CAD models of hardware

[Tunalover]

Today I was laughed at by a Program Manager because of my practice of modeling fasteners at worst-case conditions. For example. I modeled flat washers at maximum OD and maximum thickness. The ID is modeled at maximum also to present the possibility of what I call "the worst case locus" of the washer about the screw. This is robust design! For a mounting hole on a printed circuit board, for example, the orbiting of the washer about the screw at worst-case condition could short nearby traces or touch nearby components.

My answer to him was "the CAD model only has to be done once. Once it's modeled then us designers can go about our merry way producing robust, conservative and low-risk designs without wondering how the CAD model is done."

Folks, what would you say to this guy?

I'm working in a place where, until now, they have designed ONLY "onsey-twosy" R&D products. I was hired in part because I have extensive experience in production environments but I am constantly running into "quick and dirty" types who scoff at robust design methods.




Tunalover

 

[Guest0527211403]

I'd tell him to stop micro-managing and let me do my job.

 

[peppinu]

Tunalover,
For this purpose you can use "dim bounds" in PROE. You can model on nominal and provided you put your tolerances in the model you can make the geometry of your model go on mean, nominal, max and min. It is a pity that your so called program manager does not undersatand the potential of PROE.

Joe Borg

 

[fighterpilot]

I'd have to agree w/ your manager. Worst case to you might work for you but not for another person. You mention modeling washers at the maximum thickness. What if I was designing something and the minimum thickness of the washer was critical to me? I'd have to go in and modify the model. Not something you want to be doing to "standard parts"

My point is if you create your standard parts at nominal size and let the engineer use those parts in their designs. Hopefully they will use their practical engineering skills and the dim bound command in Pro/E to determine the tolerance stack ups of the assembly.

--
Fighter Pilot
Manufacturing Engineer

 

[Tunalover]

joeboard1 and figherpilot-
Where can I find this "dim bounds" functionality?


Tunalover

 

[Heckler]

In Part Mode goto Edit > Setup > Dim Bound

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
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Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.