THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
1
CYLINDRICITY
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
2
Cylindricity
Cylindricity refers to a condition of a surface, whichforms a cylinder where the surface elements in crosssections parallel to the axis are straight and parallel and incross sections perpendicular to the axis are round.Cylindricity thus combines in one term geometrical formtolerances for roundness, straightness and parallelism ofthe surface elements.
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
3
Cylindricity tolerances can only be applied to cylindrical
surface, such as round holes and shafts.
No specific geometrical tolerances have been devised for other
circular forms, which require the use of several geometrical
tolerances.
A conical surface, for example, must be controlled by a
combination of tolerances for roundness, straightness, and
angularity.
Cylindricity
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
4
Cylindricity
Errors of Cylindricity may be caused by out of roundness, like ovality or
lobing
Errors of straightness caused by bending or by diametral variation
Errors of parallelism like conicity or taper
Random irregularities from a true cylindrical form.
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
5
CYLINDRICITY SYMBOL
• The geometric characteristic symbol for cylindricity consists
of a circle with two tangent lines at 60.
• The circle diameter is 62% of the height of the feature
control symbol frame.
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
6
• The Cylindricity tolerance symbol is used in a feature control symbol
• Directed to the cylindrical surface, in either the side view or end view
CYLINDRICITY TOLERANCE DIRECTED TO EITHER VIEW.
CYLINDRICITY TOLERANCE
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
7
A Cylindricity tolerance specifies a tolerance zone consisting of the annular space between two coaxial cylinders, having a difference in radii equal to the specified tolerance zone of 0.05 on radial dimension.
CYLINDRICITY TOLERANCE
PERMISSIBLE FORM ERRORS
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
8
CYLINDRICITY TOLERANCE
When the part is at the maximum diameter limit the major diameter of the Cylindricity tolerance zone would likely be larger than the maximum diameter limit.This may be due to lobing, and other irregularities or bending.
DIAMETER OF THE TOLERANCE ZONE MAY BE
LARGER THAN MAXIMUM DIAMETER OF THE PART
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
9
Checked by revolving in vee-blocks while taking indicator readings on the
top surface, in a manner similar to methods described for the measurement of
roundness
The roundness near both ends is first checked by making indicator readings
directly over blocks of varying angles to ensure that lobing will not
significantly affect the results.
The part is then mounted in identical short length vee-blocks, which are
located at each end of the part
PART IN VEE – BLOCKS FOR CYLINDRICITY TESTS
MEASURING METHODS
THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY
10
Cylindricity tolerances are applicable to internal cylindrical surfaces, such as round holes.
Measurement
• Large holes can be assessed by means of indicator or electronic gauges.
• Best method is to assess the holes with a plane round GO gauge of
length at least equal to the full length or depth of the hole and having the
diameter equal to the max. material size minus the specified tolerance
CYLINDRICITY OF HOLES
Top Related