Position tolerance of a Plane (Surface in my case) result interpretation

[[Sa...]]

Hello experts,

I need a short help in the topic position tolerance of a plane which is a surface.

I want to calculate a position of a plane which is a surface and important for assembly. After measurement in GOM, i get a result of 0.3 deviation. My question is how can we interpret this result in reality. I am sending a picture for better view. If you look in aview showed as arrow green, the position will be seen as a line and the magenta color shows the deviation 0.3. But how to see it where it is 0.3 and where the lowest. Is the position of the plane allows measured from the center? I hope to explain you my question. Thanks

 

 

Kind Regards

Samkit

[[Di...]]

Hi Samkit,

this is kind of a longer story which should be learned on the basis of a full blown GD&T training. Because the topic of a basic GD&T understanding is much larger then it could be explained in a forum thread.

Nevertheless I will try to explain it as short as possible.

The result of a GD&T computation is always the width of a computed tolerance zone. It can be a planar, circular or spherical zone.

So when you read deviation 0.3 this means that the space for between the two computed tolerance zone planes resulted in a distance of 0.3. The actual deviation (the one that you can actually improve by adding or removing material) is only half of the deviation namely 0.15. The principles of the computation can be found in the corresponding ISO or ASME standards or in our help documents.

The attached picture explains how the position tolerance or better the position deviation is computed.

The remaining question is how to determine the min. and max. distance form tolerance zone center.

This is as well shown in the attached pictures.

If you need more detailed information please consult the direct help in the software and search for Introduction to Geometric Dimensioning and Tolerancing

or our tech guide under https://techguide.gom.com/en/article/general_gd_and_t_general.html

 

Hope this helps

Edited November 2, 2021