gps gdt sarar

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DIMENSIONING & TOLERANCE

DIMENSIONING AND TOLERANCE

Dr. Jack Zhou

Department of Mechanical Engineering and MechanicsDrexel University, Philadelphia, PA

You can find a similar presentation in my website:http://www.mem.drexel.edu/faculty/zhou/teaching/mfgcourses/dim/

Copy Right @ Jack Zhou

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Dimensional and Geometric ToleranceIdeal CAD drawings can have perfect dimensions and no errors

Manufactured products always have various manufacturing errors

Products Error Type Control Standard Dim. Scale

Dimensional Error Dimensional Tolerance Large

Small

PARTS Form, Orientation,Position Errors

Geometric DimensionTolerance

After Waviness No Control Standard Yet

Manufacturing Roughness Surface Roughness


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Flatness

Waviness

Roughness

X 10 to 100

X 10 to 100

X 10 to 100

Dimension Scale Relations of Four ErrorsCopy Right @ Jack Zhou

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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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DIMENSIONING & TOLERANCETOLERANCING - FITS


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TOLERANCING - FITS (Cont)Clearance Fits


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Interference FitsAn interference fit is the condition that exist when, due to thelimits of the dimensions, mating parts must be pressed together.

TOLERANCING - FITS (Cont)

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Transition FitsThe fit can have either clearance or interference.



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Transition FitsH7/h6 = Locational clearance fitH7/k6 or K7/h6 = Locational transition fitH7/n6 or N7/h6 = Locational transition 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

Interference FitsH7/p6 or P7/h6 = Locational transition fitH7/s6 or S7/h6 = Medium drive fitH7/u6 or U7/h6 = Force fit


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Standard Hole Tolerance RangeTOLERANCING - FITS (Cont)


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Standard Shaft Tolerance RangeTOLERANCING - FITS (Cont)


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TOLERANCING - TYPESSpecific 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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TOLERANCING - TYPES (Cont)Bilateral Tolerance


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Unilateral ToleranceTOLERANCING - TYPES (Cont)


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Limit DimensionsTOLERANCING - TYPES (Cont)


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TOLERANCING - TYPES (Cont)

Symmetric Tolerance

3.035 ± 0.015


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Equations for Dimensional Tolerance 1. Hole tolerance: TH = Hmax – Hmin

2. Shaft tolerance: TS = Smax – Smin

3. Maximum clearance: Cmax = Hmax – Smin

4. Minimum clearance: Cmin = Hmin – Smax

5. Maximum interference: Imax = Hmin – Smax

6. Maximum interference: Imin = Hmax – Smin

7. Fit tolerance: TF = TH + TS

Hole: 25+0.021

0.0

Shaft: 25-0.007

-0.02

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Home work

1. Find TH, Ts, Tf, Cmax, Cmin, and what kind of fit it is ? Hole Φ 50 upper deviation +0.041, lower deviation 0.0 Shaft Φ 50 upper deviation -0.014, lower deviation -0.040

2. Find TH, Ts, Tf, Cmax, Imax, and what kind of fit it is ? Hole Φ 25 upper deviation +0.021, lower deviation 0.0 Shaft Φ 25 upper deviation +0.028, lower deviation +0.015

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GEOMETRIC DIMENSIONING AND TOLERANCING (GDT)

Dr. Jack Zhou

Department of Mechanical Engineering and MechanicsDrexel University, Philadelphia, PA

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DIMENSIONING & TOLERANCESYMBOLS & ABBREVIATIONS

Geometric Characteristics & Symbols

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DATUM REFERENCING

Datum Reference Frame

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DIMENSIONING & TOLERANCEDATUM FEATURE SYMBOL

Datum Feature SymbolDatum Feature

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DIMENSIONING & TOLERANCEDATUM FEATURE SYMBOL (Cont)

Feature Surface and extension line

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When the datum is the axis or center plane

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When the datum is the axis

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Where no geometrical tolerance and feature control frame used

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When the feature controlled is the datum axis/datum center plane

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MAXIMUM MATERIAL CONDITION

MMC

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LEAST MATERIAL CONDITION

LMC

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TOLERANCES OF FORM

Straightness

Straightness Tolerance Zone

Straightness Tolerance

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DIMENSIONING & TOLERANCETOLERANCES OF FORM

Flatness

Flatness Tolerance Zone

Flatness Tolerance

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Circularity

TOLERANCES OF FORM

Circularity Tolerance Zone

Circularity Tolerance

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CylindricityTOLERANCES OF FORM

Cylindricity Tolerance Zone

Cylindricity Tolerance

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Perpendicularity

TOLERANCES OF ORIENTATION

Perpendicularity Tolerance Zone

Perpendicularity Tolerance

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Angularity


Angularity Tolerance Zone

Angularity Tolerance

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Parallelism


Parallelism Tolerance Zone

Parallelism Tolerance

T: Tangent Plane

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Profile

TOLERANCE OF PROFILE

Profile Tolerance Zone of Line

Profile Tolerance of Line

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Profile (Cont)

TOLERANCE OF PROFILE (Cont)

Profile Tolerance of Surface

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DIMENSIONING & TOLERANCETOLERANCE OF RUNOUT

Runout

Circular Runout Tolerance Zone

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Runout (Cont)TOLERANCE OF RUNOUT (Cont)

Circular Runout Tolerance

Total Runout Tolerance

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ConcentricityTOLERANCE OF LOCATION

Concentricity Tolerance Zone

Concentricity Tolerance

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Position Tolerance Zone

Position

TOLERANCE OF LOCATION

Position Tolerance

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Symmetry

TOLERANCE OF LOCATION

Symmetry Tolerance Zone

Symmetry Tolerance

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DIMENSIONING & TOLERANCEHome work

If a shaft is 10±0.05 inch what is its maximum and minimum material conditions.

Please draw circularity and perpendicularity symbol blocks and tolerance zones for a cylinder and a upside down T shape block, respectively.

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gps gdt sarar

Documents

errorscopy right

default tolerancecopy

force fitcopy right

basic dimensioncopy

limit tolerance

stated tolerance

perfect dimensions

locational transition