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ALEX P.M.

0206

FLATNESSMEASUREMENT

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FLATNESS ?

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Flatness measurement :jackscrewmethod

Part is mounted on

jackscrews

Jackscrews are preleveled

using a height gage.

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jackscrewmethod :

Part surface has been leveledto the surface plate.

Comparing the surface tothe optimum plane. (FIM)

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Flatness measurement : wobble - platemethod

Leveling Wobble plate in use.

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Flatness measurement : fixed - planemethod

Part resting on threeequal pins. FIM being obtained from

the inverted surface.

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Flatness measurement : direct - contactmethod

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Direct - contact method

Mastering the probewith a precisionparallel

Inspecting the part.

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Optical flatness inspection

Viewing the bands on the surface of the part with a

optical flat.

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Optical flatness inspection

Contact method

Wedge method

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Interpreting the Bands for Flatness Error

Straight, parallel &equally spaced bandsshows that the surface

is flat.

One band of error equals11.57 millionths out offlatness.

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Interpreting the Bands for Flatness Error

Concave : out of

flat by 2 bands.

Spherical concave : out of

flat by 2 bands

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Interpreting the Bands for Flatness Error

Spherical convex : outof flat by 2 bands(23.14 millionths).

Peaks & valleys : outof flat by 5 bands(57.85 millionths).

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MEASUREMENT

STRAIGHTNESS

ALEX P.M.0206

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STRAIGHTNESS ?

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STRAIGHTNESS MEASUREMENT

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Axis Vs surface element straightness

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Straightness of surface element :cylindrical parts

f f

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Straightness of surface element :jackscrew method

Establishing zero on the

part surface at one end.

Jackscrews are preleveled

using a height gage.

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Straightness of surface element :jackscrew method

The indicator istraversed alongthe surfaceelements of theshaft (at the top

dead center) forstraightness errormeasurement

St i ht f f l t

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Straightness of surface element :Precision straightedge method

A precision straightedge can be usedwhen tolerances are relatively loose.

St i ht f f l t

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Straightness of surface element :Comparator method

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Straightness of surface element :Two - Block method

The part is placed on top of

two equal height blocks.

Dial indicator indicates line

elements of the surface.

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Straightness of surface element :

Noncylindrical parts

Jack screw method

Precision straightedge method

Conical parts

Optical comparator method Precision straightedge method

Wobble plate method

St i ht f i

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Straightness of an axis :

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Straightness of an axis :Differential measurement methods

Exploring a line element of the shaft.

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Straightness of an axis :Differential measurement methods

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Straightness of an axis :Precision spindle method

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Straightness of an axis :Precision spindle method

Example of a graph for

axial straightness error.

Polar graph showing that

the part is acceptable.

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Straightness of an axis :Precision spindle method

(A) Bowed shaft (B) Eccentric

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Straightness of an axis :Precision spindle method

(C) Out of round (D) Hourglass condition

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Straightness of a centerplane :

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Straightness of centerplane :Differential measurement methods

Indicating line elements of the part on the surface plate.

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Some possible outcomes of centerplane straightness measurement

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