0 - spesifikasi geometrik lanjutan 2016 - tp
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PROSES MANUFAKTUR - I
FAKULTAS TEKNIK MESIN DAN DIRGANTARA
INSTITUT TEKNOLOGI BANDUNG
By
: Dr. Ir. Tri Prakosa
, M
. Eng.
Untuk Menjamin Kualitas Produk
Spesifikasi
Geometridan
Metrologi
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Toleransi Geometrik
Geometric Tolerances
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Toleransi Geometrik
(Geometric Tolerances)
Geometric tolerances define the shape of a feature asopposed to its size.
1. Form tolerances: straightness, circularity,
flatness, cylindricity;
2. Orientation tolerances; perpendicularity,
parallelism, angularity; and
3. Position tolerances: position, symmetry,concentricity.
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Symbols for Geometric
Tolerances
Form
Orientation
Position
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Tools for Measuring Dimensions
Micrometer
Depth GaugeComparator
Surface Plate
Dial Indicator
Caliper
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Feature Control Frame
A geometric tolerance is prescribed using a feature control frame.It has three components:
1. the tolerance symbol,
2. the tolerance value,
3. the datum labels for the reference frame.
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Toleransi Bentuk
orm Tolerances
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Toleransi Bentuk
(Form Tolerances)
Form tolerances control: Straightness (kelurusan)
Flatness (kerataan)
Circularity (kebulatan) Cylindricity (kesilindrisan)
Form tolerances are applicable to single
(individual) features, elements of single
features, or features of size.
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Straightness
Straightness is a condition where an element of asurface, or derived median line, is a straight line. It
is applied in the view where the elements to be
controlled are represented by a straight line.
There are two types of straightness:
Surface Straightness
Axis Straightness
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Straightness
http://www.gdandtbasics.com/straightness/
Surface Straightness: The standard form of straightness is a 2-Dimensional
tolerance that is used to ensure that a part is uniform across a
surface or feature. Straightness can apply to either a flat feature
such as the surface of a block, or it can apply to the surface of acylinder along the axial direction. It is defined as the variance of
the surface within a specified line on that surface.
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Surface Straightness
http://www.gdandtbasics.com/straightness/
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Axis Straightness: The form of straightness that controls the central axis of a part is
sometimes referred to as Axial Straightness. This tolerance callout
specifies how straight the axis of a part is (usually a cylinder). By
definition, axis straightness is actually a 3D tolerance that constrains the
center axis of the part preventing it from bending or twisting too far.
Axis Straightness
http://www.gdandtbasics.com/straightness/
Axis Straightness with Maximum
Material Condition
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Axis Straightness
http://www.gdandtbasics.com/straightness/
S f St i ht G i /
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Surface Straightness Gauging/
Measurement http://www.gdandtbasics.com/straightness/
A part is constrained
and a gauge measures
along a straight line.
In this example theheight variance is
measured to see how
flat or straight the line
is along this surface.
A i St i ht G i /
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Axis Straightness Gauging/
Measurement http://www.gdandtbasics.com/straightness/
To gauge axis straightness effectively, MMC is commonly called out.To ensure that a part or feature is axially straight, a cylinder gauge is
used to determine if the part fits in its total envelope at MMC. This is
both a control of the diameter and of the axial straightness. The ID of
the cylinder gauge represents the maximum virtual condition of the
part. Gauge Cylinder ID = Max Ø part (MMC) + Straightness Tolerance
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Surface Straightness Example
http://www.gdandtbasics.com/straightness/
A steel bar is welded in a T pattern to another steel
bar. If you want to make sure that the surface of the
tube is always uniform, where the weld occurs, you
would need to either greatly tighten the dimensionaldiameter of the tube, (which would be very costly for
such a simple part!), or callout straightness along the
mating surface.
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Surface Straightness Example
http://www.gdandtbasics.com/straightness/
Ensuring straightness without GD&T
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Surface Straightness Example
http://www.gdandtbasics.com/straightness/
Controlling the surface of the tube in the weld area wi th
GD&T straightness callout.
A is Straightness ith MMC
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Axis Straightness with MMC
Examplehttp://www.gdandtbasics.com/straightness/
A boss pin on an engine housing is inserted into thechassis of a car to set the alignment before being
bolted in.
The pin is always in the correct position, however
since it is so critical the dimension of the chassis
mating hole is very tight.
To ensure that this pin is always a correct fit for the
hole, straightness is called out on the axis withmaximum material condition.
