Transcript No Slide Title
DIMENSIONAL ENGINEERING
Based on the ASME Y14.5M 1994 Dimensioning and Tolerancing Standard
INTRODUCTION
Geometric dimensioning and tolerancing (GD&T) is an international engineering language that is used on engineering drawings (blue prints) to describe product in three dimensions. GD&T uses a series of internationally recognized symbols rather than words to describe the product. These symbols are applied to the features of a part and provide a very concise and clear definition of design intent.
GD&T is a very precise mathematical language that describes the form, orientation and location of part features in zones of tolerance. These zones of tolerance are then described relative to a Cartesian coordinate system.
ASME Y14.5M-1994 American national Standards Institute/
American Society of Mechanical Engineers
Tolerances of Form
Straightness
(ASME Y14.5M-1994, 6.4.1)
Flatness
(ASME Y14.5M-1994, 6.4.2)
Circularity
(ASME Y14.5M-1994, 6.4.3)
Cylindricity
(ASME Y14.5M-1994, 6.4.4)
Extreme Variations of Form Allowed By Size Tolerance
25.1 25 25 (MMC) 25 (MMC) 25.1 (LMC) 25.1 (LMC) MMC Perfect Form Boundary 25.1 (LMC)
Internal Feature of Size
Extreme Variations of Form Allowed By Size Tolerance
25 24.9
24.9 (LMC) MMC Perfect Form Boundary 25 (MMC) 24.9 (LMC) 25 (MMC) 24.9 (LMC)
External Feature of Size
25 +/-0.25
Straightness
(Flat Surfaces)
0.5
0.1
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 Tolerance Zone 24.75 min 0.1 Tolerance Zone 25.25 max
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.
The straightness tolerance is applied in the view where the elements to be controlled are represented by a straight line
Straightness
(Surface Elements)
0.1
0.1 Tolerance Zone MMC 0.1 Tolerance Zone MMC 0.1 Tolerance Zone MMC
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
MMC 0.1 Diameter Tolerance Zone Outer Boundary (Max) 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
0.1
M 15 (MMC) 0.1 Diameter Tolerance Zone 15.1 Virtual Condition 14.85 (LMC) 0.25 Diameter Tolerance Zone 15.1 Virtual Condition
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.
Flatness
0.1
25 +/-0.25
0.1 Tolerance Zone 24.75 min 0.1 Tolerance Zone 25.25 max
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.
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.
Circularity
(Roundness)
0.1
0.1
90 90 0.1 Wide Tolerance Zone
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.
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
Cylindricity
0.1
0.1 Tolerance Zone MMC
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.
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.
Form Control Quiz
Questions #1-5 Fill in blanks (choose from below) 1.
The four form controls are
____________
,
________
,
___________
, and
____________
. 2.
Rule #1 states that unless otherwise specified a feature of size must have
____________
at MMC.
3.
____________
and
___________
are individual line or circular element (2-D) controls.
4.
________
and
____________
are surface (3-D) controls.
5.
Circularity can be applied to both
________
and
_______
cylindrical parts.
straightness straight perfect form cylindricity flatness tapered circularity angularity profile true position
Answer questions #6-10 True or False 6.
Form controls require a datum reference.
7.
Form controls do not directly control a feature’s size.
8.
A feature’s form tolerance must be less than it’s size tolerance.
9.
Flatness controls the orientation of a feature.
10.
Size limits implicitly control a feature’s form.
Tolerances of Orientation
Angularity
(ASME Y14.5M-1994 ,6.6.2)
Perpendicularity
(ASME Y14.5M-1994 ,6.6.4)
Parallelism
(ASME Y14.5M-1994 ,6.6.3)
Angularity
(Feature Surface to Datum Surface)
20 +/-0.5
0.3 A 30 o
A
19.5 min 20.5 max 30 o 30 o
A
0.3 Wide Tolerance Zone
A
0.3 Wide Tolerance Zone
The tolerance zone in this example is defined by two parallel planes oriented at the specified angle to the datum reference plane.
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.
Angularity
(Feature Axis to Datum Surface)
NOTE: Tolerance applies to feature at RFS
0.3 A 0.3 Circular Tolerance Zone 0.3 Circular Tolerance Zone 60 o
A
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.
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.
Angularity
(Feature Axis to Datum Axis)
NOTE: Feature axis must lie within tolerance zone cylinder
A
0.3 Circular Tolerance Zone 0.3 A
NOTE: Tolerance applies to feature at RFS
0.3 Circular Tolerance Zone 45 o Datum Axis A
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.
Angularity is the condition of the feature axis at a specified angle (other than 90 degrees) to the datum reference axis, within the specified tolerance zone.
Perpendicularity
(Feature Surface to Datum Surface)
0.3 A
A
0.3 Wide Tolerance Zone 0.3 Wide Tolerance Zone
A
The tolerance zone in this example is defined by two parallel planes oriented perpendicular to the datum reference plane.
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 Axis to Datum Surface)
0.3 Diameter Tolerance Zone 0.3 Circular Tolerance Zone
C
0.3 C
NOTE: Tolerance applies to feature at RFS
0.3 Circular Tolerance Zone
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 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 Axis)
NOTE: Tolerance applies to feature at RFS
0.3 A
A
0.3 Wide Tolerance Zone Datum Axis A
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.
