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G D & T - Overview Natarajan R Director EGS Computers India Private Limited www.egs.co.in * www.egsindia.com

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Page 1: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

G D & T - OverviewNatarajan R

Director

EGS Computers India Private Limitedwww.egs.co.in * www.egsindia.com

Page 2: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Agenda

• Introduction to GD & T• DimXpert for GD & T• G D & T by examples• Benefits of G D & T

Page 3: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is GD & T?

• GD&T is a Universal Language for communicating engineering design specifications

• Includes all symbols, definitions, mathematical formulae and application rules necessary to convey specifications

• Conveys nominal dimensions and tolerances for a part• Independent of Country and native language• Approved by ASME, ANSI and DoD• Language that designers use to translate design

requirements into measurable specifications

Page 4: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is GD&T?

• Way of communicating dimensional and tolerance requirements

• Allowable imperfection• GD&T practices are governed by

standards manuals

ASME Y14.5M-2004

ASME Y14.41-2003

Page 5: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is GD&T?

• ANSI -– Y14.5M-2004: Application of

GD&T– Y14.41-2003: Display of GD&T

in 3D• ISO -

– ISO 1101: Application of GD&T – ISO 16792: Display of GD&T in

3D

ASME

ISO

Page 6: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is GD&T?

Geometric TolerancingPlus/Minus Tolerancing

Page 7: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Why use GD & T?

• It is important for the designer, manufacturer and inspector to understand part dimensions in the same manner

• GD & T principles result in time and cost savings• Ensures adherence to quality criteria• Reduces part rejection, mis-interpretation of drawings,

reworking, inter-departmental crossfire and art-to-part transformation time

• Avoids assembly mis-match, failures and quality problems

Page 8: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

• Variation is inherent in nature– Nothing real is perfect!

• CAD doesn’t manufacture components– Actual Manufacturing Processes do!

Why use GD & T?

Page 9: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

“Thousands of Hyundai's, Nissans and BMWs are targets of recalls --- Nissan announced the recall of about 116,000 Sentras because of a sensor problem.” ASSOCIATED PRESS,

•Improving productivity by reducing wasteful costs is imperative in today’s increasingly tough, competitive environment - ultimately affecting a company’s survival and its bottom line.

•Need for a holistic integrated systems solution to the COPQ problem.

The Truth - Cost of Poor Quality (COPQ) Design Quality Progress Magazine

Why use GD & T?

Page 10: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Why use GD & T?

GD & T and Tolerance Analysis target and solve these assembly build quality issues to reduce/eliminate COPQ

Page 11: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Upfront Information Saves Money

• GD & T and Tolerance Analysis during the part design phase permits optimization of the part from both functional and manufacturing perspectives before any tools are cut.

$Design Production

PRODUCT LIFE CYCLE

DFSSEnables!

COST BENEFIT

Cost of poor qualityEnd result:• No surprises• Higher Quality

Parts• Lower Cost• Material Flexibility

Page 12: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Design Methodolgoy with GD & T and Tolerance Analysis

• Evaluate different design conceptsLocating schemesAssembly methods

• Evaluate manufacturing processes• Re-assign Tolerances

Loosen if possible,Tighten if required

• Cost Savings Opportunities

Cost is Directly Related to Tolerances

SPECIAL EQUIPMENT

HIGH ACCURACY BORING

GENERAL BORING

DRILLING

0.0 0.1 0.2 0.3 0.4 0.5

10

15

20

25

30

Rel

ativ

e C

ost

mm

SOURCE: British Std. BSI PD-6470

*

*

Page 13: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

How does GD&T Work?

Four simple steps:• Identify part surfaces to serve as origins and provide

specific rules to establish starting point and direction for measurements

• Convey nominal (ideal) dimensions and orientations from origins to other surfaces

• Establish boundaries and / or tolerance zones for specific attributes of each surface along with specific rules for conformance

• Allow dynamic interaction between tolerances (simulating actual assembly possibilities) where appropriate to maximize tolerances

Page 14: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

14

Features of Size - Four Fundamental Levels of Control

Level 1:Controls size and circularity (for cylinders and spheres) at each cross section only

Level 2:Adds overall form control

Level 3:Adds Orientation control

Level 4:Adds location control

Each higher-level tolerance adds a degree of constraint demanded by feature’s functional requirement

All lower-level controls remain in effect

Single feature can be subject to many tolerances simultaneously

Page 15: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

15

Example

Page 16: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

16

Resultant Interpretation

Page 17: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

17

With GD&T

Page 18: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

18

Explanation

Page 19: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

19

Geometric Characteristic Symbols

Page 20: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

20

Modifier Symbols

Page 21: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

How can GD&T make a difference?

