Geometric Dimensioning Tolerancing 102

REV. A

ASME Y14.5M, 1994

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 2 of 102

8. Location Tolerance .......................................... 83

7. Runout Tolerance ............................................ 75

6. Profile Tolerance ............................................. 65

5. Orientation Tolerance ...................................... 54

4. Form Tolerance ............................................... 46

3. Datum .............................................................. 19

2. Geometric Characteristics and Symbols ........... 8

1. General Rules.................................................... 3

Table of Contents

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

n19.9(MMC)

n20.1 (MMC)

n20.1 (LMC)

Page 3 of 102

b) Where the actual local size of a feature has departed from MMC toward Least Material Condition (LMC), a variation in form is allowed equal to the amount of such departure.

n19.9 (LMC)

n19.9(MMC)

n20.1 (LMC)

+0.1 n20 -0.1

INTERNAL FEATURE

n19.9(LMC)

BOUNDARY OF PERFECT FORM AT MMC

n20.1 (MMC)

n20 -0.1

+0.1

EXTERNAL FEATURE

1.1.3. Variations of Form (Envelope Principle) a) The surface or surfaces of a feature shall not extend beyond a boundary (envelope) of perfect form at Maximum Material Condition (MMC). This boundary is the true geometric form represented by the drawing. No variation in form is permitted if the feature is produced at its MMC limit of size.

1.1.2. Variations of Size The actual size of an individual feature at any cross-section shall be within the specified tolerance of size.

1.1.1. Individual Feature of Size Where only a tolerance of size is specified, the limits of size of an individual feature prescribe the extent to which variations in its geometric form and size are allowed.

1.1. Rule 1 – Limits of Size

1. General Rules

Geometric Dimensioning & Tolerancing

j n0.5m Am

j n0.5m A

Page 4 of 102

A MAJOR n

j n0.5 A MAJOR n

1.4. Pitch Rule a) Each tolerance of orientation or position and datum reference specified for a screw thread applies to the axis of the thread derived from the pitch cylinder.

1.3. Rule 3 All other controls is implied Regardless of Feature Size (RFS).

j n0.5 A

FOR ALL Applicable Geometric Tolerances: RFS applies will respect to the individual tolerance, datum reference, or both, where NO MODIFYING SYMBOL is specified. . “ASME Y14.5-1994”

They may be datum features or other features whose axes or centre planes are controlled by geometric tolerances.

1.2. Rule 2 – Applicability of Feature Size Applicability of material condition modifier (RFS, MMC, LMC) is limited to features subject to variations in size.

Features shown perpendicular, coaxial, or symmetrical to each other must be controlled for location or orientation to avoid incomplete drawing requirements.

1.1.4. Relationship between Individual Features The limits of size do not control the orientation or location relationship between individual features.

LMC SIZE

ASME Y14.5M-1994

c) There is no requirement for a boundary of perfect form as LMC.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

VC = Size MMC – Tolerance VC = Size LMC + Tolerance

VC = Size MMC + Tolerance VC = Size LMC – Tolerance

HOLE:

PIN:

Page 5 of 102

The virtual condition of a feature is the extreme boundary of that feature which represents the ‘worst case’ for, typically, such concerns as a clearance of fit possibility relative to a mating part or situation.

1.5. Virtual Condition A constant boundary generated by the collective effects of a size feature’s specified MMC or LMC material condition and the geometric tolerance for that material condition.

External Thread (screw)

PD n

Internal Thread (tapping)

A PD n

j n0.5 A

b) Each tolerance of orientation or position and datum reference specified for features other than screw threads, such as gears and splines, must designate the specific feature to which each applies.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 6 of 102

12. What is the MMC of the feature shown below?

n15.00+0.25

________________________________________________________________________

________________________________________________________________________

11. Define Maximum Material Condition (MMC).

10. Give an example of a unilateral tolerance. _____________________

9. Give an example of an unequal bilateral tolerance. ______________

8. Give an example of an equal bilateral tolerance. ________________

7. What is the nominal dimension of the dimension shown in question 5? ___________________

6. What is the tolerance of the dimension in question 5?____________

5. What are the limit of the dimension 25±0.4? ___________________

4. All Dimensions shall have a tolerance except for dimensions that are identified as: a) reference. b) maximum. c) minimum. d) stock sizes. e) all of the above.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

3. Define Tolerance.

2. _________________ is a general term applied to a physical portion of a part.

1.6. Exercise 1. A(n) _________________ is a numerical value expressed in appropriate units of measure, indicated on a drawing and in documents to define the size and/or geometric characteristics and/or locations of features of a part.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

____________________________________________________

____________________________________________________

2)

3)

n

19.43 19.18 n

19.76 19.50

______________________________________________________

Page 7 of 102

18. Is the fit between the two parts shown below a clearance or a force fit?

____________________________________________________

1)

17. List the three general groups related to the standard ANSI fits between mating parts.

16. What is the LMC of the feature shown in question 13? ___________

15. What is the LMC of the feature shown in question 12? ____________

_____________________

________________________________________________________________________

________________________________________________________________________

14. Define Least Material Condition (LMC).

n15.00+0.25

13. What is the MMC of the feature shown below? _________________

Geometric Dimensioning & Tolerancing

Form

Type of Tolerance

Page 8 of 102

Runout

Location

For Profile Individual or Related Features For Related Orientation Features

For Individual Features

2.1. Symbol

h t

h t Total Runout

i Circular Runout

i

r Symmetry

r

f

f Parallelism

j

b

b Perpendicularity

j

a

a Angularity

Concentricity

d

d Profile of a Surface

Position

k

g

g

Cylindricity

k

e

e

Circularity Profile of a Line

c

c

u

u

Symbol ISO

Flatness

Symbol ASME Y14.5M-1994

ASME Y14.5M-1994

Straightness

Characteristic

2. Geometric Characteristics and Symbols

Geometric Dimensioning & Tolerancing

Statistical Tolerance

Free State

ST

F

T

z

Tangent Plane

Page 9 of 102

NONE

F

T

z

y

NONE

CR

Controlled Radius

y

SR

SR

Spherical Radius

Slope

R

R

Radius

Conical Taper

10

10

Arc Length

Between NONE

x

x

Depth

All Round

w

w

Countersink

o

o

Square X

Sn

Sn

Spherical Diameter

v

n

n

Diameter

X

p

p

Projected Tolerance Zone

v

NONE

NONE

Regardless of Feature Size

Counterbore

l

l

At Least Material Condition

Number of Places

m

ISO

m

ASME Y14.5M

ASME Y14.5M-1994

At Maximum Material Condition

Symbol for:

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

R

Page 10 of 102

On drawing

12.7 12.3

12.7 CR 12.3

Controlled Radius, CR

On drawing

Radius, R

Meaning

Part contour must be a fair curve with no reversals. All radii points must be 12.3 min to 12.7 max.

Max Radius 12.7

Min Radius 12.3

Meaning

Part contour must fall within zone defined by Max and Min radius tolerance

Max Radius 12.7

Min Radius 12.3

There are two types of radii tolerance that can be applied, the radius and controlled radius. The radius (R) tolerance is for general applications. The controlled radius (CR) is used when it is necessary to place further restrictions on the shape of the radius, as in high stress applications.

Radius, Controlled Radius

Geometric Dimensioning & Tolerancing

20.2 19.8

0.5

0.2

A

B

A

n

B

16.1 15.9

Page 11 of 102

NOTE: FEATURES INDENTIFIED AS STATISTICAL TOLERANCE SHALL BE PRODUCED WITH STATISTICAL PROCESS CONTROLS, OR TO THE MORE RESTRICTIVE ARITHMETIC LIMITS

n

16.07 n 15.93

Statistical Tolerance may be applied to features to increase tolerances and reduce manufacturing cost. To ensure compatibility, the larger tolerance identified by the statistical tolerance symbol may only be used where appropriate statistical process control will be used. A note such as the one shown below shall be placed on the drawing.