Parallelism
(Feature Surface to Datum Surface)
25 +/-0.5
A
0.3 Wide Tolerance Zone 0.3 A 0.3 Wide Tolerance Zone 25.5 max 24.5 min
A
The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.
A
Parallelism is the condition of the planar feature surface equidistant at all points from the datum reference plane, within the specified tolerance zone.
Parallelism
(Feature Axis to Datum Surface)
NOTE: The specified tolerance does not apply to the orientation of the feature axis in this direction NOTE: Tolerance applies to feature at RFS
0.3 A 0.3 Wide Tolerance Zone
A
The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.
A
Parallelism is the condition of the feature axis equidistant along its length from the datum reference plane, within the specified tolerance zone.
B
Parallelism
(Feature Axis to Datum Surfaces)
0.3 Circular Tolerance Zone 0.3 Circular Tolerance Zone 0.3 A B
NOTE: Tolerance applies to feature at RFS
0.3 Circular Tolerance Zone
B 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 planes.
A
Parallelism is the condition of the feature axis equidistant along its length from the two datum reference planes, within the specified tolerance zone.
Parallelism
(Feature Axis to Datum Axis)
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. NOTE: Tolerance applies to feature at RFS
0.1 Circular Tolerance Zone 0.1 A
A
0.1 Circular Tolerance Zone Datum Axis A Parallelism is the condition of the feature axis equidistant along its length from the datum reference axis, within the specified tolerance zone.
Orientation Control Quiz
Questions #1-5 Fill in blanks (choose from below) 1.
The three orientation controls are
__________
,
___________
, and
________________
. 2.
A
_______________
is always required when applying any of the orientation controls.
3.
________________
is the appropriate geometric tolerance when controlling the orientation of a feature at right angles to a datum reference.
4.
Mathematically all three orientation tolerances are
_________
.
5.
Orientation tolerances do not control the
________
of a feature.
perpendicularity datum feature angularity datum target location identical datum reference parallelism profile
Answer questions #6-10 True or False 6.
Orientation tolerances indirectly control a feature’s form.
7.
Orientation tolerance zones can be cylindrical.
8.
To apply a perpendicularity tolerance the desired angle must be indicated as a basic dimension.
9.
Parallelism tolerances do not apply to features of size.
10.
To apply an angularity tolerance the desired angle must be indicated as a basic dimension.
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)
Features Applicable to Runout Tolerancing
Internal surfaces constructed around a datum axis External surfaces constructed around a datum axis Datum axis (established from datum feature Datum feature Angled surfaces constructed around a datum axis
Surfaces constructed perpendicular to a datum axis
Circular Runout
Maximum Full Indicator Movement Maximum Reading + 0 Minimum Reading Total Tolerance
Circular runout can only be applied on an RFS basis and cannot be modified to MMC or LMC.
Minimum Measuring position #1 (circular element #1) Full Part Rotation Measuring position #2 (circular element #2)
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).
Circular Runout
(Angled Surface to Datum Axis)
0.75 A A 50 +/-0.25
Means This:
Allowable indicator reading = 0.75 max.
(
Full Indicator Movement
)
0 + When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
50 +/- 2 o
As Shown on Drawing
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.
Collet or Chuck Datum axis A Single circular element Rotation
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
Circular Runout
(Surface Perpendicular to Datum Axis)
0.75 A A 50 +/-0.25
Means This:
Single circular element Rotation
As Shown on Drawing
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.
0 + When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
Allowable indicator reading = 0.75 max.
Datum axis A
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
Circular Runout
(Surface Coaxial to Datum Axis)
0.75 A A 50 +/-0.25
As Shown on Drawing Means This:
Allowable indicator reading = 0.75 max.
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.
+ 0 When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
Single circular element Datum axis A Rotation
NOTE: Circular runout in this example will only control variation in the 2-dimensional circular elements of the surface (circularity and coaxiality) not the entire feature surface
Circular Runout
(Surface Coaxial to Datum Axis)
0.75 A-B A B
As Shown on Drawing Means This:
Allowable indicator reading = 0.75 max.
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.
+ 0 When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
Machine center Single circular element Datum axis A-B Rotation Machine center
NOTE: Circular runout in this example will only control variation in the 2-dimensional circular elements of the surface (circularity and coaxiality) not the entire feature surface
Circular Runout
(Surface Related to Datum Surface and Axis)
0.75 A B A B 50 +/-0.25
As Shown on Drawing Means This:
Allowable indicator reading = 0.75 max.
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.
Single circular element Stop collar + 0 Collet or Chuck Rotation Datum axis B When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
Datum plane A
Total Runout
Maximum Full Indicator Movement Maximum Reading + 0 Minimum Reading Total Tolerance
Total runout can only be applied on an RFS basis and cannot be modified to MMC or LMC.
Minimum Indicator Path + 0 Full Part Rotation
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).
Total Runout
(Angled Surface to Datum Axis)
0.75 A A 50 +/-0.25
Means This:
When measuring total runout, the indicator must not be reset when repositioned along the feature surface.
0 + 0 + 50 +/- 2 o
As Shown on Drawing
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.
Allowable indicator reading = 0.75 max.