Page 22: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

G D & T Simplified

Page 23: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gear Box Cover Design

Page 24: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

G D & T – Reflecting Fit, Form & Functional Requirements

Page 25: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gripper Assembly

Page 26: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gripper Assembly

Page 27: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gripper Assembly – Exploded View

Page 28: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gripper Holder Drawing

Page 29: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Gripper Holder – Completeness of GD & T

Page 30: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

How to develop GD & T schemes? DimXpert Example

• Intelligent, automated dimensioning and tolerancing of 3D models

• Visual feedback on dimensional completeness

• Automatically displays in 2D drawing

• Integrated with Tolerance Analysis

Page 31: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

GD & T Scheme for Hydraulic Actuator Flange

Page 32: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

GD & T Scheme for Hydraulic Actuator Flange

Page 33: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Complete 3D GD & T Annotation

Page 34: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Completeness of GD & T

Page 35: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

GD & T Drawing

Page 36: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Dimensional Functionality: Schemes

• Geometric and Plus-minus dimension and tolerance schemes

Geometric Plus-Minus

Page 37: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Dimensional FunctionalityShow Tolerance Status

• Show Tolerance Status– Informs user when the

dimension and tolerance scheme is complete

– Each face is colored based on its status:• Green = Fully constrained• Yellow = Under constrained• Red = Over constrained• Native color = Not Recognized

by DimXpert

Before

After

Page 38: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Benefits of G D & T

• Maximizes Tolerances thereby reducing per part cost

• Ensures unambiguous translation of designs into measurable specification

• Eliminates re-work and ensures assembly all the time

• Reduces product development cycle time

Page 39: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Thank You !

Page 40: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Stack Up Analysis - Overview

Page 41: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Agenda

• Introduction to Tolerance Stacks• Why Tolerance Stacks?• Tolerance Analysis – Step by Step Process• Review by Example• Benefits of Tolerance Stack Up Analysis

Page 42: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is a Tolerance Stack ?

A method of mathematically predicting the resultant effect of piece part and subassembly tolerances along with assembly process and fixturing variation on a particular build objective of the assembly.

Page 43: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is Tolerance Stack-up Analysis?

Worst-case analysis– Assumes dimensions vary within the entire range of their tolerance

zones and that the accumulation of tolerances will experience all possible variations

Gmin = L1 + L2 + L3 + L4… + Ln

= L1 + L2 + L3 + L4

= 152.75 + (-60.75) + (-42) + (-50.5) = -0.5 Interference

Performing worst-case analysis using a tolerance graph and hand calculation to determine the smallest permissible gap (G)

Page 44: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

What is Tolerance Stack-up Analysis?

Worst-case tolerance analysis is dependent on how parts are actually assembled in real life

It is incorrect to think max worst case is when the parts are at their largest and min worst case is when they are at their smallest

PartNominal Assembly Worst-case

MaximumWorst-case Minimum

Page 45: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

● Also referred to as dimensional control, dimensional variation management or dimensional engineering

● A process by which the design, fabrication, and inspection of a product are systematically defined and monitored to meet predetermined dimensional quality goals.

● An engineering process that is combined with a set of tools that make it possible to understand and design for variation.

● Aim is to improve first-time quality, performance, service life, and associated costs.

Dimensional Management

Page 46: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

A typical Dimensional Management system consists of the following tools● Simultaneous or Concurrent Engineering Teams● Written Goals and Objectives● Design for Manufacturability and Assembly (DFMA)● Geometric Dimensioning and Tolerancing (GD&T)● Key Characteristics (KCC/KPC)● Statistical Process Control (SPC)● Variation Measurement and Reduction● Variation Simulation Tolerance Analysis

Dimensional Management

Page 47: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Historic Build-Test-Fix Method

Concept Model Design (CAD)

Default andCarry overTolerances

Manufacturing

Analysis (FEA)

Customer

Fire Fighting&

TroubleShooting

Iterative Loop

B-T-F Process

COPQWarrantyReworkRetoolECO'sOvertimeLost TimeEtc...

Dimensional Management

Page 48: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Concept Model

Define Performance Requirement

Design (CAD) & Analysis (FEA)

Functional Datum Structure Logic

Manufacturing Process Capability

3-D Variation Modeling

Design Evaluation, Optimization & Validation

ManufacturingSatisfied Customer

Evaluate Geometric sensitivity

Evaluate and Optimize Assembly Process

Functional Gauging & Fixturing

Key Characteristics SPC

Quality Process Manual

MaintenanceSmooth Launch

New PD Process

Dimensional Management

Page 49: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

● Analyze and optimize dimensional variability within an assembly system

● Establish piece part tolerances ● Reduce product costs by increasing tolerances● Identify key tolerance contributors● Reduce product cycle time and improve quality● Determine if existing design and tooling will meet the

build objective requirements (CTQs)

Why Perform Tolerance Analysis?

