gdt

http://nileshshah.tk/

Dimensioning and Dimensioning and

TolerancingTolerancing

perper

ASME Y14.5MASME Y14.5M--19941994

visit http://nileshshah.tk/

Shah, Nilesh


Tolerances

of Form

Straightness Flatness

Circularity Cylindricity

(ASME Y14.5M-1994, 6.4.1)

(ASME Y14.5M-1994, 6.4.3)

(ASME Y14.5M-1994, 6.4.2)

(ASME Y14.5M-1994, 6.4.4)


25 +/-0.25

0.1 Tolerance

0.5 Tolerance

Straightness is the condition where an element of a

surface or an axis is a straight line

Straightness (Flat Surfaces)

0.5 0.1


Straightness (Flat Surfaces)

24.75 min25.25 max

0.5 Tolerance Zone

0.1 Tolerance Zone

The straightness tolerance is applied in the view where the

elements to be controlled are represented by a straight line

In this example each line element of the surface must lie

within a tolerance zone defined by two parallel lines separated by the specified tolerance value applied to each

view. All points on the surface must lie within the limits of size and the applicable straightness limit.


Straightness (Surface Elements)

MMC

0.1 Tolerance Zone

0.1

MMC

0.1 Tolerance Zone

MMC

0.1 Tolerance Zone

In this example each longitudinal element of the surface must

lie within a tolerance zone defined by two parallel lines separated by the specified tolerance value. The feature must

be within the limits of size and the boundary of perfect form at MMC. Any barreling or waisting of the feature must not

exceed the size limits of the feature.


Straightness (RFS)

0.1

Outer Boundary (Max)

MMC

0.1 Diameter

Tolerance Zone

Outer Boundary = Actual Feature Size + Straightness Tolerance

In this example the derived median line of the feature’s actual local size must lie

within a tolerance zone defined by a cylinder whose diameter is equal to the

specified tolerance value regardless of the feature size. Each circular element of

the feature must be within the specified limits of size. However, the boundary of

perfect form at MMC can be violated up to the maximum outer boundary or

virtual condition diameter.


Straightness (MMC)15 14.85

15.1 Virtual Condition

15 (MMC)

0.1 Diameter Tolerance Zone

15.1 Virtual Condition

14.85 (LMC)


Virtual Condition = MMC Feature Size + Straightness Tolerance

In this example the derived median line of the feature’s actual local size

must lie within a tolerance zone defined by a cylinder whose diameter is equal to the specified tolerance value at MMC. As each circular element

of the feature departs from MMC, the diameter of the tolerance cylinder is allowed to increase by an amount equal to the departure from the local

MMC size. Each circular element of the feature must be within the specified limits of size. However, the boundary of perfect form at MMC

can be violated up to the virtual condition diameter.

0.1 M


Flatness

Flatness is the condition of a surface having all elements in

one plane. Flatness must fall within the limits of size. The

flatness tolerance must be less than the size tolerance.

25 +/-0.25

24.75 min25.25 max

0.1

0.1 Tolerance Zone

0.1 Tolerance Zone

In this example the entire surface must lie within a tolerance

zone defined by two parallel planes separated by the specified tolerance value. All points on the surface must lie within the

limits of size and the flatness limit.


Circularity is the condition of a surface where all points of the

surface intersected by any plane perpendicular to a common

axis are equidistant from that axis. The circularity tolerance

must be less than the size tolerance

90

90

0.1

0.1 Wide Tolerance Zone

Circularity (Roundness)

In this example each circular element of the surface must lie within a

tolerance zone defined by two concentric circles separated by the specified tolerance value. All points on the surface must lie within the

limits of size and the circularity limit.

0.1


Cylindricity

Cylindricity is the condition of a surface of revolution in which

all points are equidistant from a common axis. Cylindricity is a

composite control of form which includes circularity

(roundness), straightness, and taper of a cylindrical feature.

0.1 Tolerance Zone

MMC

0.1

In this example the entire surface must lie within a tolerance zone

defined by two concentric cylinders separated by the specified tolerance value. All points on the surface must lie within the limits of

size and the cylindricity limit.


____________ and ___________ are individual line or circular

element (2-D) controls.

Form Control Quiz

The four form controls are ____________, ________,

___________, and ____________.

Rule #1 states that unless otherwise specified a feature of

size must have ____________at MMC.

________ and ____________are surface (3-D) controls.

Circularity can be applied to both ________and _______ cylindrical

parts.

1.

2.

3.

4.

5.

Form controls require a datum reference.

Form controls do not directly control a feature’s size.

A feature’s form tolerance must be less than it’s size

tolerance.

Flatness controls the orientation of a feature.

Size limits implicitly control a feature’s form.

6.

7.

8.

9.

10.

Questions #1-5 Fill in blanks (choose from below)

straightness

flatness

circularity

cylindricity

perfect form

straight tapered profile

true position

angularity

Answer questions #6-10 True or False


Tolerances of Orientation

Angularity

Perpendicularity

Parallelism

(ASME Y14.5M-1994 ,6.6.2)

(ASME Y14.5M-1994 ,6.6.4)

(ASME Y14.5M-1994 ,6.6.3)


Angularity (Feature Surface to Datum Surface)

Angularity is the condition of the planar feature surface at a

specified angle (other than 90 degrees) to the datum

reference plane, within the specified tolerance zone.

A

20 +/-0.5

30 o

A

19.5 min

0.3 Wide Tolerance

Zone

30 o

A

20.5 max

0.3 Wide

Tolerance Zone

30 o

The tolerance zone in this example is defined by two parallel planes oriented at the

specified angle to the datum reference plane.

0.3 A


Angularity is the condition of the feature axis at a specified

angle (other than 90 degrees) to the datum reference plane,

within the specified tolerance zone.

A

0.3 A

A

60 o

The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented

at the specified angle to the datum reference plane.

0.3 Circular Tolerance Zone


Angularity (Feature Axis to Datum Surface)

NOTE: Tolerance applies to feature at RFS



NOTE: Tolerance applies to feature

at RFS

Angularity is the condition of the feature axis at a specified

angle (other than 90 degrees) to the datum reference axis,



A

Datum Axis A

Angularity (Feature Axis to Datum Axis)

The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented

at the specified angle to the datum reference axis.

