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Fundamental of GD&T

For Design, Industrial and QA Engineers

Background

Geometric Dimensioning and Tolerancing (GD&T) is the international symbolic language of precise definition of assembly parts. The language comprises a well-defined set of symbols, rules, definitions and conventions.

GD&T was developed to ensure compatibility and interchangeability of assembly parts (enhancing quality and reducing costs) using a standardized symbol set that allows the clear, measureable and repeatable expression of the design constraints.

Course Description

This course offers a solid basis of the principles, meaning and application of GD&T. It first reviews the needs that brought about the development of this discipline, continues to presenting a thorough examination of its principles, conventions and symbols and then describes the advantages of GD&T implementation from an organizational viewpoint.

Goals

  • Familiarization with the fundamental principles of GD&T and the meaning and application of its tolerances and its symbols
  • Understanding GD&T definitions and the impact of their application on material conditions, MMC (Maximum Material Condition) and LMC (Least Material Condition)
  • Reading and writing geometric requirement specifications using GD&T

Course Structure

  • Three days (24 academic hours)
  • Interactive workshop format including shared discussion, questions and practical exercises
    • This format requires limiting the number of participants per course to 16
  • Experience dictates the need for one additional day devoted to practical exercises that apply the learned material to example company parts and assemblies

Target Audience

The course is targeted for mechanical engineers/designers, quality assurance personnel and industrial engineers.

Course Instructor

Gili Omri is the course instructor. Mr. Omri is a development engineer with 20 years’ experience in mechanical design and an expert in GD&T. Mr. Omri is Israel’s first and only GD&T instructor with ASME certification at its highest level, Senior GDTP Certificate Holder.

Course Content

Introduction:

  • Principles of technical draftsmanship
  • Comparing actual measurements with geometrical tolerances
  • Basic GD&T nomenclature

Terminology:

  • Supplementary symbols in GD&T
  • The envelope rule
  • Basic measurements
  • Virtual condition
  • Granting tolerance bonuses

Form Controls:

Flatness, Straightness, Circularity and Cylindricity

Reference Frames and Datums:

  • Choosing the reference frame
  • Choosing the datum
  • Applying material conditions to datums from a measurement-dependent element
  • Datums from partial elements (Datum Targets)

Orientation Control:

Angularity, perpendicularity and parallelism of LMC, MMC and RFS (Regardless of Feature Size) material conditions

Position Control:

  • Definitions and standards
  • Material condition (RFS, MMC, LMC) advantages
  • Special applications

Runout Controls:

  • Circular runout
  • Total runout

Profile Controls:

  • Profile definition
  • Profile of a line
  • Profile of a surface

Geometric Requirements Specifications:

  • Identifying functional constraints
  • Writing functional constraints using GD&T
  • Reading functional constraints from geometrical tolerances

General review and summary exercise

Prerequisites:

  • Knowledge of and experience in reading technical (engineering) drawings

 

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