geometrical tolerances

Geometrical Tolerances

By Hassan Habib

Objectives

• Introduction to Dimensions

• Terminologies

• Important Fundamental Rules

• Basics about Dimensioning

• Dimensioning Features

• Introduction to Tolerances

• Applications

• Direct Tolerancing Methods

• Tolerance Expressions

• Tolerancing on various Features

Introduction to Dimensions

• About The Standard ASME Y14.5

• The need of Dimensions

• Historical Perspective

Introduction to Dimensions

• Terminologies

• Dimension (Basic, Reference)

• Geometric Tolerance

• Datum

• Feature

• Feature Control Frame

• MMC & LMC

Introduction to Dimensions

• Important Fundamental Rules

• Each dimension should have a tolerance

• It should fully define the geometry with no room left for assumptions or over definition

• The dimensions define the finished part, any processing required should be specified

• There should be only one interpretation of every dimension

• Dimensions are valid only where they are specified

Introduction to Dimensions

•Types of dimensioning

• Millimeter dimensioning

• Zero precedes when the dimension is less than 1 mm.

• In case of whole number neither the decimal point nor the 0 is shown

• Last digit of fractional dimension is not followed by a zero

Introduction to Dimensions

•Types of dimensioning

• Millimeter dimensioning

Introduction to Dimensions

•Types of dimensioning

• Inch dimensioning

• Zero does not precede when the dimension is less than 1 in.

• A dimension is expressed in the same number of zeroes as the tolerances

Introduction to Dimensions

•Types of dimensioning

• Inch dimensioning

Introduction to Dimensions

• Basics of Dimensions

• Dimension Lines

• Alignment

• Spacing

Introduction to Dimensions

• Basics of Dimensions

• Extension Lines

• Crossing of extension lines

Introduction to Dimensions

• Basics of Dimensions

• Chain Lines

• Leader Lines

Introduction to Dimensions

• Basics of Dimensions

• Reference Dimensions

Introduction to Dimensions

• Dimensioning various features

• Radii

Introduction to Dimensions

• Dimensioning various features

• Foreshortened Radii

Introduction to Dimensions

• Dimensioning various features

• Irregular Outlines

Introduction to Dimensions

• Dimensioning various features

• Counter bore Holes

Introduction to Dimensions

• Dimensioning various features

• Counter sunk Holes

Introduction to Dimensions

• Dimensioning various features

• Spotfaced Holes

Introduction to Dimensions

• Dimensioning various features

• Chamfers

Introduction to Dimensions

• Dimensioning various features

• Location

Introduction to Dimensions

• Dimensioning various features

• Location

Introduction to Dimensions

• Dimensioning various features

• Repetitive features

Introduction to Dimensions

• Dimensioning various features

• Repetitive features

Introduction to Dimensions

• Dimensioning various features

• Repetitive features

Introduction to Tolerances

• Application of Tolerances

• As direct limits

• As a geometric tolerance

• In a note or table referring to specific dimensions

• In a general tolerance block referring to all dimensions on a drawing for which tolerances are not otherwise specified

Introduction to Tolerances

•Direct Tolerancing Methods

• Limit Dimensioning

Introduction to Tolerances

•Direct Tolerancing Methods

• Plus and Minus Tolerancing

Introduction to Tolerances

•Tolerance Expression

• Millimeter Tolerance

• Inch Tolerance

Introduction to Tolerances

•Tolerance Accumulation

• Chain Dimensioning

Introduction to Tolerances

•Tolerance Accumulation

• Base Line Dimensioning

Introduction to Tolerances

•Tolerance Accumulation

• Direct Dimensioning

Introduction to Tolerances

•Tolerance Accumulation

• Dimensional Limits related to an origin

Introduction to Tolerances

•Tolerance Accumulation

• Dimensional Limits related to an origin

Introduction to Tolerances

•Tolerancing on different features

• Screw Threads

• Gears and Splines

Introduction to Tolerances

•Tolerancing on different features

• Angular Surfaces

Introduction to Tolerances

•Tolerancing on different features

• Conical Tapers

Introduction to Tolerances

•Tolerancing on different features

• Radii

Introduction to Tolerances

•Tolerancing on different features

• Radii

Introduction to Tolerances

•Tolerancing on different features

• Statistical Tolerancing

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