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Old 09-03-2009, 01:29 PM
52pickup 52pickup is offline
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Location: Tucson, Az
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if it makes you feel better, David, I know and use those names for dollies... even when I'm talking to myself

Quote:
In terms of drawing, the area of the blank is at least functionally the same as the surface area of the resulting piece. Same surface area means same shape, right? Just a different form.
This is true, but you are comparing the die (which is the final shape) and the final sphape of the piece. To compare if there was any shrinking, you should be comparing the surface area of the blank you started with vs. the surface area of the finished part. I doubt you will find that they are the same. If they were, then on those little pucks you made, you should be able to cut out a piece of paper the same size as the blank you started with, and that piece should fit the puck without any folds, right? If not, there was either shrinking or stretching, or both, involved in making that piece.

Quote:
To my mind, stretching would be moving the metal's molecules further apart while drawing as little as possible into the area of the "stretch" and not pushing them out into the rest of the sheet either.

Maybe I'm just thinking too much?
I think you are looking to deep into it. As far as metalshaping is concerned, I would say any process that has an end result of reducing the thickness of the metal would be called "stretching", because as you are expanding the surface area of the material, not because of what is happening at a molecular level.

Think of it this way, if you put a panel in your wheel and went over the entire 6" x 6" panel, evenly, with enough pressure, you would end up with a slightly larger panel... granted, it may only be 6.05" x 6.05", but you would have a panel that is thinner, but has a larger footprint.
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