Outline & Introduction v3.2 [02]

T MC GEOMETRIC DIMENSIONING & TOLERANCING (GD&T)

Curriculum Outline & Introduction 1 Tony M Consulting Pty. Ltd

T MC PHILOSOPHY OF DESIGN Roll of design Engineers in Industry Engineering Structures Cost Effective Design How & Why things can ‘Go Wrong’ Communications (Role of GD&T) Function Myths The Engineers ‘Crutch’ Conventions & National Standards 2 Tony M Consulting Pty. Ltd

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T MC DATUM THEORY What is a DATUM ? 3-Plane Concept. Datum Features - Planes - Cylinders - Targets Effect of Size & Form Gauge/Inspection Datum Set-up Practical exercises 3 Tony M Consulting Pty. Ltd

T MC GEOMETRIC CHARACTERISTICS Symbols (General Outline). Detailed Discussion, application techniques, Interpretations & practical exercises. a)

Flatness, Straightness, Roundness & Cylindricity

b)

Profiles of Lines & Surfaces

c)

Parallelism, Perpendicularity & Angularity

d)

Runout, True Position, Concentricity & Symmetry

e)

True Position in depth

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T MC PRACTICAL TOLERANCING A] Capturing DESIGN INTENT B] Application C] Interpretation D] Drawing Practice E] Gauging F] “Significant Characteristics”

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T MC FMEA & GD&T Function Matrix Co-ordination & interaction

WORKSHOP Critique of drawings Review of real examples from your organization

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T MC T h e R o le o f D e s ig n E n g in e e r s in I n d u s t r y

The major function of a Design Engineer in Industry today is to Develop information which permits an idea or concept to be converted into a physical object or system that precisely meets the functions of that idea or concept.

The Design Engineer plays a pivotal role in manufacturing organizations

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T MC Design – A Definition

The PHYSICALISATION of the IMAGINATION

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Engineering Structures

T ra d itio n al: T h e tradition al stru ctu re in M an ufactu ring Ind u stries is to h ave a sp ecial D ep artm ent w ith its ow n h ierach y. T h is is furth er b roken d ow n in to sp ecialist en gin eerin g fu nctions, su ch as P roduct D esign ,M anufacturing E ngineering, T estin g etc.

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T MC Engineering Structures Modern: Engineers are incorporated into “Multi-Functional” teams with specific project responsibilities. The teams usually have members with different disciplines, ie. Engineers(their sub-disciplines are dependent on the project ), Manufacturing, Quality, Marketing, Purchasing, Finance, MIS, etc. Under this type of structure accountability is through the “Team Leader” who may or may not be an Engineer. The ability of the engineer to communicate accurately, under this structure is even more demanding than in the “traditional” structure.

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In order to be able to do his/her job properly the engineer must be trained to understand the following:

1) Laws of Physics as they apply to the concept 2) Mathematics

3) Mechanical systems, their functions & their environmental limitations 4) Various materials available, their characteristics & applicability

5) Any Legal or other demands relevant to the application of the concept 6) Costing 7) Testing methods 8) Performance evaluation techniques (statistics) 9) Manufacturing 10)Using TOOLS Effectively (eg. CAD)

11) Effective “Engineering Communications” 11 Tony M Consulting Pty. Ltd

T MC An Engineer’s capability is measured according to how well he/she applies that training to ensure that the resulting system efficiently performs the idea/concept’s function, ie,

SKILL In order to demonstrate the above capability the Engineer must be able to COMMUNICATE his/her system requirements in a way that can be UNDERSTOOD

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C O S T

E F F E C T IV E D E S IG N

Every COMPONENT drawing in whatever form has a cost C O S T

S K I L L

No. Made

No. Made

C O S T

SKILL

The above curves apply to all enterprises, whether producing components, works of art or making component drawings. 13 Tony M Consulting Pty. Ltd

T MC There are many examples in the World which demonstrate that ‘poorly executed’ drawings/specifications of an excellent concept will create a poor reputation for Manufacturing & Reliability in the Market place, While well executed drawings/specifications can make a mediocre/conservative concept achieve an excellent reputation for Manufacturing & Reliability etc. in the Market place.

Well executed Drawings/Specifications also minimize problems & delays in the process from Concept to Production.

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T MC Things That can Go Wrong Common Problems in Manufacturing Industry Example A A component is submitted for Off Tool Sample approval & found not to perform properly with its interacting components.

