GEOMETRIC DIMENSIONING AND TOLERANCING (GD&T)

INTRODUCTION FOR GEOMETRIC DIMENSIONING AND TOLERANCING (GD&T)

Geometric dimensioning and tolerancing (GD&T) is a language used on mechanical engineering drawings composed of symbols that are used to efficiently and accurately communicate geometry requirements for associated features on components and assemblies. GD&T is, and has been, successfully used for many years in the automotive, aerospace, electronic and the commercial design and manufacturing industries.

Success oriented industries and organizations which, require accurate and common lines of communications between engineering, design, manufacturing and quality should consider geometric dimensioning and tolerancing (GD&T) as their mechanical drawing standard.

COURSE OBJECTIVES

At the conclusion of this 2 days program, participants will be able to:

• Gain knowledge on what GD&T is all about
• Explain the benefits of geometric tolerancing
• Learn how to apply GD&T in their job
• Able to interpret customers requirements from the design drawing
• Understand the problems in manufacturability
• Be reminded of the Do’s & Don’t’s of proper tolerancing
• Able to set quality control criteria from design drawing
• Identify datum features and determine their order of precedence
• Identify and interpret each of the characteristic symbols
• Describe the material condition modifiers and how “bonus” tolerance occurs
• Correctly interpret GD&T feature control frames, and explain the impact on manufacturing and inspection

COURSE CONTENTS

Day 1: 9am – 5pm

1. Introduction to GD&T

1. 1. Limitations of coordinate tolerancing
   2. Advantages of GD&T
   3. Exercise 1

2. Standards

1. 1. Latest GD&T revision & governing body
   2. Exercise 2

3. Dimensioning & tolerancing fundamentals

1. 1. Basic dimension
   2. Critical dimension
   3. Reference dimension
   4. Feature control frame
   5. Exercise 3
      

4. Common symbols used in GD&T

1. 1. New symbols from rev 2009 Y14.5
   2. Exercise 4

5. Rules for drawing & design

1. 1. Rule #1
   2. Rule #2
   3. iii. Bonus Tolerance
   4. GD&T applied to a feature of size
   5. Bonus and the MMC modifier
   6. Virtual condition
   7. Gauging and inspection using GD&T
   8. Exercise 5

6. Datums

1. 1. Datum vs. datum feature
   2. The datum reference frame
   3. Primary, secondary, and tertiary datums
   4. Exercise 6

Day 2: 9am – 5pm

7. Forms

1. 1. Straightness

1. 1. 1. Straightness Brief
      2. Line Element Straightness
      3. Design
      4. Tooling / production
      5. Inspection

1. 1. Flatness

1. 1. 1. Flatness Brief
      2. Surface Flatness
      3. Design
      4. Tooling / production
      5. Inspection

1. 1. Roundness
   2. Cylindricity
   3. Exercise 7

8. Profiles

1. 1. Line profile
   2. Surface profile
   3. Exercise 8
      

9. Orientation

1. 1. Angularity
   2. Perpendicularity
   3. iii. Parellelism
   4. Exercise 9

10. Location

1. 1. Position

1. 1. 1. True position
      2. Position tolerance RFS
      3. Using MMC or LMC
      4. The “boundary” concept
      5. The pitch diameter rule

1. 1. Symmetry
   2. Concentricity
   3. Exercise 10

11. Runout

1. 1. Circular runout
   2. Total runout
   3. Exercise 11

12. Common issues/errors faced

1. 1. Exercise 12