GD&T Profile tolerance

What is the meaning of a profile tolerance in GD&T? How to interpret the callout and the concept of profiles

Profile tolerance is a very important geometric control in GD&T and is of two type

Profile of a line – controlling the profile of a line segment on a curve and not the complete surface as a whole .
Profile of a surface- controls the profile of the surface , any point on the surface should not lie beyond a tolerance zone formed by equally spaced offset surfaces from the nominal surface with a width of value mentioned in geometric tolerance
Here is an example of Profile of a sruface

The profile control applied means that the top curved profile of the pat has to be controlled in its profile of surface within the tolerance zone as shown below.

All the elements on the surface should lie within this tolerance zone or else the manufactured part would not be acceptable according to this callout.

To visualize the tolerance zone shape consider this example:

Tolerance zone shape in 3D view in pink :

Profile control can also be accompanied by limits which indicate the start and end point of surface which has to be controlled with respect to the feature control frame.

Example of profile with limits:

Important points relating to profile :

It can be used with or without datum, when used without datum it means profile control is only controlling the form (same as flatness or circularity)
Profile tolerance can control size, form, orientation and position of the targeted surface. Its called as a combined geometric control because it can control so many aspects of the feature.
Profile can be applied to flat , curved , cylindrical or irregular surfaces
Highly versatile and can also with composite or compound feature control frame that have refinement of profile control with respect to orientation , position and form .
Material modifier cannot be applied with geometric tolerance as in the case of true position

Learn more about how to Interpret GD&T callouts from this e-book on GD&T interpretations

Explore more topics in GD&T :

GD&T symbols

GD&T True position

Interview questions in GD&T

What is virtual condition in GD&T

What is Rule #1 in GD&T

GD&T tolerance zone

GD&T straightness

GD&T runout

GD&T resultant condition

GD&T Regardless of feature size