3 d Toler Ancing

Since the 80s, with the introduction of CAD-CAMsoftware, the need to clearly understand nominalspecifications has been largely solved. Indeed, until thisdate, a nominal specification was made up of several 2Dprojected geometrical drawings whose consistency wasuncertain. With the advent of 3D CAD-CAM, thespecification becomes a digital result whose consistency ismathematically certified by the software! This has been adecisive benefit that explains the worldwide success of thistechnology. Although ambiguity of the nominal specificationhas all but disappeared, the technical difficulties andbusiness conflicts are now more apparent due to theambiguities of the differences between the nominalspecification and the result. ASME and ISO tolerancingstandards have as a result grown in importance andtremendously developed through the 80s and 90s.Nonetheless, they are still topics for research anddevelopment. The tolerance specification language issuedfrom these standards allows downstream users to define theadmissible limits of the dimensional defects as well as theshape, orientation and position defects of parts andassemblies surfaces.

This booklet provides a view on this language,exemplary both for its clarity and conciseness. It is anessential tool for the beginner as well as for the experiencedtechnician.

Professor Emeritus Andr Clment,CIRP member

2FOREWORD

FOREWORD

Tolerance standardization on an international scalefor technical objects can be defined with one word: interchan-geability. Modern times have driven the necessity to sharetechnological machine features not only because of a failure,but primarily due to the systematic use of industrial suppliersto manufacture complex systems.

To get something manufactured, the client has tofirst specify their requests. The dimensional description ofthe mechanical part to manufacture is identified as the nominalspecification, and the final actual manufactured object is calledthe result. The difference between the result and the nominalspecification is a major source of conflict. This differenceneeds also to be specified; giving rise to what is called thetolerance specification, combined with the nominal dimen-sional specification.

A specification, whatever it may be, must becomprehensive, consistent and understandable withoutinterpretation by both the client and supplier.

1 FOREWORD

43 3D TOLERANCING IN PRODUCT LIFECYCLE MANAGEMENT

3D TOLERANCING IN PRODUCT LIFECYCLE MANAGEMENT

3D TOLERANCING IN PRODUCT LIFECYCLE MANAGEMENT

Customerrequirements

Maintenance

Functional,Logical and

Physicaldesign

ManufacturingQualitycontrol

Automotive Aerospace Shipbuilding

IndustrialEquipment High Tech

ConsumerGoods

LANGUAGE

TOOLS

METHOD

3D Tolerancing is at the core of Product Lifecycle Management fromcustomer requirements to maintenance.

3D Functional Tolerancing & Annotation is particularly useful in thefollowing industries.

3D Functional Tolerancing & Annotation 3D FTA

65 CONTENTS

GLOSSARY p. 7

DIMENSIONS p. 9

TOLERANCED FEATURE p. 10

DATUM AND DATUM FEATURE p. 11

TOLERANCE ZONE p. 14

GEOMETRIC TOLERANCES p. 15

Form p. 15

Profile p. 17

Orientation p. 19

Location p. 21

Runout p. 25

MAXIMUM AND LEAST MATERIAL CONDITION p. 27

TEST YOUR SKILLS! p. 38

Type Characteristic Example Page

Straightness

15Circularity

Flatness

Cylindricity

Profile of a line17

Profile of a surface

Parallelism

19Perpendicularity

Angularity

Symmetry

21Concentricity

Position

Circular Runout25

Total Runout

GEOMETRIC TOLERANCES

GEOMETRIC TOLERANCES

For

mP

rofil

eO

rient

atio

nLo

catio

nR

unou

t

CONTENTS

87

TOLERANCE ZONE P. 14A portion of space defined by perfect geometry in which thetoleranced feature has to be included to comply with the geo-metric specification.

MAXIMUM MATERIAL CONDITION (MMC) LEAST MATERIAL CONDITION (LMC) P. 27-32

The condition in which a feature of size contains the maximum(respectively least) amount of material within the stated limitsof size; for example, minimum (respectively maximum) holediameter, maximum (respectively minimum) shaft diameter.