Axis Straightness with MMC
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Axis Straightness with MMC
Examplehttp://www.gdandtbasics.com/straightness/
Ensuring straightness on the drawing
Axis Straightness with MMC
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Axis Straightness with MMC
Examplehttp://www.gdandtbasics.com/straightness/
To quickly check for this a gauge was made to checkthat the pin always fits into the hole in the maximum
material condition. Using the calculation below the ID
of the cylinder gauge can be determined to check for
this during production.
Gauge Cylinder ID = MMC + Straightness
Gauge ID = Maximum Material Condition of Part +
Straightness Bonus Tolerance
Gauge ID = 10.100 + 0.050
Gauge ID = 10.150 mm
Axis Straightness with MMC
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Axis Straightness with MMC
Examplehttp://www.gdandtbasics.com/straightness/
Gauge control for axis/MMC straightness
Axis Straightness with MMC
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Axis Straightness with MMC
Examplehttp://www.gdandtbasics.com/straightness/
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Flatness
Flatness is the condition of a surface or derivedmedian plane having all elements in one plane.
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Flatness
GD&T Flatness is verystraight forward. It is a
common symbol that
references how flat a surface
is, regardless of any otherdatum’s or features.
http://www.gdandtbasics.com/flatness/
It comes in useful if a feature is to be defined on a
drawing that needs to be uniformly flat
without tightening any other dimensions on the
drawing.
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Flatness
The flatness tolerance references two parallel planes(parallel to the surface that it is called out on) that
define a zone where the entire reference surface must
lie.
Flatness tolerance is always less than the dimensional
tolerance associated with it.
http://www.gdandtbasics.com/flatness/
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Flatness, Tolerance Zone
Two Sets of Parallel Planes where the entire referenced
surface must lie.
http://www.gdandtbasics.com/flatness/
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Flatness, Gauging/ Measurement
Flatness is can be measured using a height gauge runacross the surface of the part if only the reference
feature is held parallel.
http://www.gdandtbasics.com/flatness/
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Flatness, Gauging/ Measurement
Flatness can be measured using a height gauge runacross the surface of the part if only the reference
feature is held parallel.
You are trying making sure that any point along the
surface does not go above or below the tolerance
zone.
http://www.gdandtbasics.com/flatness/
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Flatness, Gauging/ Measurement
Modern CMM’s are best
for measuring the part as
they can create virtual
planes that the true surface profile can be compared to.
This is a 3D measurement
so points must be measured
across the length and widthof the part to ensure the
entire surface is in
tolerance.
http://www.gdandtbasics.com/flatness/
http://www.coord3-cmm.com/wp-
content/uploads/2012/01/Coord3-Kronos-CMM.jpg
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Flatness, Gauging/ Measurement
Flatness cannot be measured by simply placing the part on a granite slab and running height gauge over
it.
This would be measuring parallelism instead as you
are fixing the bottom of the part as a datum.
http://www.gdandtbasics.com/flatness/
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Circularity or Roundness
Circularity is a condition of a surface where for a feature other than a sphere, all points of the
surface intersected by any plane perpendicular to an
axis or spine (curved line) are equidistant from that
axis or spine for a sphere, all points of the surface intersected by
any plane passing through a common center are
equidistant from that center.
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Circularity
http://www.gdandtbasics.com/circularity/
Circularity Gauging/
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Circularity Gauging/
Measurement Examplehttp://www.gdandtbasics.com/circularity/
If you had a hole that was around a rotating shaft, Both piecesshould be circular and have a tight tolerance. Without
circularity, the diameter of the hole and shaft would have to be
very tight and more expensive to make.
Example 1: Controll ing ci rcularity w ithout GD&T Symbol
Circularity Gauging/
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Circularity Gauging/
Measurement Examplehttp://www.gdandtbasics.com/circularity/
Example 2: Control ling both features with circularity allows the diameter
tolerances of the part to be opened up much larger.
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Cylindricity
Cylindricity is a condition of a surface of revolution in which all points of the surface are
equidistant from a common axis.
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Cilindricity
http://www.gdandtbasics.com/cylindricity/
Cilindricity Gauging/
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Cilindricity Gauging/
Measurement http://www.gdandtbasics.com/cylindricity/
If you had a bushing that was to be pressed into ahousing, the bushing would take the form of the
housing bore when inserted. To ensure that the
bushing maintains its round shape, and wears evenly
along its surface, the housing bore needs to be verycylindrical.