2 SURF 2 SURF

5.6

Page 12 of 102

M

36.8

B

n 0.2

4X n 5.4 - 5.6

UNLESS OTHERWISE SPECIFIED, ALL UNTOLERANCED DIMENSIONS ARE BASIC. PART IS TO BE RESTRAINED ON DATUM A WITH 4 5M SCREWS

32

A

3 F

A

The free state symbol means that dimensions and tolerances that have the free state symbol applied are checked in the free state and not in the restrained condition.

A note or specification on the drawing should explain how the part is restrained and the force required to facilitate the restraint. A sample note can be found on the drawing below.

65

Statistical tolerancing is the assignment of tolerances to related components of an assembly on the basis of sound statistics. An example is, the assembly tolerance is equal to the square root of the sum of the squares of the individual tolerance.

Unless otherwise specified, all dimensioning and tolerancing applies in a free state condition with no restraint. Some parts, such as sheet metal, thin metal, plastics and rubber are non-rigid in nature. It may be necessary to specify design requirements on the part in a natural or free state as well as in a restrained condition. The restraint or force on the nonrighi9d parts is usually applied in such a manner to resemble or approximate the functional or mating requirements.

ASME Y14.5M-1994

Often, tolerances are calculated on an arithmetic basis. Tolerances are assigned to individual features on a component by dividing the total assembly tolerance by the number of components and assigning a portion of this tolerance to each component. When tolerances are stacked up in this manner, the tolerance may become very restrictive or tight.

Geometric Dimensioning & Tolerancing

Free State

ASME Y14.5M-1994

Statistical Tolerance

Geometric Dimensioning & Tolerancing

25

128

129, 406, 1101, 1660, R1661, 2692, 5455, 5458, 5459, 7083, 8015, 10579; (also 14660-1 & 14660-2)

6410-1, 6410-2, 6410-3

Y14.3 – Sections & Views

Y14.5 – Dimensioning & Tolerancing

Y14.6 – Screw Thread Representation

Y14.36 – Surface Texture Symbols

Page 13 of 102

1302

3098

Y14.2 – Lines & Lettering

Y14.8 – Casting & Forgings

ISO Standards

ASME Y14.5M-1994

ASME Y14 Series

Geometric Dimensioning & Tolerancing

Page 14 of 102

Datum Target Line

Datum Target Point

Datum Target Area

Feature Control Frame

Dimension Origin

Ø8 A1

A1

A1

Ø 0.5

M

A1

Ø20

A B C

(68)

Reference Dimension (auxiliary dimension in ISO) Datum Feature

65

A

A

ASME Y14.5M-1994

Basic Dimension (theoretically exact dimension in ISO)

Geometric Dimensioning & Tolerancing

Geometric Charactieristic Overview

Applicability of Datum Modifiers

Controls

Applicability of Feature Modifiers

2D or 3D

Symbol

N/A

u

Form

u

Straightness Line Element

Datums NOT allowed

Characteristic

Type of Tolerance

Datums

N/A

Straightness Axis or Median Plane

Axis or Surface Median Plane

No

X

2D

N/A

Yes

X

3D

N/A

No

3D

c

Flatness

X

No

N/A

No

2D

e

Circularity

X

3D

g

Cylindricity

X

Yes if size features

No

X

2D

k

Yes if size features

No

3D

d

Profile of a Surface

X

3D

j

Position

M

Profile of a Line

Profile

Datums Required

O

Yes

Yes if size features

X

No

No

No

No

3D

r

N

3D

i

Concentricity

N

Yes if size features Yes if size features X

Symmetry

Location

ASME Y14.5M-1994

3D Q b Perpendicularity

X 3D Q a Angularity Orientation Datums Requied

Yes if size features Yes if size features Parallelism

X 3D Q f

X

X

Yes if size features X

No No

Yes if size features 2D h

Page 15 of 102

Runout

Circular Runout

X

No No X 3D t Total Runout

P

Geometric Dimensioning & Tolerancing

There are special case where position and profile may not require datums These characteristics control opposing median points Can also control surface boundary Can control form, orientation and location These characteristics can be made 2D by writing “LINE ELEMENTS” under the feature control frame

M N O P Q

ASME Y14.5M-1994

___________________ ___________________ ___________________

k d j

Page 16 of 102

___________________

g

___________________

___________________

c e

___________________

u

___________________

___________________

h t

___________________

___________________

___________________

___________________

___________________

b

a

f

i

r

3. Name each of the following geometric characteristic symbols.

e) ____________________________________________________________

d) ____________________________________________________________

c) ____________________________________________________________

b) ____________________________________________________________

a) ____________________________________________________________

2. Name the five types of geometric characteristic symbols.

e) ____________________________________________________________

d) ____________________________________________________________

c) ____________________________________________________________

b) ____________________________________________________________

a) ____________________________________________________________

1. List the five basic types of geometric dimensioning and tolerancing symbols.

A dimensioning and tolerancing template is recommended for drawing proper symbols on this test and on future tests.

2.2 Exercise

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

ASME Y14.5M-1994

(G)

(F)

(E)

(D)

Page 17 of 102

___________________ ___________________ ___________________ ___________________

Sn X v w

Page 18 of 102

___________________

___________________

___________________

CR

SR

___________________

R

(B)

(C)

___________________

n

11. Name the following symbols.

(A)

j n0.05m A Bm C

o

r

___________________

___________________

___________________

___________________

___________________

___________________

65

ST

___________________

___________________

z ___________________

y

x

(68)

______________________________________

__________________________________________________________________________

______________________________________

8. Label the parts of the following feature control frame.

__________________________________________________________________________

10. How are basic dimensions shown on a drawing?

__________________________________________________________________________

__________________________________________________________________________

7. What information is placed in the top half of the datum target symbol?

__________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

6. What information is placed in the lower half of the datum target symbol?

__________________________________________________________________________

__________________________________________________

__________________________________________________________________________

__________________________________________________________________________

9. Completely define the term “basic dimension”.

Geometric Dimensioning & Tolerancing

__________________________________________________________________________

5. When may datum feature symbols be repeated on a drawing?

____.

4. Any letter of the alphabet can be used to identify a datum except for ____, ____, or

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 19 of 102

Datum plane: The theoretically exact plane established by the true geometric counterpart of the datum feature.

Simulated datum: The plane established by the inspection equipment such as a surface plate or inspection table.

Datum feature: The actual surface of the part.

By the above definition, a datum on an engineering drawing is always assumed to be “perfect”. However, since perfect parts cannot be produced, a datum on a physically produced part is assumed to exist in the contact of the actual feature surface with precise manufacturing or inspection equipment such as machine tables, surface plates, gage pins, etc. These are called datum simulators which create simulated datum planes, axes, etc., and, while not perfectly true, are usually of such high quality that they adequately simulate true references. This contact of the actual feature with precise equipment is also assumed to simulate functional contact with a mating part surface.

Every feature on a part can be considered a possible datum. That is, every feature shown on a drawing depicts a theoretically exact geometric shape as specified by the design requirements. However, a feature normally has no practical meaning as a datum unless it is actually used for some functional relationship between features. Thus a datum appearing on an engineering drawing can be considered to have a dual nature: it is (1) a “construction” datum, which is geometrically exact representation of any part feature, and (2) a “relationship” datum, which is any feature used as a basis for a functional relationship with other features on the part. Since the datum concept is used to establish relationships, the “relationship” datum is the only type used on engineering drawings.

A datum is a theoretically exact point, axis, or plane derived from the true geometric counterpart of a specified datum feature. A datum is the origin from which the location of geometric characteristics of features of a part are established. Datums are established by specified features or surfaces. Where orientation or position relationships are specified from a datum, the features involved are located with respect to this datum and not with respect to one another.

