DIMENSIONING AND TOLERANCING A COURSE MODULE IN CONCURRENT ENGINEERING FOR GATEWAY EEC PROJECT

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DIMENSIONING AND TOLERANCING A COURSE MODULE IN
CONCURRENT ENGINEERING FOR GATEWAY EEC PROJECT

• Dr. Jack Zhou
• Department of Mechanical Engineering and
  Mechanics
• Drexel University, Philadelphia, PA

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OVERVIEW

• Dimensioning
• Introduction / ANSI Standards
• Basic Concepts
• Arrow Heads
• Dimension Line Spacing
• Datum Dimensions
• Dimensioning of Various Shapes
• Tolerancing
• Dimensional Tolerances
• Fits
• Standard t Clearance
• Transition t Intereference
• Types of Tolerances
• Bilateral t Unilateral t Limit Dimesions

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INTRODUCTION TO DIMENSIONING

• A complete detail drawing includes multiviews
  and dimensions, which provide both shape and size
  descriptions. There are two classifications of
  dimensions
• Size Dimensions
• Location Dimensions

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ANSI (American National Standard Institute) The
ANSI standard document for dimensioning is titled
Dimensioning and Tolerancing ANSI Y14.5M. The
following eight fundamental rules for
dimensioning are adopted from ANSI Y14.5M. 1)
Each dimension shall have a tolerance, except for
those identified as reference, maximum,
minimum, or stock dimensions. 2) Dimensions
for size, form, and location of features shall be
complete to the extent that there is full
understanding of the characteristics of each
feature.
DIMENSIONING - ANSI STANDARDS
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DIMENSIONING - ANSI STANDARDS (Cont)
3) Each necessary dimension of an end product
shall be shown. No more than those necessary
for complete definition shall be given. 4)
Dimensions shall be selected and arranged to suit
the function and mating relationship of a part
and shall not be subject to more than one
interpretation. 5) The drawing should define
a part without specifying manufacturing
methods.
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DIMENSIONING - ANSI STANDARDS (Cont)
6) Dimensions should be arranged to provide
required information for optimum
readability. 7) Wires, cables, sheets, rods,
and other materials manufactured to gage or
code numbers shall be specified by linear
dimensions indicating the diameter or
thickness. 8) A 900 angle is implied where
centerlines and lines depicting features are
shown on a drawing at right angles and no angle
is specified.
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Dimension Line Spacing
DIMENSIONING - BASIC CONCEPTS
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Basic Arrowhead Style
DIMENSIONING - BASIC CONCEPTS (Cont)
Arrowheads
Optional Arrowhead Styles
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Datum Dimensioning
DIMENSIONING - DATUM
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DIMENSIONING - DATUM (Cont)
Datum DimensioningThis figure shows how
dimensions can be symmetrical about a center
plane used as a datum.
Center Plane Datum Exp.1
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DIMENSIONING - DATUM (Cont)
Datum Dimensioning
Center Plane Datum Ex.2
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DIMENSIONING - GENERAL
Dimensioning Cylindrical Shapes
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DIMENSIONING - GENERAL (Cont)
Square Shapes.
Dimensioning Square Features
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The followings are strongly suggested options for
correct and incorrect dimensioning. Always Try,
When possible.
DIMENSIONING - METHODS
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The following figures show both correct and
incorrect dimensioning methods.
DIMENSIONING - METHODS (Cont)
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DIMENSIONING - METHODS (Cont)
The following figures show both correct and
incorrect dimensioning methods.
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Dimensioning AnglesAngular surfaces may be
dimensioned as coordinates.
DIMENSIONING - ANGLES
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DIMENSIONING - ANGLES (Cont)
Dimensioning AnglesAngular surfaces may be
dimensioned as angles in degrees.
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DIMENSIONING - ANGLES (Cont)
Dimensioning AnglesAngular surfaces may
bedimensioned as a flat taper.
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Dimensioning Chamfers (External)
DIMENSIONING - CHAMFERS
External, Exp. 1
External, Exp. 2
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DIMENSIONING - CHAMFERS (Cont)
Dimensioning Chamfers (Internal)
Internal, Ex 2
Internal, Ex 1
Internal, Ex 3
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DIMENSIONING - CHAMFERS (Cont)
Dimensioning Chamfers (Others)
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DIMENSIONING - CONICAL
Dimensioning Conical Shapes
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DIMENSIONING - CONICAL (Cont)
Dimensioning Conical Shapes
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DIMENSIONING - ARCS
Example 1
Example 2
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DIMENSIONING - ARCS
Dimensioning Arcs
Example 3
Example 4
Example 5
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DIMENSIONING - ARCS
Dimensioning ArcsLong break symbol used to
shorten dimension and leader when actual center
will not fit on sheet.
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DIMENSIONING - ARCS
Dimensioning ArcsThe length of an arc may be
dimensioned as following three ways.
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DIMENSIONING - ARCS
Dimensioning ArcsThe length of an arc may be
dimensioned as following three ways.
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DIMENSIONING - ARCS
Dimensioning ArcsThe length of an arc may be
dimensioned as following three ways.
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DIMENSIONING - ARCS
Dimensioning ArcsA spherical radius may be
dimensioned with the abbreviation SR preceding
the numerical value, as shown
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DIMENSIONING - ARCS
Dimensioning ContoursCoordinates or
pointsalong the contour arelocated from
commonsurfaces or datum as shown.
Example 1
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DIMENSIONING - ARCS
Dimensioning ContoursCoordinates or
pointsalong the contour arelocated from
commonsurfaces or datum as shown.
Example 2
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TOLERANCING - INTRODUCTION

• Tolerances define the manufacturing limits for
  dimensions. All dimensions have tolerances
  either written directly on the drawing as part of
  the dimension or implied by a predefined set of
  standard tolerances that apply to any dimension
  that does not have a stated tolerance
• Specified Dimensions
• Dimensional Tolerance

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TOLERANCING - FITS
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TOLERANCING - FITS (Cont)
Clearance Fits
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TOLERANCING - FITS (Cont)
Interference FitsAn interference fit is the
condition that exist when, due to the limits of
the dimensions, mating parts must be pressed
together.
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Transition FitsH7/h6
Locational clearance fitH7/k6 or K7/h6
Locational transition fitH7/n6 or N7/h6
Locational transition fit
TOLERANCING - FITS (Cont)
Interference FitsH7/p6 or P7/h6 Locational
transition fitH7/s6 or S7/h6 Medium drive
fitH7/u6 or U7/h6 Force fit
Clearance FitsH11/c11 or C11/h11 Loose
running fitH9/d9 or D9/h9 Free running
fitH8/f7 or F8/h7 Close running
fitH7/g6 or G7/h6 Sliding fit
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Standard Hole Tolerance Range
TOLERANCING - FITS (Cont)
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Standard Shaft Tolerance Range
TOLERANCING - FITS (Cont)
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TOLERANCING - TYPES
Specific Tolerance Dimensioning Types Default
Tolerance
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TOLERANCING - TYPES (Cont)
Specific Tolerance Dimensioning Types Zero and
Bilateral Tolerance
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TOLERANCING - TYPES (Cont)
Specific Tolerance Dimensioning Types Limit
Tolerance and Basic Dimension
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Bilateral Tolerance
TOLERANCING - TYPES (Cont)
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Unilateral Tolerance
TOLERANCING - TYPES (Cont)
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TOLERANCING - TYPES (Cont)
Limit Dimensions