NOTE: Feature axis must lie within tolerance zone cylinder

0.3 A

o45


0.3 A

A


A A

Perpendicularity is the condition of the planar feature

surface at a right angle to the datum reference plane, within

the specified tolerance zone.

Perpendicularity (Feature Surface to Datum Surface)


The tolerance zone in this example is defined by two parallel planes oriented

perpendicular to the datum reference plane.


C

Perpendicularity is the condition of the feature axis at a right

angle to the datum reference plane, within the specified

tolerance zone.

Perpendicularity (Feature Axis to Datum Surface)

0.3 C




NOTE: Tolerance applies

to feature at RFS

The tolerance zone in this example is defined by a cylinder equal to the length of

the feature, oriented perpendicular to the datum reference plane.


Perpendicularity (Feature Axis to Datum Axis)


The tolerance zone in this example is defined by two parallel planes oriented

perpendicular to the datum reference axis.

Perpendicularity is the condition of the feature axis at a right

angle to the datum reference axis, within the specified

tolerance zone.


A

Datum Axis A

0.3 A


0.3 A

A

25 +/-0.5

25.5 max


A

24.5 min


A

Parallelism is the condition of the planar feature surface

equidistant at all points from the datum reference plane,


Parallelism (Feature Surface to Datum Surface)

The tolerance zone in this example is defined by two parallel planes

oriented parallel to the datum reference plane.


A


Parallelism (Feature Axis to Datum Surface)

0.3 A

A

NOTE: The specified tolerance does not apply to the orientation

of the feature axis in this direction

Parallelism is the condition of the feature axis equidistant

along its length from the datum reference plane, within the

specified tolerance zone.

The tolerance zone in this example is defined by two parallel planes

oriented parallel to the datum reference plane.


to feature at RFS


A

B

Parallelism (Feature Axis to Datum Surfaces)

A

B




Parallelism is the condition of the feature axis equidistant

along its length from the two datum reference planes, within

the specified tolerance zone.

The tolerance zone in this example is defined by a cylinder equal to the

length of the feature, oriented parallel to the datum reference planes.


to feature at RFS

0.3 A B


Parallelism (Feature Axis to Datum Axis)

Parallelism is the condition of the feature axis equidistant along

its length from the datum reference axis, within the specified

tolerance zone.

A

0.1 A



Datum Axis A

The tolerance zone in this example is

defined by a cylinder equal to the length of the feature, oriented

parallel to the datum reference axis.



Orientation Control Quiz

The three orientation controls are __________, ___________,

and ________________.

1.

2.

3.

4.

5.

A _______________ is always required when applying any of

the orientation controls.

________________ is the appropriate geometric tolerance when

controlling the orientation of a feature at right angles to a datum

reference.

Orientation tolerances indirectly control a feature’s form.

Mathematically all three orientation tolerances are _________.

Orientation tolerances do not control the ________ of a feature.

6.

Orientation tolerance zones can be cylindrical.

Parallelism tolerances do not apply to features of size.

To apply an angularity tolerance the desired angle mustbe indicated as a basic dimension.

7.

8.

9.

10.

To apply a perpendicularity tolerance the desired angle

must be indicated as a basic dimension.


angularity

perpendicularity

parallelism

datum reference

identical

location

profile

datum feature

datum target



Tolerances

of Profile

Profile of a Line

Profile of a Surface

(ASME Y14.5M-1994, 6.5.2b)

(ASME Y14.5M-1994, 6.5.2a)


18 Max

Profile of a Line

2 Wide SizeTolerance Zone

1 A B C

A

17 +/- 1

1 Wide ProfileTolerance Zone

C

A1

20 X 20

A2

20 X 20

A3

20 X 20

B

The profile tolerance zone in this example is defined by two

parallel lines oriented with respect to the datum reference frame. The profile tolerance zone is free to float within the

larger size tolerance and applies only to the form and orientation of any individual line element along the entire

surface.

Profile of a Line is a two-dimensional tolerance that can be applied to a part feature in situations where the control of the entire feature surface as

a single entity is not required or desired. The tolerance applies to the line element of the surface at each individual cross section indicated on the

drawing.

16 Min.


Profile of a Surface is a three-dimensional tolerance that can be applied to a part feature in situations where the control of the entire feature

surface as a single entity is desired. The tolerance applies to the entire surface and can be used to control size, location, form and/or orientation

of a feature surface.


2 Wide Tolerance Zone Size, Form and Orientation

A

A1

20 X 20

A2

20 X 20

A3

20 X 20

C 2 A B C

23.5

23.5Nominal Location

The profile tolerance zone in this example is defined by two parallel planes oriented with respect to the datum reference frame. The profile tolerance zone is located and aligned in a way that enables the part surface to vary equally about the true profile of the feature.

B



A1

20 X 20

A2

20 X 20

A3

20 X 20

B

C

50

B

C

50

1 Wide Total Tolerance Zone

(Bilateral Tolerance)

The tolerance zone in this example is defined by two parallel planes oriented with respect to the datum reference frame. The profile tolerance zone is located and aligned in a way that enables the part surface to vary equally about the true profile of the trim.

1 A B C

Nominal Location

0.5 Inboard

0.5 Outboard

Profile of a Surface when applied to trim edges of sheet metal parts will control the location, form and orientation of the entire trimmed surface. When a bilateral value is specified, the tolerance zone allows the trim edge variation and/or locational error to be on both sides of the true profile. The tolerance applies to the entire edge surface.



A1

20 X 20

A2

20 X 20

A3

20 X 20

B

C

50

B

C

50

0.5 Wide Total Tolerance Zone

(Unilateral Tolerance)

Profile of a Surface when applied to trim edges of sheet metal parts will control the location, form and orientation of the entire trimmed surface. When a unilateral value is specified, the tolerance zone limits the trim edge variation and/or locational error to one side of the true profile. The tolerance applies tothe entire edge surface.

The tolerance zone in this example is defined by two parallel planes oriented with respect to the datum reference frame. The profile tolerance zone is located and aligned in a way that allows the trim surface to vary from the true profile only in the inboard direction.

