When used without datums, Profile of a line can also be thought to be similar to flatness or cylindricity as these symbols are only more specific versions of the profile of a surface symbol. The difference between them is that profile of a surface would cover the entire required surface, making sure that every point falls in the tolerance zone, not just at a cross-section. Profile of a surface is the 3D version of profile of a line. If a simple surface is called out, such as a radius on a corner, a height gauge can be used to trace the part as long as the gauge can stay the same distance away from the surface as rotates around the surface. The CMM would compare the 3D scan of the profile to the dimensions called out on the drawing to see if it was in spec. Profile is usually measured using a CMM due to the complexity of some of the surfaces that are called out. This tolerance zone may or may not be referenced by a datum. GD&T Tolerance Zone:ģ-Dimensional tolerance zone existing of 2 parallel surface curves that follow the contour of the surface profile across the entire length of the surface. Usually, when surface profile is required, there are no tolerances on the dimensions that describe the surface and use the GD&T callout to give the acceptable range. Any point on the surface would not be able to vary inside or outside by more than the surface profile tolerance. Profile controls all the points along the surface within a tolerance range that directly mimics the designed profile. If it is called out on a curved surface, like a fillet on a welded part, the entire surface where the radius is has to fall within the tolerance zone. Profile of a surface describes a 3-Dimensional tolerance zone around a surface, usually which is an advanced curve or shape. GD&T Symbol: Relative to Datum: Optional MMC or LMC applicable: No Drawing Callout:
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