3.1. Datum Concepts

3. Datum

Geometric Dimensioning & Tolerancing

Part

Simulated Datum Surface of manufacturing or verification equipment

Datum Plane – theoretically exact

ASME Y14.5M-1994

Page 20 of 102

ESTABLISH PRIMARY DATUM PLANE (MIN 3 POINT) CONTACT WITH DATUM SURFACE A

MEASURING DIRECTION FOR RELATED DIMENSIONS

90O

90O

90O

90O

ESTABLISH TERTIARY DATUM PLANE (MIN 1 POINT) CONTACT WITH DATUM SURFACE C

ESTABLISH SECONDARY DATUM PLANE (MIN 2 POINT) CONTACT WITH DATUM SURFACE B

Generally three datum features are selected that are perpendicular to each other. These three datums are called the datum reference frame. The datums that make up the datum reference frame are referred to as the primary datum, secondary datum, and tertiary datum. As their names imply, the primary datum is the most important, followed by the other two in order of importance.

Datum features are selected based on their importance to the design of the part.

3.2. Establishing Datum Planes

Datum Feature

Geometric Dimensioning & Tolerancing

Datum Axis

Datum Planes origin of measurement

90o

Direction of measurements

Datum Axis

Datum Axis

ASME Y14.5M-1994

C

A

Datum Feature Symbol placed on edge view of surface or extension line from edge view

B

C

A

30

B

Angled Surface

Page 21 of 102

Surface Datum Feature Symbol must be offset from dimension line arrowheads

D

When a surface is used to establish a datum plane on a part, the datum feature symbol is placed on the edge view of the surface or on an extension line in the view where the surface appears as a line. A leader line may also be used to connect the datum feature symbol to the view in some applications.

3.3. Datum Identification

90o

Datum Point

90o

Geometric Dimensioning & Tolerancing

50 10

30

Y

AXIS

X

B

n80

A

PART

Y TERTIARY DATUM

A n12

A

D

Ø 0.4 M

n12

n12

A

X SECONDARY DATUM

n12

A

PRIMARY DATUM PLANE

DATUM AXIS

C B A

Placement of the Datum Feature Symbol for a Datum Axis

30

Page 22 of 102

30

30

ASME Y14.5M-1994

A cylindrical object may be a datum feature. When the cylindrical datum feature is used, the centre axis is known as the datum axis. There are two theoretical planes intersecting at 90º. These planes are represented by the centrelines of the drawing. Where these planes intersect is referred to as the datum axis. The datum axis is the origin for related dimensions, while the X and Y planes indicate the direction of measurement. A datum plane is added to the end of the object to establish the datum frame.

3.4. Datum Axis

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

DATUM FEATURE SIMULATOR

DATUM FEATURE SIMULATOR

SIMULATED DATUM LARGEST INSCRIBED CYLINDER

Page 23 of 102

Simulated datum axis for an internal datum feature

DATUM AXIS

DATUM FEATURE (PART)

Simulated datum axis for an external datum feature

DATUM AXIS

SIMULATED DATUM SMALLEST CIRCUMSCRIBED CYLINDER

DATUM FEATURE (PART)

Simulated datum axis The simulated datum axis is the axis of a perfect cylindrical inspection device that contacts the datum feature surface. For an external datum feature, the inspection device is the smallest (MMC) circumscribed cylinder. The inspection device for an internal datum feature is the largest (MMC) inscribed cylinder.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

SIMULATED PAIR OF COAXIAL CIRCUMSCRIBED CYLINDERS

B

Page 24 of 102

A specific feature such as the major diameter should be identified when a gear or spline is used as a datum axis. When this is done, the note “MAJOR DIA”, “MINOR DIA”, or “PITCH DIA” is placed next to the datum feature symbol as appropriate. The use of a screw thread, gear, or spline should be avoided for use as a datum axis unless necessary.

When a screw thread is used as a datum axis, the datum axis is established from the pitch cylinder unless otherwise specified. If another feature of the screw thread is desired, then note “MAJOR DIA” or “MINOR DIA” is placed next to the datum feature symbol.

3.6. Datum Axis of Screw Threads, Gears, and Splines

THE MEANING

THE DRAWING

A

t 0.2 A-B

Coaxial means two or more cylindrical shapes that share a common axis. Coaxial datum features exist when a single datum axis is established by two datum features that are coaxial. When more than one datum feature is used to establish a single datum, the datum reference letters are separated by a dash and placed in one compartment of the feature control frame. These datum reference letters are of equal importance and may be placed in any order.

3.5. Coaxial Datum Features

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Datum Center Plane

12

B

28

A

C

Page 25 of 102

j 0.2 m A Bm

12

Datum Center Plane

A

12

Elements on a rectangular shaped symmetrical part or feature may be located and dimensioned in relationship to a datum centre plane. The representation and related meaning of datum center plane symbols are as shown in the following.

3.7. Datum Center Plane

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 26 of 102

Datum Feature Simulator

Datum Center Plane A

Datum Feature Simulator

True geometric counterpart of datum feature A parallel planes at maximum separtation (MMC)

Datum Center Plane A

Datum Feature A

Datum Feature A

True geometric counterpart of datum feature A parallel planes at mimimum separtation (MMC)

The simulated datum centre plane is the centre plane of a perfect rectangular inspection device that contacts the datum feature surface. For an external datum feature the datum centre plane is established by two parallel planes at minimum (MMC) separation. For an internal datum feature, the datum centre plane is established by two parallel planes at maximum (MMC) separation.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

n30

6X 60 o

A

Page 27 of 102

Datum Axis B

B

j n0.05m A

6X n 8.4 8.0

The center of a pattern of features, such as the holes in the part may be specified as the datum axis when the datum feature symbol is placed under, and attached to, the middle of the feature control frame. In this application, the datum axis is the center of the holes as a group.

3.8. Pattern of Holes as a Datum

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 28 of 102

M

20

M

20

L

45

Datum Target Area Area Shown

L

Datum Target Point

45

N

N

n12 N1

N1

N1

M

20

45

Datum Target Area Area Not Shown

L

Datum Target Line

45

n6 N1

N1

N1

N

N

In many situations it is not possible to establish an entire surface, or entire surfaces, as datums. When this happens, then datum targets may be used to establish datum planes. This procedure is especially useful on parts with surface or contour irregularities, such as some sheet metal, sand cast, or forged parts that are subject to bowing or warpage. This method can also be applied to weldments where heat may cause warpage. Datum targets are designated points, lines, or surface areas that are used to establish the datum reference frame.

3.9. Datum Targets

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

X1

X2

Datum Plane X

X1, X2

40

15

Datum Feature

The Part

50

X3

50

Locating Pins

The Fixture Setup

15

Page 29 of 102

X3

The Drawing

35

15

When datum target points are used on a drawing to identify a datum plane, the datum plane is established by locating pins at the datum tangent points. The locating pins are rounded or pointed standard tooling hardware.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 30 of 102

Datum Plane X

X3, n12

n12 X3

40

20

20

20

The Part

60

X1, n12

Locating Pins

n12 X2

n12 X1

The Fixture Setup

Datum Feature

The Drawing

X2, n12

50

50

60

Areas of contact may also be used to establish datums. The shape of the datum target area is outlined by phantom lines with section lines through the area. Circular areas are dimensioned with basic or tolerance dimensions to located the center. The diameter of the target area is provided in the upper half of the datum target symbol or with a leader and dot pointing to the upper half. The locating pins for target areas are flat end tooling pins with the pin diameter equal to the specified size of the target area.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Datum Plane X

X3, n6

n6 X3

40

20

20

20

The Part

60

X1, n6

Locating Pins

n6 X2

n6 X1

Page 31 of 102

The Fixture Setup

Datum Feature

The Drawing

X2, n6

50

50

60

When the area is too small to accurately or clearly display on a drawing, a datum target point is used at the center location. The top half of the datum target symbol identifies the diameter of the target area.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 32 of 102

50

50

PART

Y

The Drawing

The Fixture Setup

LOCATING PIN

Y1

Y1

A datum target line is indicated by the target point symbol “X” on the edge view of the surface and by a phantom line on the surface view. If the locating pins are cylindrical, then the datum target line is along the tangency where the pins meet the part. The pins may also be knife-edged. A surface is often placed at 90º to the pin to create the datum reference frame.