To do this without GD&T you would need very tight
dimensions on the diameter of the bore, which may be very hard to control when being machined (and
expensive)
Cilindricity Gauging/
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Cilindricity Gauging/
Measurement http://www.gdandtbasics.com/cylindricity/
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Toleransi Orientasi
Orientation Tolerances
l f
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Tolerances of Orientation
An orientation tolerance controls parallel,perpendicular, and all other angular
relationships.
There are three orientation relationshipsand three symbols to define those
relationships.
Angularity Parallelism
Perpendicularity
l
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Angularity
Description:Angularity is the
symbol that describes
the specific orientation
of one feature to
another at a referenced
angle.
http://www.gdandtbasics.com/angularity/
It can reference a 2D line referenced to another 2Delement, but more commonly it relates the orientation
of one surface plane relative to another datum plane in
a 3-Dimensional tolerance zone.
A l i
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Angularity
Description:The tolerance does not directly control the angle
variation and should not be confused with an
angular dimension tolerance such as ± 5°. In fact
the angle for now becomes a Basic Dimension,
since it is controlled by your geometric tolerance.
The tolerance indirectly controls the angle by
controlling where the surface can lie based on the datum. See the tolerance zone below for more details.
http://www.gdandtbasics.com/angularity/
A l i
http://www.gdandtbasics.com/datum/http://www.gdandtbasics.com/datum/http://www.gdandtbasics.com/datum/http://www.gdandtbasics.com/datum/http://www.gdandtbasics.com/datum/
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Angularity
Description:Maximum material condition or axis control can also
be called out for angularity although the use in design
and fabrication is very uncommon since gauging a
hole or pin at an angle is difficult. When angularity is
called out on an axis, the tolerance zone now
becomes a cylinder around the referenced axis at an
angle to the datum.The page on Perpendicularity goes into this type of
reference in further detail since it is more common
with perpendicularity.
http://www.gdandtbasics.com/angularity/
Angularity, GD&T Tolerance
http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/perpendicularity/http://www.gdandtbasics.com/perpendicularity/http://www.gdandtbasics.com/maximum-material-condition/
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Angularity, GD&T Tolerance
Zone
Two parallel planes or lines which are oriented at thespecified angle in relation to a datum. All points on the
referenced surface must fall into this tolerance zone.
http://www.gdandtbasics.com/angularity/
Angularity, Gauging/
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Angularity, Gauging/
Measurement http://www.gdandtbasics.com/angularity/
Angularity is measured by constraining a part, usuallywith a sine bar, tilted to the reference angle, so that
the reference surface is now parallel to the granite
slab.
By setting the part at an angle the flatness can now be
measured across the now horizontal reference surface.
The entire variation must not fall outside the
tolerance zone.
Angularity, Gauging/
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Angularity, Gauging/
Measurement http://www.gdandtbasics.com/angularity/
A l i E l
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Angularity, Example
http://www.gdandtbasics.com/angularity/
Angulari ty example 1: Tightening the angle and/or the thickness are
required if angularity is not called out.
A l it E l
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Angularity, Example
http://www.gdandtbasics.com/angularity/
Angulari ty example 2: A s imple call to angulari ty now ensures that the
stamped surface now has both proper angle and
flatness. The angle must be a basic dimension, but
now allows your part thickness to open up more.
(Note this drawing is unconstrained and would need
additional size dimensions to be accurate.)
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Parallelism
Description:Parallelism is a fairly
common symbol that
describes a parallel
orientation of one
referenced feature to a
datum surface or line.
http://www.gdandtbasics.com/parallelism/
It can reference a 2D line referenced to anotherelement, but more commonly it relates the orientation
of one surface plane parallel to another datum plane
in a 3-Dimensional tolerance zone.
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Parallelism
Description:The tolerance indirectly controls the 0° angle between
the parts by controlling where the surface can lie
based on the datum. See the tolerance zone below for
more details.
Note: Parallelism does not control the angle of the
referenced feature, but only creates an envelope in
which the feature must lie.
http://www.gdandtbasics.com/parallelism/
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Parallelism
Description:It is important to determine what the reference feature
is (surface or axis) and then what is acting as the
datum (surface or axis) to determine how the
parallelism is to be controlled.
http://www.gdandtbasics.com/parallelism/
Parallelism
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Parallelism
http://www.gdandtbasics.com/parallelism/
Parallelism Gauging/
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g g/Measurement
http://www.gdandtbasics.com/parallelism/
Parallelism Example
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Parallelism Example
http://www.gdandtbasics.com/parallelism/
A gear has to maintain constant axial load on both faces. Toensure even contact one side of the gear is held parallel to the
other side. To do this without parallelism, the gear width would
have to be tightly controlled, which could be very difficult to do.