WHY ? 1) The component was not made to drawing because:a) The supplier made a mistake b) The Supplier Mis-interpreted the Drawing

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T MC Things That can Go Wrong

Example A (cont’d) 2) The component was made to the Drawing BUT:a) The Engineer/Draughtsman made a mistake b) The Engineer/Draughtsman put INCORRECT information on the Drawing because he/she did not understand fully the FUNCTIONAL RELATIONSHIP with its interacting components.

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T MC Things That can Go Wrong Common Problems in Manufacturing Industry Example B A component is submitted for Off Tool Sample approval which(after an extensive test program) was found to work satisfactorily with its interacting components, although it does NOT CONFORM to the Drawing

WHY ? 1) The Supplier process was not capable of producing parts within the Specified tolerance range & making changes to the tooling would jeopardise the cost &/or the program timing.

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T MC Things That can Go Wrong

Example B (cont’d) 2) The Engineer/Draughtsman did not investigate the TRUE tolerance allowance for the feature(s) because:a) He/she ‘played safe’ in allocating the tolerance(s) b) he/she did not understand/investigate the true FUNCTIONAL VARIABLES of the component with its INTERACTING components.

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T MC These examples are intended to illustrate some of the problems that can affect a Company’s relationship with a Customer or the effective operations within the Company.

Highlighted are the effects of not understanding or using the means of communication properly between Designers, Engineers or Draughtsmen with those responsible for making the Components/Assemblies.

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Cost of correction

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Design

Prototype

Tooling

Pilot Prodn.

Serial Prodn.

In Market

Prod. Recall

Error Detection Stage 20 Tony M Consulting Pty. Ltd

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T MC IMPORTANT! Engineering drawings & specifications are “LEGAL DOCUMENTS”

1] In respect to contract between Supplier & Customer. 2] In respect to ‘Product Liability’ issues that can arise from the market place

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COMMUNICATIONS Communications between Human Beings is by means of “LANGUAGE”

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To UNDERSTAND and, to ensure that you convey the true meaning of your Feelings, Needs, Ideas etc., the LANGUAGE MUST BE LEARNED 23 Tony M Consulting Pty. Ltd

T MC All languages have common attributes:SOUNDS are used to communicate feelings, needs, ideas etc. directly to another person or group who understand the spoken language.

SYMBOLS are used to communicate feelings, needs, ideas etc. to another person or group who are remote and understand the written language.

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T MC WRITTEN communication is also NECESSARY when continuous reference is required to ensure that the information does not change from one reading to the next. Reliance on VERBAL communication used in conveying PRECISE information can lead to many mistakes & so be sources of conflict.

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T MC Geometric Dimensioning & Tolerancing System -Is the Language that Engineers use to communicate their requirements of a component or an assembly so that the end product meets the DESIGN INTENT-

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T MC WHY USE GEOMETRIC DIMENSIONING AND TOLERANCING? Why is it that we should be so interested in this subject? FIRST AND FOREMOST ITS USE SAVES MONEY! It saves money directly by providing for maximum producibility of the part through maximum production tolerances. It provides "bonus" or extra tolerances in many cases. It ensures that design dimensional and tolerance requirements, as they relate to actual function, are specifically stated and thus carried out. It adapts to, and assists, computerization techniques in design and manufacture. It ensures interchangeability of mating parts at assembly. It provides uniformity and convenience in drawing delineation and interpretation, thereby reducing controversy and guesswork.

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T MC WHY USE GEOMETRIC DIMENSIONING AND TOLERANCING?

Aside from the primary reasons stated before there are others of a more general nature: “The intricacies of today's sophisticated engineering design demand new and better ways of accurately and reliably communicating requirements. Old methods simply no longer suffice.” “Diversity of product line and manufacture makes considerably more stringent demands of the completeness, uniformity, and clarity of drawings.” “It is increasingly becoming the "spoken word" throughout industry, the military, and internationally, on engineering drawings & documentation. Every engineer or technician involved in originating or reading a drawing should have a working knowledge of this new state of the art.”

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FUNCTION How do we define “FUNCTION”

There are TWO entities that require consideration from an engineering aspect: 1) An ASSEMBLY (or Sub-assembly) 2) An individual COMPONENT

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T MC FUNCTION 1) An ASSEMBLY (or Sub-assembly)

An Assembly (or Sub-assembly) is a group of components that are joined together and/or interact, such that for a given physical INPUT manipulates that input to create an OUTPUT which achieves a desired objective.

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FUNCTION 2) An Individual COMPONENT

A COMPONENT is a single piece within an Assembly (or Sub-assembly) that has essential characteristics/features which interact with other components in order that the Assembly (or Sub-assembly) can reliably perform its design intent.