Page 50: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance: Engineering specifications that are put in place to define or control the extreme limits of variation from nominal geometry. Defined based on product functionVariation: The deviation of a geometric feature property from its nominal. A property of the manufacturing process

Tolerance Vs Variation

Page 51: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Start

Setting BuildObjectives

Define VectorLoop and

ContributorCharacterisitics

Calculate MeanValue of BO

Determine methodof Analysis

Calculate Variationof BO

Optimize forRobustness

End

Tolerance Analysis Process

Page 52: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

● Early in the design process● Customer Focus - perceptions of quality● Benchmarking, Focus Group Meetings● Representation from all internal groups● Formal buy off - signatures

Setting Build Objectives

Page 53: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

● Key measurable characteristics of a product or process whose performance standards or specification limits must be met in order to satisfy the customer

● They align improvement or design efforts with customer requirements.

CTQ's – Critical To Quality Characteristics

Page 54: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

● Fit● Finish● Function

Types of Build Objectives

Page 55: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

• Component Mating• 100% Assemblability• Hole/Pin interface• Clearance/Interference Pin

Diameter

Hole Diameter

Fit Objective

Page 56: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

• Aesthetics• Gap• Flush• Centering• Consistency• Consumer Products

Speaker grille over flush to the door substrate

Door Substrate

Speaker Grille

Finish Objective

Page 57: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

• Assembly Function• Range of Motion• Locks• Latches• Alignments• Guides

Latch Engagement

Latch

Functional Objective

Page 58: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

XYZ Inc. - Build Objectives, Product XXX• Competition

- Benchmarking- Competitive Assess.- QFD- VOC

• Quality• Warranty• Costs

- Scrap- Down Time- Bottlenecks- Lost

Customers

Qualify Quantify

Function

Fit

Finish

Build Objectives

Page 59: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Start

Setting BuildObjectives

Define VectorLoop and

ContributorCharacterisitics

Calculate MeanValue of BO

Determine methodof Analysis

Calculate Variationof BO

Optimize forRobustness

End

Tolerance Analysis Process

Page 60: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Loops (Vector Loops)

• A systematic method of approaching a tolerance stack, and selecting the contributing tolerances.

• A tolerance loop allows for the evaluation of not only the stack variation, but also the stack nominal value.

Page 61: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

10 ± 0.02D1

4 ± 0.015D2

3 ± 0.01D3

B.O.

Starting PointFinish Point

+

• Establish start and finish points on each side of the objective.• Travel from the start point to the finish point in the shortest

route, this direction will be called +.

Tolerance Loops

Page 62: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

10 ± 0.02

4 ± 0.015 3 ± 0.01 B.O.

Starting PointFinish Point

+

D1

D2 D3

B.O. = D1 – D2 – D3

• Go around the tolerance circuit in the opposite direction from previous step, taking the most direct route.

• Add signs to the nominal values according to their direction.

Tolerance Loops

Page 63: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Loops - Steps

D1 (-)

D2 (+) D3 (+) B.O. (+)

Loop Start Surface

• Start at one side of the objective surface• Subtract each dimension that moves to left while adding each

dimension that moves to right until the starting objective surface has been reached

Page 64: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

10 ± 0.02

4 ± 0.015 3 ± 0.01 B.O.

Starting PointFinish Point

+

D1

D2 D3

Example Assembly

• Equal Bilateral Tolerancing

Page 65: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Vector Loop Equation

0..321 =+++− OBDDD

321.. DDDOB −−=

Page 66: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Start

Setting BuildObjectives

Define VectorLoop and

ContributorCharacterisitics

Calculate MeanValue of BO

Determine methodof Analysis

Calculate Variationof BO

Optimize forRobustness

End

Tolerance Analysis Process

Page 67: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Worst Case Analysis

Worst case stacks simply sum all the tolerances in the assembly in a linear direction and predicts the maximum variation expected for a particular build objective.

Page 68: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Worst Case Analysis Formula

Build Objective Variation = T1 + T2 + T3 + T4 +…..+ Tn

- Ti are the tolerance contributorsaffecting a particular build objective

- Ti are assumed equal bilateral tolerances - n is the number tolerances in the stack

Page 69: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Worst Case Analysis

• Ignores tolerance distribution types • Assumes all tolerances at their extreme limits• Guarantees 100% assembleability• Drives tight piece part tolerances / higher costs• Restrict to critical mechanical interfaces

Page 70: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

X = 3 ± 0.045 or as a range = 2.955 to 3.045.