0.5 A B C

Nominal Location



A1

20 X 20

A2

20 X 20

A3

20 X 20

B

C

50

1.2 A B C

B

C

50

0.5 Inboard

0.7 Outboard

1.2 Wide Total Tolerance Zone

(Unequal Bilateral Tolerance)

Profile of a Surface when applied to trim edges of sheet metal parts will control the location, form and orientation of the entire trimmed surface. Typically when unequal values are specified, the tolerance zone will represent the actual measured trim edge variation and/or locational error. The tolerance applies to the entire edge surface.

The tolerance zone in this example is defined by two parallel planes oriented with respect to the datum reference frame. The profile tolerance zone is located and aligned in a way that enables the part surface to vary from the true profile more in one direction (outboard) than in the other (inboard).

0.5

Nominal Location


A

25

A0.5

0.1

25.2524.75


A

Composite Profile of Two Coplanar Surfaces w/o Orientation Refinement


Form Only

Location & Orientation




25.25

24.75

A

A

A

25

A0.5

A0.1 Form & Orientation

Composite Profile of Two Coplanar Surfaces With Orientation Refinement


Location


6.

Profile Control Quiz

Profile tolerances always require a datum reference.


1.

Profile of a surface tolerance is a 2-dimensional control.

Profile of a line tolerances should be applied at MMC.

Profile tolerances can be applied to features of size.

2.

3.

4.

5.

Profile of a surface tolerance should be used to control

trim edges on sheet metal parts.

Profile tolerances can be combined with other geometric

controls such as flatness to control a feature.

Profile of a line tolerances apply to an entire surface.7.

Profile of a line controls apply to individual line elements.8.

Profile tolerances only control the location of a surface.9.

Composite profile controls should be avoided becausethey are more restrictive and very difficult to check.

10.

Profile tolerances can be applied either bilateral orunilateral to a feature.

11.

Profile tolerances can be applied in both freestate and

restrained datum conditions.12.

Tolerances shown in the lower segment of a composite

profile feature control frame control the location of afeature to the specified datums.

13.


In composite profile applications, the tolerance shown in the upper

segment of the feature control frame applies only to the ________ of

the feature.


The two types of profile tolerances are _________________,

and ____________________.

1.

2.

3.

4.

5.

Profile tolerances can be used to control the ________, ____,

___________ , and sometimes size of a feature.

Profile tolerances can be applied _________ or __________.

_________________ tolerances are 2-dimensional controls.

____________________ tolerances are 3-dimensional controls.


6. _________________ can be used when different tolerances are

required for location and form and/or orientation.

7. When using profile tolerances to control the location and/or orientation of

a feature, a _______________ must be included

in the feature control frame.

8. When using profile tolerances to control form only, a ______

__________ is not required in the feature control frame.

9.

profile of a linedatum reference

composite profile bilateral

location form

primary datum

true geometric counterpart

orientationprofile of a surface

unilateral

virtual condition


Tolerances of Location

True Position

Concentricity

Symmetry

(ASME Y14.5M-1994, 5.2)

(ASME Y14.5M-1994, 5.12)

(ASME Y14.5M-1994, 5.13)

http://nileshshah.tk/Notes


10.25 +/- 0.5

10.25 +/- 0.5

8.5 +/- 0.1

RectangularTolerance Zone

10.25

10.25

8.5 +/- 0.1

Circular Tolerance

Zone

B

A

C

Coordinate vs Geometric

Tolerancing Methods

Coordinate Dimensioning Geometric Dimensioning

Rectangular Tolerance Zone Circular Tolerance Zone

1.4

+/- 0.5

+/- 0.5

57% Larger

Tolerance Zone

Circular Tolerance Zone

Rectangular Tolerance Zone

Increased Effective Tolerance

1.4 A B C


Formula to determine the actual radial position of a feature using measured coordinate values (RFS)

Z positional tolerance /2

X2 Y2+Z =

X =2

Y =2

X

Y

ZFeature axis actual

location (measured)

Positional

tolerance zone cylinder

Feature axis true position (designed)

Positional Tolerance Verification

Z = total radial deviation

“X” measured deviation

“Y” measured deviation

Actual feature boundary

(Applies when a circular tolerance is indicated)


Formula to determine the actual radial position of a feature using measured coordinate values (MMC)

Z

X2 Y2+Z =

X =2

Y =2

X

Y

ZFeature axis actual

location (measured)

Positional

tolerance zone cylinder

Feature axis true position (designed)

Positional Tolerance Verification

Z = total radial deviation

“X” measured deviation

“Y” measured deviation

Actual feature boundary

+( actual - MMC)

2

= positional tolerance

(Applies when a circular tolerance is indicated)

http://nileshshah.tk/Bi-directional True Position

Rectangular Coordinate Method

3510

10

AC

B

1.5 A B C

0.5 A B C2X

2X

10 35

1.5 Wide

Tolerance Zone

0.5 WideTolerance Zone

True Position Related

to Datum Reference Frame

10B

C

Each axis must lie within the 1.5 X 0.5 rectangular tolerance zone basically located to the datum reference frame

As Shown

on Drawing

Means This:

2X 6 +/-0.25

http://nileshshah.tk/Bi-directional True Position

Multiple Single-Segment Method

3510

10

AC

B

10 35

1.5 Wide

Tolerance Zone

0.5 WideTolerance Zone

True Position Related

to Datum Reference Frame

10B

C

Each axis must lie within the 1.5 X 0.5 rectangular tolerance zone basically located to the datum reference frame

As Shown

on Drawing

Means This:

2X 6 +/-0.251.5 A B C

0.5 A B


3510

10

AC

B As Shown

on Drawing

Means This:

1.5 A B C 0.5 A B CBOUNDARY BOUNDARY

10 3510

B

C

2X 13 +/-0.25 2X 6 +/-0.25

12.75 MMC width of slot

-1.50 Position tolerance

11.25 Maximum boundary

Both holes must be within the size limits and no

portion of their surfaces may lie within the area described by the 11.25 x 5.25 maximum

boundaries when the part is positioned with

respect to the datum reference frame. The

boundary concept can only be applied on anMMC basis.

o90

True position boundary relatedto datum reference frame

A

Bi-directional True PositionNoncylndrical Features (Boundary Concept)

MM

5.75 MMC length of slot

-0.50 Position tolerance

5.25 maximum boundary

http://nileshshah.tk/Composite True Position

Without Pattern Orientation Control

3510

10

AC

B

10 35

True Position Relatedto Datum Reference

Frame

10B

C

Each axis must lie within each tolerance zone simultaneously

As Shown

on Drawing

Means This:

2X 6 +/-0.251.5 A B C

0.5 A

0.5 Feature-RelatingTolerance Zone Cylinder

1.5 Pattern-Locating

Tolerance Zone Cylinderpattern location relative

to Datums A, B, and Cpattern orientation relative to

Datum A only (perpendicularity)

http://nileshshah.tk/Composite True PositionWith Pattern Orientation Control

3510

10

AC

B

10 35

True Position Relatedto Datum Reference

Frame

10B

C

Each axis must lie within each tolerance zone simultaneously

As Shown

on Drawing

Means This:

2X 6 +/-0.25

0.5 Feature-RelatingTolerance Zone Cylinder

1.5 Pattern-Locating

Tolerance Zone Cylinderpattern location relative

to Datums A, B, and C

pattern orientation relative to

Datums A and B

1.5 A B C

0.5 A B

http://nileshshah.tk/Location (Concentricity)

Datum Features at RFS

A

15.9515.90

As Shown on Drawing

Derived Median Points of Diametrically Opposed Elements

Axis of DatumFeature A

Means This:

Within the limits of size and regardless of feature size, all median points of diametrically opposed elements must lie within a 0.5 cylindrical tolerance zone. The axis of the tolerance zone coincides with the axis of datum feature A. Concentricity can only be applied on an RFS basis.

0.5 A

6.35 +/- 0.05

0.5 Coaxial Tolerance Zone

http://nileshshah.tk/Location (Symmetry)

Datum Features at RFS

A

15.9515.90

0.5 A

6.35 +/- 0.05

Derived MedianPoints

Center Plane of Datum Feature A


Means This:

Within the limits of size and regardless of feature size, all median points of opposed elements must lie between two parallel planes equallydisposed about datum plane A, 0.5 apart. Symmetry can only be applied on an RFS basis.

As Shown on Drawing


True Position Quiz


Positional tolerances are applied to individual or patternsof features of size.

1.

Cylindrical tolerance zones more closely represent the

functional requirements of a pattern of clearance holes.

True position tolerances can control a feature’s size.

Positional tolerances are applied on an MMC, LMC, or

RFS basis.

2.

3.

4.

5.

True position tolerance values are used to calculate the

minimum size of a feature required for assembly.

6. Composite true position tolerances should be avoided

because it is overly restrictive and difficult to check.

Composite true position tolerances can only be appliedto patterns of related features.

7.

The tolerance value shown in the upper segment of acomposite true position feature control frame applies

to the location of a pattern of features to the specified

datums.

8.

Positional tolerances can be used to control circularity

9.

10.

11.

The tolerance value shown in the lower segment of a

composite true position feature control frame appliesto the location of a pattern of features to the specified

datums.

True position tolerances can be used to control centerdistance relationships between features of size.


Positional tolerance zones can be ___________, ___________,

or spherical

1.

2.

3.

4.

5.

________________ are used to establish the true (theoretically

exact) position of a feature from specified datums.

Positional tolerancing is a _____________ control.

Positional tolerance can apply to the ____ or ________________ of

a feature.

_____ and ________ fastener equations are used to determine

appropriate clearance hole sizes for mating details

6.

7.

_________ tolerance zones are recommended to prevent fastener

interference in mating details.

8.

projected3-dimensional

surface boundary floating

location fixed

basic dimensions

maximum material

cylindricalpattern-locating rectangular

feature-relating

True Position Quiz


The tolerance shown in the upper segment of a composite true

position feature control frame is called the ________________tolerance zone.

The tolerance shown in the lower segment of a composite true

position feature control frame is called the ________________tolerance zone.

9. Functional gaging principles can be applied when __________

________ condition is specified

axis


Tolerances of Runout

Circular Runout

(ASME Y14.5M-1994, 6.7.1.2.1)

Total Runout

(ASME Y14.5M-1994 ,6.7.1.2.2)


Datum feature

Datum axis (established

from datum feature

Angled surfaces

constructed around a datum axis

External surfaces constructed around

a datum axis

Internal surfaces

constructed around a datum axis

Surfaces constructed

perpendicular to a datum axis

Features Applicable

to Runout Tolerancing


0+ -

Full Indicator

Movement

Maximum Minimum

Total

Tolerance

Maximum Reading

Minimum

Reading

Full Part

Rotation

Measuring position #1

(circular element #1)

Circular Runout

When measuring circular runout, the indicator must be reset to zero at each measuring position

along the feature surface. Each individual circular element of the surface is independently allowed the full specified tolerance. In this example, circular runout can be used to detect 2-

dimensional wobble (orientation) and waviness (form), but not 3-dimensional characteristics

such as surface profile (overall form) or surface wobble (overall orientation).

Measuring position #2

(circular element #2)

Circular runout can only be applied on an

RFS basis and cannot be modified to

MMC or LMC.


o360 Part Rotation

50 +/- 2o o

As Shown

on Drawing

Means This:

Datum axis A

Single circular

element

Circular Runout(Angled Surface to Datum Axis)

0.75 A

A

50 +/-0.25

0+-

NOTE: Circular runout in this example only

controls the 2-dimensional circular elements (circularity and coaxiality) of the angled feature surface not the entire angled feature surface

Full Indicator

Movement( )

The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.

Allowable indicator reading = 0.75 max.

When measuring circular runout, the indicator mustbe reset when repositioned along the feature surface.

Collet or Chuck


As Shown

on Drawing

50 +/-0.25

0.75 A

Circular Runout (Surface Perpendicular to Datum Axis)

o360 Part

Rotation

0+-

Datum axis A

Single circular element

NOTE: Circular runout in this example will only control variation in the 2-dimensional

circular elements of the planar surface (wobble and waviness) not the entire feature surface


Means This:


When measuring circular runout, the indicator mustbe reset when repositioned along the feature surface.

A


0+ -



o360 Part

Rotation

Means This:

As Shown

on Drawing

50 +/-0.25

0.75 A

Datum axis A

When measuring circular runout, the indicator must be reset when repositioned along the feature surface.

