Duration
UNDERSTANDING GEOMETRIC DIMENSIONING AND TOLERANCING (GD&T)
[Basic~Intermediate level]
2 days
Overview
The quality of product must follow the design requirements that should have the criteria such as fit, form, function, and/or reliability. In order to fulfil the requirements, the size and geometrics such as form, orientation and location of the product must be within the given specifications. A system which is concerning about the size (dimension) and geometrics shall be within the specifications is so-called geometric dimensioning and tolerancing abbreviated as GD&T.
Nowadays, complexities in manufacturing increase, and there was an increased need for drawings of parts and their assemblies rather than being fitted to only one assembly. With the tolerance was specified as a plus/minus tolerance unable to fulfil and complete explain about these complexity assemblies. Then the geometric tolerances will play the important role in this situation. Besides that, there is a need for interchangeability of parts and assemblies manufactured around the world being brought together in an assembly plant that makes automobiles, tractors, airplanes, televisions, projectors, spacecraft, and so on. These items also need replacement parts that assemble readily without a lot of rework. Thus, the GD&T is the idea system to overcome of these difficult tasks.
The GD&T is contented of symbols, rules, vocabulary, mathematical definition and standards. In order to improve communications, control, and productivity, the GD&T must be standardized and mathematize which means that anyone who knows the Standard knows what the drawing means. Furthermore, the GD&T can be used as reference throughout the world by applying the standardized symbols. This is because the drawing composes with the symbols and abbreviations are used to efficiently and accurately communicate size and geometry requirements for associated features on components and assemblies.
A standard is a model or rule with which other similar things are to be made to or compared. GD&T is a standard for symbols, principles, and rules that is provided internationally. In the United States, the standard is maintained by the American Society for Mechanical Engineers (ASME). In the European countries and other parts around the world, the standard is maintained by the International Organization for Standards. In the Asia, some of the countries have their own standard for this GD&T system such as Japan, China, and Korea. These standards may not be identical, but today there are quite similar due to everybody have the same intention to improve the communication by using DG&T in order to manufacture the best quality of the products.
During the early day, plus and minus tolerances system will create a square tolerance zone instead of round by GD&T system, thus for functional in the assembly, the round one will accept more 57% of the product compare to square tolerance zone. Besides that, the advantage of GD&T system is complete specification of the product, which is unable handled by just based on the plus and minus system. The other's advantage of using GD&T is allowed to increase the tolerance under certain conditions for manufacturing that can make significant savings in production costs. When the feature is implied maximum material condition, the GD&T system is permitted to use the functional gauge (fix gauge) for checking the products, this will help us to save our time and cost for inspection on mass production.
All the part feature may have the four major characteristics or types of variation such as location, orientation, size, and form. The symbols for the geometric tolerances that have been developed to control each of these characteristics. The location always controls orientation while size usually controls form. In certain cases, location may control all of the other characteristics. The form tolerance consists of straightness, flatness, circularity and cylindricity. The orientation tolerance is the perpendicularity, parallelism and angularity, whereas the location tolerance comprises of concentricity, symmetry and position. The other's geometric tolerances are the composite control that is circular runout and total runout, and profile of a line and profile of a surface. The position tolerance is one of the most effective and used controls in GD&T, due to easy to understand and the tolerance zone may be modified with the geometric modifiers that is allows the specified tolerance to increase and will accept more parts. The next commonly use is the profile tolerance, which may control the four major characteristics are mention above and for irregular surfaces.
The GD&T is created for designer’s intent effectively communicates to the manufacturer, and then the inspector will follow the designer’s requirements to determine the products acceptance. With the proper application of geometric tolerances ensures the interchangeability of parts. GD&T is very rapidly becoming a common language throughout industry internationally.
Scope
This course will focus on interpreting and application of Geometric Dimensioning and Tolerancing (GD&T) based on ASME Y14.5 standard; simple design GD&T; dimensional metrology used in GD&T system; single segment, multi-segment and composite feature control frames; and the symbols use as communication tools.
The important information using GD&T system:
- The four major geometric characteristics; size, form, orientation and location
- The five family of geometric tolerances; form, orientation, location, runout and profile
- Form; straightness, flatness, circularity and cylindricity
- Orientation; parallelism, perpendicularity and angularity
- Location; concentricity, symmetry and position
- Runout; circular runout and total runout
- Profile; profile of a line and profile of a surface
- The modifiers; least material condition, maximum material condition, regardless of feature size, projected tolerance zone, tangent plane and free state.
