Achievement Award also in 2000 from

Ted Doiron is the leader of and a physicist in the Engineering Metrology Group.

of the Precision Engineering Division, one of five divisions of the Manufac.turing.Engineering.Laboratory.at.NIST He.is.the.author.or.the.coauthor.of.many.techni-cal.papers.and.is.considered.one.of.the.U.S experts.on.gage.blocks.and.gage.block.metrology He.is.also.responsible.for.complex.dimensional.standards.at.NIST

Marion B (Bill)

Grant.is.a.technical.steward.for.metrology.and.advanced.manu-facturing.for.Caterpillar.Inc in.Peoria,.Illinois He.received.his.PhD.in.physics.from.the.University.of.Illinois.in.1985 Dr Grant.is.active.in.ASME.serving.on.the.B46.and.B89.committees,.is.the.U.S representative.on.the.ISO.TC213.Committee.on.coordinate.metrology,.and.has.several.publications.to.his.credit

Robert J Hocken.is.the.Norvin.Kennedy.Dickerson,.Jr.,.Distinguished.Professor.

of.Precision.Engineering.and.Director.of.the.Center.for.Precision.Metrology.at.the.University of North Carolina, Charlotte Before 1988, Dr Hocken worked at the.National Bureau of Standard—NBS (now NIST) as chief, Precision Engineering.Division Dr Hocken.received.his.PhD.in.physics.from.the.State.University.of.New.York.at.Stony.Brook.in.1969.and.is.an.author.or.a.coauthor.of.60.articles.and.research.reports Dr Hocken.is.a.key.contributor.to.many.national.and.international.standards.organizations He has received many awards including the Presidential Executive.Award

Jörg Hoffmann is a research assistant at the Chair Quality Management and.

ber.of.VDI-GMA.Section.3.44.“Dimensional.Measurands”.and.is.nominated.for.CIRP.Research.Affiliates Dipl.-Ing Hoffmann.is.doing.research.in.the.field.of.probing.sys-tems.for.the.measurement.of.microparts.and.multisensor.coordinate.metrology He.is.the.author.or.the.coauthor.of.21.scientific.papers,.lecturer.at.the.VDI.seminar.“Multisensor.Coordinate.Metrology”.and.developed.an.STM-based.probing.system.for.nanometer.resolving.CMMs.(patent.pending)

Manufacturing.Metrology.of.University.Erlangen-Nuremberg.(Germany),.active.mem-Wolfgang Knapp.is.the.head.of.metrology.at.the.Institute.of.Machine.Tools.and.

Manufacturing (IWF) at the Swiss Federal Institute of Technology (ETH) and a.consultant in precision manufacturing, with his office located in Schleitheim,.Switzerland Dr Knapp received his PhD from the Swiss Federal Institute of.Technology.in.1984 The.theme.of.Dr Knapp’s.thesis.was.a.proposed.method.for.testing.CMMs He.has.authored.several.technical.papers.and.is.currently.the.Swiss.expert.on.international.standards.committees.pertaining.to.machine.tools

Edward

Morse.has.more.than.20.years.of.experience.with.both.coordinate.measur-ing.machines.and.geometric.tolerancing He.was.first.interested.in.tolerancing.and.metrology.while.in.the.master.of.engineering.program.at.Cornell.University.in.the.late.1980s After.earning.his.ME,.he.worked.at.the.Brown.&.Sharpe.Manufacturing.Company—first as an applications engineer and then as a project leader in the.advanced.systems.group,.linking.industrial.shop.floor.controls.to.measuring.equip-ment He.returned.to.Cornell.to.earn.his.MS.and.PhD.in.mechanical.engineering

of Mechanical Assembly,” namely, how tolerances can be analyzed to determine

if the assembly of intolerance components can be guaranteed Since completing.his graduate studies in 1999, Dr Morse has been a member of the faculty in the.Mechanical.Engineering.and.Engineering.Science.Department.at.the.University.of.North.Carolina,.Charlotte,.home.of.a.world-renown.graduate.program.in.dimensional.metrology His.research.interests.include.tolerancing.for.assembly,.CMM.testing.and.standards, estimation and evaluation of task-specific measuring uncertainty, and.large-scale metrology systems and standardization Dr Morse holds Senior Level.Certification.as.an.ASME.Geometric.Dimensioning.and.Tolerancing.Professional He.is.a.member.of.the.ASME.Y14.subcommittee.5.1.(Mathematical.definition.of.Y14.5.dimensioning.and.tolerancing.principles) He.is.also.a.member.of.ASME.B89.Committee (Dimensional Metrology), B89.4 (Coordinate Measuring Technology),.and.B89.7.(Measurement.Uncertainty),.in.addition.to.several.project.teams.within.the.B89.4.group In.the.area.of.international.standards,.Dr Morse.serves.as.a.subject.matter.expert.for.the.United.States.in.ISO.Technical.Committee.213.for.Working.Group.10.(Coordinate.Measuring.Machines),.Working.Group.4.(Uncertainty),.and.Advisory.Group.12.(Mathematical.support.group.for.GPS)

Hans Joachim Neumann studied radio engineering at the Mittweida High.

School.of.Engineering.in.Saxony,.Germany After.two.years.of.development.in.optoelectronic.engineering.at.the.Carl.Zeiss.Company.in.Jena,.he.transferred.to.Carl Zeiss in Oberkochen, Germany, in 1957 There, he first worked in mana-gerial.roles.in.the.fields.of.electronic.engineering.for.telescopes.and.precision.measuring.equipment,.then.in.software.and.applications.engineering,.and.finally.as.manager.of.marketing.communication.in.the.industrial.measuring.technology.division Until.2001,.he.was.in.charge.of.standardization.and.technical.informa-tion.as.a.consultant.for.the.corporation.and.a.member.of.the.ISO.committee.for.coordinate.measuring.technology For.11.years,.he.was.the.chairman.of.the.VDI/DIN joint committee for coordinate measuring technology, for which he was.awarded.an.honorary.badge.by.VDI He.currently.works.as.a.technical.author.and.instructor

Jun Ni is the Shien-Ming (Sam) Wu Collegiate Professor of Manufacturing.

Science.and.professor.of.mechanical.engineering.at.the.University.of.Michigan,.U.S He is as the founding Dean of the University of Michigan–Shanghai Jiao.Tong.University.Joint.Institute.located.in.Shanghai,.China.(2006–2014) He.also.serves as the director of the S M Wu Manufacturing Research Center and as.the.co-director.of.a.National.Science.Foundation.sponsored.Industry/University.Cooperative.Research.Center.for.Intelligent.Maintenance.Systems Professor.Ni’s.research and teaching interests are in the areas of manufacturing science and.engineering,.the.design.of.optimal.maintenance.operations,.and.statistical.quality.control and improvement He has received many honors and awards, including.ASME’s William T Ennor Manufacturing Technology Award, the Presidential.Faculty Fellows Award from the National Science Foundation, and the elected.Fellow.of.ASME.and.SME

Paulo H Pereira has over 28 years of experience in manufacturing and is

cur-rently.part.of.the.Global.Quality.Processes.team.at.Caterpillar.Inc in.Peoria,.IL responsible for the corporate quality management system Before that, he was.the chief metrologist for five years at the Integrated Manufacturing Operations.Division—East Peoria facility of Caterpillar Inc., where he was in charge of.metrology .planning and .implementation Before that, he was an internal consul-tant.in.metrology.for.Caterpillar.for.about.five.years Dr Pereira.received.his.PhD

in mechanical engineering (metrology) from the University of North Carolina,.Charlotte,.in.2001 Dr. Pereira.has.been.a.certified.quality.engineer.by.ASQ.since.2006.and.holds.both.his.bachelor’s.and.master’s.degrees.in.mechanical.engineering.from.the.University.of.São.Paulo–São.Carlos,.Brazil Dr Pereira.is.a.member.of.the.ASME.B89.committee.(Dimensional.Metrology).and.also.serves.as.a.subject.mat-ter.expert.for.the.United.States.in.the.ISO.Technical.Committee.213.for.Working.Group.10.(Coordinate.Measuring.Machines)

Steven D Phillips is the group leader of the Large Scale Coordinate Metrology.

sional metrology He holds three U.S patents and received the Department of.Commerce’s.Gold.and.Silver.Medals.for.work.in.coordinate.metrology Dr Phillips.is.the.author.of.25.archival.research.publications.in.diverse.fields.such.as.chemis-try,.physics,.applied.optics,.and.precision.engineering Dr Phillips.holds.a.MS.and.PhD.in.physics.from.the.University.of.California.at.Santa.Barbara,.a.BS.in.math-ematics and an MBA He is also the SME-1 U.S representative to TC213WG10.and TC213WG4 responsible for developing international standards for coordinate.metrology.applications.and.dimensional.measurement.uncertainty

Group.at.NIST.and.serves.as.the.vice.chair.of.the.ASME.B89.committee.for.dimen-Craig M Shakarji.heads.NIST’s.Algorithm.Testing.and.Evaluation.Program.for.