(applies to the entire feature surface) Collet or Chuck Full Part Rotation Datum axis A
NOTE: Unlike circular runout, the use of total runout will provide 3-dimensional composite control of the cumulative variations of circularity, coaxiality, angularity, taper and profile of the angled surface
Total Runout
(Surface Perpendicular to Datum Axis)
0.75 A 10 35 50 +/-0.25
A
As Shown on Drawing Means This:
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.
10 35 Full Part Rotation 0 + 0 + When measuring total runout, the indicator must not be reset when repositioned along the feature surface.
Allowable indicator reading = 0.75 max.
(applies to portion of feature surface indicated) Datum axis A
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.
Runout Control Quiz
Answer questions #1-12 True or False 1.
Total runout is a 2-dimensional control.
2.
Runout tolerances are used on rotating parts.
3.
Circular runout tolerances apply to single elements .
4.
Total runout tolerances should be applied at MMC.
5.
Runout tolerances can be applied to surfaces at right angles to the datum reference. 6.
Circular runout tolerances are used to control an entire feature surface.
7.
Runout tolerances always require a datum reference.
8.
Circular runout and total runout both control axis to surface relationships.
9.
Circular runout can be applied to control taper of a part.
10.
Total runout tolerances are an appropriate way to limit “wobble” of a rotating surface.
11.
Runout tolerances are used to control a feature’s size.
12.
Total runout can control circularity, straightness, taper, coaxiality, angularity and any other surface variation.
Tolerances of Profile
Profile of a Line
(ASME Y14.5M-1994, 6.5.2b)
Profile of a Surface
(ASME Y14.5M-1994, 6.5.2a)
Profile of a Line
20 X 20 A1 B A3 20 X 20 20 X 20 A2 1 A B C C 17 +/- 1 2 Wide
Size
Tolerance Zone 18 Max A 1 Wide
Profile
Tolerance Zone 16 Min.
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.
Profile of a Surface
20 X 20 A1 B A3 20 X 20 20 X 20 A2 A C 2 A B C 23.5
2 Wide Tolerance Zone
Size, Form and Orientation
23.5
Nominal 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.
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.
Profile of a Surface
(Bilateral Tolerance)
20 X 20 A1 B 20 X 20 A3 20 X 20 A2 1 A B C C 50 1 Wide Total Tolerance Zone B 0.5 Inboard 0.5 Outboard C 50 Nominal Location
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.
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.
Profile of a Surface
(Unilateral Tolerance)
20 X 20 A1 B 20 X 20 A3 20 X 20 A2 0.5 A B C C 50 0.5 Wide Total Tolerance Zone B C 50 Nominal Location
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.
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 to the entire edge surface.
Profile of a Surface
(Unequal Bilateral Tolerance)
20 X 20 A1 B 20 X 20 A3 20 X 20 A2 0.5
1.2 A B C C 50 1.2 Wide Total Tolerance Zone B 0.5 Inboard 0.7 Outboard C 50 Nominal Location
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).
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.
Profile of a Surface
0.5
0.1
A Location & Orientation Form Only 25 A 25.25
0.1 Wide Tolerance Zone 24.75
A
Composite Profile of Two Coplanar Surfaces w/o Orientation Refinement
Profile of a Surface
0.5
0.1
A A Location Form & Orientation 25 25.25
A 0.1 Wide Tolerance Zone 24.75
A 0.1 Wide Tolerance Zone A
Composite Profile of Two Coplanar Surfaces With Orientation Refinement
Profile Control Quiz
Answer questions #1-13 True or False 1.
Profile tolerances always require a datum reference.
2.
Profile of a surface tolerance is a 2-dimensional control.
3.
Profile of a surface tolerance should be used to control trim edges on sheet metal parts.
4.
Profile of a line tolerances should be applied at MMC.
5.
Profile tolerances can be applied to features of size.
6.
Profile tolerances can be combined with other geometric controls such as flatness to control a feature.
7.
Profile of a line tolerances apply to an entire surface.
8.
Profile of a line controls apply to individual line elements.
9.
Profile tolerances only control the location of a surface.
10.
Composite profile controls should be avoided because they are more restrictive and very difficult to check.
11.
Profile tolerances can be applied either bilateral or unilateral to a feature.
12.
Profile tolerances can be applied in both freestate and restrained datum conditions.
13.
Tolerances shown in the lower segment of a composite profile feature control frame control the location of a feature to the specified datums.
Profile Control Quiz
Questions #1-9 Fill in blanks (choose from below) 1.
The two types of profile tolerances are
_________________
, and
____________________.
2.
Profile tolerances can be used to control the
________
,
____
,
___________
, and sometimes size of a feature.
3.
Profile tolerances can be applied
_________
or
__________.
4.
_________________
tolerances are 2-dimensional controls.
5.
____________________
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.