Geometric Dimensioning & Tolerancing

45o

45o

A

B2

B1

10

B1

B2

40

A1

A2

4X n6.3-6.4

n38

100

A2

j n0.1m A B C

A1

From ASME Y14.5M-1994, p78

Example 1

Geometric Dimensioning & Tolerancing

A3 C1 C2

C2

C1

20

15

Page 33 of 102

A3

ASME Y14.5M-1994

3

15

ASME Y14.5M-1994

Page 34 of 102

SIMULATED DATUM (FIXTURE SURFACE)

THE FIXTURE SETUP

CHAIN LINE

THE DRAWING

26

DATUM FEATURE

52

A

THEORETICALLY EXACT DATUM PLANE

A portion of a surface may be used as a datum. For example, this may be done when a part has a hole or group of holes at one end where it may not be necessary to establish the entire surface as a datum to effectively locate the features. This may be accomplished on a drawing using a chain line dimensioned with basic dimensions to show the location and extent of the partial datum surface. The datum feature symbol is attached to the chain line. The datum plane is then established at the location of the chain line.

3.10. Partial Datum Surface

Geometric Dimensioning & Tolerancing

12

ASME Y14.5M-1994

5.

Page 35 of 102

4. Below are examples of a hole (Figure 1) and a pin (Figure 2) that will be identified as datum features. Sketch on the figure and explain how the datum axis for each would be determined.

3. The primary datum requires a minimum of _________ points. The secondary datum requires a minimum of _________ points. The tertiary datum requires a minimum of _________ points.

2. Draw the symbol that is known as the Datum Reference Symbol.

_________________________________________________________________

1. List the 3 primary items that are considered Datum features on an object or part.

3.11. Exercise

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 36 of 102

13. Datum features may be either features of size or features without size. On the drawing, identify features of size by placing a ‘Z’ next to them, and identify the features without size by placing an ‘x’ next to them.

12. Specify the two ∅6 holes as Datum S.

11. Specify the 13 slot as Datum P.

10. Specify the right hand edge of the 13 slot as Datum M.

9. On the bottom surface, specify a partial Datum K over a distance of 40 from the right edge of the part.

8. Specify the right hand edge as Datum G.

7. Specify the ∅12 hole as Datum D.

6. Specify the left hand edge as Datum A.

On the following exercises, using the drawing provided on next page (Figure 4),

Figure 3

d)__________________

b)__________________

a)__________________

c)__________________

On the following, Figure 3, identify the: datum feature, part, simulated datum, and the datum plane.

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

13 Page 37 of 102

25

16

12 THRU

50

114

151

2X

6 THRU

Geometric Dimensioning & Tolerancing

Figure 4 16 32

51

70

ASME Y14.5M-1994

Page 38 of 102

FUNCTIONAL GAGE

PLUS/MINUS METHOD 20+ 0.5

A

POSITIONAL METHOD

40+1

7+ 0.5

14+1

14. What is the relationship between the center plane of the slot and the center plane of the part? What is the total location tolerance that the center plane of the slot vary from the center plane of the part? Is design intent clear?

Geometric Dimensioning & Tolerancing

Page 39 of 102

The picture below represents a cast part. It was determined that the part should have datum targets specified to standardise the initial machining set-up. On the drawing next page, sketch the datum targets in proper format as you would expect to see them on an engineering drawing. Surface X should have three ∅10 target pads, Surface Y should have two targets lines of contact and Surface Z should have one point of contact. Arrange these targets on the indicated surfaces to your preference. Show all basic dimensions and just estimate the distances.

Page 40 of 102

Geometric Dimensioning & Tolerancing

Z

ASME Y14.5M-1994

17.5 0.69 1.18 30

0.49 12.5 0.39 10

7 0.28 3 80 Y

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

X

0.39 10 2.76 70

X

Understanding Datum Reference Frame Application (DRF) Example 1

Degrees of Freedom Matrix Rx Ry Rz Tx Ty

Tz

Datum Features

152

Ø 38.5 - 40.0

0 128 0 120

28

A

Geometric Dimensioning & Tolerancing

C

Ø 0.4 M A B C Ø 0.12 A

74 74 24

20 20

ASME Y14.5M-1994

96

Page 41 of 102

64 50

Y

Y

24

Z

X

B

Page 42 of 102

Degrees of Freedom Matrix Rx Ry Rz Tx Ty

Tz

Datum Features

Ø 38.5 - 40.0

128 128 120 120

28

A

Geometric Dimensioning & Tolerancing

Understanding Datum Reference Frame Application (DRF) Example 2

152

C

Ø 0.4 M C B A Ø 0.12 A

74 24

20

ASME Y14.5M-1994

96 64 50

Y

Y

24

Z

X

B

Understanding Datum Reference Frame Application (DRF) Example 3

Rx

Ry

Rz

Tx

Ty

Tz

Datum Features

Ø 38.5 - 40.0 Ø 0.4 M A B C Ø 0.12 A D 74 74

46 46

Geometric Dimensioning & Tolerancing

C

Ø 19.0 - 19.3

24

Ø 0.25 M A D B A A D

M

B

What effect does the MMC Modifier have in this second FCF arrangement?

ASME Y14.5M-1994

24 24

Page 43 of 102

50

Y

Y

X

Z

B

Page 44 of 102 Ø 0.98

Ø 0.25 M D E A M

D E

Rx

A

Ry

Rz

Tx

Ty

Tz

Datum Features

Ø 38.5 - 40.0

1.

Ø 0.4 M A B C Ø 0.12 A

2.

A M

Geometric Dimensioning & Tolerancing

Understanding Datum Reference Frame Application (DRF) Example 4

22.2 - 22.5

E

M

D 74 74

C

3.

D

46 46

Ø 19.0 - 19.3

48

Ø 0.25 M A D B A E

ASME Y14.5M-1994

24 50

Y

Y

Z

X

B

D

Ø 0.4 M A B C Ø 0.12 A

G

Ø 0.25 M A D B

Degrees of Freedom Matrix

ASME Y14.5M-1994

50

Y

Page 45 of 102

Y

25.56 24

Geometric Dimensioning & Tolerancing

Features

Understanding Datum Reference Frame Application (DRF) Example 5

Ø 38.5 - 40.0

22.2 - 22.5

Ø 0.98

46 46

74 74

Ø 19.0 - 19.3

48

C

Z X

B

Ø 0.25 M A D - G B

A

Page 46 of 102

Each longitudinal element of the surface must lie between two parallel lines 0.05 apart in the left view and 0.1 in the right view of the drawing.

MEANING

0.05 Tolerance

ON THE DRAWING

0.05

Line Element – Plane Surface

4.1. Straightness

4. Form Tolerance

Geometric Dimensioning & Tolerancing

0.1

0.1 Tolerance

ASME Y14.5M-1994

0.02

n0.04

16.00 15.89

(b)

n16.00 MMC

(c)

n16.00 MMC

n16.04 outer boundary

0.04 diameter tolerance zone

n16.00

MEANING

MEANING

0.02 wide tolerance zone

0.02 wide tolerance zone

0.02 wide tolerance zone

n16.00 MMC

(a)

ASME Y14.5M-1994

Page 47 of 102

The derived median line of the feature’s actual local size must lie within a cylindrical tolerance zone of 0.04 diameter, regardless of the feature size. Each circular element of the surface must be within the specified limits of size.

ON THE DRAWING

n

Axis at Regardless of Feature Size (RFS)

Note: Waisting (b) or barreling (c) of the surface, though within the straightness tolerance, must not exceed the limits of size of the feature

Each longitudinal element of the surface must lie between two parallel lines 0.02 apart where the two lines and the nominal axis of the part share a specified limits of size and the boundary of perfect form at MMC 16.00

ON THE DRAWING

n 16.00 15.89

Line Element – Cylinder

Geometric Dimensioning & Tolerancing

n0.04m

16.00 15.89

With the pin at minimum diameter 15.89, the gage will accept the pin with up to 0.15 variation in straightness.