Circular Runout (Surface Coaxial to Datum Axis)



circular elements of the surface (circularity and coaxiality) not the entire feature surface

A


0+ -



o360 Part Rotation

Means This:

As Shown

on Drawing

0.75 A-B

Datum axis A-B


Circular Runout (Surface Coaxial to Datum Axis)



circular elements of the surface (circularity and coaxiality) not the entire feature surface

Machine

center

Machine

center

BA


As Shown

on Drawing

50 +/-0.25

Circular Runout (Surface Related to Datum Surface and Axis)

o360 Part

Rotation

0+ -

Datum axis B


The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is located against the datum surface and rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.

Means This:

A



Collet or Chuck

Stop collar

0.75 A B

Datum plane A

B


0+

Full Indicator

Movement

Total

Tolerance

Maximum

ReadingMinimum Reading

Full Part

Rotation

-

0+ -

Total Runout

Maximum Minimum

When measuring total runout, the indicator is moved in a straight line along the feature surface

while the part is rotated about the datum axis. It is also acceptable to measure total runout by

evaluating an appropriate number of individual circular elements along the surface while the part

is rotated about the datum axis. Because the tolerance value is applied to the entire surface, the

indicator must not be reset to zero when moved to each measuring position. In this example, total runout can be used to measure surface profile (overall form) and surface wobble (overall

orientation).

Indicator

Path

Total runout can only be applied on an

RFS basis and cannot be modified to

MMC or LMC.


Full Part

Rotation

50 +/- 2o o

As Shown

on Drawing

A

50 +/-0.25

0.75 A

Means This:

Datum axis A

0+-

The tolerance zone for the entire angled surface is equal to the total allowable movement of a dial indicator positioned normal to the true geometric shape of the feature surface when the part is rotated about the datum axis and the indicator is moved along the entire length of the feature surface.0

+-

NOTE: Unlike circular runout, the use of total runoutwill provide 3-dimensional composite control of the cumulative variations of circularity, coaxiality, angularity, taper and profile of the angled surface

Total Runout (Angled Surface to Datum Axis)

Collet or Chuck

When measuring total runout, the indicator must not be reset when repositioned along the feature surface.

(applies to the entire feature surface)Allowable indicator reading = 0.75 max.


0+-

Total Runout (Surface Perpendicular to Datum Axis)

As Shown

on Drawing

A

50 +/-0.25

0.75 A

35

10

0+-

Datum axis AFull Part

Rotation

35

10

Means This:

NOTE: The use of total runout in this example

will provide composite control of the cumulative variations of perpendicularity (wobble) and flatness (concavity or convexity) of the feature surface.

The tolerance zone for the portion of the feature surface indicated is equal to the total allowable movement of a dial indicator positioned normal to the true geometric shape of the feature surface when the part is rotated about the datum axis and the indicator is moved along the portion of the feature surface within the area described by the basic dimensions.

When measuring total runout, the indicator must not be reset when repositioned along the feature surface.

(applies to portion of feature surface indicated)Allowable indicator reading = 0.75 max.


Runout Control Quiz


Total runout is a 2-dimensional control.1.

Runout tolerances are used on rotating parts.

Total runout tolerances should be applied at MMC.

Runout tolerances can be applied to surfaces at rightangles to the datum reference.

2.

3.

4.

5.

Circular runout tolerances apply to single elements .

6. Circular runout tolerances are used to control an entire

feature surface.

Runout tolerances always require a datum reference.7.

Circular runout and total runout both control axis to surface relationships.

8.

Circular runout can be applied to control taper of a part.9.

Total runout tolerances are an appropriate way to limit “wobble” of a rotating surface.

10.

Runout tolerances are used to control a feature’s size.11.

Total runout can control circularity, straightness, taper,coaxiality, angularity and any other surface variation.

12.


Fixed and

Floating

Fastener

Exercises


2x M10 X 1.5(Reference)

B

A

?.?

2x 10.50 +/- 0.25

M Calculate Required Positional Tolerance

0.5

2x ??.?? +/- 0.25

M

Calculate Nominal Size

A

B

T = H - FH = Minimum Hole Size = 10.25

F = Max. Fastener Size = 10

T = 10.25 -10

T = ______

Floating Fasteners

H = F +TF = Max. Fastener Size = 10T = Positional Tolerance = 0.50

H = 10 + 0.50

H = ______

In applications where two or more mating details are assembled, and all parts have clearance holes for the fasteners, the floating fastener formula shown

below can be used to calculate the appropriate hole sizes or positional tolerance

requirements to ensure assembly. The formula will provide a “zero-interference” fit when the features are at MMC and at their extreme of positional tolerance

H= Min. diameter of clearance hole

F= Maximum diameter of fastener T= Positional tolerance diameter

H=F+T or T=H-F

General Equation Applies to

Each Part Individually

remember: the size tolerance must be

added to the calculated MMC hole size to obtain the correct nominal value.



B

A

0.25

2x 10.50 +/- 0.25

M

0.5

2x 10.75 +/- 0.25

M

A

B

Floating Fasteners

REMEMBER!!! All Calculations Apply at MMC



H=F+T or T=H-F

General Equation Applies to

Each Part Individually

T = H - FH = Minimum Hole Size = 10.25


T = 10.25 -10

T = 0.25

Calculate Required Positional Tolerance

F = Max. Fastener Size = 10T = Positional Tolerance = 0.5

H = 10 + .5

H = 10.5 Minimum

H = F +T

In applications where two or more mating details are assembled, and all parts have clearance holes for the fasteners, the floating fastener formula shown

below can be used to calculate the appropriate hole sizes or positional tolerance

requirements to ensure assembly. The formula will provide a “zero-interference” fit when the features are at MMC and at their extreme of positional tolerance

remember: the size tolerance must be

added to the calculated MMC hole size to obtain the correct nominal value.

Calculate Nominal Size


F = Max. Fastener Size = 10.00

T = Positional Tolerance = 0.80


B

A

0.8

2x ??.?? +/- 0.25

M

Calculate Required Clearance Hole Size.

2X M10 X 1.5

A

B

Fixed Fasteners

H = 10.00 + 2(0.8)

H = _____



H=F+2T or T=(H-F)/2

General Equation Used When

Positional Tolerances Are Equal

In fixed fastener applications where two mating details have equal positional tolerances, the fixed fastener formula shown below can be used to calculate the

appropriate minimum clearance hole size and/or positional tolerance required to

ensure assembly. The formula provides a “zero-interference” fit when the features are at MMC and at their extreme of positional tolerance. (Note that in this example

the positional tolerances indicated are the same for both parts.)