NominalDimensions

Tolerances

+

+10 0.020

-4 0.015

-3 0.010

+3 0.045

D1:

D2:

D3:

Worst Case Example

• Sum the Nominal Values• Sum the Tolerances

Page 71: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Worst Case Example - Mean

321.. DDDOB µµµµ −−=

33410.. =−−=OBµ

Page 72: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Worst Case Example - Variation

3 ± 0.045

Page 73: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Nominal Dimensions

± Tolerance

+

-0.820 0.008

+0.810 0.008

+0.090 0.006

-0.065 0.008

+0.015 0.030

Example

Page 74: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

One Dimensional Loop Calculation

Page 75: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Flange Gap Study in Sheet Metal

Page 76: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Stacks – Assembly Study

Page 77: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Mechanism – Elevator Gear Train

M O T O R WO R M G E A R T IP M O V E M E NTSpecification: L SL= 0.0000, Nominal= 0.0000, USL= 0.1500Control L imits: L CL =-0.0023, Mean= 0.0506, UCL = 0.1652

%Out of spec.= 0.9200, Cp= 0.8958, Cpk= 0.8740, Mean Shift= 0.0506

1 1 0 . 0

9 9 . 0

8 8 . 0

7 7 . 0

6 6 . 0

5 5 . 0

4 4 . 0

3 3 . 0

2 2 . 0

1 1 . 0

0 . 0

90.0

0

10.0

0

90.00%: 10.00%: GEAR 1 BA S E

Distr. Type: Gamma 5000S ample S ize:

95.0% Conf. Int. in Est. S ample Est. Low. CI Upp. CI (99.7%)

Mean: 0 .0 4 9 7 0 .0 5 1 5 Min.: 0 .0 0 0 4 -0 .0 0 2 3

S td Dev: 0 .0 3 1 6 0 .0 3 2 8 Max.: 0 .3 1 3 9 0 .1 6 5 2

Cp: 0 .8 7 8 3 0 .9 1 3 4 %<LS L: 0 .0 0 0 0 0 .0 0 0 0

Cpk: 0 .8 5 4 5 0 .8 9 3 4 %>US L: 0 .9 2 0 0 0 .9 2 0 0

%OutS : 0 .6 6 0 0 1 .1 8 0 0 %OutS : 0 .9 2 0 0 0 .9 2 0 0

ppm OutS : 6 6 0 0 1 1 8 0 0 ppm OutS : 9 2 0 0 9 2 0 0

Freq

uency

-0.0

313

-0.0

098

0.0

118

0.0

334

0.0

550

0.0

765

0.0

981

0.1

197

0.141

3 0.1

628

0.1

844

0.2

060

0.2

276

0.2

491

0.2

707

0.2

923

0.3

139033

6699133166199232266299332365399432465499

NOMINAL− 3 σ + 3 σ

USLLSL

Measurement Summary Bar Chart for WOR M GEAR TIP MOVEMENTMOTOR WOR M GEAR TIP MOVEMENT

0.3455

0.3075

0.2696

0.2317

0.1937

0.1558

0.1179

0.0799

0.0420

0.0041

-0.0339

Simulation Number

Mea

sure

men

t

50 100 150 200 250 300 350 400 450 500

LSL

USL

LCL

UCL

Mean

Mean: 0.0506 Nominal: 0.0000 Mean Shift: 0.0506 %<LSL: 0.0000 ppm OutS: 9200LCL: -0.0023 LSL: 0.0000 Std Dev: 0.0322 %>USL: 0.9200 Cp: 0.8958UCL: 0.1652 USL: 0.1500 Range: 0.1674 %OutS: 0.9200 Cpk: 0.8740

Page 78: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Stack-Up Analysis

Page 79: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Tolerance Stack-Up Analysis

Page 80: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Problem Definition – Specifying Build Objective

Page 81: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Specifying the Vector Loop

Page 82: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Incorporating G D & T in Stack Up Calculations

Page 83: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Node Tree Definition for Vector Loop

Page 84: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Roll Up Calculations

Page 85: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Sensitivity Report for Tolerances affecting Assembly Build Objective

Page 86: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Predicting PPM

Page 87: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Summary of Features

• Maximum/minimum tolerance stack-up

• Identifies key contributors• Graphically displays result• Reduces prototyping and

testing for assembly fit• Leverages DimXpert• Eliminates error-prone hand

calculations• Enables fast tolerance

optimization

Page 88: EGSIndia - SolidWorks Sales & Technical · PDF fileWhat is GD&T? • Way of communicating dimensional ... systems solution to the COPQ ... variation management or dimensional engineering

Summary of Benefits

• Eliminates ambiguity in Drawing Generation

• Confirms to Standards• Eliminates re-work• Selective Tolerancing

controls Cost• Eliminates Rejection• Reduces per-piece cost• Helps understand and

correct process deviations• Increases profitability

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Thank You