VIRTUAL CONDITION P. 28, 29The envelope or boundary that corresponds to the collectiveeffects of a size features specified MMC or LMC materialcondition and the geometric tolerance for that material condition.

GLOSSARY

GLOSSARY

TOLERANCED FEATURE P. 10An actual feature or a derived feature from an actual featureof a part which supports a geometric specification (size, form,profile, orientation, location, runout and roughness).

DATUM FEATURE P. 11, 12An actual feature of a part (physical plane, physical hole,physical slot, etc ) which is used to establish a datum.

DATUM P. 11-13 A theoretically perfect geometric feature (exact point, axis, orplane) derived from the true geometric counterpart of adatum feature. Datums are used as references from whichgeometric tolerances (position, profile, orientation, runout)are established.

DATUM TARGET P. 11, 12 A point, a line or an area of an actual feature of the part whichis used to establish a datum.

GLOSSARY

M L

The following definitions are based on ASME Y14.41-2003.

109

When the note n surfaces is mentioned, several surfacesare considered as a single interrupted or noncontinuous surface.The control is the same applied to a single plane surface.

An actual feature or a derived feature from an actual featureof a part which supports a geometric specification (size, form,profile, orientation, location, runout and roughness).

TOLERANCED FEATURES

DIMENSIONS

DIMENSIONS

TOLERANCED FEATURE

COPLANAR SURFACES

Surface selection

Axis selection

Median plane selection

Unless Perfect Form at MMC not required is mentioned, the limitsof size rule is applied. When only a size dimension is given:

2 the size dimension at any cross section shall be within thesize tolerance,

2 the surface(s) shall not extend beyond the perfect formdefined by the MMC size.

DIMENSIONS

49 ai 50

ANGLE DIMENSIONS

Toleranced Feature

34.7 di 35.3

Leg

end

1211 DATUM DATUM

DATUM

Datum Association Criteria

Point

Line

Plane

Plane:Complexsurface

A theoretically perfect geometric feature (exact point, axis, or plane)derived from the true geometric counterpart of a datum feature.Datums are used as references from which geometric tolerances(position, profile, orientation, runout) are established.

Single Datum

Multiple Datum

Datum Reference Frame

Datum Target

The datum triangle is placed on a featuresurface or on an extension line of the featureoutline. When the Datum Feature is the lineor surface itself, the triangle must be separatedfrom the dimension line.

The datum triangle is placed on the extension of a dimension arrowwhen the datum feature is the axis or the median plane. The datumtriangle can replace a dimension arrow if there is not enough room.

Center ofthe smallestcircumscribedsphere

Center ofthe largestinscribedsphere

Axis ofthe largest inscribedcylinder

Axis ofthe smallest circumscribedcylinder

Tangent plane closest to theactual surface / Least squaresplane / etc...

Median plane of thelargest circumscribedparallel planes / etc...

Datum feature Datum

Lege

nd

1413 DATUM TOLERANCE ZONE

TOLERANCE ZONE

As seen in this example, the order in which the datums are placedin the tolerance frame is very important. On a functional perspective,these two ways of annotating are totally different.

A portion of space defined by perfect geometry in which the tolerancedfeature has to be included to comply with the geometric specification.

A geometric tolerance is expressed on the model by:2 an arrow indicating the toleranced feature,2 a tolerance frame containing the tolerancing characteristics.

Here are some tolerance zones:

Some tolerance zones are not fixed into space; they have the possibilityto move along different directions or rotate around several axes (DOF:Degree Of Freedom).This compass indicates which move is possible for each tolerance zone:

DATUMCASE OF A SPECIFIED DATUM SYSTEM

A B B ADIFFERENCE BETWEEN AND

Datum plane A

Actual surface A

Datum Axis B

Actualsurface B

Freerotations

Lockedtranslations

Freetranslations

Lockedrotations

1615 FORM FORM

FORM Toleranced Feature Tolerance Zone Legen

d

Straightness

Circularity

Flatness

Cylindricity

1817 PROFILE PROFILE

PROFILE

Profileof a line

Profileof a surface

Profileof a surface

Toleranced Feature Datum feature Datum Tolerance Zone

Leg

end

2019 ORIENTATION ORIENTATION

ORIENTATION

Parallelism

Perpendicularity

Perpendicularity

Angularity


Leg

end

2221 LOCATION LOCATION

LOCATION

Concentricity

Symmetry

Position


Leg

end

2423 LOCATION LOCATION

LOCATION

Position

Position:a composite

tolerance

0.2 A B

0.1 A B

0.2 A B

0.1 A B

x2

x2


Leg

end

2625 RUNOUT RUNOUT

RUNOUT

Circular runout

Total runout

AXIAL


Leg

end

RADIAL

2827 MAXIMUM AND LEAST MATERIAL CONDITION

MAXIMUM AND LEAST MATERIAL CONDITION


CLASSIC TOLERANCING WITHOUT MMC

Maximum and Least Material Condition are powerful tolerancingtools allowing the user to transcribe easily and rapidly some of thefunctional aspects of assembly parts. They are also of great valueduring conception, manufacturing and inspection stages.

MMC is used to ensure interchangeability.

This male part is rejected because it exceeds the specifications limits( L = 19.94 mm and = 0.23 mm ). However, it can still beassembled with conform female parts and it answers to the factor G 0.The tolerancing for this function isnt adapted.

Is it possible to respect to the assembly function G 0 without over-constraining the parts geometry?

It can indeed be done by respecting the virtual condition. The virtualcondition is the perfect geometric feature centered around the assemblyfunction binding complementary parts which must be put together:

Gmin = (20 + 0.2) (20.5 - 0.3) = 0 mm

Gmax = 20.6 - 19.9 = 0.7 mm

part 1

part 2

In this example, part 1 and part 2 form a rigid joint.There is a functional condition (Gap) for the assembly: G 0

M L

M

L

0.20.23

19.919.94

20.0

Tolerancingarea




The male part is the only one dealtwith in this section; the process isthe same with the female one.

It is possible to go on with this transfer by exclusively putting the tolerancevalue on the dimension and to reach tolerance zero with the geometrictolerance:

20 and 0.2 20 and 0If the Maximum Material Condition is not dimensionally reached, it ispossible to transfer the margin (difference between the tolerance sizeand the actual size) on the geometric specification (and vice versa).The Maximum Material Condition must not be exceeded.

Virtual Condition: The envelope or boundary that corresponds to thecollective effects of a size features specified MMC or LMC materialcondition and the geometric tolerance for that material condition.

M L

L

0.2

0.3

19.9

Tolerancingarea

20.0

Virtual L = Lmin - max = 20.5 - 0.3= 20.2

Virtual L = Lmax + max= 20 + 0.2= 20.2

L

0.2

0.3

19.9

Tolerancingarea

20.0 20.2

0

-0.1

+0.2

-0.1

TOLERANCING WITH MMC M TOLERANCING WITH MMC AT TOLERANCE ZERO M




CONCLUSION OF MMC

LEAST MATERIAL CONDITION

The Least Material Condition is also used to facilitate the fabricationprocess. It can be used to maintain a critical wall thickness to avoidruptures or to guarantee a maximal value to a defect. This exigencyallows greater control of the precision of a mechanical guide

(example: prismatic joint ensured by two complementary components)ensuring not to exceed the virtual state at least material. As seen in the diagram above with MMC, the concept of expandingthe range of acceptable components can also be applied for LMC.

M

M

L

L

0.2

0.3

19.9

Tolerancingarea

20.0L

0.2

0.3

19.9

Tolerancingarea

20.0 20.2L

0.2

19.9 20.0

L

Tolerancingarea

Decrease cost

3433 3D FUNCTIONAL TOLERANCING AND ANNOTATION

3D FUNCTIONAL TOLERANCING AND ANNOTATION

3D FUNCTIONAL TOLERANCING AND ANNOTATION

CATIA 3D Functional Tolerancing and Annotation is a new-generationCATIA product addressing the easy definition and management oftolerance specifications and annotations of 3D parts and assemblies.

FTA is fully compliant with the ASME Y14.41-2003 standard.

