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Geometric TolerancingPMPA Technical Conference
Developing Todays Talent For Tomorrows $uccess
Corona, California
April 15, 2013
Gary K. Griffith
Session 1
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Gary K. Griffith
Technical Book AuthorQualityEngineeringShop Technical
42 Years Exp.AutomotiveAerospace
EngineeringManufacturingQuality
Photos Reference: Geometric TolerancingApplications and
Inspection (Prentice Hall)
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Outline Session 1
Limitations are:1. Inspectors Knowledge / Skills 2. Available
Inspection Equipment
Form TolerancesFlatnessStraightnessCircularityCylindricity
Orientation TolerancesParallelismPerpendicularity
Angularity
Form & Orientation Tolerances Interpretation &
Inspection
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T.I.R. F.I.M.
Some Geometric Tolerance measurements are:
T.I.R. Total Indicator ReadingF.I.M. Full Indicator Movement
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Flatness Tolerance
Flatness
Flatness measurement is a T.I.R. (or F.I.M.) that is
achieved with a probe or dial indicator
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Flatness Tolerance
Leveling (Wobble) Plate Method Jack Screws Method
Surface must be leveled (optimum plane) so that the
probe sees only hills and valleys of flatness error
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Flatness Tolerance
Indian Pins Set
Alternative is Indian Pins. Three pins at exactly the
same height within millionths. The pins level the surface.
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Straightness ofSurface Elements
Applies to individual line elements at the surface, not
the axis.
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Straightness ofSurface Elements
Setup with two jack screws, a parallel, and a V-Block.
Jacks are used to level the line element, then a top-dead-center
T.I.R.
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Straightness ofSurface Elements
Alternative is two equal height gage block stacks, then a
bottom-dead-center T.I.R.
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Straightness ofan Axis - RFS
Challenging inspection. Differential measurements
are required for inspection. Two opposing indicators to
trackaxial deviation
This part is acceptable
h f
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Straightness ofan Axis - MMC
This type of straightness could be evaluated with a
Functional Gage (as with any tolerance at MMC)
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Circularity (Roundness)
Roundness tolerance zone is two concentric circles.
Roundness is a radial measurement, not diametral.
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Precision Spindle
Circularity (Roundness)
A precision spindle (or CMM) could be used.
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CylindricityCylindricity combines measurement of roundness,
straightness of surface elements, and taper per side.
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Parallelismof a Surface
Parallelism of a Surface
Tolerance Zone
Parallelism measurement is a T.I.R. once the datumhas been
mounted.
P ll li
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Parallelismof a Surface
Parallelism Inspection
Dial indicator is being traversed across the entiresurface. The
resulting T.I.R. shall not exceed thetolerance. Flatness is
automatically controlled.
P di l i
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Perpendicularityof a Surface
Perpendicularity of a Surface
Tolerance Zone
Perpendicularity measurement is also a T.I.R.
Flatness is inherently controlled.
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Perpendicularityof a Surface
Inspection
Since there is only one datum, the part must be best-fit
for secondary alignment.
P di l it
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Perpendicularityof a Surface
(Secondary Datum)
Perpendicularity of a Surface
Inspection
When there is a secondary datum, the part is aligned.
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Angularity
xx
Angularity Requirement
Tolerance Zone
Angularity measurement is also a T.I.R.
Flatness is inherently controlled.
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Angularity
xx
Angularity Requirement
Inspection
A Sine Bar, Sine Plate, or CMM could be used.
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Griffith TrainingOn-Site Tailored GD&T Training :
Basic Intermediate Advanced
Tolerance Stackup AnalysisFunctional Gage
DesignInspectionQuality Courses
Consulting:
Functional Design DrawingReviewsTolerance StackupsFunctional
Gage Designs
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Questions and Answers
[email protected] 951-733-9678
www griffithtraining com
Need Training?
mailto:[email protected]:[email protected]