Coordinate.Measuring.Systems Dr Shakarji.chairs.the.ASME.B89.project.team.on.CMM.software.and.serves.as.a.subject.matter.expert.and.editor.of.several.standards.in.the.ISO.213.standards.committee.on.CMMs He.was.awarded.the.Department.of.Commerce.Gold.Medal.for.his.achievements.in.CMM.standards.harmonization

Dr. Shakarji,.a.mathematician,.received.his.PhD.from.the.University.of.California,.Los.Angeles.and.his.master’s.degree.from.Caltech,.and.in.1996.joined.NIST,.where.he.has.done.extensive.research.in.the.computational.metrology.field

Dennis A Swyt.received.his.PhD.in.physics.from.Case.Western.Reserve.University.

ing.responsibilities Dr Swyt.is.the.author.of.50.technical.papers,.has.a.U.S patent,.and.serves.on.several.advisory.panels In.1980,.he.received.the.NIST.Silver.Medal.Award.for.his.development.of.a.photomask.linewidth.standard Dr. Swyt.retired.from.NIST.as.chief.of.the.Precision.Engineering.Division

in.1971 After.joining.NIST.in.1972,.he.had.a.number.of.assignments.with.increas-Albert Weckenmann.is.professor.at.and.head.of.the.Chair.Quality.Management.

low.of.CIRP.and.vice-chairman.of.CIRP.STC.P Dr.-Ing Weckenmann.has.been.doing.research.in.coordinate.metrology.for.more.than.32.years.and.is.the.coauthor

and.Manufacturing.Metrology.of.University.of.Erlangen-Nuremberg.(Germany),.fel-of a number and.Manufacturing.Metrology.of.University.of.Erlangen-Nuremberg.(Germany),.fel-of VDI/VDE and DIN standards, as well as books on coordinate.metrology and geometrical product specification He is chairman of IMEKO TC.14.(Measurement.of.Geometrical.Quantities),.chairman.of.the.German.VDI-GMA.Section 3.40 “Micro- and Nanometrology” and member of the advisory board of.DIN-Section NATG (Fundamentals in Engineering) Dr.-Ing Weckenmann is the.author or coauthor of more than 300 scientific papers and 5 books and editor or.coeditor.of.19.books He.is.the.inventor.or.coinventor.of.17.patented.inventions.

Guoxiong Zhang was conferred a degree of Honorary Doctor by Moscow State.

University of Technology (Stankin) in 1996 He has been honored with the titles

of All-China Model Teacher, Model Worker of Tianjin City, Honorary Expert in.Measuring and Testing Technologies and Instruments of Tianjin City for his out-standing contributions in teaching and research work He was the chairman of.the Department of Precision Instrument Engineering, Tianjin University, China,.1986–1995;.and.dean.of.the.College.of.Precision.Instrument.and.Opto-Electronics.Engineering,.Tianjin.University,.1995–1997 He.was.elected.as.the.chairman.of.the.Scientific.and.Technical.Committee.on.Precision.Engineering.of.the.International.Academy.for.Production.Engineering.(CIRP),.1991–1994;.president.of.the.Chinese.Production.Engineering.Institution,.1995–1999;.chairman.of.the.All-China.Teaching.Guiding.Committee.on.Instruments.and.Gauges,.1996–2001 He.worked.as.a.visit-ing.scholar.at.the.U.S National.Bureau.of.Standards,.1981–1984;.visiting.professor.at.the.University.of.North.Carolina.at.Charlotte.in.1991,.1998,.2003,.and.2007 He.has.completed.more.than.60.projects.including.12.international.cooperative.programs.and three United Nation Development Programs He has published 13 books and.more.than.500.academic.papers Among.them,.more.than.50.papers.were.indexed.by.the.Science.Citation.Index.(SCI).and.180.by.the.Engineering.Index.(EI) He.received.a.China.National.Invention.Award.and.six.awards.for.Advancement.for.Science.and.Technology.conferred.by.The.Ministry.of.Education.of.China,.Tianjin.City.and.other.provinces.of.China One.of.the.projects.completed.by.him.and.his.American.col-leagues.when.he.worked.at.the.U.S National.Bureau.of.Standards.received.a.U.S government.award

Measurement

Robert J Hocken and John A Bosch

Measurement is an integral part of our everyday lives It is something that most .people.take.for.granted In.looking.back.at.the.evolution.of.measurement,.one.finds that it relates directly to the progress of mankind This chapter provides a brief .historical.summary.of.this.evolution.from.the.perspective.of.industrial.metrology

CONTENTS

1.1 .Pyramids.Provide.Evidence.of.Early.Measuring Skills 2

1.1.1 The.Cubit—One.of.the.Earliest.Units.of.Measure 3

1.2 .Accuracy.in.Navigation.Is.Basis.for.the.Micrometer 4

1.2.1 Gage.Blocks.Satisfy.Need.for.Measuring.References 5

1.2.2 Early.Comparators.Set.New.Standards.for.Accuracy 7

1.3 .Interchangeable.Parts.Gain.International.Recognition 8

1.4 Dial.Indicator.Simplifies.Measuring 11

1.5 .Automobile.Accelerates.Developments.in Metrology 12

1.5.1 .Reed.Mechanism.Provides.Greater.Shop.Floor.Precision 13

1.5.2 .Air.Gaging.Proves.Effective.for.Checking.Tight.Tolerance.Parts 14

1.5.3 .Electronic.Gaging.Expands.Capability.for.Process.Control 17

1.5.4 .Machine.Tools.Evolve.into.Early Coordinate.Measuring.Machines 17

1.6 .First.Coordinate.Measuring.Machine.Developed.as.Aid.to Automated Machining 19

1.6.1 .Sheffield.Introduces.Coordinate.Measuring.Machines.to.the North.American.Market 21

1.6.2 .Digital.Electronic.Automation.Is.First.Company.Formed.to Produce.Coordinate.Measuring.Machines 23

1.6.3 .Coordinate.Measuring.Machine.Developments.Initiated.in Japan.by.Mitutoyo 24

1.6.4 .Touch-Trigger.Probes.Expand.Versatility.of.Coordinate Measuring.Machines 24

1.6.5 Software.Becomes.Essential.to.Coordinate.Metrology 26

1.6.6 Carl.Zeiss.Contributions.to.Coordinate.Metrology 28

1.6.7 .Coordinate.Measuring.Machine.Industry Follows.Traditional Business.Patterns 29

1.7 Summary 30

Acknowledgments 30

Measurement standards and devices were required to build the pyramids and.other.ancient.structures With.land.ownership.and.the.beginning.of.farming,.a.means.of.measuring.distances.was.required To.explore.the.world,.navigation.techniques.requiring.great.accuracy.needed.to.be.developed To.overcome.the.poor.reliability.and.high.maintenance.associated.with.the.military.rifle,.the.concept.of.interchange-able parts gained increased recognition The manufacturing needs of producing.interchangeable.parts.gave.rise.to.gage.blocks.and.functional.gaging As.the.auto-mobile industry flourished with mass production, it was necessary to have parts.made to exacting standards From this need, the comparator became extensively.used.in.the.factory.and.new.gaging.techniques.were.developed The.automation.of.machine.tools.created.the.need.for.a.faster.and.more.flexible.means.of.measuring This.requirement.resulted.in.a.new.industry.manufacturing.three-dimensional.mea-suring.machines In.more.recent.times,.the.emphasis.on.quality.improvement.and.international.competition.has.accelerated.the.demand.for.faster.and.more.accurate.measurements Coordinate.measuring.machines.(CMMs).and.systems.of.many.types.have.evolved.to.fulfill.these.growing.requirements.

