WHY TOLERANCE?

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Answers to the above Questions

Answers to the above Questions

Geometric Dimensioning and Tolerancin

FORM TOLERANCE

FLATNESS TOLERANCE

EXAMPLE:

Gauging / Measurement:

Flatness is can be measured using a height gauge run across 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. 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 width of the part to ensure the entire surface is in tolerance. 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.

Final Notes: Flatness is not the same as parallelism. Parallelism uses a datum to control a

surface while flatness does not. Think of a table with two missing legs at an angle to

the floor. The table top may be within flatness tolerance but would not be parallel to the

floor.

STRAIGHTNESS TOLERANCE

EXAMPLE:

CIRCULARITY TOLERANCE

EXAMPLE:

CYLINDRICITY TOLERANCE

EXAMPLE:

ORIENTATION TOLERANCE

ANGULARITY TOLERANCE

PERPENDICULARITY TOLERANCE

PARALLELISM TOLERANCE

LOCATION TOLERANCE

POSITION TOLERANCE

CONCENTRICITY

SYMMETRY

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HAVE TO GIVE EXAMPLES TO ANGUKARITY

PERPENDICULARITY PARALISIM