Ensuring even surfaces without GD&T
Parallelism Example
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Parallelism Example
http://www.gdandtbasics.com/parallelism/
With parallelism you can open up the dimension of the gear andcontrol the faces without rejecting good gears.
Controlling two faces with GD&T parallelism callout.
Perpendicularity
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Perpendicularity
Perpendicularity is the condition of a surface,feature’s center plane, or feature’s axis at a right
angle to a datum plane or datum axis.
Perpendicularity
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Perpendicularity
Perpendicularity in GD&T can mean two very differentthings depending which reference feature is called out.
Surface Perpendicularity and Axis Perpendicularity
http://www.gdandtbasics.com/perpendicularity/
Perpendicularity
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Perpendicularity
http://www.gdandtbasics.com/perpendicularity/
a tolerance that controls
Perpendicularity between
two 90° surfaces, or
features. Surface
Perpendicularity is
controlled with two
parallel planes acting as its
tolerance zone.
The normal form or Surface Perpendicularity is
Perpendicularity
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Perpendicularity
http://www.gdandtbasics.com/perpendicularity/
a tolerance that controls
how perpendicular a
specific axis needs to be to
a datum. Axis
Perpendicularity is
controlled by a cylinder
around a theoretical perfectly parallel axis.
Axis Perpendicularity is
Surface Perpendicularity
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Surface Perpendicularity
http://www.gdandtbasics.com/perpendicularity/
Surface Perpendicularity
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f p yGauging/Measurement
http://www.gdandtbasics.com/perpendicularity/
Surface Perpendicularity
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f p y Example:
http://www.gdandtbasics.com/perpendicularity/
Axis Perpendicularity
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Axis Perpendicularity
http://www.gdandtbasics.com/perpendicularity/
Axis Perpendicularity
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p yGauging/Measurement
To ensure that a part or feature is axially perpendicular,Maximum material condition is most often called out on axis
perpendicularity to allow easy measurement with a gauge. This
allows it to be designed for either a negative (hole) or positive
(pin) feature and can take into account a bonus tolerance.*
Gauge size for an internal feature (like a hole):
Gauge Ø (pin gauge)= Min Ø of hole (MMC) –
Perpendicularity Tolerance
Gauge size for an external feature (like a pin):
Gauge Ø (hole gauge) = Max Ø of pin (MMC) +
Perpendicularity Tolerance
Axis Perpendicularity
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Gauging/Measurement http://www.gdandtbasics.com/perpendicularity/
Axis Perpendicularity Example:
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Axis Perpendicularity Example:
http://www.gdandtbasics.com/perpendicularity/
Tolerances of Location
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Tolerances of Location
It Includes position, concentricity, and symmetry
SymmetrySymmetrical relationships may be controlled using
either positional, profile, or symmetry tolerances.
Symmetry
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GD&T Symmetry is a 3-Dimensional tolerance that isused to ensure that two features on a part are uniform
across a datum plane.
Symmetry
http://www.gdandtbasics.com/symmetry/
Symmetry
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An established “true” central plane is established from the datumand for the symmetry to be in tolerance, the median distance
between the every point on the two surface features need to fall
near that central plane.
Symmetry
http://www.gdandtbasics.com/symmetry/
Symmetry
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Each set of points on the reference features wouldhave a midpoint that is right between the two. If you
take all the midpoints of the entire surface, this must
lie within the tolerance zone to be in specification.
Symmetry is not a very common GD&T callout since
it has very limited functional uses (centering location
is done with Position) and the verification and
measurement of symmetry can be difficult (See: Final Notes).
Symmetry
http://www.gdandtbasics.com/symmetry/
Symmetry Gauging/ Measurement
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Symmetry Gauging/ Measurement
http://www.gdandtbasics.com/symmetry/
Symmetry, when used?
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When you want to make sure that the center plane oftwo symmetric features is always held exactly center
AND has even form along the surface of the part.
This symbol only has specific uses for mass balance
and form distribution.