In composite profile applications, the tolerance shown in the upper segment of the feature control frame applies only to the
________
the feature.
of
composite profile profile of a surface bilateral virtual condition primary datum orientation datum reference location unilateral profile of a line true geometric counterpart form
Tolerances of Location
True Position
(ASME Y14.5M-1994, 5.2)
Concentricity
(ASME Y14.5M-1994, 5.12) Symmetry (ASME Y14.5M-1994, 5.13)
Notes
Coordinate vs Geometric Tolerancing Methods
8.5 +/- 0.1
Rectangular Tolerance Zone
10.25 +/- 0.5
8.5 +/- 0.1
1.4 A B C Circular Tolerance Zone 10.25
B 10.25
C 10.25 +/- 0.5
Coordinate Dimensioning +/- 0.5
A
Geometric Dimensioning 1.4
+/- 0.5
Rectangular Tolerance Zone Circular Tolerance Zone
57% Larger Tolerance Zone
Circular Tolerance Zone
Rectangular Tolerance Zone
Increased Effective Tolerance
Positional Tolerance Verification
(Applies when a circular tolerance is indicated)
X
Z
Feature axis actual location (measured) Positional tolerance zone cylinder Actual feature boundary
Y
Feature axis true position (designed)
Formula to determine the actual radial position of a feature using measured coordinate values (RFS)
Z = X
2
+ Y
2
Z positional tolerance /2 Z = total radial deviation “X” measured deviation “Y” measured deviation
Positional Tolerance Verification
(Applies when a circular tolerance is indicated)
X
Z
Feature axis actual location (measured) Positional tolerance zone cylinder Actual feature boundary
Y
Feature axis true position (designed)
Formula to determine the actual radial position of a feature using measured coordinate values (MMC)
Z = X
2
+ Y
2
Z +( actual 2 = positional tolerance MMC) Z = total radial deviation “X” measured deviation “Y” measured deviation
Bi-directional True Position Rectangular Coordinate Method
2X 1.5 A B C 2X 0.5 A B C C A 10 10 35 2X 6 +/-0.25
Means This:
1.5 Wide Tolerance Zone C B
As Shown on Drawing
True Position Related to Datum Reference Frame 10 10 35 B 0.5 Wide Tolerance Zone Each axis must lie within the 1.5 X 0.5 rectangular tolerance zone basically located to the datum reference frame
Bi-directional True Position Multiple Single-Segment Method
2X 6 +/-0.25
1.5 A B C 0.5 A B C A 10 10 35
Means This:
1.5 Wide Tolerance Zone C B
As Shown on Drawing
True Position Related to Datum Reference Frame 10 10 35 B 0.5 Wide Tolerance Zone Each axis must lie within the 1.5 X 0.5 rectangular tolerance zone basically located to the datum reference frame
Bi-directional True Position Noncylndrical Features (Boundary Concept)
2X 13 +/-0.25
BOUNDARY 2X 6 +/-0.25
BOUNDARY C A 10 10 35 B
As Shown on Drawing Means This:
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 an MMC basis.
True position boundary related to datum reference frame C 5.75 MMC length of slot -0.50
Position tolerance 5.25 maximum boundary 12.75
-1.50
MMC width of slot Position tolerance 11.25 Maximum boundary 90 o 10 A 10 35 B
Composite True Position Without Pattern Orientation Control
2X 6 +/-0.25
1.5 A B C 0.5 A C A 10 10 35
Means This:
0.5 Feature-Relating Tolerance Zone Cylinder
pattern orientation relative to Datum A only (perpendicularity)
C B
As Shown on Drawing
1.5 Pattern-Locating Tolerance Zone Cylinder
pattern location relative to Datums A, B, and C
10 10 35 B True Position Related to Datum Reference Frame Each axis must lie within each tolerance zone simultaneously
Composite True Position With Pattern Orientation Control
2X 6 +/-0.25
1.5 A B C 0.5 A B C A 10 10 35
Means This:
True Position Related to Datum Reference Frame C B
As Shown on Drawing
1.5 Pattern-Locating Tolerance Zone Cylinder
pattern location relative to Datums A, B, and C
10 10 35 B 0.5 Feature-Relating Tolerance Zone Cylinder
pattern orientation relative to Datums A and B
Each axis must lie within each tolerance zone simultaneously
Location (Concentricity) Datum Features at RFS
6.35 +/- 0.05
0.5 A A 15.95
15.90
As Shown on Drawing
Means This:
Axis of Datum Feature A 0.5 Coaxial Tolerance Zone Derived Median Points of Diametrically Opposed Elements 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.
A
Location (Symmetry) Datum Features at RFS
6.35 +/- 0.05
0.5 A 15.95
15.90
Means This:
As Shown on Drawing
Center Plane of Datum Feature A 0.5 Wide Tolerance Zone Derived Median Points Within the limits of size and regardless of feature size, all median points of opposed elements must lie between two parallel planes equally disposed about datum plane A, 0.5 apart. Symmetry can only be applied on an RFS basis.
True Position Quiz
Answer questions #1-11 True or False 1.
Positional tolerances are applied to individual or patterns of features of size.
2.
Cylindrical tolerance zones more closely represent the functional requirements of a pattern of clearance holes.
3.
True position tolerance values are used to calculate the minimum size of a feature required for assembly.
4.
True position tolerances can control a feature’s size.
5.
Positional tolerances are applied on an MMC, LMC, or RFS basis.
6.
Composite true position tolerances should be avoided because it is overly restrictive and difficult to check.
7.
Composite true position tolerances can only be applied to patterns of related features.
8.
The tolerance value shown in the upper segment of a composite true position feature control frame applies to the location of a pattern of features to the specified datums.
9.