- Tolerance zones; cylindrical, two parallel lines, two parallel planes, two concentric circles and two concentric cylinders
- Type of features; regular feature, irregular feature, feature of size and location dimension
- General rules for GD&T; regarding size tolerances, regarding tolerance modifiers, screw and gear rules, and datum features at virtual condition rule
- Datum; datum feature of size, datum simulator, datum surface, datum features patterns, compound datum and datum target
- Four steps to apply GD&T;
- Identify datum features to establish datums (origins of measurement).
- Control the datum features.
- Locate other features by using appropriate geometric controls.
- Refine with auxiliary datums, orientation, size and form as necessary.
Target Group
Designer & Drafting personnel, tool makers, machinist, engineers, inspectors and all others require to interpret or apply GD & T. This course will greatly help companies striving to obtain QS-9000/IATF16949 certification and who need to meet GD&T requirement.
Targeted Industries
Automotive, Aerospace, Engineering, Tooling, Fabrication, Mould maker, Medical devices manufacturer and all industries involving GD&T.
Training Objective
This training teaches the concepts of geometric dimensioning and tolerancing, GD&T and when properly applied to provide design assurance that the product will have the appropriate fit, form, function, and/or reliability. GD&T base on symbols and abbreviations (Universal Language)
according to ASME Y14.5 that are used to specify the rules and functional relationship between or within part features to give a direct bearing on how the part must be produced or inspected.
The universal language will help us easy to communicate among the designer, manufacturer, and inspector that may up to internationally to ensure the quality of the products that will be used by the end-users.
Once the trainee understands these concepts, then able to apply GD&T that used to complete explain and control the mechanical parts and determine the conformity of these parts through analyzing the measurement results. In order to ensure the conformity of the products, we need an appropriate measuring method that will properly evaluate the part feature being controlled.
Training Outcome
After seriously committed to this course, the trainee should be able to do the following:
- Understand certain importance terms are used in GD&T and the contents of a feature control frame that use as geometric control to the feature(s).
- Know the object consist of four major geometric characteristics with fourteen elements group into five family used to geometric controls for a mechanical part.
- Understand GD&T symbols and abbreviations are used to specify the functional relationship between or within part features and have specific rules about them that have a direct bearing on how the part must be inspected and produce.
- Understand types of features either regular or irregular that will decide which the geometric tolerance is suitable to attach at the feature.
- Understand the application of the modifiers, it helps to improve accept more functional parts by maximizing the tolerances that will increase productivity.
- Determine the bonus tolerance when the feature implied MMC or LMC and the virtual condition size when the feature is modified with MMC.
- Knowing the four practical steps of applying GD&T in engineering drawings that provide a design guarantee for the product to have the proper fit, form, function and/or reliability.
- Understand datum that is the starting point for the measurement and setting for the part to manufacture that will produce the products are according to designer intention, and calculation of measured tolerance zone.
- Understand a variety of inspection and gauging equipment, and gauging method that will properly evaluate the part feature being controlled.
- Demonstrate Proficiency in the requirements for the engineering drawing with the GD&T system and then increase interesting using the GD&T system, which is the complete specification for easy and complete communicates to others, which will be becoming increasingly important with the growing interrelated ownerships of companies around the world.
Methodology
Training slides, Demo Kits, Review Questions, Exercises, Case Study, Q&A, Test Before Training, Test After Training. (Optional: CMM measurement).
