Combined and Separate Tolerance Zones for element group - way of calculation

[[Yi...]]

Hi

It would be helpful if you could clarify the explanation that appears in the software and the effect it has on the measurement results.

In this case, I am referring to the possibility of testing a partial portion of a datum.

It is possible to test as a single zone or a combined zone by creating a group of elements.

Using the combined zone test option leads to a significantly higher result that does not match reality as reflected in the overall color map.

As a result of this issue, I reviewed the software instructions for these two options and understood that, when a CZ option is selected, the software performs a sort of cumulative sum of all the errors into one aggregate result, resulting in the high value result as described previously that I did not understand at first.

Can you please provide a detailed explanation of the mathematical calculation performed here as well as references to the ISO and ASME standards.

I greatly appreciate your assistance

[[Ma...]]

Using CZ it will perform one element from group and evaluate it as one. Here on SZ it looks like you have pattern of elements - this will give you direction, but SZ will be performed on each element independently but with restricted direction.

ISO and ASME will perform as usual - using Gauss or Tangential evaluation.

[[Ch...]]

For a detailed explanation please have an look into ISO 1101 (general explanation of CZ/SZ modifier) and ISO 5458 (general explanation of pattern evaluation). There you should find some examples describing the difference between CZ and SZ. 

This should described what the actual value is (in short a definition of the actual value) that is displayed from the software. Sorry, but we can not revealed how we compute the actual value exactly. We promised that we doing the thing that described in the standard but the exact algorithm is restricted.

 

Best regards

Christoph Schult

[[Yi...]]

Thank you very much for your answer.

When I talked about the calculation, I did not mean to ask for the software formula but to receive a practical example of the situation described in the help, according to which it is possible that the deviations of all the partial surfaces separately will be combined into a single composite result, all in order to try to better understand the results I am receiving.

[[Ch...]]

If you have access to ISO 5458 please have to look into the appendix of this standard. There you can find multiple examples describing the different modifier. Sorry, I can copy the full section due to copyright restriction, but I assume that to summarize a simple example is ok.

 

Lets have an look onto this technical drawing

This indication means that the center of the tolerance zone for each cylinder is located 25 mm away from the datum system axis and have to parallel to the datum system axis. But it is nothing say about the location of the tolerated cylinder to each other. Only the location to the datum line is tolerated and the actual value is the biggest of independent actual value of single cylinder.

If you want to add a constraint that the tolerated cylinder have an angle of 180 degree to each other, i.e. they lies on different side of the datum, then you have to replace the SZ modifier with the CZ one. Then the both pattern is computed together and not independent anymore.

As I said if the standard is available there are illustration for common cases to make the differences clear.

 

Hope this helps

Christoph Schult

Edited 4 hours ago