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CIRCULAR RUNOUT
ZONE OF TOLERANCE :- TWO COPLANAR CONCENTRIC CIRCLES
SYMBOL :-
OBJECTIVES
Ways of specifying datum axis for runout application.
Describe what the circular runout is.
Describe the tolerance zone for a circular runout control(applied to a diameter ,applied to surfaces).
Describe how circular runout can be a composite control.
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Considerations for establishing the datum axis:
Functional design requirements and part shape areconsidered.
The features used for the datum axis, are the samefeatures that locate the part in the assembly and duringinspection.
I
) A single diameter of sufficient length
A single diameter is used when the diameter is long enough to orient the part
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ii) A surface and a diameter at right angles
A surface is primary and diameter is secondary ,when the surface orients the pan.
When a surface is primary, the diameter should be very short.
Definition
:
A composite control (form, location, orientation)
Applies independently to each circular element of a diameter.
When applied to the diameter, it controls the form (circularity) and location of
the diameter to the datum.
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Tolerance zone:
Tolerance zone are two co-axial circles
whose centers are located on the
datum axis Radial distance between the circles is
equal to the runout tolerance value.
The size of the largest circle of the
tolerance zone is established by the
radius to the surface element that is
farthest from the datum axis.
Inner circle is the offset of the largest
by the runout tolerance value
Verification an overview:
The dial indicator is placed perpendicularto the surface being verified.
The part is rotated 360 The indicator measures the distanced
between the circles
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As a composite control
It limits the circularity , orientation and axis offset of the diameter.
When verifying runout, the dial indicator reading includes several
types of above said errors3.
Here the part is dimensioned with circular runout control. The
figure also demonstrate how various indicator reading could occur
Possibilities:
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The out of round element is still within the size limits
the circular elements are still perfectly coaxial with thedatum axis.
The indicator will read the out of round of the circular
element as runout error
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I ) When applied to diameter:
Diameter shouldmeet its size
At RFS only.
Applies to eachcircular element of
the toleranceddiameter.
The tolerance zoneis two coaxial
circles toleranceapart.
Possible offset ofthe axis is oftolerance zone
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Controls the wobbleof the surface.
RFS only
Applies at each
circular element.
Tolerance zone is
two conc. circles
offset axially.
The circular runout
does not control the
orientation of the
surface.
ii) Applied to surface perpendicular to datum axis:
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To describe
what the total runout is.
The tolerance zone.
Total runout can be a composite
control.
Maximum amount ofaxis offset.
Definition
Total runout is a composite
control affecting the form,
orientation, location of all surface
elements simultaneously of the
diameter (or surface) relative to the
datum axis.
Total runout control is a
geometric tolerance that limits the
amount of total runout of the
surface.
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When verifying a dial indicator is
placed on the surface.
The part is rotate 360degrees
The dial is moved along the
diameter.
It gives the radial distance between
the cylinders.
Verificationan overview:
Applies to the entire length of the
diameter simultaneously.
It controls form (cylindricity),
orientation, and location of the
diameter relative to a datum axis.
Total runout is the combination
of all circularelements viewed
collectively.
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Total runout as a composite control
A composite control (Controls cylindricity, orientation , and axis offset
of a diameter).
Affects the Worst-case boundary of the diameter.
When verifying total runout it includes all three type of part errors.
Total runout as a composite control
When the dial indicator is moved along the axis as the parts is rotating
affects the straightness and taper of the surface.
Maximum permissible axis offset for total runout is equal to one half the
runout tolerance value.
But the gage reading does not separate form error and axis offset.
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A profile is the outline of a part feature in a given plane.
A true profile is the exact profile of a part feature as
described by basic dimensions
There are two types of profile controls:
profile of a surface
profile of a line.
Profile Terminology
Profi le Tolerances
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A unique aspect of profile control is that it can be specified with datum
reference (as a datum related feature control) or without a datum (as a form
control).
Profile of a surface is considered the most powerful control in the
geometric tolerancing system-it can be used to control the size, location,
orientation and form of a part feature.
Profile of a surface or line can be used to tolerance planar surfaces,
cylinders, cones curves, and irregular curves.
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Profile Tolerance Zones
Profile of surface control: Tolerance zone is a uniform boundary
(a 3-D tolerance zone) along length, width and depth.
Profile of line control: Tolerance zone is two uniform lines
(a 2-D tolerance zone) along the length of the surface.
Unless otherwise indicated, where a profile control is associated with afeature, the tolerance zone is a bilateral tolerance zone with equal
distribution.
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Profile Tolerance Zones
The most commonapplication of profile
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Profile Tolerance Zones
Use of phantom
lines and basic
dimension specifythe amount of
unequal
distribution
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Profile Tolerance Zones
The use of a
phantom line
denotes the
direction the
tolerance zone is
offset
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Profile Tolerance Zones
The use of a
phantom line
denotes the
direction the
tolerance zone is
offset
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If desired, the profile tolerance zone coverage can be
specified.
Three ways to specify1. A note associated with the control
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If desired, the profile tolerance zone coverage can be
specified.
Three ways to specify2.The between symbol
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If desired, the profile tolerance zone coverage can be
specified.
Three ways to specify3.The all around symbol
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Profile of a Line
A profile of a line control is a geometric tolerance that limits the amount
of error for line elements relative to their true profile
The tolerance zone for profile of a line is two dimensional
The tolerance zone is two uniform lines applied at any cross section of the
surface
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