Tolerance Chains & Tolerance Stack-up 4

[steedj]

Does anyone know where I can find information on Tolerance Chains, Tolerance Stack-up, etc. I've searched the web and found very little.
I'd love to find a website link but any information whatsoever is greatley appreciated.
Thank You very much and Merry Christmas!

 

[steedj]

To all who have replied, and to all who will reply, to my Question:

Thank you so much!
All of you have provided me with both helpful-information and interesting-insight into Tolerance Stack-ups. I know much more now than I did prior to posting my question.

Thank You very much and Merry Christmas!

 

[Damien2002]

As someone without any prior knowledge of the topic I have found the current thread very interesting. Some clarification please. Am I right in assuming that "tolerance stacking" is a method of ensuring that each tolerance range is defined so the widest (or most convenient) tolerance range possible is chosen for each dimension?

Viktor,

You mentioned optimisation (appropriate only for large run manufacture), how would you realistically go about this? From my own knowledge its is only possible to do this if an accurate mathematical model of the system is available, or a large number of costly experiments are run. Then of course you would have to decide what you wish to optimise, this would not be not be straightforward if you are simply trying to ensure your assembly fits together.

Thanks in advance

Damien

 

[Viktor]

Optimization in the calculations of dimension chains simply means the solution of the so-called reverse problem, i.e. assigning tolerances on the chain components knowing the desired tolerance of the basic link. There are a number of methods of doing such calculations.

As known, any solution of the reverse problem is not unique. The word “optimization” means the solution which meets the assigned criterion of optimization. It could be the minimum cost criterion, the best fit criterion, the same class of tolerance of each component, etc. Viktor

http://viktorastakhov.tripod.com

 

[diaabid]

Does anyone know where I can find information about how to use Kinematic Assembly Operation in VSA software. My problem is I could not figure out how to define a stop surface in the assmbly process.

 

[diamondjim]

There are ways to dimension which reduce the
tolerance stack up and much of it depends on
what is critical and how the parts go together.
I always use bilateral tolerances and sometimes
it is a rough call to determine which datums
are necessary to dimension from. Only the
designer can make these decisions or consult
with a good detailer and shop man.