However in most cases it is better to avoid using
since this is a very difficult callout to measure and
can easily be replaced with a Position tolerance.
Symmetry, when used?
http://www.gdandtbasics.com/symmetry/
Symmetry Example
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If you had a rotating U-Joint a groove that needed toalways have even balancing, you would need to make
sure that the mating part is always located to fall into
the center of the groove and that the surface form is
properly balanced.
Instead of widening the groove causing the
connection to be loose, you could constrain it with
symmetry.
Symmetry Example
http://www.gdandtbasics.com/symmetry/
Symmetry Example
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Symmetry Example
http://www.gdandtbasics.com/symmetry/
Symmetry Example 1: Call out symmetry to ensure the groove is
centered on the median plane of the latch block.
Symmetry Example
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The part would then need to be measured to ensure that all themedian points of the sides of the latch block are symmetrical
about the central axis. The part would have to be measured in
the following way:
1. Measure the width and location of both sides of the blockreference by datum A (40mm) and determine where the
exact median plane is located to establish our tolerance
zone.
2. Side 1 and Side 2 of the part are scanned for their actual
profiles
3. Using a program, the median points of the Side 1 and Side
2 scans are laid over the virtual tolerance zone planes and
determined if they are in tolerance.
Symmetry Example
http://www.gdandtbasics.com/symmetry/
Symmetry Example
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Symmetry Example
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Toleransi Posisi
Position Tolerances
Position
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Position
Position is the location of one or more features of size
relative to one another or to one or more datums.
True Position
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True center position of a hole (RFS w/ 2 Datums)
True Position
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True position of a hole under MMC (3 Datums)
True Position
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True position of a hole under MMC (3 Datums)
True Position –
Location of af t
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feature
A 2 dimensional cylindrical zone or, more commonlya 3-Dimensional cylinder, centered at the true
position location referenced by the datums.
The cylindrical tolerance zone would extend though
the thickness of the part if this is a hole. For the 3-
dimensional tolerance zone existing in a hole, the
entire hole’s axis would need to be located within this
cylinder.
http://www.gdandtbasics.com/true-position/
True Position –
Location of af t
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featurehttp://www.gdandtbasics.com/true-position/
True Position Gauging/M t
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Measurement http://www.gdandtbasics.com/true-position/
True Position –
Location of a Feature
True Position Gauging/Measurement
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Measurement
True Position Using material modifiers (MMC only)
http://www.gdandtbasics.com/true-position/
Gauging of an Internal Feature
True Position Gauging/Measurement
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Measurement
True Position Using material modifiers (MMC only)
http://www.gdandtbasics.com/true-position/
Gauging of an External Feature
True Position Example
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Location of Hole Example 1
True Position Example
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Location of Hole Example 1
True Position Example
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Hole size and location using MMC Example 2
True Position Example
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Hole size and location using MMC Example 2
True Position Example
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Hole size and location using MMC Example 2
Concentricity
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Concentricity is a tolerance that controls thecentral axis of the referenced feature, to a datum
axis.
Concentricity
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ConcentricityGauging/Measurement
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Gauging/Measurement http://www.gdandtbasics.com/concentricity/
Concentricity Example
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Tolerances of Profile
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A profile tolerance may be applied to anentire part, multiple features, individual
surfaces, or to individual profiles taken at
various cross sections through a part.There are two types
Line profile
surface profile
Line profile
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Each line element tolerance zone established bythe profile of a line tolerance requirement is two-
dimensional (an area) and the tolerance zone is
normal to the true profile of the feature at each
line element.
Surface Profile
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Description:Profile of a surface
describes a 3-
Dimensional tolerance
zone around a surface,usually which is an
advanced curve or
shape.
http://www.gdandtbasics.com/profile-of-a-surface/
If it is called out on a curved surface, like a fillet on a
welded part, the entire surface where the radius is has
to fall within the tolerance zone.
Surface Profile
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Description:Profile controls all the points along the surface within
a tolerance range that directly mimics the designed
profile.
Any point on the surface would not be able to vary
inside or outside by more than the surface profile
tolerance. Usually when surface profile is required,
there are no tolerances on the dimensions thatdescribe the surface and use the GD&T callout to
give the acceptable range.
http://www.gdandtbasics.com/profile-of-a-surface/
Surface Profile
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Surface Profile Gauging/Measurement
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Measurement http://www.gdandtbasics.com/profile-of-a-surface/
Surface Profile Gauging/Measurement Example
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Measurement Examplehttp://www.gdandtbasics.com/profile-of-a-surface/
Tolerances of Runout
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Runout is a tolerance used to control thefunctional relationship of one or more
features to a datum axis established from a
datum feature specified at RMB (Regardlessof Material Boundary).