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Define the CONDITIONS & EXPECTATIONS for the Functions Corrosion Resistance

Environment

Temperature/Humidity Ageing (Accelerated)

Customer Number of Cycles

Life Expectation Fatigue

& Legal Requirements

Interacting Features

Critical Features

Strength

Specifications

Mass Manufacturability

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Function Loss Matrix Refer ISO/QS 9000 PPAP Manual

1) List all the Features of the Component/system/assembly. 2) Indicate which features have a DATUM function 3) Determine the Criticality/Severity Rating if those features are OUTSIDE the Specification [L-Low, M-Medium or H-High] 4) Indicate each feature’s dependence [datum reference] 5) Indicate the control symbol(s) appropriate to each feature 6) Review the Matrix 33 Tony M Consulting Pty. Ltd

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Design Function/Relationship Matrix (Dimensioning)

Component/Sub-Assy. Pt. No. Datum Feature

Prim

Secon

Criticality Rating Tert.

Size

Position

Shape

Control Symbol Prim. Datum

Sec. Datum

‘A’ Surface ‘B’ Hole ‘C’ Hole ‘D’ Thickness ‘E’ Width Etc.

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MYTHS 1) Using GD&T increases Cost !! Proper use of GD&T reduces cost by MAXIMISING the tolerances of features.

It is provable that the cost of production of a feature increases according to the inverse of the size of the tolerance

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MYTHS 2) Computer generated Data/Drawings are precise & do not require additional information !! Complex surfaces such as “styled” features must still be located in a ‘mechanical environment’ within an acceptable tolerance.

Eg. A instrument panel surface profile must be located so that it fits properly in its environment so that the overall style of the interior of the vehicle meets the designers intent.

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MYTHS 3) GD&T can not be applied to all situations !! GD&T is not just the use of a library of symbols, but a LANGUAGE to communicate design intent. If a situation occurs during the establishment of functional requirement of a feature that is not covered by the standard library then the requirement can be noted using the GD&T principles to convey that requirement. Use the GD&T language/vocabulary in a combination that truly conveys the DESIGN INTENT

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T MC What is the Engineer’s “CRUTCH”? That note on the drawing that classifies the tolerance according to the number of decimal points on the feature dimension. 0 ---------- +/- 1 mm 0.0---------+/- 0.2 mm 0.00--------+/- 0.1 mm

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What should we do instead? 1) Refer to the Function Matrix for guidance to evaluate the REAL tolerance requirement. 2) Are there any formal standards that cover the function that is required? Eg, Hole/shaft fits, Injection moulding tolerances, codes of practice etc. 3) Consider how the feature will be Manufactured, & what is the relative cost in Tooling & Piece cost.

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T MC International Standards & Conventions Agreement between US ANSI/ASME & ISO Standards covering GD&T is about 90 – 95% . Other national standards such as Australian Stds. Are generally aligned with ISO. Overall it can be considered that the GD&T “language” is UNIVERSAL in its application & understanding. Ie, no matter which ethnic group needs to know what the designers intent is, can understand, provided the GD&T language is understood.

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Standards necessary for GD&T coverage ANSI/ASME Y14.5M The following documents must be considered when adopting ISO/GD&T standards 1. 15011101Technical Drawings Geometrical tolerancing 2. ISO/5458Technical Drawings Positional tolerancing 3. ISO/5459Technical Drawings Datums and Datum Systems 4. ISO/2692Technical Drawings Maximum material principle Technical Drawings Cones 5. ISO/3040Technical Drawings Profiles 6. ISO/1660Technical Drawings General principles 7. ISO/129Technical Drawings Linear and angular dimensions 8. ISO/4069. ISO/10578 Technical Drawings Projected tolerance zones 10. ISO/2692:1988/DAM 1 Technical Drawings Least material principle 11. ISO/8015 Technical Drawings Fundamental tolerance principle 12. ISO/7083 Technical Drawings Symbols proportions Technical Drawings Non-rigid parts 13. ISO/10579 Additional 1S0 standards involved: 1. ISO/1000 - SI Units 2. ISO/286 - Limits & Fits Technical Drawings-Verification principles 3. ISO/TR5460 4. ISO/2768-2 General geometrical tolerances - Surface Texture 5. ISO/1302 6. 7.

ISO/2768-1 Tolerances for linear and angular dimensions Other peripheral standards on screw threads, gears, drills, welding, etc., may also be required for coverage beyond Y 14.5 for product design.

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T MC Complete Symbols List

Items Marked # are not described in detail in this course as they are self explanatory

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