The tolerance value shown in the lower segment of a composite true position feature control frame applies to the location of a pattern of features to the specified datums.
10.
Positional tolerances can be used to control circularity 11.
True position tolerances can be used to control center distance relationships between features of size.
True Position Quiz
Questions #1-9 Fill in blanks (choose from below) 1.
Positional tolerance zones can be
___________
,
___________
, or spherical 2.
________________
are used to establish the true (theoretically exact) position of a feature from specified datums.
3.
Positional tolerancing is a
_____________
control.
4.
Positional tolerance can apply to the
____
a feature.
or
________________
of 5.
_____
and
________
fastener equations are used to determine appropriate clearance hole sizes for mating details 6.
_________
tolerance zones are recommended to prevent fastener interference in mating details.
7.
The tolerance shown in the upper segment of a composite true position feature control frame is called the
________________
tolerance zone.
8.
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
surface boundary pattern-locating floating rectangular feature-relating cylindrical 3-dimensional location basic dimensions maximum material
axis
projected fixed
Notes
Notes
Fixed and Floating Fastener Exercises
Floating Fasteners
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 2x M10 X 1.5
(Reference) A B
General Equation Applies to Each Part Individually
H=F+T or T=H-F
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
2x 10.50
?.?
M +/- 0.25
Calculate Nominal Size
A B 2x
Calculate Required Positional Tolerance
T = H - F
H = Minimum Hole Size = 10.25 F = Max. Fastener Size = 10 T = 10.25 -10 T = ______ ??.??
+/- 0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
H = F +T
F = Max. Fastener Size = 10 T = Positional Tolerance = 0.50
H = 10 + 0.50 H = ______
Floating Fasteners
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 2x M10 X 1.5
(Reference) A B
General Equation Applies to Each Part Individually
H=F+T or T=H-F
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
2x 10.50
0.25
M +/- 0.25
Calculate Nominal Size
A B 2x
Calculate Required Positional Tolerance
T = H - F
H = Minimum Hole Size = 10.25 F = Max. Fastener Size = 10 T = 10.25 -10 T = 0.25
10.75
+/- 0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
H = F +T
F = Max. Fastener Size = 10 T = Positional Tolerance = 0.5
H = 10 + .5 H = 10.5 Minimum
REMEMBER!!! All Calculations Apply at MMC
Fixed Fasteners
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.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Equal
H=F+2T or T=(H-F)/2
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
Calculate Required Clearance Hole Size.
2x ??.??
+/- 0.25
0.8
M
remember: the size tolerance must be added to the calculated MMC size to obtain the correct nominal value.
2X M10 X 1.5
0.8
M P 10 A
Nominal Size (MMC For Calculations)
H = F + 2T
F = Max. Fastener Size = 10.00 T = Positional Tolerance = 0.80
H = 10.00 + 2(0.8) H = _____ B
Fixed Fasteners
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.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Equal
H=F+2T or T=(H-F)/2
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
Calculate Required Clearance Hole Size.
2x 11.85
+/- 0.25
0.8
M
remember: the size tolerance must be added to the calculated MMC size to obtain the correct nominal value.
2X M10 X 1.5
0.8
M P 10 A
Nominal Size (MMC For Calculations)
H = F + 2T
F = Max. Fastener Size = 10.00 T = Positional Tolerance = 0.80
H = 10.00 + 2(0.8) H = 11.60 Minimum B
REMEMBER!!! All Calculations Apply at MMC
Fixed Fasteners
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.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Equal
H=F+2T or T=(H-F)/2
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
Calculate Required Clearance Hole Size.
2x 11.85
+/- 0.25
0.8
M
remember: the size tolerance must be added to the calculated MMC size to obtain the correct nominal value.
2X M10 X 1.5
0.8
M P 10 A
Nominal Size (MMC For Calculations)
H = F + 2T
F = Max. Fastener Size = 10 T = Positional Tolerance = 0.8
H = 10 + 2(0.8) H = 11.6 Minimum B
REMEMBER!!! All Calculations Apply at MMC
Fixed Fasteners
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.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Equal
H=F+2T or T=(H-F)/2
H= Min. diameter of clearance hole F= Maximum diameter of fastener T= Positional tolerance diameter
2x 11.25
0.5
M +/- 0.25
Calculate Required Positional Tolerance . (Both Parts)
A
Nominal Size (MMC For Calculations)
2X M10 X 1.5
0.5
M P 10
T = (H - F)/2
H = Minimum Hole Size = 11 F = Max. Fastener Size = 10 T = (11 - 10)/2 T = 0.50
B
REMEMBER!!! All Calculations Apply at MMC
Fixed Fasteners
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 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 not equal.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Not Equal
H=F+(T
1
+ T
2
)
H = Min. diameter of clearance hole F = Maximum diameter of fastener T 1 = Positional tolerance (Part A) T 2 = Positional tolerance (Part B)
Calculate Required Clearance Hole Size.
2x ??.??