TYPES OF RUNOUT TOLERANCES
Circular Runout Total Runout
Circular Runout
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Circular runout provides control of circular
elements of a surface. The tolerance is applied
independently at each circular measuring position
as the part is rotated the full angular extent of the
surface about the simulated datum axis.
Circular Runout
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Circular RunoutGauging/Measurement
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Gauging/Measurement http://www.gdandtbasics.com/runout/
Circular RunoutGauging/Measurement Example
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Gauging/Measurement Examplehttp://www.gdandtbasics.com/runout/
Total Runout
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Total runout provides control of all surfaceelements. The tolerance is applied simultaneously
to all circular and profile measuring positions as
the part is rotated 360⁰ about the datum axis.
Total Runout
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Total Runout Gauging/ Measurement
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Total Runout Gauging/ Measurement Example
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phttp://www.gdandtbasics.com/total-runout/
True Position, description
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True position is defined as the total permissiblevariation that a feature can have from its “true”
position. Depending on how it is called out, true
position can mean several different things.
It can be used with Max Material Condition(MMC),Least Material Condition (LMC), projected
tolerances, and tangent planes.
http://www.gdandtbasics.com/true-position/
True Position, description
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It may apply to everything from points to axes to
planes to entire features. In these examples we will
use holes, since these are the most common types of
features controlled by true position.
Keep in mind though that true position can be used onany feature.
http://www.gdandtbasics.com/true-position/
MMC (Maximum-Material-Condition), symbol:
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), y
Definition:Maximum Material Condition or for short, MMC, is a
feature of size symbol that describes the condition of
a feature or part where the maximum amount of
material (volume/size) exists within its dimensionaltolerance.
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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) y
If it is a hole or internal feature: MMC = smallesthole size
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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) y
If it is a pin or external feature: MMC = largest size
of the pin
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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) y
The only GD&T Symbols where Max MaterialCondition can be applied are:
Straightness (axis)
Parallelism
Perpendicularity
Angularity
True Position – very common
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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y
Reason for Use:If you want to ensure that:
two parts never interfere, or
limit the amount of interference between the parts
when they are at their worst tolerances
MMC can be called out. Take a shaft that must go
through a hole with clearance between the two.
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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Reason for Use:The MMC of the shaft would be the
Maximum diameter
The MMC of the hole would be its Minimum
diameter
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), symbol:
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Reason for Use:
If you made sure that the MMC of the shaft was always
smaller than the MMC of the hole,
you guarantee there will always be clearance
between the parts.
This is important for any tolerance stack to ensurethat when the tolerances are at their least desirable
condition, the part still functions properly.
http://www.gdandtbasics.com/maximum-material-condition/
MMC (Maximum-Material-Condition), Gauging MMC
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Maximum material condition comes in handy when itcomes to making a functional gauge for the part. If
you want to limit the size of your feature, you can
specify the max material condition call out
additionally control it with GD&T.For example if you wanted to ensure that a pin always
fits into a hole when the hole is at MMC, we could
design a pin gauge that
mimics the lower limit of the hole. The gauge that
controls the Max Material Condition of a part is
called a Go-Gauge (Meaning the Part must always
Go into it)
MMC (Maximum-Material-Condition), Gauging MMC
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MMC (Maximum-Material-Condition), Gauging MMC
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The Go-Gauge for a hole or internal feature wouldexist of a pin that is just a tiny bit (few microns)
smaller than the Maximum Material Condition of the
hole. The gauge pin would then be inserted into the
hole and as long as the pin Goes into the hole, the partis in spec.
(Note: The pin gauge may be made slightly smaller (a
few microns) than the MMC to account for any
straightness or tolerance issues that may be inherent
in producing the gauge)
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MMC (Maximum-Material-Condition), Gauging MMC
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KK TPM
MMC (Maximum-Material-Condition), Gauging MMC
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Remember
when no GD&T is called on the hole the envelope
principal applies –
meaning the geometric and size effects of the hole
cannot be larger or smaller than the tolerances
specified.
KK TPM
MMC Combination Gauging withGD&T Symbols
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The true benefit of using the maximum materialcondition on a feature is the ability to call out GD&T
with dimensional tolerances and be able to gauge for
them at the same time.
