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Simulation Mechanical and Multiphysics

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Registered: ‎12-13-2010

Simulation and Manufacturing Tolerances

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10-02-2013 09:52 AM

I apologize if this topic has already been discussed, but here is my dilemma. 


My company manufactures components that are primarily weldments made from plate and structural steel.  When these weldments are made, generally we design the components smaller than their actual size for fit-up.  For instance, if a components exact measurement is supposed to be 96", we might detail it out at 95-15/16" so that our shop has room to fit the component up and weld it in place.


I am an engineer, so I am repsonsible for coming up with the designs and running the necessary simulations, and then I pass it off to one of our detail designers that will detail all the components and verify the BOM.


I'm curious as to how people are dealing with this situation.  Ideally, I would like my work flow to be that I design the component how it needs to be (with the tolerances built in for manufacturing), and then one of our designers will do the detail drawings.  On the flip side of things, we also have situations where a component might already be modeled in Inventor with appropriate manufacturing tolerances, but we need to do FEA after it was already designed.


In the case where I had a model made and had the manufacturing tolerances built in, I converted the model to a weldment and inserted welds between the components that had gaps.  This does work, however I find that having all those welds really makes the model more complex than it needs to be, as it adds a considerable amount of time to both meshing and analysis.  Overall, for what I was trying to accomplish I felt like this was a lot more cumbersome than it was worth.  I think the primary issues were that I had to define contact sets for each component, instead of just defining the contact of the entire model "welded".


Likewise, I did another model where everything was designed to exact size, and the results were what I expected, and the model was a lot simpler in terms of it's meshing and whatnot.  However, in this case the designer had to copy my design, and change all the components with all the manufacturing tolerances.  I don't really like this method, because ideally I'd like to have all of my production models as ready as possible to run FEA on.  As I said before, we also have models that are already designed that we may need to run FEA on, and I'd like to minimize the amount of work necessary to prepare the models for FEA.