+/- 0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
A 2X M10 X 1.5
1 M P 10
Nominal Size (MMC For Calculations)
H=F+(T
1
+ T
2
)
F = Max. Fastener Size = 10 T 1 = Positional Tol. (A) = 0.50 T 2 = Positional Tol. (B) = 1 H = 10+ (0.5 + 1) H = ____ B
Fixed Fasteners
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 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 not equal.) 10 APPLIES WHEN A PROJECTED TOLERANCE ZONE IS USED 2x M10 X 1.5
(Reference) A B
General Equation Used When Positional Tolerances Are Not Equal
H= F+(T
1
+ T
2
)
H = Min. diameter of clearance hole F = Maximum diameter of fastener T 1 = Positional tolerance (Part A) T 2 = Positional tolerance (Part B)
Calculate Required Clearance Hole Size.
2x 11.75
+/- 0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
2X M10 X 1.5
1 M P 10 A
Nominal Size (MMC For Calculations)
H=F+(T
1
+ T
2
)
F = Max. Fastener Size = 10 T 1 = Positional Tol. (A) = 0.5 T 2 = Positional Tol. (B) = 1 H = 10 + (0.5 + 1) H = 11.5 Minimum B
REMEMBER!!! All Calculations Apply at MMC
Fixed Fasteners
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.
APPLIES WHEN A PROJECTED TOLERANCE ZONE IS NOT USED H F P D A B H= Min. diameter of clearance hole F= Maximum diameter of pin T 1 = Positional tolerance (Part A) T 2 = Positional tolerance (Part B) D= Min. depth of pin (Part A) P= Maximum projection of pin
Calculate Nominal Size
2x ??.?? +/-0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
A 2x 10.05 +/-0.05
0.5
M B
H= F + T
1
+ T
2
(1+(2P/D))
F = Max. pin size = 10 T 1 = Positional Tol. (A) = 0.5
T 2 = Positional Tol. (B) = 0.5 D = Min. pin depth = 20. P = Max. pin projection = 15 H = 10.00 + 0.5 + 0.5(1 + 2(15/20)) H = __________
Fixed Fasteners
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.
APPLIES WHEN A PROJECTED TOLERANCE ZONE IS NOT USED P D H A B F
H= F + T
1
+ T
2
(1+(2P/D))
H= Min. diameter of clearance hole F= Maximum diameter of pin T 1 = Positional tolerance (Part A) T 2 = Positional tolerance (Part B) D= Min. depth of pin (Part A) P= Maximum projection of pin
Calculate Nominal Size
2x 12 +/-0.25
0.5
M
remember: the size tolerance must be added to the calculated MMC hole size to obtain the correct nominal value.
A 2x 10.05 +/-0.05
0.5
M B
H= F + T
1
+ T
2
(1+(2P/D))
F = Max. pin size = 10 T 1 = Positional tol. (A) = 0.5
T 2 = Positional tol. (B) = 0.5 D = Min. pin depth = 20 P = Max. pin projection = 15 H = 10 + 0.5 + 0.5(1 + 2(15/20)) H = 11.75 Minimum
REMEMBER!!! All Calculations Apply at MMC
Answers to Quizzes and Exercises
Rules and Definitions Quiz
Questions #1-12 True or False 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 FALSE TRUE FALSE
Material Condition Quiz
Fill in blanks
Internal Features 10.75 +0.25/-0 23.45 +0.05/-0.25
123. 5 +/-0.1
.895
.890
External Features 10.75 +0/-0.25
23.45 +0.05/-0.25
123. 5 +/-0.1
.890
.885
MMC LMC
10.75 11 23.2 23.5
123.4 123.6
.890 .895
MMC LMC
10.75 10.5
23.5 23.2
123.6 123.4
.890 .885
Calculate appropriate values
Datum Quiz
Questions #1-12 True or False 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.
7. Datums are actual part features.
8. All datum features must be dimensionally stable.
9. Datum planes constrain degrees of freedom.
10. Tertiary datums are not always required.
11. All tooling locators (CD’s) are used as datums.
12. Datums should represent functional features.
FALSE FALSE
FALSE FALSE TRUE TRUE FALSE TRUE TRUE TRUE FALSE TRUE
Datum Quiz
Questions #1-10 Fill in blanks (choose from below) 1.
The three planes that make up a basic datum reference frame are called
primary
,
secondary
, and
tertiary
. 2.
An unrestrained part will exhibit
3-linear
of freedom.
and
3-rotational
degrees 3.
A planar primary datum plane will restrain
1-linear
degrees of freedom.
and
2-rotational
4.
The primary and secondary datum planes together will restrain
five
of freedom.
degrees 5.
The primary, secondary and tertiary datum planes together will restrain all
six
degrees of freedom.
6.
The purpose of a datum reference frame is to
restrain movement
of a part in a gage or tool.
7.
A datum must be
functional
,
repeatable
, and
coordinated
.
8.
A
datum feature
is an actual feature on a part.
9.
A
datum
is a theoretically exact point, axis or plane.
10.
A
datum simulator
simulated datum.
is a precise surface used to establish a
restrain movement tertiary three two functional datum feature five 3-rotational one datum coordinated primary datum simulator secondary repeatable 2-rotational 1-linear 3-linear six
Form Control Quiz
Questions #1-5 Fill in blanks (choose from below) 1.
The four form controls are
straightness
,
flatness
,
circularity
, and
cylindricity
. 2.
Rule #1 states that unless otherwise specified a feature of size must have
perfect form
at MMC.
3.
