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DIMENSIONING & TOLERANCE

DIMENSIONING AND TOLERANCE

Dr. Jack Zhou Department of Mechanical Engineering and Mechanics Drexel University, Philadelphia, PA You can find a similar presentation in my website: http://www.mem.drexel.edu/faculty/zhou/teaching/mfgcourses/dim/

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DIMENSIONING & TOLERANCE

Dimensional and Geometric Tolerance Ideal 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

PARTS

Form, Orientation, Position Errors

Geometric Dimension Tolerance

After

Waviness

No Control Standard Yet

Manufacturing

Roughness

Surface Roughness

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DIMENSIONING & TOLERANCE

Flatness

Waviness

X 10 to 100

X 10 to 100 X 10 to 100

Roughness

Dimension Scale Relations of Four Errors DU

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DIMENSIONING & TOLERANCE

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 DU

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DIMENSIONING & TOLERANCE

TOLERANCING - FITS

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DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont) Clearance Fits

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DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont) Interference Fits An 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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DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont) Transition Fits The fit can have either clearance or interference.

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DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont)

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Interference Fits H7/p6 or P7/h6 H7/s6 or S7/h6 H7/u6 or U7/h6

= Locational transition fit = Medium drive fit = Force fit

Clearance Fits H11/c11 or C11/h11 H9/d9 or D9/h9 H8/f7 or F8/h7 H7/g6 or G7/h6

= Loose running fit = Free running fit = Close running fit = Sliding fit

Transition Fits H7/h6 H7/k6 or K7/h6 H7/n6 or N7/h6

= Locational clearance fit = Locational transition fit = Locational transition fit Copy Right @ Jack Zhou

DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont) Standard Hole Tolerance Range

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DIMENSIONING & TOLERANCE

TOLERANCING - FITS (Cont) Standard Shaft Tolerance Range

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES

Specific Tolerance Dimensioning Types: Default Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES (Cont)

Specific Tolerance Dimensioning Types: Zero and Bilateral Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES (Cont) Specific Tolerance Dimensioning Types: Limit Tolerance and Basic Dimension

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES (Cont) Bilateral Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES (Cont) Unilateral Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCING - TYPES (Cont) Limit Dimensions

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TOLERANCING - TYPES (Cont) Symmetric Tolerance

3.035 ± 0.015

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DIMENSIONING & TOLERANCE

Equations for Dimensional Tolerance 1. Hole tolerance: TH = Hmax – Hmin +0.021

2. Shaft tolerance: TS = Smax – Smin

Hole: 25

3. Maximum clearance: Cmax = Hmax – Smin

-0.007

Shaft: 25 4. Minimum clearance: Cmin = Hmin – Smax 5. Maximum interference: Imax = Hmin – Smax 6. Maximum interference: Imin = Hmax – Smin 7. Fit tolerance: TF = TH + TS

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0.0

-0.02

DIMENSIONING & TOLERANCE

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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DIMENSIONING & TOLERANCE

GEOMETRIC DIMENSIONING AND TOLERANCING (GDT)

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

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DIMENSIONING & TOLERANCE

SYMBOLS & ABBREVIATIONS

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Geometric Characteristics & Symbols

DIMENSIONING & TOLERANCE

DATUM REFERENCING

Datum Reference Frame DU

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DATUM FEATURE SYMBOL

Datum Feature DU

Datum Feature Symbol

DIMENSIONING & TOLERANCE

DATUM FEATURE SYMBOL (Cont)

Feature Surface and extension line DU

DIMENSIONING & TOLERANCE

DATUM FEATURE SYMBOL (Cont)

When the datum is the axis or center plane DU

DIMENSIONING & TOLERANCE

DATUM FEATURE SYMBOL (Cont)

When the datum is the axis DU

DIMENSIONING & TOLERANCE

DATUM FEATURE SYMBOL (Cont)

Where no geometrical tolerance and feature control frame used DU

DIMENSIONING & TOLERANCE

DATUM FEATURE SYMBOL (Cont)

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

DIMENSIONING & TOLERANCE

MAXIMUM MATERIAL CONDITION

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MMC

DIMENSIONING & TOLERANCE

LEAST MATERIAL CONDITION

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LMC

DIMENSIONING & TOLERANCE

TOLERANCES OF FORM Straightness

Straightness Tolerance Zone

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Straightness Tolerance

DIMENSIONING & TOLERANCE

TOLERANCES OF FORM Flatness

Flatness Tolerance Zone Flatness Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCES OF FORM Circularity

Circularity Tolerance Zone

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Circularity Tolerance

DIMENSIONING & TOLERANCE

TOLERANCES OF FORM Cylindricity Cylindricity Tolerance Zone

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Cylindricity Tolerance

DIMENSIONING & TOLERANCE

TOLERANCES OF ORIENTATION Perpendicularity Perpendicularity Tolerance Zone

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Perpendicularity Tolerance

DIMENSIONING & TOLERANCE

TOLERANCES OF ORIENTATION Angularity Angularity Tolerance Zone

Angularity Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCES OF ORIENTATION Parallelism

Parallelism Tolerance Zone

T: Tangent Plane

Parallelism Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCE OF PROFILE Profile Profile Tolerance Zone of Line

Profile Tolerance of Line

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DIMENSIONING & TOLERANCE

TOLERANCE OF PROFILE (Cont) Profile (Cont)

Profile Tolerance of Surface

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DIMENSIONING & TOLERANCE

TOLERANCE OF RUNOUT Runout

Circular Runout Tolerance Zone

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DIMENSIONING & TOLERANCE

TOLERANCE OF RUNOUT (Cont) Runout (Cont) Circular Runout Tolerance

Total Runout Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCE OF LOCATION Concentricity

Concentricity Tolerance Zone

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Concentricity Tolerance

DIMENSIONING & TOLERANCE

TOLERANCE OF LOCATION Position Position Tolerance Zone

Position Tolerance

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DIMENSIONING & TOLERANCE

TOLERANCE OF LOCATION Symmetry

Symmetry Tolerance Zone

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Symmetry Tolerance

DIMENSIONING & TOLERANCE

Home 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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DIMENSIONING & TOLERANCE

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