When geometric control and material control are usedtogether, they form the true maximum envelope or
virtual condition that the part can be in and still be
to specification.
KK TPM
MMC Combination Gauging withGD&T Symbols
h // d d b i / i i l di i /
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For example, you have a pin with a dimensional and perpendicularity call outs.
The pin needs to be within both perpendicular
enough and small enough so that it doesn’t get stuck
when inserted into its mating hole at a 90° angle tothe face of the part.
In this case all you really care about is the pin fits into
the hole at the worst case limits (MMC and max
perpendicularity tolerance make up the maximum
envelope of the part)
KK TPM
MMC Combination Gauging withGD&T Symbols
htt // d dtb i / i t i l diti /
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The virtual condition can be controlled with a functional gauge.
Functional gauges can be a huge benefit to production environments
where measuring on the line quickly is critical.
KK TPM
Gauging for MMC withGeometric tolerances:
htt // d dtb i / i t i l diti /
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For the Gauging
of a hole with
perpendicularitycall out:
Gauge Ø (pin gauge) = Min Ø of hole (MMC) – GD&T
Symbol Tolerance
KK TPM
Gauging for MMC withGeometric tolerances:
htt // d dtb i / i t i l diti /
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For Gauging of a
pin with a
perpendicularitycallout:
Gauge Ø (hole gauge) = Max Ø of pin (MMC) + GD&T
Symbol Tolerance
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LMC (Least-Material-Condition),symbol
htt // d dtb i /l t t i l diti /
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Definition:Least material condition is a feature of size symbol
that describes a dimensional or size condition where
the least amount of material (volume/size) exists
within its dimensional tolerance.
http://www.gdandtbasics.com/least-material-condition/
KK TPM
LMC (Least-Material-Condition),symbol
http // gdandtbasics com/least material condition/
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If it is a hole or internal feature: LMC =Largest hole
size (least material in part)
http://www.gdandtbasics.com/least-material-condition/
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LMC (Least-Material-Condition),symbol
http://www gdandtbasics com/least material condition/
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If it is a pin or external feature: LMC = Smallest size
of the pin
http://www.gdandtbasics.com/least-material-condition/
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LMC (Least-Material-Condition),symbol
http://www gdandtbasics com/least material condition/
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If you want to ensure that two always have contact ora press fit Least Material condition can be called out.
It is most often the control of parts that are pressed
together to ensure that they always have a snug fit
and no clearance.If you made sure that the LMC of the shaft was
always larger than the LMC of the hole, you ensure
that there will always be a tight fit between the parts.
This creates a condition where you can use a
functional gauge to ensure that the external feature is
not too small or that the internal feature is too loose.
http://www.gdandtbasics.com/least-material-condition/
KK - TPM
LMC (Least-Material-Condition),symbol , Use in GD&T:
http://www gdandtbasics com/least material condition/
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Least Material Condition is fairly rare in geometricdimensioning and tolerancing.
There are only a few reasons why a LMC should be
called. The most common reason for calling it would
be that you have a hole or other internal feature that isvery close to the edge of a part.
If you call LMC with true position in figure 2 below
– you would be specifying that if the hole is at its
largest size, it can only vary by as much as the true
position tolerance.
http://www.gdandtbasics.com/least-material-condition/
KK - TPM
LMC (Least-Material-Condition),symbol , Use in GD&T:
http://www gdandtbasics com/least material condition/
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Thin Wall Hole Example
However if the holeis smaller than its
Least Material
Condition, you can
apply a bonus
tolerance to the part,
because now the true
center of the hole can
be closer to the edge,
without minimizingthe thickness of the
material.
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Concept of LMC with No-GoGauges
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The concept of the least material condition (not theGD&T symbol) comes in handy when a functional
gauge is needed to control a part.