1.1   PYRAMIDS PROVIDE EVIDENCE OF EARLY 

MEASURING SKILLS

ing.how.they.could.have.been.created.with.the.tools.and.measuring.equipment.then.available Examples.include.the.Great.Wall.of.China,.the.monoliths.on.Easter.Island,.Mayan temples in South America, and Stonehenge in England The pyramids of.Egypt.are.among.the.most.impressive The.Great.Pyramid.of.Cheops.(Khufu),.built.about 4,500 years ago, covers 52,000 square meters and contains approximately.2,300,000.stone.blocks.having.an.average.mass.of.2,270.kg.each It.has.been.esti-mated.that.it.took.100,000.men.from.20.to.30.years.to.complete.the.pyramid This.is.about.the.same.effort.in.man-years.as.it.took.to.put.a.man.on.the.moon The.only.heavy.construction.tools.available.to.the.Egyptians.were.levers,.rollers,.and.immense.earthen.ramps The.Egyptians’.measuring.capability.may.have.been.highly.refined.because.it.has.been.estimated.that.the.difference.in.height.of.opposite.corners.of.the.pyramid.at.its.base.is.only.13.mm.(Morse.and.Babcock.2009)

Many.ancient.civilizations.left.behind.great.stone.structures.that.leave.one.wonder-An.early.recording.of.measuring.was.found.in.the.tomb.of.Rekhmire.at.Thebes.(Figure 1.1), which dates back to the fifteenth century bc To those involved in industrial.metrology,.it.is.interesting.to.note.that.the.measuring.task.is.occurring.concurrently.with.the.work.process

The.trend.today.is.to.place.measuring.machines.close.to.the.machining.process Modern.manufacturers.are.simply.striving.to.return.to.the.fundamentals.as.shown.in.this.first.recording.of.measuring A.possible.interpretation.of.the.illustration.suggests.that.the.surfaces.around.the.edges.were.cleared.off.by.using.a.square.and.a.cord It.was.much.harder.to.get.the.entire.surface.flat To.achieve.this,.three.bronze.pegs.of.equal.heights.were.used The.top.of.two.of.them.were.mounted.on.the.cleared.edges.and.the.string.pulled.taut The.third.peg.was.then.passed.under.it.to.determine.where.the.surface.was.too.high.and.to.clear.the.surface.off.with.a.chisel When.this.was.done.in.all.directions,.a.flat.face.was.attained The.picture.clarifies.the.procedure

1.1.1  T he  C ubiT —O ne Of The  e arliesT  u niTs Of  M easure

Man.followed.his.natural.instinct.and.ego.by.selecting.his.own.body.as.a.basis.for.the.first.units.of.measure—the.length.of.his.forearm,.foot,.and.width.of.his.finger Such.units.were.always.available.and.easily.understood Of.these,.the.cubit.became.the.most.widely.used.throughout.the.ancient.world The.cubit.is.defined.as.the.distance.from.the.elbow.to.the.end.of.the.outstretched.middle.finger

Figure 1.2 shows a replica of the master standard of the royal Egyptian cubit The standard.was.based.on.the.length.of.the.forearm.of.the.Pharaoh.Amenhotep I.(ca. 1550.bc) It.was.about.524.mm.long.and.was.known.as.the.royal.cubit As.shown.in.this.replica,.the.standard.was.subdivided.by.scribed.lines.that.divided.the.cubit.into.2.spans,.6.palms,.and.24.digits The.digits,.in.turn,.were.divided.into.halves,.thirds,.quarters,.and.down.to.16.parts The.royal.cubit.master.was.made.of.black.granite.and placed.in.the.custody.of.the.royal.architect “Working”.cubits.made.of.wood.were.duplicated.from.the.royal.cubit.and.used.by.artisans.in.the.great.pyramid,.tombs,.and.temple

FIGURE 1.1 

One.of.the.earliest.records.of.precise.measurement.is.the.Egyptian.wall.paint-ing.in.the.tomb.of.Rekhmire.at.Thebes.built.in.ca 1440.bc.

FIGURE 1.2  A.replica.of.the.royal.Egyptian.cubit.

Navigation.using.the.position.of.the.sun,.moon,.and.stars.requires.very.accurate.mea-Gascoigne’s challenge was to accurately measure the image in his telescope Using.a.scale.graduated.to.hundredths.of.an.inch.would.have.been.too.crude Even.if.a.finer.scale.had.been.available,.difficulty.in.reading.it.would.have.ruled.it.out Another.means.of.measurement.was.needed

Gascoigne.solved.the.measurement.problem.by.devising.calipers,.the.indicating.fingers.of.which.were.moved.simultaneously.in.opposite.directions.by.a.screw.having.a.left-handed.thread.on.one.end.and.a.right-handed.thread.on.the.other Gascoigne.measured.the.number.of.threads.per.inch.with.a.graduated.scale.and,.thus,.computed.the.pitch.of.the.screw Likewise,.he.computed.the.advance.for.any.fractional.turn.of.the.screw This.is.the.fundamental.idea.on.which.the.modern.micrometer.is.based According.to.his.own.records,.Gascoigne.was.able.to.measure.angles.to.seconds.Gascoigne.was.not.concerned.with.mechanical.measurements.and.could.not.fore-see.the.future.possibilities.of.his.discovery In.fact,.he.made.no.attempt.to.patent.his.device Records.show.that.the.first.patent.on.a.“screw.caliper”.was.issued.to.a.French.mechanic,.Jean.Laurent.Palmer,.in.1848.(Roe.1916) This.was.a.pocket.instrument.and.the.forerunner.of.the.present.micrometer

A.biography.of.Joseph.R Brown.states.that.in.1852.he.invented.a.dividing.engine.from.which.he.constructed.a.vernier.caliper.reading.to.thousandths.of.an.inch His.first dividing engine is located at the American Precision Museum in Windsor,.Vermont Further.development.of.the.micrometer.continued

In.1867,.trouble.occurred.between.the.Bridgeport.Brass.Company.and.the.Union.Metallic.Cartridge.Company.concerning.the.thickness.of.sheet.brass.that.Bridgeport.furnished.to.Union Union.returned.the.shipment.as.unacceptable On.rechecking.the.sheets,.Bridgeport.found.them.to.meet.specifications The.trouble.was.that.the

Union.Company’s.gage.differed.from.Bridgeport’s.gage Both.differed.from.a.third.gage.brought.in.to.settle.the.dispute All.of.the.gages.were.supposed.to.be.based.on.the.U.S Standard.for.wire.gages.adopted.in.1857 This.situation.called.for.a.remedy.The superintendent of Bridgeport, S R Wilmot, designed a micrometer that.measured.to.thousandths.of.an.inch It.was.read.by.a.pointer.that.moved.across.an.engraved.spiral.having.the.same.pitch.as.the.micrometer.screw Axial.lines.on.the.engraved.spiral.indicated.the.size.of.the.micrometer.opening Wilmot’s.attempts.to.market.his.micrometer.were.unsuccessful.because.the.instrument.was.too.complex.for.practical.use The.closeness.of.the.graduations.made.reading.them.difficult.and.allowed.no.room.for.figures.