With the pin at maximum diameter 16.00, the gage will accept the pin with up to 0.04 variation in straightness.

The maximum diameter of the pin with perfect form is shown in a gage with a 16.04 diameter hole.

Page 48 of 102

•

•

•

Acceptance Boundary

n16.00

15.90 15.89

16.00 15.99 15.98

Feature Size

MEANING

The derived median line of the feature’s actual local size must lie within a cylindrical tolerance zone of 0.04 diameter at MMC. As each actual local size departs from MMC, an increase in the local diameter of the tolerance cylinder is allowed which is equal to the amount of such departure. Each circular element of the surface must be within the specified limits of size.

ON THE DRAWING

n

Axis at Maximum Material Condition (MMC)

Geometric Dimensioning & Tolerancing

n15.89

n16.00

0.14 0.15

0.04 0.05 0.06

Diameter tolerance zone allowed

n16.04 Virtual Condition

n16.04

n0.15

n16.04

n0.04

n16.04

ASME Y14.5M-1994

0.25

25

100

100

25mm of length

n0.1 tolerance zone in each

n16.04 tolerance zone

MEANING

ON THE DRAWING

MEANING

0.25 wide tolerance zone

The derived median line of the feature’s actual local size must lie within a cylindrical tolerance zone of n0.4 for the total 100mm of length and within a 0.1 cylindrical tolerance zone for any 25mm length, regardless of feature size. Each circular element of the surface must be within the specified limits of size.

ASME Y14.5M-1994

Page 49 of 102

The surface must lie between two parallel planes 0.25 apart. The surface must be within the specified limits of size.

ON THE DRAWING

4.2. Flatness

n15.89-16.00

n16.04 outer boundary

n0.1/25

n0.4

n 16.00 15.89

Per Unit Length

Geometric Dimensioning & Tolerancing

SECTION A-A

MEANING

0.25 wide tolerance zone

A

A

90

ASME Y14.5M-1994

A

A

MEANING

0.25 wide tolerance zone

SECTION A-A

MEANING

Each circular element of the surface in a plane passing through a common center must lie between two concentric circles, one having a radius 0.25 larger than the other. Each circular element of the surface must be within the specified limits of size.

0.25 wide tolerance zone

Page 50 of 102

The cylindrical surface must lie between two concentric cylinders, one having a radius 0.25 larger than the other. The surface must be within the specified limits of size.

ON THE DRAWING

0.25

n25.0+0.5

4.4. Cylindricity

ON THE DRAWING

0.25

Sn19.2+0.5

Each circular element of the surface in a plane perpendicular to an axis must lie between two concentric circles, one having a radius 0.25 larger than the other. Each circular element of the surface must be within the specified limits of size.

ON THE DRAWING

0.25

4.3. Circularity (Roundness)

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 51 of 102

which are 0.05mm apart. This control would be called ____________________

8. On Figure 2, indicate on the bottom surface a control that requires all elements and points relative to each other be within a tolerance zone that is two planes

7. What is the Virtual Condition of the pin for the requirement of question 5? _____

6. What is the cylindricity of this pin? ___________________

The condition of ______________ is often desired. Indicate this with a straightness tolerance of 0.4mm.

5. On Figure 1(d), assume that the pin will assemble with the hole shown in 1 (e).

4. On Figure 1(c), indicate that axis straightness may violate Rule #1 and allow a total bend of up to 0.4mm.

3. What is the circularity (roundness) of this pin? ___________________________

2. On Figure 1(b), indicate an element straightness maximum of 0.012mm.

1. On Figure 1(a), indicate control of element straightness by use of Rule #1 so that maximum possible error is no more than mm if the feature maximum size is ∅16mm.

4.5. Exercise

Geometric Dimensioning & Tolerancing

Page 52 of 102

(d)

Ø 16.0 - 15.9

Figure 1

Ø (Virtual Condition)

Ø 16.00 - 15.97

Ø 16.00 - 15.97

Geometric Dimensioning & Tolerancing

(e)

ASME Y14.5M-1994

(c)

(b)

(a)

18 ± 0.4 45

20 ± 0.4 45

Ø 12

+ 0.1 -0

Geometric Dimensioning & Tolerancing

Figure 2

110.00 110 ± 0.6

MAIN VIEW

28 °

4545 ± 0.4

Page 53 of 102

30° 30

4045 ± 0.4

ASME Y14.5M-1994

0.12 A

ON THE DRAWING

f

Datum Plane A

0.12 wide tolerance zone

MEANING

Possible orientation of the surface

ASME Y14.5M-1994

A

0.12 A

Datum Plane A

0.12 wide tolerance zone

MEANING

Possible orientation of feature axis

Page 54 of 102

What would be the result if a diameter symbol was added to the callout?

Ø 0.12 A

Regardless of feature size, the feature axis must lie between two parallel planes 0.12 apart which are parallel to datum plane A. The feature axis must be within the specified tolerance of location.

f

ON THE DRAWING

Axis related to a Surface Plane

The surface must lie between two parallel planes 0.12 apart which are parallel to datum plane A. The surface must be within the specified limits of size.

A

Surface Plane

5.1. Parallelism

5. Orientation Tolerance

Geometric Dimensioning & Tolerancing

A

ON THE DRAWING

n0.2

MEANING

Datum Axis A

Possible orientation of feature axis

A

ON THE DRAWING

n0.05m

Datum Axis A

MEANING

0.050 0.051 0.052 0.071 0.072

10.021 10.022

Diameter tolerance zone allowed

10.000 10.001 10.002

Feature Size

Possible orientation of feature axis

Page 55 of 102

Where the feature is at maximum material condition (10.000), the maximum parallelism tolerance is n0.050. Where the feature departs from its MMC size, an increase in the parallelism tolerance is allowed which is equal to the amount of such departure. The feature axis must be within the specified tolerance of location.

A

f

10.022 n10.000

Axis related to another Axis at Maximum Material Condition (MMC)

Regardless of feature size, the feature axis must lie within a 0.2 diameter cylindrical zone parallel to datum axis A. The feature axis must be within the specified tolerance of location.

A

f

ASME Y14.5M-1994

n0.2 tolerance zone

Axis related to another Axis at Regardless of Feature Size (RFS)

Geometric Dimensioning & Tolerancing

0.12 A

Possible orientation of the surface

Datum Plane A

0.12 wide tolerance zone

MEANING

ASME Y14.5M-1994

A

Datum Plane A

0.12 wide tolerance zone

MEANING

Possible orientation of the feature center plane

Page 56 of 102

Regardless of feature size, the feature center plane must lie between two parallel planes 0.12 apart which are perpendicular to datum plane A. The feature center plane must be within the specified tolerance of location.

ON THE DRAWING

Center Plane

The surface must lie between two parallel planes 0.12 apart which are perpendicular to datum plane A. The surface must be within the specified limits of size.

A

b

ON THE DRAWING

Surface Plane

5.2. Perpendicularity

Geometric Dimensioning & Tolerancing

0.12 A b

A

0.2

A

Possible orientation of feature axis

Datum Axis A

0.2 wide tolerance zone

MEANING

ASME Y14.5M-1994

A

n0.4 A

Possible orientation of feature axis

Datum Plane A

0.4 diameter tolerance zone

MEANING

Page 57 of 102

Regardless of feature size, the feature axis must lie within a cylindrical zone 0.4 diameter which is perpendicular to and projects from datum plane A for the feature height. The feature axis must be within the specified tolerance of location.

b

ON THE DRAWING

Axis to Plane (RFS)

Regardless of feature size, the feature axis must lie between two parallel planes 0.2 apart which are perpendicular to datum axis A. The feature axis must be within the specified tolerance of location. Note: This applies only to the view on which it is specified.

b

ON THE DRAWING

Axis to Axis

25+0.5

Possible orientation of feature axis

Datum Plane A

A

MEANING

0.050 0.051 0.052 0.067 0.068

15.976 15.966

Diameter tolerance zone allowed 15.984 15.983 15.982

Feature Size

ASME Y14.5M-1994

(A)

n16.034

n15.984

(B)

n0.050 n16.034

n15.984

(C)

n0.068 n16.034

n15.966

Page 58 of 102

(A)The maximum diameter pin with perfect orientation is shown in a gage with a 16.034 diameter hole. (B)With the pin at maximum diameter (15.984), the gage will accept the part with up to 0.05 variation in perpendicularity. (C)The pin is at minimum diameter (15.966), and the variation in perpendicularity may increase to 0.068 and the part will be acceptable.

