This is both a control of the diameter and of the axial straightness. 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. It is defined as the variance of the surface within a specified line on that surface.Īxis straightness:– Axis straightness is actually a 3D tolerance that constrains the center axis of the part preventing it from bending or twisting too far. 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. There are two types a ) Surface straightness b) Axis straightness. Or derived median line mean- Exact center line of part. A straightness tolerance is applied in the view where the elements to be controlled are represented by a straight line.įrom definition- an element of a surface mean edge of part, Bottom face, side face, etc.
A straightness tolerance specifies a tolerance zone within which the considered element of a surface or derived median line must lie. According to ASME Y14.5-2009 definition of straightness is as belowĭefinition:– Straightness is a condition where an element of a surface, or derived median line, is a straight line.
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