About.the.same.time,.J R Brown.and.Lucian.Sharpe,.while.visiting.the.Paris.Exposition,.saw.a.Palmer.micrometer Using.what.they.considered.the.best features

of both the Palmer and Wilmot designs, they introduced the Brown & Sharpe.micrometer.in.1867 This.was.the.first.practical.mechanic’s.micrometer.marketed.in.the.United.States.(Figure.1.3) By.1877,.these.micrometers.were.well.established.in.the.metalworking.industry

1.2.1  G aGe  b lOCks  s aTisfy  n eed fOr  M easurinG  r eferenCes

surement.directly.into.the.machine.shop In.1887,.at.the.age.of.23,.Johansson.started.his.apprenticeship.in.Carl.Gustafs.Rifle.Factory.at.Eskilstuna,.Sweden This.com-pany.supplied.the.Swedish.army.with.rifles Because.the.very.purpose.of.rifles.made.reliability.imperative,.accurate.manufacturing.was.required.(Althin.1948)

Carl.Edvard.Johansson.did.more.than.any.of.his.predecessors.to.bring.accurate.mea-The.accuracy.of.that.day.left.much.to.be.desired The.measuring.instruments.in.the.rifle.factory.consisted.of.snap.gages,.sliding.calipers,.and.one.micrometer The.manufacturing.gages.were.steel.blocks,.one.for.each.dimension Although.the.idea.of.tolerances.had.been.recognized,.none.were.shown.on.working.drawings

ing.problem.was.compounded An.order.for.magazine.rifles.was.placed.with.Mauser-Werke,.a.German.firm The.contract.provided.that.a.commission.from.the.Eskilstuna

When.the.Swedish.government.selected.a.rifle.with.a.magazine,.the.manufactur-FIGURE 1.3  The.first.practical.micrometer,.1867 (Courtesy.of.Brown.&.Sharpe.[now.a.part.

of.Hexagon.Metrology,.Inc.].)

plant inspect the new rifles and be given sufficient information to permit further.production.at.Eskilstuna Johansson.was.a.member.of.this.commission.that.went.to.Germany.in.1894.

The.task.of.producing.individual.gage.blocks.in.the.customary.way.for.the.many.critical dimensions of the new Mauser rifle appalled Johansson He believed that.there.must.be.a.more.effective.way.to.control.dimensions Johansson.then.had.his.great.idea.to.create.a.set.of.blocks.increasing.in.uniform.size,.which.could.be.used.singly.or.in.combination.to.equal.the.many.manufacturing.dimensions.encountered On.his.return.to.Sweden.in.1896,.Johansson.had.completed.his.computation.of.block.sizes His.patent.application.(Althin.1948).specified.the.dimensions.of.111.blocks.in.four.series From.these.blocks,.any.dimension.from.2.to.202.mm.could.be.set.up.in.steps.of.0.001.mm.for.a.total.of.200,000.different.measurement.combinations An.early.typical.set.is.shown.in.Figure.1.4

Johansson.had.the.utmost.faith.in.his.basic.idea,.but.lack.of.funds.to.launch.its.full-scale.development.as.an.independent.business.caused.gage.block.manufactur-ing.to.be.done.on.a.part-time.basis Preliminary.work.on.the.blocks.was.done.under.contract.by.the.rifle.factory All.finishing.was.done.in.Johansson’s.home.workshop.with.improvised.equipment.during.his.free.time

The.first.set.of.blocks,.with.an.accuracy.of.0.001.mm,.was.sent.to.the.Mauser.rifle.factory in 1896 and immediately put into service Johansson proceeded with this.part-time.business.development.until.1914.when.he.resigned.his.position.as.armorer.at.the.factory.and,.thereafter,.devoted.all.his.time.to.gage.blocks

Obtaining.a.Swedish.patent.on.gage.blocks.proved.difficult,.but.the.patent.was.finally.issued.in.January,.1904.with.priority.allowed.to.1901 The.British.patent.was.issued.in.1902.(Althin.1948)

Another.idea.developed.and.patented.by.Johansson.in.1907.was.termed progressive

tolerances Prior.to.that,.it.had.been.customary.to.use.a.bilateral.constant tolerance.in.making.fixed-size.gages,.regardless.of.their.nominal.size In.other.words,.the same.tolerance.for.a.10-mm.gage.would.apply.as.that.for.a.meter.gage

FIGURE 1.4  Set.of.gage.blocks (Courtesy.of.the.American.Precision.Museum.)

“were.not.to.be.had.at.any.price.”.The.Bureau.of.Standards,.persuaded.by.William.E Hoke,.obtained.the.sum.of.$375,000.from.the.Ordnance.Department.to.make.them,.and.after.some.effort.produced.50.sets.for.the.war.production.effort.(Cochrane.1966)

nel.have.been.trained.on.the.proper.use.and.handling.of.gage.blocks

“Jo.Blocks”.remain.in.common.use.today Over.the.years,.millions.of.factory.person-1.2.2  e arly  C OMparaTOrs  s eT  n ew  s Tandards fOr  a CCuraCy

Without.detracting.from.Johansson’s.important.achievement,.it.must.be.stated.that.the.indicating.shop.comparator.was.necessary.to.give.the.gage.block.concept.its.full.effectiveness and flexibility The shop comparator is the only practical means of.bridging.block.increments

Early.length.standards,.such.as.“Iron.Ulna,”.dating.from.the.reign.of.Edward.I,.and.the.brass.yard.standards.made.during.the.reign.of.Henry.VII.(1496).and.Queen.Elizabeth.I.(1588).were.end.standards The.earliest.scientific.device.used.as.a.compar-ator.was.a.form.of.calipers.or.beam.compass Incidentally,.an.early.means.of.dissemi-nating.“true”.measures.was.to.embed.inside.end.standards.(i.e.,.calipering).in.masonry.walls.at.some.convenient.central.location,.such.as.the.market.square.(Evans.1989).In.the.eighteenth.century,.pressure.for.improved.accuracy.increased In.England.in.1742,.George.Graham.compared.standards.of.length.by.using.a.device.where.the.jaws.were.moved.by.micrometer.screws.with.divided.heads About.the.same.period,.the.clock.makers.were.expressing.an.interest.in.thermal.effects.on.materials This.led to the development by Graham and others of “precision dilatometers,” which.use.either.a.micrometer.screw.to.measure.thermal.expansion.of.the.test.price.or.a.mechanical.lever.to.amplify.the.displacement.and.a.pulley.system.to.connect.the.lever.movement.to.a.dial.indicator.or.optical.system In.later.years,.special.alloys.were.developed.to.minimize.thermal.effects.around.room.temperature.for.the.con-struction.of.length.standards,.leading.to.a.Nobel.Prize.in.physics.for.Charles.Edouard.Guillaume.in.1920

Microscope-based.comparators.are.clearly.more.applicable.to.line.standards.than.to.end.standards Their.emergence,.perhaps,.reflects.the.growth.of.de.facto.standard-ization.on.scales,.a.situation.clarified.in.England.in.1824.when.use.of.John.Bird’s.1760.standard.was.legalized End.standards.have.long.remained.the.working.stan-dards.of.industry;.however,.means.of.comparing.end.and.line.standards.has.been.an.underlying.theme.in.the.history.of.engineering.metrology.(Evans.1989)

The.Rogers-Bond.Universal.Comparator.was.constructed.in.1879.by.the.Pratt.&.Whitney.Company.from.plans.proposed.by.Professor.W A Rogers.and.Mr George.M Bond This.comparator.was.more.elaborate,.had.more.refinements,.and.was.more.versatile than its predecessors It was adaptable for measuring both line and end.standards.and.offered.a.choice.of.five.separate.comparison.methods A.more.modern.comparator.is.shown.in.Figure.1.5

1.3   INTERCHANGEABLE PARTS GAIN INTERNATIONAL 

RECOGNITION

Until.the.end.of.the.eighteenth.century,.it.was.the.general.practice.for.the.individual.craftsman.to.make.a.complete.product.(Battison.1976) This.involved.fitting.each.component.as.it.was.being.constructed Depending.on.the.craftsman’s.training.and.ability,.the.products.were.more.or.less.acceptable,.but.no.two.similar.products.or.components.were.functionally.the.same

The need for interchangeable parts began to be recognized as manufacturing volumes increased Examples of early products made with interchangeable parts.are.clocks.and.pulley.blocks.for.naval.vessels The.military.rifle,.however,.brought international.recognition.to.the.system.of.interchangeable.parts

One of the first artisans to recognize the benefits of interchangeable parts for muskets.was.a.French.gunsmith.named.Honoré.LeBlanc In.1785,.Thomas.Jefferson,

FIGURE 1.5  A.comparator.commonly.used.in.factories.

as.the.U.S minister.to.France,.heard.about.LeBlanc,.who.had.developed.a.plan.for.manufacture of interchangeable musket parts 15 years previously Jefferson was.keenly interested and tried unsuccessfully to bring LeBlanc to the United States,.where.he.would.have.been.encouraged.to.implement.his.plan.for.the.manufacture.of.muskets.with.interchangeable.parts.