0.8 M 10P

APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED

Nominal Size (MMC For Calculations)

H = F + 2T

remember: the size tolerance must be added to the calculated MMC size to obtain the correct nominal value.

10



B

A

2x 11.85 +/- 0.25

0.8 M


A

B





Fixed Fasteners

H = F + 2TF = Max. Fastener Size = 10.00


H = 10.00 + 2(0.8)

H = 11.60 Minimum



H=F+2T or T=(H-F)/2



0.8 M 10P


2X M10 X 1.5Nominal Size

(MMC For Calculations)



10



B

A

2x 11.85 +/- 0.25

0.8 M


A

B





Fixed Fasteners

H = F + 2TF = Max. Fastener Size = 10


H = 10 + 2(0.8)

H = 11.6 Minimum



H=F+2T or T=(H-F)/2



0.8 M 10P






10



B

A

0.5

2x 11.25 +/- 0.25

MCalculate Required Positional Tolerance . (Both Parts)

A

B

In applications where two mating details are assembled, and one part has restrained fasteners, the fixed fastener formula shown below can be used to

calculate appropriate hole sizes and/or positional tolerances required to ensure

assembly. The formula will provide a “zero-interference” fit when the features are at MMC and at their extreme of positional tolerance. (Note: in this example the

resultant positional tolerance is applied to both parts equally.)

Fixed Fasteners

T = (H - F)/2H = Minimum Hole Size = 11


T = (11 - 10)/2

T = 0.50



H=F+2T or T=(H-F)/2



2X M10 X 1.5

0.5 M 10P


Nominal Size (MMC For Calculations)


10



B

A

0.5

2x ??.?? +/- 0.25

M


A

B

Fixed Fasteners

H = Min. diameter of clearance hole

F = Maximum diameter of fastener T1= Positional tolerance (Part A) T2=

Positional tolerance (Part B)

H=F+(T1 + T2)


Positional Tolerances Are Not Equal


T1 = Positional Tol. (A) = 0.50

T2 = Positional Tol. (B) = 1

H = 10+ (0.5 + 1)

H = ____

H=F+(T1 + T2)

In fixed fastener applications where two mating details have unequal positional tolerances, the fixed fastener formula shown below can be used to calculate the

appropriate minimum clearance hole size and/or positional tolerances required to


the positional tolerances indicated are not equal.)




remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.

10

1 M 10P



B

A

0.5

2x 11.75 +/- 0.25

M


A

B

In fixed fastener applications where two mating details have unequal positional tolerances, the fixed fastener formula shown below can be used to calculate the

appropriate minimum clearance hole size and/or positional tolerances required to


the positional tolerances indicated are not equal.)

Fixed Fasteners



T2 = Positional Tol. (B) = 1

H = 10 + (0.5 + 1)

H = 11.5 Minimum


H = Min. diameter of clearance hole

F = Maximum diameter of fastener T1= Positional tolerance (Part A) T2=

Positional tolerance (Part B)

H= F+(T1 + T2)


Positional Tolerances Are Not Equal

H=F+(T1 + T2)

1 M 10P





10


D

P

H F

A

B

APPLIES WHEN A PROJECTED TOLERANCE ZONE IS NOT USED

2x 10.05 +/-0.05

B

A

0.5 M

2x ??.?? +/-0.25Calculate Nominal Size

0.5 M

In applications where a projected tolerance zone is not indicated, it is necessary to select a positional tolerance and minimum clearance hole size

combination that will allow for any out-of-squareness of the feature containing the

fastener. The modified fixed fastener formula shown below can be used to calculate the appropriate minimum clearance hole size required to ensure

assembly. The formula provides a “zero-interference” fit when the features are at MMC and at the extreme positional tolerance.

Fixed Fasteners

H = 10.00 + 0.5 + 0.5(1 + 2(15/20))

H = __________

H= F + T1 + T2 (1+(2P/D))


H= Min. diameter of clearance hole F= Maximum diameter of pin

T1= Positional tolerance (Part A) T2= Positional tolerance (Part B)

D= Min. depth of pin (Part A)

P= Maximum projection of pin

F = Max. pin size = 10


T2 = Positional Tol. (B) = 0.5 D = Min. pin depth = 20. P

= Max. pin projection = 15


D

P

H F

A

B

H= Min. diameter of clearance hole F= Maximum diameter of pin

T1= Positional tolerance (Part A) T2= Positional tolerance (Part B)

D= Min. depth of pin (Part A)

P= Maximum projection of pin

APPLIES WHEN A PROJECTED TOLERANCE ZONE IS NOT USED

2x 10.05 +/-0.05

B

A

0.5 M

2x 12 +/-0.25Calculate Nominal Size

0.5 M

F = Max. pin size = 10

T1 = Positional tol. (A) = 0.5

T2 = Positional tol. (B) = 0.5 D = Min. pin depth = 20 P

= Max. pin projection = 15

H= F + T1 + T2 (1+(2P/D))

H = 10 + 0.5 + 0.5(1 + 2(15/20))

H = 11.75 Minimum

In applications where a projected tolerance zone is not indicated, it is necessary to select a positional tolerance and minimum clearance hole size

combination that will allow for any out-of-squareness of the feature containing the

fastener. The modified fixed fastener formula shown below can be used to calculate the appropriate minimum clearance hole size required to ensure

assembly. The formula provides a “zero-interference” fit when the features are at MMC and at the extreme positional tolerance.