Straightness
and
circularity
element (2-D) controls.
are individual line or circular 4.
Flatness
and
cylindricity
are surface (3-D) controls.
5.
Circularity can be applied to both
straight
parts.
and
tapered
cylindrical
straightness straight perfect form cylindricity flatness tapered circularity angularity profile true position
Answer questions #6-10 True or False 6.
Form controls require a datum reference.
7.
Form controls do not directly control a feature’s size.
8.
A feature’s form tolerance must be less than it’s size tolerance.
9.
Flatness controls the orientation of a feature.
10.
Size limits implicitly control a feature’s form.
FALSE TRUE TRUE FALSE TRUE
Orientation Control Quiz
Questions #1-5 Fill in blanks (choose from below) 1.
The three orientation controls are
angularity
,
parallelism
, and
perpendicularity
. 2.
A
datum reference
is always required when applying any of the orientation controls.
3.
Perpendicularity
is the appropriate geometric tolerance when controlling the orientation of a feature at right angles to a datum reference.
4.
Mathematically all three orientation tolerances are
identical
.
5.
Orientation tolerances do not control the
location
of a feature.
perpendicularity datum feature angularity datum target location identical datum reference parallelism profile
Answer questions #6-10 True or False 6.
Orientation tolerances indirectly control a feature’s form.
7.
Orientation tolerance zones can be cylindrical.
8.
To apply a perpendicularity tolerance the desired angle must be indicated as a basic dimension.
9.
Parallelism tolerances do not apply to features of size.
10.
To apply an angularity tolerance the desired angle must be indicated as a basic dimension.
TRUE TRUE FALSE FALSE TRUE
Runout Control Quiz
Answer questions #1-12 True or False 1.
Total runout is a 2-dimensional control.
2.
Runout tolerances are used on rotating parts.
3.
Circular runout tolerances apply to single elements .
4.
Total runout tolerances should be applied at MMC.
5.
Runout tolerances can be applied to surfaces at right angles to the datum reference. 6.
Circular runout tolerances are used to control an entire feature surface.
7.
Runout tolerances always require a datum reference.
8.
Circular runout and total runout both control axis to surface relationships.
9.
Circular runout can be applied to control taper of a part.
10.
Total runout tolerances are an appropriate way to limit “wobble” of a rotating surface.
11.
Runout tolerances are used to control a feature’s size.
12.
Total runout can control circularity, straightness, taper, coaxiality, angularity and any other surface variation.
FALSE TRUE TRUE FALSE TRUE FALSE TRUE TRUE FALSE TRUE FALSE TRUE
Profile Control Quiz
Questions #1-9 Fill in blanks (choose from below) 1.
The two types of profile tolerances are
profile of a line
, and
profile of a surface .
2.
Profile tolerances can be used to control the
location
,
form
,
orientation
, and sometimes size of a feature.
3.
Profile tolerances can be applied
bilateral
or
unilateral
.
4.
Profile of a line
tolerances are 2-dimensional controls.
5.
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
frame.
must be included in the feature control 8.
When using profile tolerances to control form only, a
datum reference
is not required in the feature control frame.
9.
In composite profile applications, the tolerance shown in the upper segment of the feature control frame applies only to the
location
feature.
of the
composite profile profile of a surface bilateral virtual condition primary datum orientation datum reference location unilateral profile of a line true geometric counterpart form
Profile Control Quiz
Answer questions #1-13 True or False 1.
Profile tolerances always require a datum reference.
FALSE
2.
Profile of a surface tolerance is a 2-dimensional control.
FALSE
3.
Profile of a surface tolerance should be used to control trim edges on sheet metal parts.
4.
Profile of a line tolerances should be applied at MMC.
TRUE FALSE
5.
Profile tolerances can be applied to features of size.
6.
Profile tolerances can be combined with other geometric controls such as flatness to control a feature.
TRUE
7.
Profile of a line tolerances apply to an entire surface.
FALSE
8.
Profile of a line controls apply to individual line elements.
TRUE TRUE
9.
Profile tolerances only control the location of a surface.
FALSE
10.
Composite profile controls should be avoided because they are more restrictive and very difficult to check.
FALSE
11.
Profile tolerances can be applied either bilateral or unilateral to a feature.
TRUE
12.
Profile tolerances can be applied in both freestate and restrained datum conditions.
TRUE
13.
Tolerances shown in the lower segment of a composite profile feature control frame control the location of a feature to the specified datums.
FALSE
True Position Quiz
Answer questions #1-11 True or False 1.
Positional tolerances are applied to individual or patterns of features of size.
2.
Cylindrical tolerance zones more closely represent the functional requirements of a pattern of clearance holes.
3.
True position tolerance values are used to calculate the minimum size of a feature required for assembly.
4.
True position tolerances can control a feature’s size.
5.
Positional tolerances are applied on an MMC, LMC, or RFS basis.
6.
Composite true position tolerances should be avoided because it is overly restrictive and difficult to check.
TRUE TRUE TRUE FALSE TRUE FALSE
7.
Composite true position tolerances can only be applied to patterns of related features.
TRUE TRUE
8.
The tolerance value shown in the upper segment of a composite true position feature control frame applies to the location of a pattern of features to the specified datums.
9.
The tolerance value shown in the lower segment of a composite true position feature control frame applies to the location of a pattern of features to the specified datums.