Datum Plane A

ACCEPTANCE BOUNDAY

Where the feature is at maximum material condition (15.984), the maximum perpendicularity tolerance is n0.050. Where the feature departs from its MMC size, an increase in the perpendicularity tolerance is allowed which is equal to the amount of such departure. The feature axis must be within the specified tolerance of location.

ON THE DRAWING

A

b n0.05m

15.984 n15.966

Axis to Plane (MMC)

Geometric Dimensioning & Tolerancing

25+0.5

Geometric Dimensioning & Tolerancing

Feature Height

Feature Height

A

0.4

ON THE DRAWING

a

A

30o

Datum Plane A

MEANING

Possible orientation of actual surface

0.4 wide tolerance zone

ASME Y14.5M-1994

a

n16

0.2

A

Datum Plane A

60o

MEANING

0.2 wide tolerance zone Possible orientation of feature axis

Page 59 of 102

Regardless of feature size, the feature axis must lie between two parallel planes 0.2 apart which are inclined 60o to datum plane A. The feature axis must be within the specified tolerance of location.

A

60o

ON THE DRAWING

Axis to Surface Plane

The surface must lie between two parallel planes 0.4 apart which are inclined at 30o to datum plane A. The surface must be within the specified limits of size.

30o

Surface Plane

5.3. Angularity

Geometric Dimensioning & Tolerancing

A

60o

n16 a n0.2 A B

Datum Plane A

60o

MEANING

Possible orientation of feature axis

n0.2 tolerance zone

ASME Y14.5M-1994

A

0.1 T A

Tangent Plane

0.1 wide tolerance zone

MEANING

Page 60 of 102

A plane contacting the high points of the surface shall lie within two parallel planes 0.1 apart. The surface must be within the specified limits of size.

f

ON THE DRAWING

5.4. Use of Tangent Plane Symbol

Regardless of feature size, the feature axis must lie within a 0.2 diameter cylindrical zone inclined 60o to datum plane A. The feature axis must be within the specified tolerance of location.

B

ON THE DRAWING

Geometric Dimensioning & Tolerancing

50.0+.05

50.16 50.00

b n0 m

n

A

MEANING

Datum Plane A

50.15 50.16

50.00 50.01 50.02

Feature Size

Possible orientation of feature axis

0.15 0.16

0.00 0.01 0.02

Diameter tolerance zone allowed

ASME Y14.5M-1994

50.16 50.00

b n0 m n0.1 MAX A

n

MEANING

Datum Plane A

0.10 0.10

50.16

0.00 0.01 0.02

Diameter tolerance zone allowed

50.10

50.00 50.01 50.02

Feature Size

Page 61 of 102

Where the feature is at maximum material condition (50.00), its axis must be perpendicular to datum plane A. Where the feature departs from its MMC size, a perpendicularity tolerance is allowed which is equal to the amount of such departure, up to the 0.1 maximum. The feature axis must be within the specified tolerance of location.

ON THE DRAWING

A

Possible orientation of feature axis

Where the feature is at maximum material condition (50.00), its axis must be perpendicular to datum plane A. Where the feature departs from its MMC size, a perpendicularity tolerance is allowed which is equal to the amount of such departure. The feature axis must be within the specified tolerance of location.

ON THE DRAWING

A

5.5. Use of Zero Tolerance at MMC

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 62 of 102

_________.

If the hole is produced at ∅12.1mm? __________

6. What is the total permissible perpendicularity if the hole size is produced at ∅12mm?

5. Sketch how the tolerance zone is established for the requirement of question 4.

4. Assume that in Figure 2, the ∅12mm hole has been located with position dimensions and tolerance. Add an orientation tolerance to control the relationship of the hole to the bottom surface within ∅0.08mm total.

3. Working on Figure 2, indicate that the right vertical surface is to be square with the front surface within 0.08mm.

2. Show below (sketch) how the tolerance zone is established for the requirement of question 1.

1. On Figure 2, indicate that the right vertical surface in the main view is to be square to the lower surface within 0.08mm.

5.6. Exercise

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

10. Sketch how the tolerance zone is established for the 30° angle.

Page 63 of 102

9. On Figure 2, indicate requirements to control the angles within a total tolerance of 0.1mm.

hole is produced at ∅12.1mm? ___________.

∅12mm? ________. If the hole is produced at ∅12.05mm? __________. If the

8. What THEN is the total permissible perpendicularity if the hole size is produced at

7. Suppose the perpendicularity of the produced feature was allowed to increase as the size of the feature increased, how would that be indicated?

Geometric Dimensioning & Tolerancing

Page 64 of 102

18 ± 0.4 45

20 ± 0.4 45

Ø 12

+ 0.1 -0

28 °

Figure 2

110.00 110 ± 0.6

MAIN VIEW

Geometric Dimensioning & Tolerancing

30° 30

4545 ± 0.4

4045 ± 0.4

ASME Y14.5M-1994

0.8 A

(A) Bilateral Tolerance

A

d

d

0.8 A

A

A

0.2

d

Page 65 of 102

Datum Plane A

0.6

MEANING

Datum Plane A

MEANING

True profile relative to Datum Plane A

Actual profile

0.8 wide tolerance zone unequally disposed on one side of the true profile as indicated

True profile relative to Datum Plane A

Actual profile

(D) Bilateral Tolerance unequal distribution

0.8 A

ON THE DRAWING

(C) Unilateral Tolerance (Outside)

0.8 A

MEANING

Datum Plane A

Datum Plane A

0.8 wide tolerance zone entirely disposed on one side of the true profile as indicated

True profile relative to Datum Plane A

Actual profile

0.8 wide tolerance zone entirely disposed on one side of the true profile as indicated

True profile relative to Datum Plane A

Actual profile

MEANING

Profile of a Surface

ASME Y14.5M-1994

0.8 wide tolerance zone equally disposed about the true profile (0.4 each side)

k

(B) Unilateral Tolerance (Inside)

A

ON THE DRAWING

d

ON THE DRAWING

d

Profile of a Line

ON THE DRAWING

6.1. Bilateral & Unilateral

6. Profile Tolerance

Geometric Dimensioning & Tolerancing

D

21.4

17.5

C

23 23

E

17.5

D

19.8

7X 7

E

C

D

7

0.1 E F

R8

C

d

MEANING

8+0.12

E

A

90o

Datum Plane A

F

D

0.05 E F

ON THE DRAWING

C

B

d

d 0.25 A B C

78.8

R80

R82

0.25 wide tolerance zone

21.7

B

B

0.12 E F

Datum Plane C

65+0.25

49+0.12

A

R12

23.4

10

75

o

A

ASME Y14.5M-1994

Page 66 of 102

The surface between points D and E must lie between two profile boundaries 0.25 apart, perpendicular to datum plane A, equally disposed about the true profile and positioned with respect to datum planes B and C.

Datum Plane B

A

D

8+0.05

E

8+0.1

d

Geometric Dimensioning & Tolerancing

2X 8.6+0.12

26 ± 0.04

12

18

Geometric Dimensioning & Tolerancing

Page 67 of 102

ASME Y14.5M-1994

Page 68 of 102

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Distance X

Distance V

70

L

K

L

0.3 A B C

Distance W

L

40

H

35

B

60

0.09 A B C K

________________

(b) Surface Z W: ________________

(a) Surface Y:

Page 69 of 102

2. On the same part, considering the applicable profile callouts, what is the maximum perpendicularity of the following surfaces in relation to Datum A?

