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mc233

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    1. MC233 Geometric Dimensioning and Tolerancing (GD&T)

    4. Feature Control Frame Is a rectangular “box” with compartments that enclose the geometric characteristic symbol, specified geometric tolerance, and datum reference - if required.

    5. Simple feature control frame

    6. Form Tolerances Examples: straightness, flatness, circularity When a feature is at its maximum material condition (largest size for external features like shafts, smallest size for internal features like holes) the form would have to be perfect to fit So may need tighter control – GD&T

    8. Form Tolerances - Control Straightness, flatness, circularity, and cylindricity. Do not relate to datums, but are applicable to single (individual) features or elements of single features.

    9. Form Tolerances - Straightness is where an element of a surface or an axis is a straight line. Specifies a tolerance zone within which the considered element or axis must lie.

    10. Straightness tolerance Specifies a tolerance zone within which an axis or all points of the considered element must lie.

    11. Form Tolerances - Flatness is the condition of a surface having all elements in one plane. Specifies a tolerance zone defined by two parallel planes within which the surface must lie.

    12. Flatness tolerance specifies a tolerance zone defined by two parallel planes within which the surface must lie.

    13. Form Tolerances - Circularity (roundness) is a condition where all points of the surface intersected by any plane perpendicular to a common axis are equidistant from the axis. Specifies a tolerance zone bounded by two concentric circles within which each circular element of the surface must lie.

    14. Roundness (circularity) tolerance specifies a tolerance zone bounded by two concentric circles within which each circular element of the surface must lie. Equal distance from the axis.Equal distance from the axis.

    15. Profile Control - is the tolerance to be maintained on the outline of an object in a given plane (two-dimensional figure). Elements are straight lines, arcs, and other curved lines. Specifies a uniform boundary along the true profile within which the elements of the surface must lie.

    16. Profile Tolerance (example)

    17. Datum surface and features Datum surfaces and datum features are used as references to control other features on the part Datum features should be actual features on the part, such as a point, line, plane, cylinder, or other geometric form that is assumed to be exact

    18. Tolerances for related features Parallelism, perpendicularity, and angularity are tolerances that relate the orientation of one feature to another

    19. Parallelism - Plane surface (example) Specified for surface feature by two planes or lines parallel to a datum plane or axis The surface must lie between two parallel planes 0.05 apart which are parallel to datum plane A.

    20. Parallelism - cylindrical feature (example) Feature axis must lie between two planes 0.1 apart and parallel to datum B.

    21. Perpendicularity (example) Surface must lie between two parallel lines 0.15 apart and perpendicular to datum axis A.

    22. Angularity (example) Surface must lie between two parallel planes 0.3 apart which are inclined at 45 degrees.

    23. Angularity (example) The feature axis must lie between two parallel planes 0.1 apart.

    24. Basic Dimensions Are the theoretically exact, untoleranced dimensions that specify the perfect location, size, shape, or angle of a feature Closed within a box These dimensions are exact values from which variations are defined through a feature control frame

    25. Positional tolerance Establishes a tolerance zone around the perfect location for a feature

    28. Runout Tolerance is a composite tolerance used to control the functional relationship of one or more features of a part to a datum axis. Two types: Circular runout, Total runout

    29. Circular Runout Controls circular elements of a surface.

    30. Circular Runout At any measuring position, each circular element of these surfaces must be within the specified runout tolerance when the part is rotated 360 degrees about the datum axis Controls circularity and concentricity

    31. Circular Runout (example)

    32. Total Runout Entire surface must lie within the specified tolerance zone when the part is rotated 360 degrees. Used to control cumulative variations of circularity, straightness, coaxiality, angularity, taper, and profile of a surface. Remember this has to do with FIM (full indicator movement) over the entire surface - so this is a cumulative process.Remember this has to do with FIM (full indicator movement) over the entire surface - so this is a cumulative process.

    33. Total Runout (example)

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