The period of the Napoleonic Wars emphasized the imperative need for interchangeable.parts For.the.first.time,.very.large.armies.with.muskets.were.put.into the field Maintenance of the muskets soon became a huge problem because.each.spare.part.had.to.be.made.and.fitted.individually

Making.and.fitting.individual.parts.was.a.very.slow.and.expensive.operation At.one.time,.the.British.government.had.more.than.200,000.muskets.waiting.for.repair This.was.reported.to.be.more.than.were.in.serviceable.condition It.was.a.problem.that.had.to.be.solved

The two essentials for interchangeability are reliable measurements and good.machine.tools At.this.time,.no.uniformity.in.measurement.standards.existed,.and.machine.tools.were.in.their.infancy

The.developments.in.machinery.and.gaging.methods.over.the.preceding.50.years.came.together.in.the.small.town.of.Windsor,.Vermont,.in.1845 It.was.in.Windsor.that.the.American.system.was.brought.to.the.highest.level.then.known,.and.from.there,.it.began.to.extend.its.influence.to.the.rest.of.the.world

Richard Lawrence was a man with an innate technical sense and mechanical.skills He.first.used.his.talents.at.N Kendall.&.Company,.a.Windsor.gunsmithing.firm In.1843,.Lawrence.and.Kendall.became.partners.and.started.a.new.custom.gun.shop One.year.later,.S E Robbins,.a.local.retired.businessman,.approached.the.two.gun.makers.with.the.suggestion.to.bid.on.a.government.contract.for.10,000.rifles They quickly formed a new partnership.named Robbins, Kendall,.and Lawrence,.submitted.a.bid.of.$10.90.per.rifle,.and.won.the.contract.by.underbidding.established.contractors The.contract.was.to.be.completed.in.three.years

ment.and.private.armories.and.selected.the.best.manufacturing.methods,.especially.those.used.at.the.well-established.Springfield.Armory.in.Massachusetts The.con-tract.for.the.10,000.model.1841.rifles,.was.so.successfully.completed.that.the.part-ners.immediately.received.another.contract.for.15,000.more.in.1848 At.this.point,.Kendall.sold.his.interest.in.the.company

By.1846,.the.partners.had.built.a.new.plant They.recruited.top.talent.from.govern-With a second government contract, Robbins & Lawrence began designing.and.building.improved.machinery The.most.important.machines.developed.from.their.efforts.included.an.improved.standard.milling.machine,.a.profile.miller,.and

a .vertical-axis turret lathe They also began producing the new Jennings breech-.loading rifle that used special ammunition patented in 1849 The Jennings’ rifle.evolved.into.the.Volcanic,.Henry,.and.eventually.the.well-known.Winchester.Robbins & Lawrence recognized the commercial potential of their work and.exhibited.their.guns.at.the.“Crystal.Palace”.industrial.exposition.in.London.in.1851,.which.turned.the.attention.of.the.industrialized.world.to.America.(Battison.1976) Success.must.have.produced.excitement.for.them.with.their.new manufacturing.con-cepts,.new.machine.tools,.new.gun.technology,.and.refined.gaging.practices

Robbins & Lawrence rifles, along with.other American light goods, took the.European exhibition at the Crystal Palace.by.storm A.group.of.England’s.best.engi-neers.attended.the.exhibition.to.study.man-ufacturing.methods The.engineers’.report.coined.the.phrase,.“the.American.system.of.manufacture,”.and.created.a.major.stimulus.to.develop.interchangeable.parts.manufac-turing.(Evans.1989).

The.Robbins.&.Lawrence.rifles.won.an.award and attracted a great deal of atten-tion,.inducing.Parliament.to.send.a.commis-sion to the United States Its mission was

to study the “American System” of changeable manufacturing and to secure.the machinery necessary to introduce the.system.at.the.Enfield.Armory.near.London Some.typical.gages.used.at.the.Robbins.&.Lawrence.factory.are.shown.in.Figure.1.6.The.Robbins.&.Lawrence.firm.received

inter-an immediate order for 25,000 Enfield.rifles with interchangeable parts and for

141 metalworking machines to equip the.Enfield.Armory The.Crimean.War.created.an.urgent.need.for.the.rifles

The.financial.risks.associated.with early.efforts toward mass production are illus-trated.by.the.fact.that.only.four.years.after.the Crystal Palace Exposition, Robbins &.Lawrence.declared.bankruptcy,.the.victim

of poor management and some bad luck

A venture into railroad car building had left the company financially weakened Further.heavy.expenditures.for.new.plants.and.equipment.were.made.on.the.promise.of.a.large.additional.contract.for.Enfield.rifles,.which.did.not.materialize Although.Robbins.&.Lawrence’s.success.was.short-lived,.it.does.not.detract.from.the.ingenu-ity.and.enterprise.displayed.at.their.factory.in.Windsor,.Vermont The.machine.tool.industry.and.the.role.of.measuring.in.manufacturing.had.taken.shape

The.Robbins.&.Lawrence.factory.in.Windsor.that.produced.rifles.for.the.Crystal.Palace Exposition is still standing and is the home of the American Precision.Museum After.Robbins.&.Lawrence’s.bankruptcy,.the.factory.became.an.armory.and.was.used.to.produce.50,000.special.model.Springfields.for.the.Union.army.dur-ing.the.Civil.War The.building.was.then.used.to.produce.basic.machine.tools.and.products,.such.as.sewing.machines,.for.the.commercial.market In.1870,.the.building.became.a.cotton.mill.and.served.as.a.hydroelectric.power.station.from.1898.until.it.was.donated.to.the.American.Precision.Museum.in.1966

1.4  DIAL INDICATOR SIMPLIFIES MEASURING

The.familiar.dial.indicator.is.a.legacy.from.European.watchmakers In.the.nineteenth.century,.New.England.watchmakers.made.further.developments.on.the.dial.indica-tor It.was.developed.primarily.as.a.gage.for.the.production.of.accurate.watches Its.broad.usefulness.to.industry.was.recognized.later

The.records.of.the.U.S Patent.Office.show.that.on.May.15,.1883,.John.Logan.of.Waltham,.Massachusetts.filed.a.patent.application.for.a.dial.indicator.to.which.he.referred.as.“an.improvement.in.gages.”.In.appearance,.the.instrument.did.not.differ.much.from.present.dial.indicators,.but.its.movement.was.quite.different Instead.of.using.the.familiar.rack.and.pinion,.Logan.used.a.fine.Swiss.watch.chain.to.transmit.the.motion.of.the.gaging.spindle.to.the.indicating.pointer The.practical.limitation.on.the.amount.of.amplification.by.this.method.was.probably.the.reason.that.Logan.later.switched.from.the.chain.movement.to.a.rack.and.pinion.mechanism

tor, bought the Logan patents in 1896 In partnership with Francis G Stickney,.Logan undertook the manufacture and marketing of dial indicators Afterwards,

Recognizing.the.broad.market.for.the.dial.indicator,.Frank.E Randall,.an.inven-B. C Ames.entered.the.field.with.a.gear-type.indicator

try was searching for new measuring instruments of greater accuracy In 1890,.Professor.Ernst.Abbe.established.the.measuring.instrument.department.of.the.Zeiss.Works By.1904,.Zeiss.had.developed.a.number.of.instruments.for.the.general.mar-ket.among.which.was.the.dial.indicator.(Auerbach.1904) In.the.United.States,.one.of.the.major.producers.of.dial.indicators.was.Federal.Products An.example.of.their.dial.indicators.is.shown.in.Figure.1.7

Felix.Auerbach,.writing.of.the.Zeiss.Works.in.Jena,.indicated.that.German.indus-FIGURE 1.7  Early.dial.indicator,.ca 1924 (Courtesy.of.Federal.Products.[now.a.part.of.

Mahr-Federal,.Inc.].)

