gd&t cylindricity
TRANSCRIPT
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8/10/2019 GD&T Cylindricity
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 1 QuitMaster Table of ContentsGlossary
FORM CONTROLS
CYLINDRICITY
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8/10/2019 GD&T Cylindricity
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 2 QuitMaster Table of ContentsGlossary
CYLINDRICITY
Cylindricity: A condition of a surface of revolution in which all points on the surface are
perpendicular and equidistantfrom a common axis. Cylindricity can control
straightness and circulari ty
Cylindricity Tolerance: A 3D boundarydef ined by two theoretically perfect coaxial
cylinderswithin which all the elements of the specified surface must lie.
Cylindricity (3D) Tolerance Zone: The radial distance between the two coaxial cylinders
defines the tolerance zone and represents the amount that surface elements are allowed
to vary from a perfect cylinder. This numerical value (always less than one-half of the
diametrical tolerance) is specified in the tolerance cell of the feature control frame.
Note: As a surface form control, cylindricity is always considered RFS, and the physical
limits imposed by size dimensions cannot be violated. Datums are neither proper nor
allowed in the feature control frame, and the tolerance cannot be modified to consider
additional tolerance as departure from MMC occurs. A diameter symbol zone
descriptor cannot be used in the feature control frame.
Tolerances Of FormCylindricity
Definitions of Terms
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 3 QuitMaster Table of ContentsGlossary
When cylindricity control is applied to an externalfeature, the outer boundary
(larger cylinder) is typically established by circumscribing the high points of thesurface. The inner boundary is radially smaller by the amount of the specified
tolerance. The feature, at any point of measurement (a plane, perpendicular to the
axis), must be within the limits of size.
Tolerances Of Form - Cylindricity
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 4 QuitMaster Table of ContentsGlossary
Tolerances Of Form - Cylindricity
When cylindricity control is applied to an internalfeature, the inner boundary (smaller
cylinder) is typically established by gage contact with the high points of the surface.
The outer boundary is radially larger by the amount of the specified tolerance. The
feature, at any point of measurement, must be within the limits of size.
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 5 QuitMaster Table of ContentsGlossary
GEOMETRIC CONTROLFOR CYLINDRICITY
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GD&T Form Table of ContentsReturn to the Previous Slide Slide 6 QuitMaster Table of ContentsGlossary
The geometric control for cylindricity is a featureformtolerance which controls
circular, longitudinal, and parallel elements of the featuresurface elementsonly.
Because it is strictly a surface element control, datums are neither proper nor allowed.
As is the case with all surface controls, cylindricity always applies regardless of feature
size.
Because cylindricity can onlybe applied to features and cannot be applied to features
of size, material condition modifiers cannotbe used with a cylindricity specification.
The size envelope imposed by dimensional limits and Rule #1 are never overridden by
a geometric tolerance for cylindricity, and the geometric tolerance becomes the
controlling factor only when departure from MMC exceeds the cylindricity tolerancevalue. Therefore, the virtual conditionof the controlled feature is notaffected.
Tolerances Of Form - Cylindricity
OVERVIEW
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0.4
A feature control frame describing cylindricity control may be called out in either
view and is applied by using a leader line, as shown.
0.4OR
Verifying Cylindricity Geometric Tolerance
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8/10/2019 GD&T Cylindricity
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0.4
Tolerance zone is two
coaxialcylinders
Verifying Cylindricity Geometric Tolerance
Multiple-section
measurements are
taken just like the
measurements for
circularity, except thegauge is NOT reset
between sections.
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8/10/2019 GD&T Cylindricity
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0.4
Smallest true cylinder
that circumscribes
the high points
of the feature
diameter.
0.4 Radial Distance
Tolerance zone is two
coaxialcylinders
Verifying Cylindricity Geometric Tolerance
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0.2
10.5
9.5
The size tolerance zone consists of two coaxial
cylinders, 0.5 mm apart. This tolerance defines
the actual local size limits.
Cylindricity Geometric ToleranceAlways RFS
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0.2
10.5
9.5
The cylindricity tolerance zone consists of two
coaxial cylinders, 0.2 mm apart. This tolerance
can float within the larger size tolerance.
Cylindricity Geometric ToleranceAlways RFS
The size tolerance zone consists of two coaxial
cylinders, 0.5 mm apart. This tolerance defines
the actual local size limits.
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8/10/2019 GD&T Cylindricity
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Coaxial cylinders establish the
tolerance zone for feature cylindricity.
Cylindricity Geometric ToleranceAlways RFS
Feature size tolerance. (While
surface elements are restricted to
the refined tolerance zone, the
actual local [measured] sizeof
the cylindrical feature may vary
within the larger boundaries.)
0.2
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8/10/2019 GD&T Cylindricity
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Coaxial cylinders establish the
tolerance zone for feature cylindricity
(RFS).
At any measuring position, allsurface elements must be within
the cylindricity tolerance zone.
They may vary within the zone,
and the entire zone may expand
or contract within the larger size
tolerance.
Cylindricity Geometric ToleranceAlways RFS
0.2
Feature size tolerance. (While
surface elements are restricted to
the refined tolerance zone, the
actual local [measured] sizeof
the cylindrical feature may vary
within the larger boundaries.)
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8/10/2019 GD&T Cylindricity
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The cylindricity tolerance zonemay extend beyond the lower
limit of the size tolerance, but
no elements on the surface can
be located outside of those
limits. That part of the tolerance
would be sacrificed.
Cylindricity Geometric ToleranceAlways RFS
0.2
Feature size tolerance. (While
surface elements are restricted to
the refined tolerance zone, the
actual local [measured] sizeof
the cylindrical feature may vary
within the larger boundaries.)
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The geometric tolerance forcylindricity becomes the
controlling factor only when
departure from MMC exceeds
the cylindricity tolerance value.
Cylindricity Geometric ToleranceAlways RFS
0.2
Feature size tolerance. (While
surface elements are restricted to
the refined tolerance zone, the
actual local [measured] sizeof
the cylindrical feature may vary
within the larger boundaries.)
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