10.
Positional tolerances can be used to control circularity 11.
True position tolerances can be used to control center distance relationships between features of size.
FALSE FALSE TRUE
True Position Quiz
Questions #1-9 Fill in blanks (choose from below) 1.
Positional tolerance zones can be
rectangular
,
cylindrical
, or spherical 2.
Basic dimensions
are used to establish the true (theoretically exact) position of a feature from specified datums.
3.
Positional tolerancing is a
3-dimensional
control.
4.
Positional tolerance can apply to the
axis
of a feature.
or
surface boundary
5.
Fixed
and
floating
fastener equations are used to determine appropriate clearance hole sizes for mating details 6.
Projected
tolerance zones are recommended to prevent fastener interference in mating details.
7.
The tolerance shown in the upper segment of a composite true position feature control frame is called the
pattern-locating
tolerance zone.
8.
The tolerance shown in the lower segment of a composite true position feature control frame is called the
feature-relating
tolerance zone.
9.
Functional gaging principles can be applied when
maximum material
condition is specified
surface boundary pattern-locating floating rectangular feature-relating cylindrical 3-dimensional location basic dimensions maximum material
axis
projected fixed
E N D
Notes
Notes
Notes
Extreme Variations of Form Allowed By Size Tolerance
25.1 25 25 24.9
25 (MMC) 25 (MMC) 25.1 (LMC) 24.9 (LMC) 25.1 (LMC) MMC Perfect Form Boundary 25 (MMC) 24.9 (LMC) 25 (MMC) 25.1 (LMC) 24.9 (LMC)
Virtual and Resultant Condition Boundaries
Internal and External Features (MMC Concept)
Virtual Condition Boundary
Internal Feature (MMC Concept) 14 +/- 0.5
A C XX.X
XX.X
B ( Virtual Condition Inner Boundary Maximum Inscribed ) Diameter Boundary of MMC Hole Shown at Extreme Limit
As Shown on Drawing
1 Positional Tolerance Zone at MMC True (Basic) Position of Hole True (Basic) Position of Hole Other Possible Extreme Locations Axis Location of MMC Hole Shown at Extreme Limit Calculating Virtual Condition 13.5 MMC Size of Feature 1 Applicable Geometric Tolerance 12.5 Virtual Condition Boundary
Resultant Condition Boundary
Internal Feature (MMC Concept) 14 +/- 0.5
A C XX.X
XX.X
B
As Shown on Drawing
( Resultant Condition Outer Boundary Minimum Circumscribed Diameter ) Boundary of LMC Hole Shown at Extreme Limit True (Basic) Position of Hole
Calculating Resultant Condition
(Internal Feature) 14.5 LMC Size of Feature 2 Geometric Tolerance (at LMC) 16.5 Resultant Condition Boundary 2 Positional Tolerance Zone at LMC True (Basic) Position of Hole Other Possible Extreme Locations Axis Location of LMC Hole Shown at Extreme Limit
Virtual Condition Boundary
External Feature (MMC Concept) 14 +/- 0.5
A C XX.XX
XX.X
B ( Virtual Condition Outer Boundary Minimum Circumscribed Diameter ) Boundary of MMC Feature Shown at Extreme Limit
As Shown on Drawing
1 Positional Tolerance Zone at MMC True (Basic) Position of Feature True (Basic) Position of Feature Other Possible Extreme Locations Axis Location of MMC Feature Shown at Extreme Limit Calculating Virtual Condition 14.5 MMC Size of Feature 1 Applicable Geometric Tolerance 15.5 Virtual Condition Boundary
Resultant Condition Boundary
External Feature (MMC Concept) 14 +/- 0.5
A C XX.X
XX.X
B ( Resultant Condition Inner Boundary Maximum Inscribed ) Diameter
As Shown on Drawing
2 Positional Tolerance Zone at LMC Boundary of LMC feature Shown at Extreme Limit True (Basic) Position of Feature True (Basic) Position of Feature Other Possible Extreme Locations Axis Location of LMC Feature Shown at Extreme Limit
Calculating Resultant Condition
(External Feature) 13.5 LMC Size of Feature 2 Geometric Tolerance (at LMC) 11.5 Resultant Condition Boundary
• 3X 5.0 5mm is 3 times repeated. A space is used after X
Maximum Material Condition (MMC):
The condition where the feature contains the maximum material within the stated limits of size – for example, the largest pin or the smallest hole.
Least Material Condition (LMC):
The condition where the feature contains the least material with in the stated limits of size - for example, the smallest pin or largest hole.
GEOMETRIC CHARACTERISTIC SYMBOLS TYPE OF TOLERANCE CHARACTERISTIC
FOR INDIVIDUAL FEATURES FORM STRAIGHNESS FLATNESS FOR INDIVIDUAL OR RELATED FEATURES FROFILE PROFILE OF A SURFACE PROFILE OF A LINE ANGULARITY ORIENTATION PERPENDICULARITY PARALLELISM FOR RELATED FEATURES POSITION CONCENTRICITY LOCATION SYMMETRY RUNOUT CIRCULARITY (ROUNDNESS) CYLINDRICITY CIRCULAR RUNOUT TOTAL RUNOUT
SYMBOL