1.5   AUTOMOBILE ACCELERATES DEVELOPMENTS 

IN METROLOGY

No.mechanical.product.has.had.a.more.profound.effect.on.our.contemporary.society.and.economy.than.the.automobile Dimensional.metrology.has.greatly.benefited.by.the.production.demands.of.the.automobile The.industry.had.its.start.in.Germany.when Karl Benz began building his first gasoline engine in 1878 Together with.Gottlieb.Daimler,.they.produced.the.first.motor.car.in.1885 Their.three-wheeled.car.had.an.electric.ignition,.a.water-cooled.engine,.and.a.differential.gear Karl.Benz.later.developed.a.float-type.carburetor.and.a.transmission.system

In.1893,.in.Springfield,.Massachusetts,.Frank.Duryea.built.the.first successful.American gasoline-powered car The American car was a single cylinder, 4-hp,.buggy-type.vehicle The.Detroit.Automobile.Company,.which.later.became Cadillac,.began.in.1899 The.Henry.Ford.Automobile.Company.was.formed.in.Detroit.in.1901.and.changed.its.name.to.the.Ford.Motor.Company.in.1903 A.dentist,.Dr. E. Pfennig,.from Chicago, bought the first Ford Motor Company car for $850 in July 1903

By March 1904, Ford had sold 658 cars Henry Ford is widely .considered  to be.the developer of the moving assembly line (Figure 1.8), which  revolutionized.manufacturing

mobile production occurred in 1908 Three Cadillac cars that had been shipped

Another.event.that.would.eventually.propel.America.into.the.forefront.of.auto-to England were completely disassembled, new parts intermixed, and then sembled.(Wren.1991) The.impact.on.the.industrial.observers.was.as.profound.as.it.had.been.in.1851.at.the.Crystal.Palace.Exposition.in.London.where.the.Robbins &.Lawrence rifles were on display Conceived by Henry Leland, the demonstration

reas-FIGURE  1.8  Early moving assembly line Flywheels and magnetos being assembled at.

Ford’s.Highland.Park,.Michigan.plant.in.1913 (Courtesy.of.Ford.Motor.Company.)

of interchangeable parts won the Dewar Trophy for Cadillac The Dewar trophy.was.awarded.each.year.by.the.Royal.Automobile.Club.(RAC).of.England.“to.the.motor car which should successfully complete the most meritorious .performance.or.test.furthering.the.interests.and.advancement.of.the.(automobile).industry.”.Of.more.importance,.the.use.of.interchangeable.parts.revolutionized.automobile.manu-facturing To.achieve.this,.considerable.effort.was.being.made.in.the.area.of.gag-ing Equally.important.was.the.growing.ability.to.establish.manufacturing.practices.needed.to.control.dimensions.traceable.to.the.accepted.standards.at.that time.

1.5.1   r eed  M eChanisM  p rOvides  G reaTer  s hOp  

f lOOr  p reCisiOn

In.the.1920s,.industrial.leaders,.especially.those.in.the.young.automotive.industry,.began.to.recognize.the.benefits.of.tolerances.closer.than.those.for.which.fixed-size.gages were suitable William Bagley, Chief Inspector for Studebaker, was among.the first to advocate replacing fixed-size gages with instrument gages for mass production.operations

Without precision comparators, the full potential of the gage block standards.introduced.by.Carl.Johansson.could.not.be.realized Also,.parts.could.not.be.classi-fied.for.selective.assembly Because.of.the.lack.of.accuracy.of.many.machine.tools.of.that.day,.selective.assembly.was.the.only.way.to.achieve.accurate.fits

The.chief.obstacle.to.such.progressive.concepts.was.that.no.practical.precision.comparator adaptable to mass production inspection was available at that time Although.precision.comparators.existed,.they.were.laboratory.instruments.requiring.a.high.degree.of.skill.to.operate.and.were.too.slow.for.inspecting.automotive.parts.The.idea.chiefly.responsible.for.circumventing.this.impasse.and.opening.the.way.for.widespread.instrument.gaging.in.production.was.the.principle.of.the.reed.mecha-nism It.consisted.of.an.ingeniously.simple.mechanical.device.for.amplifying.small.displacements,.such.as.the.displacement.of.the.gaging.spindle Essentially,.the.reed.mechanism consists of two steel blocks and four reeds, the reeds being made of.flexible.strips.of.spring.steel The.slightly.separated.blocks.are.connected.by.two.horizontal.reeds One.block.is.anchored.to.the.gage.head;.the.other,.which.carries.the.gaging.spindle,.is.free.to.move.vertically The.two.remaining.reeds.are.solidly.fastened.to.the.top.inside.faces.of.the.blocks,.one.to.each.block Displacement.of.the.floating.block.causes.the.horizontal.reeds.to.flex.and.the.connected.ends.of.the.verti-cal.reeds.to.sweep.through.an.arc,.amplified.by.a.pointer.and.further.by.an.optical.system.(Figure.1.9) A.good.description.of.the.mechanics.of.these.reed.mechanisms.is.provided.in.the.literature.(Dotson.2006)

The idea of the reed mechanism was conceived by two metrologists, dently,.but.not.concurrently The.first,.E Mark.Eden,.developed.the.idea.in.1918,.while.he.was.on.the.staff.at.the.Metrology.Division.of.the.National.Physical.Laboratory.of.England The.second,.Arthur.Schoof,.an.American.from.Western.Electric,.was.apparently.unaware.of.Eden’s.work Those.attending.a.gage.manufacturers’.meet-ing.in.Chicago.in.1927.were.invited.to.visit.the.Western.Electric.plant.and.see.the.company’s.inspection.facilities Although.no.special.attention.was.drawn.to.it,.the.display.included.an.instrument.incorporating.the.reed.principle

indepen-cance.of.the.reed.principle,.were.C H Reynolds.and.Charles.E Watterson,.rep-resenting the Sheffield Gage Corporation Reynolds and Watterson immediately.recognized the great potential of this sensitive, frictionless, amplifying device They.recognized.this.device.as.the.basis.for.a.new.line.of.comparators.that.could.be.used.in.the.shop.for.fast,.accurate.inspection.by.workers.who.had.no.special.skill.in.that.area.

Among.the.visitors.that.day.and.apparently.the.only.ones.to.grasp.the.signifi-Sheffield started negotiating with Western Electric for a license and received.one in 1929 The following year, Sheffield introduced the “Visual Gage,” which.was.an.indicating.comparator.using.the.frictionless.reed.mechanism.together.with.a.weightless.light.beam.lever.arm.for.amplification Ford.was.the.first automobile.manufacturer to use the “Visual Gage,” which proved to be ideal for measur-ing close tolerances in production Tens of thousands of these comparators were produced and are still used today, which confirms their value as a dimensional.inspection.tool

1.5.2   a ir  G aGinG  p rOves  e ffeCTive fOr  C heCkinG  

T iGhT  T OleranCe  p arTs

Another development that influenced industrial metrology was pneumatic gaging.(Curtis.and.Farago.2007) It.provided.the.capability.to.measure.closer.tolerances.at.higher.speeds.demanded.for.mass.production

FIGURE 1.9 

This.visual.gage.uses.a.reed.mechanism.to.provide.a.10,000.to.1.magnifica-tion (Courtesy.of.Sheffield.Measurement.[now.part.of.Hexagon.Metrology,.Inc.].)

According to historical records, the idea of using a fluid as a gaging medium.stems.from.Cruikshank.and.Fairweather As.early.as.1917,.they.suggested.the.rela-tionship.of.fluid.pressure.and.nozzle.area.as.the.basis.of.measurement.in.the.field.of.paper.manufacturing.