(c) Distance X: Minimum ________________ Maximum ________________

(b) Distance W: Minimum ________________ Maximum ________________

(a) Distance V: Minimum ________________ Maximum ________________

A

Surface Z

Surface Y

ASME Y14.5M-1994

1. On the part shown above, what is the minimum and maximum of the following distances in relation to the datum reference frame, as allowed by the profile callout?

H

C

6.2. Exercise

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

Page 70 of 102

40 40 ± 0.3

3. Profile of a Surface can also be used with a size tolerance to refine the size or shape. Following is an example where the three top surfaces are to be coplanar (in-line) within 0.3mm and in relation to the bottom surface of the part. Each surface is to flat within 0.1mm. Define these requirements on the drawing.

Geometric Dimensioning & Tolerancing

12

30.00 ± 0.5

20 10

ASME Y14.5M-1994

Page 71 of 102

30.00 ± 0.5

12

20 50

20

90

20

130

160 ± 0.5

Geometric Dimensioning & Tolerancing

Unless Otherwise Specified: Tolerance ± 0.05 Angles ± 1°

Page 72 of 102

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

0.05 X Y Z

18 30

20

20

20

20

20 20

20

160 ± 0.5

Geometric Dimensioning & Tolerancing

X

Y

1010

20

20 Z

130 C

20

90 50

10 10

20

20 20

20

A

ASME Y14.5M-1994

30

Page 73 of 102

18

Unless Otherwise Specified: Tolerance ± 0.05 Angles ± 1°

B

0.05 A B C

Page 74 of 102

Geometric Dimensioning & Tolerancing ASME Y14.5M-1994

ASME Y14.5M-1994

t 0.5 A

(Axis to axis control, RFS)

r n0.5 A

Page 75 of 102

Concentricity - Use where part feature axis / axes in a rotational consideration must relate to a datum axis. Concentricity is applicable only on an RFS basis.

(Axis to axis control, MMC)

j n0.5m Am

Position - Use where part feature surfaces relate to a datum axis on a functional or inter-changeability basis; typically mating parts are involved. Position is normally applied only on an MMC basis (occasionally an RFS datum is used).

(Surface to axis control, RFS)

Total Runout

Runout

h 0.5 A

Runout - Use where part feature surfaces in a rotational consideration must relate to a datum axis. Runout is applicable only on an RFS basis.

7.1. Coaxial Features There are three types of coaxial feature control. Proper selection is based upon which of the below controls best suits the functional design requirement.

7. Runout Tolerance

Geometric Dimensioning & Tolerancing

A

Datum Feature A

Datum Feature Simulator (Collet)

ON THE DRAWING

n 20+0.5

FIM 0.05

Rotate Part

Datum Axis A

MEANING

A

Each Circular Element Individually

0.05

n 40+0.5 h

ASME Y14.5M-1994

FIM 0.05

n 40+0.5

Rotate Part

Datum Axis A

MEANING

A

All Elements Together

t 0.05

Page 76 of 102

Total Runout: All surface elements, total, across entire surface must be within the runout tolerance and within 0.05 wide tolerance zone (FIM) in relation to datum axis A.

Simulated Datum Feature A (True Geometric Counterpart)

Datum Feature A

Datum Feature Simulator (Collet)

ON THE DRAWING

A

n 20+0.5

Runout: Each circular element of the feature must be within the runout tolerance and within 0.05 wide tolerance zone (FIM) in relation to datum axis A

Simulated Datum Feature A (True Geometric Counterpart)

7.2. Runout

Geometric Dimensioning & Tolerancing

Part Mounted on Two Functional Diameters

7.3. Examples

Geometric Dimensioning & Tolerancing

Page 77 of 102

ASME Y14.5M-1994

ASME Y14.5M-1994

Page 78 of 102

Part Mounted on Functional Face Surface (Datum) and Diameter (Datum)

Geometric Dimensioning & Tolerancing

Part Mounted on Two Functional Diameters

Geometric Dimensioning & Tolerancing

Page 79 of 102

ASME Y14.5M-1994

ASME Y14.5M-1994

n6+0.02

Page 80 of 102

6. On the figure below, sketch how the two runout requirements would be verified.

5. On the sketch, specify a runout requirement to make the left face perpendicular to the Datum axis within 0.1mm total.

diameter in relation to the small diameter? ____________________

4. With the specified runout requirement, what is the maximum position of the large

for the larger diameter? _________________________

2. On the sketch, specify a 0.12mm circular runout requirement on the large 3. After defining the runout requirement, what is the maximum circularity (roundness)

n20+0.05

following drawing sketch? _____________________

1. What is the coaxiality requirement between the two diameters as expressed on the

7.4. Exercise

Geometric Dimensioning & Tolerancing

Page 81 of 102

_________________________________________________________________

13. What is the main difference between concentricity and position?

_________________________________________________________________

12. What is the main difference between runout and concentricity?

_________________________________________________________________

11. What is the main difference between circular and total runout?

_________________________________________________________________

10. Can the m or l modifiers be used with runout?

9. Can runout be used without a datum feature reference?____________________

60 C Page 82 of 102

90

8. On the figure below, sketch how the runout requirement would be verified.

20 70

7. On the part drawing below, specify a 0.12mm total runout relating the large diameter to both of the two small diameters together.

Geometric Dimensioning & Tolerancing

Ø80 80 A 24 Ø 25

40

ASME Y14.5M-1994

D 10 Ø 10

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

20 Ø 20

Ø24 25

ASME Y14.5M-1994

52

Tolerance ± 0.5

Position vs. Plus/Minus

96

Coordinate Tolerancing

0.5

Page 83 of 102

0.5

0.7

4X Ø 16.7 - 17.3

Hole Verification Remember that all features have depth. Therefore, when doing design or making measurements, the tolerance zone must be considered from one end of the zone to the other.

8.1. Position

8. Location Tolerance

Geometric Dimensioning & Tolerancing

0.7

1.3

If Hole #1 = ∅ 16.7 #2 = ∅ 16.9 #3 = ∅ 17.2 #4 = ∅ 17.4

Example Features: Then tolerance zone tolerance zone tolerance zone tolerance zone

= = = =

A

Ø 0.7 M A

4X Ø 16.7 - 17.3

ASME Y14.5M-1994

Each hole has its own positional tolerance zone. The zone size is dependent on the size of the produced hole. When the hole is produced at its MMC size, the positional tolerance zone is the tolerance stated in the FCF. If the hole is produced at something larger than the MMC size, the positional tolerance zone is stated FCF tolerance PLUS the amount that the hole is larger than MMC.

Page 84 of 102

♦

♦

♦

52

96 96

Position Tolerancing (Round zone)

Geometric Dimensioning & Tolerancing

Position Zone

Geometric Dimensioning & Tolerancing

Page 85 of 102

ASME Y14.5M-1994

Page 86 of 102

Z

Datum Plane "X" Direction

ASME Y14.5M-1994

Basic Dimension (from drawing)

Actual Measurement (from produced part)

"Y" Difference

Actual Produced Feature Center

"X" Difference

Formula : Z = 2 X 2 + Y 2

X

Y

Datum Plane "Y" Direction

"Z" = Actual Positional Diameter

True Position

Basic Dimension (from drawing)

Actual Measurement (from created part)

Geometric Dimensioning & Tolerancing

A

Page 87 of 102

9

18

ASME Y14.5M-1994

n0.25 at MMC, four coaxial tolerance zones located at true position relative to the specified datums within which the axes of the holes as a group must lie

Positional Tolerancing for Coaxial Holes of Same Size

n0.15 at MMC, four coaxial tolerance zones within which the axes of the holes must lie relative to each other