If you want to limit the size of your feature to insure a
proper fit, you can specify the least material conditioncallout and control it with a specific type of gauge
called a No-Go Gauge.
http://www.gdandtbasics.com/least-material-condition/
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Concept of LMC with No-GoGauges
http://www gdandtbasics com/least-material-condition/
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For example if you wanted to ensure that a pin alwayshas a tight fit into a hole, you could design the No-Go
hole gauge to mimic the least material condition of
the part. This would be a block with a hole of a
diameter equal to the pin’s LMC (min Ø).To check the part you would try to insert the pin into
the hole. If it doesn’t fit ( No-Go) then you know that
the pin is large enough to be a tight press fit into the
feature.
http://www.gdandtbasics.com/least-material-condition/
KK - TPM
Concept of LMC with No-GoGauges
http://www gdandtbasics com/least-material-condition/
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http://www.gdandtbasics.com/least-material-condition/
A No-Go gauge for a hole would use a pin gauge = Hole’s Max Ø
A No-Go gauge for a pin would use a ring gauge = Pins Min Ø
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Cannot Combine Gauging withGD&T Symbols
http://www gdandtbasics com/least-material-condition/
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Here is where the weakness of LMC comes out. Inmaximum material condition you are defining that the
size cannot go past the max material size + the
geometric callout.
This works fine because you are using two tolerancesthat are positive.
However with least material condition this you cannot
create a functional gauge that controls both.
http://www.gdandtbasics.com/least-material-condition/
KK - TPM
Cannot Combine Gauging withGD&T Symbols
http://www gdandtbasics com/least-material-condition/
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For example if you have a perpendicularitycallout and want to also control LMC on a hole, you
can check the hole for size with a no-go gauge to
ensure it is small enough for a press fit.
However if you specify a gauge that allows for a bonus tolerance on the least material condition, you
cannot make a no-go gauge also check the
perpendicularity, because a No-Go gauge is designed
not to fit!
http://www.gdandtbasics.com/least material condition/
KK - TPM
Cannot Combine Gauging withGD&T Symbols
http://www gdandtbasics com/least-material-condition/
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http://www.gdandtbasics.com/least material condition/
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Concept of LMC with No-GoGauges
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The problem is that GD&T symbols always specifythe maximum amount that a part can vary and cannot
be combined when you are controlling the a least
material control of size. The only way LMC can be
called on a feature would be if the least materialcondition and the perpendicularity were measured
and calculated separately. This, however, eliminates
the benefit and speed of a gauge.
http://www.gdandtbasics.com/least material condition/
KK - TPM
Concept of LMC with No-GoGauges
http://www.gdandtbasics.com/least-material-condition/
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For these reasons least material condition is seldomused as a control for geometry and size. While
gauging is always possible for least material
condition size in a production environment, you
cannot gauge for both GD&T and dimension at once.The takeaway should be that in GD&T
understanding least material condition as a
concept of size is important. The only time you
will truly see it is combined with true position onthin walled parts like in the Thin Wall Hole
Example above.
http://www.gdandtbasics.com/least material condition/
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
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Definition:
Regardless of Feature Size (RFS) is the default
condition of all geometric tolerances by rule #2 of
GD&T and requires no callout.
Regardless of feature size simply means thatwhatever GD&T callout you make, is controlled
independently of the size dimension of the part.
http://www.gdandtbasics.com/regardless of feature size/
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
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Definition:
This rule can be overridden by Maximum Material
Condition or Least Material Condition, which specify
the GD&T conditions at the Max or Min size of the
part.LMC or MMC must be called out on the drawing
specifically though to eliminate the regardless of
feature size default.
p // gda d bas cs co / ega d ess o ea u e s e/
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/lest-material-condition-lmc/http://www.gdandtbasics.com/maximum-material-condition/http://www.gdandtbasics.com/lest-material-condition-lmc/http://www.gdandtbasics.com/maximum-material-condition/
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Definition:
For simplicity, the definitions of all the GD&T
symbols are by default, stated as Regardless of
Feature Size.
For most geometric symbols besides those that allowmaximum material condition, RFS can never be
overridden.
Regardless of feature size eliminates any potential bonus tolerance, allowing the GD&T tolerances to be
more tightly controlled.
p g g
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
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Reason for Use:
Since Regardless of feature size is the default
condition it is used always and ignored only when
specified.
It is applied for most part conditions.
RFS is always kept where balance is critical and
where both sides of the tolerance must be maintained
independently of the GD&T callouts.
p g g
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
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Reason for Use:
Regardless of Feature size requires the axis to be
measured separately from the size of the hole and
cannot be gauged easily. However, there is no bonus
tolerance allowed in this condition so the perpendicularity would be much better controlled
regardless of the size of the hole.
In the following example, no material modifiers are
called out, RFS would be implied and the control for
the parts would be like this:
p g g
KK - TPM
Regardless-of-Feature-Size
http://www.gdandtbasics.com/regardless-of-feature-size/
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p g g
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KK - TPM