Interest.in.fluids.as.a.measurement.means.arose.spontaneously.on.both.sides.of.the.Atlantic A.U.S patent.on.an.air.gage.was.issued.to.N.T Harrington.in.1922.(Harrington.1922)

tion.of.such.characteristics.as.flatness.and.area,.the.experience.gained.prepared.the.way.for.the.dimensional.air.gage

Although.the.early.work.in.using.fluid.as.a.gaging.medium.was.in.the.investiga-The.air.gage.is.essentially.a.comparator.that.uses.the.effect.of.small.dimensional.changes.on.metered.air.in.the.pneumatic.gaging.circuit It.is.based.on.the.fact.that.the.free.flow.of.compressed.air.through.an.open.orifice.is.restricted.when.an.obstruction.is.brought.close.to.it Such.an.obstruction.reduces.the.velocity.of.flow.while.raising.the.pressure.in.the.circuit.behind.the.orifice Within.certain.limits,.the.closer.the.obstruction.is.to.the.orifice,.the.more.pronounced.the.effects

In the case of the air gage, the orifice is a jet (or jets) in the air gage tooling The.obstruction.is.the.surface.of.the.workpiece.being.gaged By.metering.either.the.change.in.back.pressure.in.the.pneumatic.circuit.or.the.change.in.its.velocity.by.flow,.the.clearance.between.jets.in.the.air.gage.tooling.and.the.adjacent.workpiece.surface.is.determined A.typical.air.gage.is.shown.in.Figure.1.10

ing First developed for measuring the dimensions of turbine blades for General.Electric,.the.Plunjet.extended.the.range.of.useful.measurement.variations.from.0.13.to.approximately.2.54.mm The.principle.of.the.Plunjet.is.based.on.limiting.the.flow.of.air.by.using.a.conical-shaped.valve.instead.of.simply.obstructing.the.flow.from.an.open.jet.by.the.master.or.part.being.measured The.sliding.valve.contracts.the

The.development.of.the.Plunjet.in.the.1950s.expanded.the.capability.of.air.gag-FIGURE  1.10  Air gaging for checking valve concentricity in an automobile engine

(Courtesy.of.Sheffield.Measurement.[now.a.part.of.Hexagon.Metrology,.Inc.].)

Whether.the.designers.of.the.first.commercial.dimensional.air.gage.realized.their.purpose.could.be.accomplished.by.metering.either.back.pressure.or.flow.velocity.is.unknown No.practical.velocity-metering.device.had.yet.been.developed The.first.air.gage.to.be.marketed.was.a.back-pressure.gage,.which.Solex,.of.Germany,.intro-duced.in.1926

The.first.air.gage.widely.marketed.in.the.United.States.was.introduced.in.1935.by.the.Sheffield.Gage.Corporation.to.explore.the.form.of.flat.and.cylindrical.surfaces.in.three.dimensions.simultaneously The.measurements.were.made.by.metering.the.pressure.loss.between.the.workpiece.surface.and.the.master

As the possibilities of air gaging became apparent, more gage makers became.interested.and.variations.in.circuitry.began.to.appear One.of.these.is.the.Venturi-type.circuit,.which.combines.characteristics.of.the.back-pressure.gages.and.the.flow-type.gage

In the 1940s, air/electronic gages were introduced The dimensions were played and recorded electronically, while the sensors remained conventional air.gages Transducers.were.used.to.convert.the.air.pressure.signals.to.electronic.sig-nals These systems made.it.possible.to.directly.measure.high-volume production.quantities.in.the.production.line.without.increasing.the.required.labor Automatic.gaging.systems.of.this.type.were.used.for.classifying.parts.for.selective.assembly.(Figure 1.11),.as.well.as.for.identifying.and.sorting.out.failed.parts These.systems

dis-FIGURE 1.11  Automatic.air/electronic.gage.for.measuring.cylinder.bores.in.a.V8.engine.

block Pistons are matched with the cylinder bores for selective assembly (Courtesy of Sheffield.Measurement.[now.a.part.of.Hexagon.Metrology,.Inc.].)

1.5.3   e leCTrOniC  G aGinG  e xpands  C apabiliTy  

fOr  p rOCess  C OnTrOl

The.practical.application.of.both.mechanical.and.electrical.methods.of.dimensional

gaging.appeared.in.the.1920s Today,.the.term.electronic

gaging.comprises.a.cate-gory.of.measuring.instruments.capable.of.detecting.and.displaying.extremely.small.dimensional.variations Any.dimensional.change.causes.an.electrical.signal.that.is.amplified.and.displayed The.sensing.element.is.frequently.a.linear.variable.differ-ential.transformer.(LVDT) Because.variations.are.being.sensed,.the.electronic.gage.requires.the.use.of.a.master.to.establish.data.or.references.from.which.the.varia-tions.are.to.be.measured Some.manufacturers.supply.both.“minimum”.and.“maxi-mum”.masters This.method.provides.the.highest.degree.of.accuracy.in.setting.the.gages.to.determine.whether.the.production.parts.are.within.the.allowable.tolerances Examples.of.electronic.gages.are.shown.in.Figure.1.11

controlled.systems.for.automatic.mastering,.statistical.data.presentations,.and.improved.flexibility.to.handle.a.wide.range.of.parts Their.accuracies.in.shop.environments.are.well.proven.because.the.gage.is.simply.a.sophisticated.comparator Dimensional.integ-rity.is.contained.within.the.master.that.is.checked.by.standards.traceable.to.the.inter-national.standard.of.length.(refer.to.Chapter.2,.The.International.Standard.of.Length)

In.recent.years,.electronic.gaging.has.become.more.effective.by.adding.computer-1.5.4   M aChine  T OOls  e vOlve inTO  e arly  C OOrdinaTe  

M easurinG  M aChines

Several.measuring.machines,.which.were.more.than.comparators.in.the.commonly.accepted.sense,.have.been.manufactured.(Hume.1953) Although.different.types.of.early.measuring.machines.varied.in.their.designs.and.principles.of.operation,.they.had.the.common.feature.of.containing.their.own.standards.of.measurement.in.the.form.of.a.scale.or.scales,.micrometer,.or.other.device

The Matrix machine was designed as an intermediate between the short-range.comparator.and.the.self-contained.measuring.machine It.relied.on.slip.gages.along.with.a.micrometer.used.in.conjunction.with.a.fiducial.indicator The.Matrix.machine.was.suitable.for.measuring.both.external.and.internal.diameters.on.plain,.tapered,.and.threaded.work The.principle.of.operation.is.rather.unusual.because.a.diameter.is.determined.by.measuring.two.radii.at.exactly.180°

The.Newall.measuring.machine.was.made.of.a.rigid.bed.on.which.a.headstock.and.a.tailstock.that.carry.the.measuring.faces.were.mounted A.number.of.one-inch.rollers.in.a.slot.were.placed.along.the.center.of.the.bed The.exact.sizes.of.the.rollers.were.selected.so.the.cumulative.deviation.from.the.nominal.distance.over.a.number.of.rollers.was.very.small A.micrometer.was.fitted.into.the.headstock.and.a.bubble.indicator.mounted.on.the.tailstock The.machine.was.particularly.suitable.for.the.measurement.of.long.gages

The Microptic measuring machines made by Messrs Hilger & Watts, Ltd., of.the.United.Kingdom,.incorporated.their.own.standard.in.the.form.of.a.glass.scale Carl.Zeiss.of.Germany.first.introduced.this.type.of.machine.in.the.late.1920s,.and.it.proved.very.popular.in.many.parts.of.the.world The.machine.was.quite.useful.for.the.direct.calibration.of.plug.gages,.and.it.had.an.almost.limitless.range.of.applica-tions.in.other.types.of.measurements.

ment.of.metrology.since.1865 They.are.the.originators.of.jig-boring.machines.in.the.modern.sense The.well-known.SIP,.Société.Genevoise.d’Instruments.de.Physique,.machines.are.of.the.universal.type.and.their.basic.designs.are.used.in.both.jig-boring.machines.and.CMMs As.an.example,.the.SIP.“Trioptic,”.which.was.introduced.in.1961,.was.later.transformed.into.the.SIP.560M.CMM

The.Société.Genevoise.of.Switzerland.has.played.an.active.part.in.the.develop-port,.Connecticut.was.based.on.the.jig-boring.machine.just.as.the.earlier-mentioned.SIP.machines.(Moore.1970) A.Moore.No 3.machine.is.shown.in.Figure.1.12.Both SIP and Moore Special Tool Company continued producing measuring.machines.based.on.jig.bore.technology.that.was.used.for.very.high.accuracy.applica-tions Moore.introduced.the.Moore.48.measuring.machines.in.about.1968,.and.a.mod-ified.version.of.this.machine,.called.the.Moore.5Z,.was.used.at.the.National.Bureau.of.Standards.(NBS;.now.National.Institute.of.Standards.and.Technology.[NIST]).for.many.years This.machine,.shown.in.Figure.1.13,.was.the.machine.on.which.software.correction.was.developed.(Hocken.et.al 1977) A.slightly.modified.Moore.machine,.called.the.M60,.is.probably.still,.for.its.size,.the.most.accurate.machine.in.the.world

The.Universal.measuring.machine,.introduced.by.Moore.Special.Tool of Bridge-FIGURE 1.12  Moore.No 3.universal.measuring.machine.introduced.in.1957 Richard.F

Moore.(right).with.customer (Courtesy.of.Moore.Tool.Company.)