The intuitive interface of CATIA 3D Functional Tolerancing andAnnotation product provides an ideal solution for new CATIA customersin small and medium size industries, looking to reduce reliance on 2Ddrawings and increase the use of 3D as the master definition.

Define in the 3D model all what is used to be defined in a 2D drawing: 2 toleranced dimensions, datums, geometrical tolerances,2 roughness, partial surfaces, 2 notes, symbols, Enhance the quality of the product definition by removinginconsistencies between 3D definition and 2D Drawing definition.

Validate the Dimensioning and Tolerancing specifications:2 assist the user in the correct definition of Dimensioning &

Tolerancing specifications (Tolerancing Advisor capabilities).2 check the validity (according to ASME or ISO standards rules) of

Dimensioning &Tolerancing specifications: for all the geometric modifications, for all the tolerancing scheme modifications.

Enhance the quality of the product definition by checkingfull compliance to ASME or ISO standards.

FTA

3635 DELMIA

3D FTA - CATIA 3D FTA - DELMIA

CATIA

REUSE OF FTA BY DOWNSTREAM APPLICATIONS

METROLOG V5

MACHINING

TOLERANCING

ASSISTANT

DELMIA can read and re-use FTA information in different workbenchesas in: 2 DELMIA Machinining Tolerancing Assistant (MTT): MTT is anadd-on product to DPM Machining Process Planner that will allowmanufacturing process planner to create in-process manufacturingtolerances on the unique in-process model generated from DPMMachining. MTT is a tolerance stack-up analysis tool that will enableplanners to analyze the stack-up distribution with respect to the FTAdefined tolerances. 2 Metrologic Inspection: FTA tolerances can also be reused in theoff-line & on-line inspection application developed by DELMIA partnersMetrologic. Metrologic software is native to V5 & reads all FTA definedtolerances & automatically creates an inspection plan.

Manufacturing,Assembly Process

Planning

Tolerance Analysis(Manufacturing

context)

Inspection

Assembly Design(Functional

Requirements)

Part Design(Functional

Specifications)

FunctionalToleranceAnalysis

(Design context)

FTA

37 CERTIFICATION

About VirtoolsAcquired by Dassault Systmes in mid-2005, Virtools is the leading provider of comprehensive software solutions for buildinghighly interactive 3D life-like applications. Virtools 3D real-time technologies and solutions are used in a wide variety ofapplications such as simulation of product usage, ergonomic testing, creating the shopping experience, training scenarios,right through to branding, advertising and web marketing applications. For more information, visit www.virtools.com

About Dassault Systmes As a world leader in 3D and Product Lifecycle Management (PLM) solutions, Dassault Systmes brings value to more than100,000 customers in 80 countries. A pioneer in the 3D software market since 1981, Dassault Systmes develops andmarkets PLM application software and services that support industrial processes and provide a 3D vision of the entire lifecycleof products from conception to maintenance. The Dassault Systmes portfolio consists of CATIA for designing the virtualproduct - SolidWorks for 3D mechanical design - DELMIA for virtual production - SIMULIA for virtual testing and ENOVIAfor global collaborative lifecycle management, including ENOVIA VPLM, ENOVIA MatrixOne and ENOVIA SmarTeam.Dassault Systmes is listed on the Nasdaq (DASTY) and Euronext Paris (#13065, DSY.PA) stock exchanges. For moreinformation, visit http://www.3ds.com

Trademarks CATIA, DELMIA, ENOVIA, SIMULIA and SolidWorks are registered trademarks of Dassault Systmes or its subsidiaries inthe US and/or other countries.

ASME is the registered trademark of The American Society of Mechanical Engineers.

Defined For Professionals2 The Dassault Systmes Professional Certification gives to engineering

users the expertise level wanted by industry market needs.2 CATIA Certification is the valuable distinction deployed like a professional

curriculum by employers working in most high-tech industries of the world.

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to build credibility within the industry market and bridges the gap betweenacademia and industry.

2 Expand your Universitys influence by becoming a Dassault SystmesAcademic Certification Partner and provide opportunities for students tobecome CATIA certified professionals.

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