Timetable
Day
Time
Chapter References
from
to
9:00am
9:30am
Pre-Test (30 Objective Questions)
9:30am
10:00am
1) Introduction to Geometric Dimensioning and Tolerance
10:00am
10:15am
Morning tea break
10:15am
11:00am
2) The Modifiers of GD&T
11:00am
12:30pm
3) General Rules For GD&T
12:30pm
1:30pm
Lunch break
1:30pm
3:00pm
4) Symbols and Abbreviation
3:00pm
3:15pm
Tea Break
3:15pm
5:00pm
5) Datum
9:00am
10:00am
6) Form Controls
10:00am
10:15am
Morning tea break
10:15am
12:30pm
7) Orientation Controls
12:30pm
1:30pm
Lunch break
1:30pm
3:00pm
8) Location Controls
3:00pm
3:15pm
Tea Break
3:15pm
4:00pm
9) Composite Controls
4:00pm
5:00pm
10) Post Test (50 Objective Questions)
Outline
1 Introduction to Geometric Dimensioning & Tolerancing (GD&T)
1.1 Objective
1.2 History and Evolution
1.3 What is GD&T
1.4 The Importance of Standards
1.5 The Advantage of GD&T on Acceptance of Parts
1.6 Pertinent Definitions
1.7 Attachment of Feature Control Frames
1.8 The Application of GD&T
1.9 Tolerance Format and Decimal Places
1.10 Chapter Review Questions
2 The Modifiers of GD&T
2.1 Introduction to Geometric Tolerancing
2.2 The Modifiers and Tolerance Zones
2.3 Type of Geometric Tolerance Zones
2.4 Bonus Tolerances
2.5 Virtual Condition
2.6 MMC, LMC, RFS and Virtual Condition
2.7 Control Wall Thickness by Using LMC
2.8 Chapter Review Questions
3 General Rules For GD&T
3.1 Rule1: Regarding Size Tolerances
3.2 Rule 2: Regarding Tolerance Modifiers
3.3 Rule 3a: Pitch Diameter Rule
3.4 Rule 3b: Gears and Splines
3.5 Rule 4: Datum Features at Virtual Condition Rule
3.6 Chapter Review Questions
4 Symbols and Abbreviation
4.1 GD&T Symbols
4.1.1 Geometric Characteristics Symbols
4.1.2 Modifying Symbols
4.1.3 Dimensioning Symbols
4.1.4 New Added Symbols (ASME Y14.5M-2009)
4.1.5 New Added Symbols (ASME Y14.5-2018)
4.1.6 Basic Dimension Symbol
4.1.7 Datum Feature Symbol
4.1.8 Datum Target Symbol
4.2 Dimensioning Symbols Used in GD&T
4.3 New Symbols of ASME Y14.5M-2009
4.4 Chapter Review Questions
5 Datum
5.1 Introduction
5.2 Datum Identification Symbols
5.3 Datum
5.3.1 Establishing Datum
5.3.2 Datum Feature Symbols
5.3.3 Three Plane Concepts
5.3.4 Datum Feature Simulator
5.3.5 Datum Target
5.3.6 Datum Surface (Feature)
5.3.7 Datum Feature of Size
5.3.8 Datum of Features Patterns
5.4 Datum At MMC
5.5 Co-Datum
5.6 Feature of Size Datum Precedence
5.7 Chapter Review Questions
6 Form Controls
6.1 Introduction
6.2 Flat Surface
6.2.1 Straightness
6.2.2 Flatness
6.3 Round Surface
6.3.1 Transverse
6.3.2 Circularity
6.3.3 Cylindricity
6.3.4 Longitudinal
6.3.5 Surface Straightness
6.3.6 Axis Straightness
6.4 Chapter Review Questions
7 Orientation Controls
7.1 Introduction
7.2 Parallelism
7.3 Perpendicularity
7.4 Angularity
7.5 Chapter Review Questions
8 Location Controls
8.1 Introduction
8.2 Concentricity
8.3 Symmetry
8.4 Position
8.5 Chapter Review Questions
9 Composite Controls
9.1 Profile Tolerances
9.1.1 Symbol
9.1.2 Definition
9.1.3 Tolerances
9.1.4 Application
9.1.5 Boundary Control for Non-cylindrical Features
9.1.6 Profile of a Line
9.1.7 Profile of a Surface
9.2 Runout Tolerance
9.2.1 Symbol
9.2.2 Definition
9.2.3 Tolerances
9.2.4 Application
9.2.5 Circular Runout
9.2.6 Total Runout
9.3 Composite Feature Control Frames
9.3.1 Multi Single-Segments Feature Control Frames
9.3.2 Composite Profile Tolerance for Coplanarity Control
9.3.3 Composite Positional Tolerance for Pattern Location Control
9.3.4 Comparison Two Single-Segment and Composite Tolerancing
9.3.5 Verification of Composite Positional Tolerance
9.4 Chapter Review Questions
10 Review Questions
10.1 Thirty Multiple-Choice Questions (Hand-out)
10.2 Fifty Multiple-Choice Questions
11 Appendix (Terminology)
11.1 Technical Drawing
11.2 Geometric Dimensioning and Tolerancing
12 References
Programme scope, delivery arrangements and suitability are confirmed during enquiry.