1.6   FIRST COORDINATE MEASURING MACHINE 

DEVELOPED AS AID TO AUTOMATED MACHINING

The first measuring machine that falls into the category most commonly called.CMMs was developed by Ferranti, Ltd., of Dalkeith, Scotland (Ogden 1970) An.early model is shown in Figure 1.14 This CMM was developed as a companion.product.to.their.growing.family.of.numerical-controlled.machine.tools It.is.interest-ing.to.note.that.Ferranti.had.not.been.in.the.measuring.equipment.business Ferranti.developed.the.CMM.in.response.to.the.need.for.faster.and.more.flexible.measuring.when.machining.became.more.automated As.is.often.the.case,.the.existing.measur-ing.equipment.manufacturers.had.not.recognized.the.potential.of.the.CMM.market.that.was.to.emerge

In.1956,.just.two.years.after.Harry.Ogden.joined.the.Numerical.Control.(NC).Division of Ferranti, Ltd as chief mechanical engineer, he invented the Ferranti.inspection.machine It.became.apparent.to.Ogden.and.others.at.Ferranti.that.parts.made.in.a.matter.of.minutes.on.their.new.NC.machines.took.hours.to.inspect Ogden.then.conceived.that.a.freely.moving,.mechanical.measuring.machine.with.electronic.numerical display would facilitate inspection of machined components This, in.effect,.changed.the.whole.economic.aspect.of.conventional.inspection.methods.by.reducing.inspection.time.and.the.skill.required.for.inspection

ability.of.an.accurate,.long-range,.electronically.compatible.digital.measuring.system The.optical.grating.and.the.moiré.fringe.sensing.system.were.ideal They.were.accu-rate,.relatively.inexpensive.to.manufacture,.and.easily.reset.to.zero Their.accuracy.was.based.upon.averaging.a.number.of.lines.and.was.not.dependent.upon.the.accuracy.of.any.one.line Credit.for.the.optical.grating.system.should.properly.go.to.David T N Williamson.of.Ferranti,.who.is.remembered.as.being.very.bright.and.inventive

The.key.element.that.made.the.development.of.the.CMM.possible.was.the.avail-FIGURE 1.13  The.fixed-bridge.measuring.machine.from.Moore.Special.Tool.(a.modified.

M48),.which.was.used.to.develop.software.correction.of.CMMs (Courtesy.of.NIST.)

The.initial.Ferranti.development.was.an.inspection.machine.with.X.and.Y.move-also.fitted.with.locks.and.fine.adjustments.on.the.x.and.y.axes.so.that.measurements.

could.be.made.by.means.of.a.projector.microscope.on.components,.which.were.flexible

or.delicate Initially,.the.z-axis.measurement.was.made.by.adding.a.support.bracket.to.

the.front.of.the.cantilever.arm.bearing.on.a.steel.straightedge.mounted.on.the.front.edge.of.the.table Full.Z.measurement.was.introduced.in.1962.(Ogden.1970)

The Ferranti CMM was a classic kinematic design rather than a conventional.machine.tool.design The.underlying.principle.of.kinematics.involves.minimum.con-straint.with.provision.for.alignment.of.the.moving.elements.(Maxwell.1890) The.design.was.radically.different.and.caused.machine.tool.designers.to.rethink.their.design.principles

This original machine created a large market throughout the industrial world.and.led.to.the.development.of.similar.machines.with.larger.capacities.and.improved.accuracies.and.resolutions Competitors.entered.the.market.at.an.average.of.two.each.year.for.the.next.25.years Such.a.proliferation.of.competitors.has.led.to.a.series.of.consolidations In.the.case.of.Ferranti,.they.ceased.production.of.CMMs.in.1992.and.sold.their.remaining.assets.to.their.previous.Korean.dealer,.which.operated.the.busi-ness.under.the.name.“International.Metrology.Systems.”.A.search.of.the.World.Wide.Web*.reveals.that.a.company.called.International.Metrology.Systems.still.markets.CMMs,.though.the.company.ownership.is.unclear

* Accessed.February.23,.2011.

FIGURE  1.14  Ferranti coordinate measuring machine (Courtesy of Ferranti, Ltd [now.

International.Metrology.Systems,.Ltd.].)

1.6.1   s heffield  i nTrOduCes  C OOrdinaTe  M easurinG  

M aChines TO The  n OrTh  a MeriCan  M arkeT

In.the.summer.of.1959,.George.Knopf,.general.manager.of.the.Industrial.Controls.section.of.the.Bendix.Corporation,.attended.the.International.Machine.Tool.Show.in.Paris While.he.was.examining.a.NC.positioning.system.in.the.Ferranti.display,.a.two-axis.CMM,.also.made.by.Ferranti,.captured.his.interest Knopf.immediately.recognized its sales potential for the Bendix Controls business and the Sheffield.Corporation,.which.had.been.acquired.by.Bendix.in.1956

Knopf.decided.to.take.immediate.action.and.flew.directly.from.the.Paris.show.to.the.Ferranti.facilities.in.Edinburgh,.Scotland Knopf.learned.more.about.details.of.the.machine.and.established.contacts.for.negotiations Later,.a.contract.was.signed.providing.Bendix.with.exclusive.rights.to.sell.Ferranti.CMMs.in.the.North.American.market

The first Ferranti machines arrived at the Industrial Controls section in early.1960 One.machine.was.shipped.to.the.Sheffield.subsidiary.of.Bendix.for.evalua-tion The.Sheffield.engineers.were.dubious.about.the.accuracy.of.the.machine,.but.it.proved.to.be.better.than.they.had.expected Not.wasting.any.time,.Bendix.displayed.the.first.CMMs.in.the.North.American.market.at.the.National.Machine.Tool.Show.in.Chicago.in.1960

ered to the Western Electric plant in Winston-Salem, North Carolina, for John.Haney,.who.was.the.supervisor.of.the.tool.and.gage.laboratory Having.read.about

In.1959,.even.before.the.first.machines.were.shipped.to.Bendix,.one.was.deliv-the.Ferranti.machine.in.American Machinist.magazine.and.having.recognized.its.

time-saving.potential,.Sheffield.representatives.Marcus.Crotts.and.Charles.Saunders.became interested Their customers were measuring with a granite surface plate,.height.gages,.and.gage.blocks Although.the.height.gage.technique.was.accurate,.it.was.extremely.time-consuming.and.cumbersome When.John.Haney.saw.the.article,.his.interest.began.to.grow Marcus.Crotts.contacted.Ferranti.and.requested.distribu-tion.rights.in.his.territory.but.learned.that.Bendix.would.handle.sales.in.the.United.States Bendix.received.sales.credit.for.the.first.machine

Western.Electric.had.just.initiated.the.return-on-investment.method.for.evalu.ating.capital.equipment.purchases Although.John.Haney.was.unfamiliar.with.the.tech-nique,.he.projected.that.the.$12,000.machine.would.pay.for.itself.in.a.reasonable.time Marcus.and.John.spent.many.hours.estimating.the.payback.period.and.felt.that.they.may.have.been.exaggerating.the.numbers.to.justify.a.payback.period.of.three years John.submitted.the.requisition.for.approval.and,.after.a.series.of meetings.with.man-agement,.received.authorization.to.purchase.the.machine The.actual.payback.period.was.only.nine.months John.kept.meticulous.records.comparing.inspection.times.and.accuracies.between.the.CMM.and.the.conventional.surface.plate,.height.stand,.and.gage.block.technique A.single.center.distance.measurement.with.the.conventional.technique would often take 20 minutes, whereas the same measurement could be.made.with.the.CMM.in.less.than.1.minute

The.senior.managers.at.Western.Electric.were.elated.and.within.a.few.months.approved.the.purchase.of.a.second.machine The.first.machine.was.known.as.serial