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Assembly Variation Analysis

Assembly Variation Analysis

Assembly Variation Analysis

Can anyone comment on useful methods to study potential assembly variation caused by piece part variation?  I am interested in analyzing the design of a sheet metal sub structure comprised of 15 to 20 parts that will be welded togeather.  Some parts are hard tooled, others are formed on a brake.  Normal process variation is known for all parts.

My goal is to estimate an achievable gap tolerance for a 5 piece thermoformed housing that will be supported by the substructure. The overall size of the assembly is 2.5 m x 1 m x 1 m.  

RE: Assembly Variation Analysis

Dassault Systèmes  www.catia.com offer the specialized software for Tolerance Analysis of Deformable Sheet-Metal Assembly. This software based on FEM methods. I think it can be useful for your tasks.


RE: Assembly Variation Analysis


I performed a Google search and there are some good links to check out:


The basic principle is similar to springs in series, in that the stiffest component will dominate the variation in the joined structure. It is obviously best studied with FEM.

There are also some technical papers I remember on the topic. I will be back in the office on Thursday and can look them up for you.

Best regards,

Matthew Ian Loew

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RE: Assembly Variation Analysis

Hi Runningman,

I am a new member in this forum. I am looking also information about final assembly variation.
If you got some informations, could you tell me as well.


RE: Assembly Variation Analysis

My dissertation is for this. And I also know that in University of Michigan. Prof. Hu and Prof. Shi are studying this field.

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RE: Assembly Variation Analysis

What about a simple Monte Carlo simulation?  If tolerances and process variations are known then Monte Carlo would provide a good means of predicting tolerance stack.

RE: Assembly Variation Analysis

Hi Runningman and Yupiter,

There are several companies and softwares available in the market to predict the effect of component tolerances on assembly process variation. Monte Carlo simulation methods are utilized to predict the overall variation.

If you need further information feel free to send me an email..I might be able to answer your questions. I've worked on several projects of this nature utilizing Monte Carlo and non-monte carlo methods.

RE: Assembly Variation Analysis

Hi Variation ....

Since I am new in this field, I would like to know more about this. I am looking for any information, how to predict the effect of component tolerances on assembly process variation. Could you please send me any reference about this problem (with or without monte carlo method)?

Thank you very much !


RE: Assembly Variation Analysis

Although it seems that many posters in this thread are not active members, I did come across this technical reference:

An Introduction to Tolerance Analysis of Flexible Assemblies
K. G. Merkley, K. W. Chase, E. Perry
Brigham Young University
Provo, UT

Also, as pointed out by bobosui (www.eng-tips.com/userinfo.cfm?member=bobosui), Professor S. Jack Hu has authored many publications. A list of these publications can be found at http://www-personal.engin.umich.edu/~jackhu/publication.... Nearly all of the publications that I indicated I would post (almost a year ago ) are authored by Dr. Hu, so I am making good on my commitment (a little late) by posting this link now.

Best regards,

Matthew Ian Loew
"Luck is the residue of design."
Branch Rickey

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