Feature Relating Position Tolerance

j n0.15m A

C

Pattern Locating Position Tolerance

n0.25m A B C

4X n10.15 +0.15 0

Position, Axis to Surface, Coaxial Axis to Axis, Coaxial

8.2. Composite Positional Tolerance

Geometric Dimensioning & Tolerancing

B

B

C

A

9

Page 88 of 102

Positional Tolerancing for Coaxial Holes of Same Size, Partial (Parallelism) Refinement of Feature-Relating Axis

18

B

ASME Y14.5M-1994

n0.25 at MMC, four coaxial tolerance zones located at true position relative to the specified datums within which the axes of the holes as a group must lie

Orientation

n0.15 at MMC, four coaxial tolerance zones within which the axes of the holes must lie relative to each other

j n0.15m A

n0.25m A B C

4X n10.15 +0.15 0

Position, Axis to Surface, Coaxial Axis to Axis, Coaxial

Geometric Dimensioning & Tolerancing

Ø80 80

A

40

20

60

C

Position, Axis to Axis, Coaxial

D

ASME Y14.5M-1994

10 Ø 10

24 Ø 25

Geometric Dimensioning & Tolerancing

Page 89 of 102

20 Ø 20

Ø24 25

70

90

24

Tolerance ± 0.5

96

4X Ø 16.7 - 17.3

ASME Y14.5M-1994

24 24

B

Page 90 of 102

100

52

C

30

Tolerance ± 0.5

134 96 96

150 Ø 0.7

M

A

A B C

4X Ø 16.7 - 17.3

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

100

52

30

134

150

Geometric Dimensioning & Tolerancing

24

B

30

Tolerance ± 0.5

134

96

150

Ø 1.5 Ø 0.7

A

M

M

A B C A

4X Ø 16.7 - 17.3

ASME Y14.5M-1994

100

24 24

52

C

B

30

Tolerance ± 0.5

134

96

150

M

M

A

A B C A B

Page 91 of 102

Ø 1.5 Ø 0.7

4X Ø 16.7 - 17.3

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

100

52

C

Geometric Dimensioning & Tolerancing

24 24

B

30

Tolerance ± 0.5

96 96

150 134

Page 92 of 102

To calculate position tolerance with fastener and hole size known: H−F T= 2 Where T = tolerance, H = MMC hole, and F = MMC fastener

Fixed Fastener

To calculate position tolerance with fastener and hole size known: T=H−F Where T = tolerance, H = MMC hole, and F = MMC fastener

Floating Fastener

8.3. Position Tolerance Calculation

100

52

C

Geometric Dimensioning & Tolerancing

Ø 1.5 Ø 0.7

A

M

M

A B C A B

4X Ø 16.7 - 17.3

ASME Y14.5M-1994

8.4.

(2)

Threaded hole axis

Clearance hole axis

Positional tolerance zone

Threaded hole axis

Clearance hole axis

Basis for projected tolerance zone

j n0.5m p10.0 A B C

Min. tolerance zone height is equal to max. thickness of mating part

True position axis

Positional tolerance zone

Interference diagram, fastener and hole

j n0.5m A B C

Tolerance zone height is equal to height of threaded hole

Interference area

True position axis

Projected Tolerance Zone (1)

Geometric Dimensioning & Tolerancing

Page 93 of 102

ASME Y14.5M-1994

ASME Y14.5M-1994

Page 94 of 102

Datum Axis A

MEANING

ON THE DRAWING

A

20.2

n 19.8

10.2 9.8 A

Tolerance Zone (RFS)

n0.2

Median points of diametically opposed elements of feature

r n 0.2

n

A concentricity tolerance is a cylindrical (or spherical) tolerance zone whose axis (or center point) coincides with the axis (or center point) of the datum feature. The median points of all correspondingly-located elements of the feature being controlled, regardless of feature size, must be within the cylindrical tolerance zone. The specified tolerance and the datum reference can only apply on an RFS basis.

Concentricity is that condition where the median points of all diametrically opposed elements of a figure of revolution (or corresponding-located elements of two or more radially disposed features) are congruent with the axis (or center point) of a datum.

8.5. Concentricity

Geometric Dimensioning & Tolerancing

ASME Y14.5M-1994

ON THE DRAWING

0.1

0.2 Wide Tolerance Zone (RFS)

Datum Centerplane A

A

Page 95 of 102

All median points of opposed elements of the slot must lie within the 0.2 wide tolerance zone, RFS. The tolerance zone being established by two paralle planes equally disposed about datum centerplane A, RFS.

MEANING

10.2 9.8

i 0.2

Datum Feature A (RFS)

A

30.2 29.8

Symmetry is that condition where the median points of all opposed or correspondingly located elements of two or more feature surfaces are congruent with the axis or center plane of a datum feature. The material condition RFS only is to apply.

8.6. Symmetry

Geometric Dimensioning & Tolerancing

24 24

96 96

150 134

#4

#2

Y= Y= Y= Y=

X= X= X=

Actual Location

Hole Size

M

A

Accept

Reject

A B C

Hole Size 17.2 17 16.9 17.1

Ø 0.7

4X Ø 16.7 - 17.3

ASME Y14.5M-1994

Position Tol.

Inspection Report Actual “X” Location Actual “Y” Location 29.75 76.5 126.3 75.85 30.4 24.43 125.91 23.48

#3

#1

30

X=

B

Page 96 of 102

4

3

2

1

Hole #

Hole # 1 2 3 4

100

52

C

8.7. Exercise 1.

Geometric Dimensioning & Tolerancing

3

2

1

Hole #

B

Hole MMC

24.25

63.66

Produced Part

24

40

C

100

30.62

#2

#1

Position Tolerance Allowed

“X” Distance

Produced Hole 15.38

#3

Produced Hole 15.30

100.35

Tolerance ± 0.5

29.47

Hole Actual Size

B

C

30

Drawing Requirements

2.

M

“Y” Distance

Accept

A

A

Reject

Page 97 of 102

A B C

Position Location

23.48

Produced Hole 15.15

Ø 1.0

3X Ø 15.0 - 15.5

Page 98 of 102

3.

8 ± 0.1 32

ASME Y14.5M-1994

4X Ø 10.9 - 11.4 B

Geometric Dimensioning & Tolerancing

Ø 0.1 M A

M A B

0.5 34.00 - 34.25 15

Ø 110 C

ASME Y14.5M-1994

Ø1 M A B C

Geometric Dimensioning & Tolerancing

2X 40 A

2X 40

8.05

11.25

11.3

11.04

11.28

1

2

3

4

34.09

B

C

Actual Size

Item #

40.48

-0.21

40.25

+0.3

0.59

+0.1

X Dimension

+0.26

40.54

+0.55

39.72

---

+0.1

Y Dimension

Inspection Report for Hub Cover

Page 99 of 102

Comments

Page 100 of 102

ASME Y14.5M-1994

4X Ø 10.9 - 11.4 B

Geometric Dimensioning & Tolerancing

8 ± 0.1 32

M A B M

0.5 34.00 - 34.25 15

Ø 110 C Ø 0.1 M A

ASME Y14.5M-1994

Ø1 M A B M C M

Geometric Dimensioning & Tolerancing

2X 40 A

2X 40

51

13

51

13

Y

B

13

C

13

Z

M

X

32

Ø 2 M A B C Ø M A

4X Ø 6.45 - 6.80

32

Ø

Ø 2 M X Y Z

4X Ø 6.45 - 6.80

Geometric Dimensioning & Tolerancing

A

Page 101 of 102

2 SURF

0.5

Hole MMC = - Screw MMC = -------------------------------------Tolerance =

6M Cap Screws

X

ASME Y14.5M-1994

B 13

C

13

Y

Page 102 of 102

51

13

51

13

Z

32

Ø 2 M A B C Ø M A

4X Ø 6.45 - 6.80

32

Ø 2 M X Y Z Ø M X

4X 6M

Geometric Dimensioning & Tolerancing

A

2 SURF

0.5

Hole MMC = - Screw MMC = -------------------------------------Tolerance =

6M Cap Screws

X

ASME Y14.5M-1994