Fixed Fasteners

H= F + T1 + T2 (1+(2P/D))




Answers to Quizzes

and Exercises


Rules and Definitions Quiz

1. Tight tolerances ensure high quality and performance.

2. The use of GD&T improves productivity.

3. Size tolerances control both orientation and position.

4. Unless otherwise specified size tolerances control form.

5. A material modifier symbol is not required for RFS.

6. A material modifier symbol is not required for MMC.

7. Title block default tolerances apply to basic dimensions.

8. A surface on a part is considered a feature.

9. Bilateral tolerances allow variation in two directions.

10. A free state modifier can only be applied to a tolerance.

11. A free state datum modifier applies to “assists” & “rests”.

12. Virtual condition applies regardless of feature size.

FALSE

TRUE

FALSE

TRUE

TRUE

FALSE

FALSE

TRUE

TRUE

TRUE

FALSE

FALSE

Questions #1-12 True or False


Material Condition Quiz

Internal Features MMC LMC

External Features MMC LMC

.890

.885

.895

.890

23.45 +0.05/-0.25

10.75 +0.25/-0

123. 5 +/-0.1

23.45 +0.05/-0.25

10.75 +0/-0.25

123. 5 +/-0.1

Calculate appropriate values

Fill in blanks

10.75 11

23.2 23.5

123.4 123.6

.890 .895

10.75 10.5

23.5 23.2

123.6 123.4

.890 .885


1. Datum target areas are theoretically exact.

2. Datum features are imaginary.

3. Primary datums have only three points of contact.

4. The 6 Degrees of Freedom are U/D, F/A, & C/C.

5. Datum simulators are part of the gage or tool.

6. Datum simulators are used to represent datums.

8. All datum features must be dimensionally stable.

9. Datum planes constrain degrees of freedom.

10. Tertiary datums are not always required.

12. Datums should represent functional features.

Datum Quiz

11. All tooling locators (CD’s) are used as datums.

Questions #1-12 True or False

7. Datums are actual part features.

FALSE

FALSE

FALSE

FALSE

TRUE

TRUE

FALSE

TRUE

TRUE

TRUE

FALSE

TRUE


Datum Quiz

The three planes that make up a basic datum reference

frame are called primary, secondary, and tertiary.

An unrestrained part will exhibit 3-linear and 3-rotational degrees

of freedom.

A planar primary datum plane will restrain 1-linear and 2-rotationaldegrees of freedom.

The primary and secondary datum planes together will restrain five degrees

of freedom.

The primary, secondary and tertiary datum planes together will

restrain all six degrees of freedom.

The purpose of a datum reference frame is to restrain movementof a part in a gage or tool.

A datum must be functional, repeatable, and coordinated.

A datum feature is an actual feature on a part.

A datum is a theoretically exact point, axis or plane.

A datum simulator is a precise surface used to establish a

simulated datum.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.


primary

secondary

tertiary 3-rotational

3-linear

2-rotational

datum

three

two

one

six

functional

restrain movement coordinated

datum simulator

datum feature

repeatablefive

1-linear


Straightness and circularity are individual line or circular

element (2-D) controls.

Form Control Quiz

The four form controls are straightness, flatness,

circularity, and cylindricity.

Rule #1 states that unless otherwise specified a feature of

size must have perfect form at MMC.

Flatness and cylindricity are surface (3-D) controls.

Circularity can be applied to both straight and tapered cylindrical

parts.

1.

2.

3.

4.

5.

Form controls require a datum reference.

Form controls do not directly control a feature’s size.

A feature’s form tolerance must be less than it’s size

tolerance.

Flatness controls the orientation of a feature.

Size limits implicitly control a feature’s form.

6.

7.

8.

9.

10.

FALSE

TRUE

TRUE

TRUE

FALSE



straightness

flatness

circularity

cylindricity

perfect form

straight tapered profile

true position

angularity


Orientation Control Quiz

The three orientation controls are angularity, parallelism,

and perpendicularity.

1.

2.

3.

4.

5.

A datum reference is always required when applying any of

the orientation controls.

Perpendicularity is the appropriate geometric tolerance when

controlling the orientation of a feature at right angles to a datum

reference.

Orientation tolerances indirectly control a feature’s form.

Mathematically all three orientation tolerances are identical.

Orientation tolerances do not control the location of a feature.


6. TRUE

Orientation tolerance zones can be cylindrical.

Parallelism tolerances do not apply to features of size.

To apply an angularity tolerance the desired angle mustbe indicated as a basic dimension.

7.

8.

9.

10.

TRUE

FALSE

FALSE

TRUE

To apply a perpendicularity tolerance the desired angle

must be indicated as a basic dimension.


angularity

perpendicularity

parallelism

datum reference

identical

location

profile

datum feature

datum target


Runout Control Quiz


TRUE

Total runout is a 2-dimensional control.1.

Runout tolerances are used on rotating parts.

Total runout tolerances should be applied at MMC.

Runout tolerances can be applied to surfaces at rightangles to the datum reference.

2.

3.

4.

5.

FALSE

Circular runout tolerances apply to single elements .

FALSE

TRUE

TRUE

6. Circular runout tolerances are used to control an entire

feature surface.

Runout tolerances always require a datum reference.7.

Circular runout and total runout both control axis to surface relationships.

8. TRUE

Circular runout can be applied to control taper of a part.9. FALSE

Total runout tolerances are an appropriate way to limit “wobble” of a rotating surface.

10.

Runout tolerances are used to control a feature’s size.11.

Total runout can control circularity, straightness, taper,coaxiality, angularity and any other surface variation.

12. TRUE

FALSE

TRUE

TRUE

FALSE


In composite profile applications, the tolerance shown in the upper

segment of the feature control frame applies only to the location of the

feature.


The two types of profile tolerances are profile of a line, and

profile of a surface.1.

2.

3.

4.

5.

Profile tolerances can be used to control the location, form,

orientation, and sometimes size of a feature.

Profile tolerances can be applied bilateral or unilateral.

Profile of a line tolerances are 2-dimensional controls.

Profile of a surface tolerances are 3-dimensional controls.


6. Composite Profile can be used when different tolerances are

required for location and form and/or orientation.

7. When using profile tolerances to control the location and/or orientation of

a feature, a datum reference must be included in the feature control

frame.

8. When using profile tolerances to control form only, a datum reference is not required in the feature control frame.

9.

profile of a linedatum reference

composite profile bilateral

location form

primary datum

true geometric counterpart

orientationprofile of a surface

unilateral

virtual condition


6.


Profile tolerances always require a datum reference.


1.

Profile of a surface tolerance is a 2-dimensional control.

Profile of a line tolerances should be applied at MMC.

Profile tolerances can be applied to features of size.

2.

3.

4.

5.

Profile of a surface tolerance should be used to control

trim edges on sheet metal parts.

