08 Runout & Profile

7/28/2019 08 Runout & Profile

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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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The most commonapplication of profile


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Use of phantom

lines and basic

dimension specifythe amount of

unequal

distribution


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The use of a

phantom line

denotes the

direction the

tolerance zone is

offset


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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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specified.

Three ways to specify2.The between symbol


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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

08 Runout & Profile

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