Profile tolerances can be combined with other geometric

controls such as flatness to control a feature.

Profile of a line tolerances apply to an entire surface.7.

Profile of a line controls apply to individual line elements.8.

Profile tolerances only control the location of a surface.9.

Composite profile controls should be avoided because

they are more restrictive and very difficult to check.

10.

Profile tolerances can be applied either bilateral or

unilateral to a feature.

11.

Profile tolerances can be applied in both freestate and

restrained datum conditions.

12.

Tolerances shown in the lower segment of a composite

profile feature control frame control the location of a

feature to the specified datums.

13.

TRUE

FALSE

FALSE

FALSE

TRUE

TRUE

TRUE

FALSE

FALSE

FALSE

TRUE

TRUE

FALSE


True Position Quiz


TRUE

Positional tolerances are applied to individual or patterns

of features of size.1.

Cylindrical tolerance zones more closely represent the

functional requirements of a pattern of clearance holes.

True position tolerances can control a feature’s size.

Positional tolerances are applied on an MMC, LMC, or

RFS basis.

2.

3.

4.

5.

FALSE

True position tolerance values are used to calculate the

minimum size of a feature required for assembly.

TRUE

TRUE

6. Composite true position tolerances should be avoided

because it is overly restrictive and difficult to check.

Composite true position tolerances can only be applied

to patterns of related features.

7.

The tolerance value shown in the upper segment of a

composite true position feature control frame applies


datums.

8. TRUE

Positional tolerances can be used to control circularity

9. FALSE

10.

11. TRUE

FALSE

TRUE

FALSE

TRUE

The tolerance value shown in the lower segment of a

composite true position feature control frame applies


datums.

True position tolerances can be used to control center

distance relationships between features of size.


Positional tolerance zones can be rectangular, cylindrical,or spherical

1.

2.

3.

4.

5.

Basic dimensions are used to establish the true (theoretically

exact) position of a feature from specified datums.

Positional tolerancing is a 3-dimensional control.

Positional tolerance can apply to the axis or surface boundaryof a feature.

Fixed and floating fastener equations are used to determine

appropriate clearance hole sizes for mating details

6.

7.

Projected tolerance zones are recommended to prevent fastener

interference in mating details.

8.

projected3-dimensional

surface boundary floating

location fixed

basic dimensions

maximum material

cylindricalpattern-locating rectangular

feature-relating

True Position Quiz


The tolerance shown in the upper segment of a composite true

position feature control frame is called the pattern-locatingtolerance zone.

The tolerance shown in the lower segment of a composite true

position feature control frame is called the feature-relatingtolerance zone.

9. Functional gaging principles can be applied when maximum

material condition is specified

axis


Virtual and

Resultant

Condition

Boundaries

Internal and External

Features (MMC Concept)


Virtual Condition BoundaryInternal Feature (MMC Concept)

12.5 Virtual Condition Boundary

13.5 MMC Size of Feature

1 Applicable Geometric Tolerance

Calculating Virtual Condition

1 A B CM

14 +/- 0.5

C

BXX.X

XX.X

A

As Shown on Drawing

Axis Location of

MMC Hole Shown

at Extreme Limit

Boundary of MMC Hole

Shown at Extreme Limit

1 Positional Tolerance Zone at

MMC

True (Basic)

Position of Hole

True (Basic)

Position of Hole

Other Possible

Extreme Locations

Virtual Condition

Inner Boundary

Maximum InscribedDiameter( )


Resultant Condition BoundaryInternal Feature (MMC Concept)

1 A B CM

14 +/- 0.5

C

BXX.X

XX.X

A

16.5 Resultant Condition Boundary

14.5 LMC Size of Feature

2 Geometric Tolerance (at LMC)

Calculating Resultant Condition (Internal Feature)

As Shown on Drawing

Axis Location of

LMC Hole Shown

at Extreme Limit

Boundary of LMC Hole



LMC

True (Basic)

Position of Hole

True (Basic)

Position of Hole

Other Possible

Extreme Locations

Resultant Condition

Outer Boundary

Minimum CircumscribedDiameter( )


Virtual Condition BoundaryExternal Feature (MMC Concept)

15.5 Virtual Condition Boundary

14.5 MMC Size of Feature

1 Applicable Geometric Tolerance

Calculating Virtual Condition

1 A B CM

14 +/- 0.5

C

BXX.X

XX.XX

A

As Shown on Drawing

Axis Location of

MMC Feature Shown

at Extreme Limit

Boundary of MMC Feature



MMC

True (Basic)

Position of Feature

True (Basic)

Position of Feature

Other Possible

Extreme Locations

Virtual Condition

Outer Boundary

Minimum CircumscribedDiameter( )


Resultant Condition BoundaryExternal Feature (MMC Concept)

1 A B CM

14 +/- 0.5

C

BXX.X

XX.X

A

11.5 Resultant Condition Boundary

13.5 LMC Size of Feature

2 Geometric Tolerance (at LMC)

Calculating Resultant Condition (External Feature)

As Shown on Drawing

Axis Location of

LMC Feature Shown

at Extreme Limit

Boundary of LMC feature



LMC

True (Basic)

Position of Feature

True (Basic)

Position of Feature

Other Possible

Extreme Locations

Resultant Condition

Inner Boundary

Maximum Inscribed

Diameter( )

http://nileshshah.tk/Extreme Variations of Form

Allowed By Size Tolerance25.1 25

25

(MMC)

25.1

(LMC)

25.1 (LMC)

25 (MMC)

25.1

(LMC)

MMC Perfect

Form Boundary

Internal Feature of Size


Allowed By Size Tolerance25 24.9

25

(MMC)24.9 (LMC)

24.9 (LMC)

MMC Perfect

Form Boundary25

(MMC)

24.9 (LMC)

External Feature of Size


Allowed By Size Tolerance25.1

25

25

24.9

25

(MMC)

25.1

(LMC)

25.1

(LMC)

25

(MMC)24.9

(LMC)

24.9

(LMC)

25

(MMC)

25.1

(LMC)

MMC Perfect

Form Boundary25

(MMC)

24.9

(LMC)


E

N

D

gdt

Documents

tolerance straightness

straightness tolerance

size tolerance http

circularity tolerance

flatness tolerance

tolerance cylinder

wide tolerance zone

specified tolerance