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As a hobbyist, how to go from a metal sheet to a metal box (1 hollow side) by using (set of) dies only?

All videos I watched involved :

  1. bending 1 side at 90° then

    • A) cut twice and discard a square portion of size : height * height
    • B) cut along the height of your box
      ... repeat 3 times ...
  2. fold the 4 sides

  3. If you chose A then weld the 4 sides at the corner.
    If you chose B then bend the sides along next sides then weld.

  4. Done.

I want to avoid welding, could those operations be replaced by a press against a die (and cut)?

I think it would have been possible maybe using heating and high pressure but I found nothing.
Anyways I don't have access to heating and high pressure (max 20T), so I think about making it in multiple steps (and dies).
Instead of going the full 90° in one go, I will bend each side by 10° at each time.
The problem is : how to deal with the extra-material at the corners?
With each step, I think it will make more an more pleats at the corners.
Any idea on how to proceed?
Should I force the corner to bend inwards at step N, then outwards at step N+1 (and repeat)?
Should I use a scallop shell shape for the corner?
Should I make the side straight and treat the corner as a special case?
Or, on the contrary, should I try to distribute all the extramaterial all along the side?

Final goal would be to turned a 330mm x 240mm x 1.5mm aluminium sheet into a 310mm x 230mm x 15mm box, using a 20T harbor freight press.

Any idea or suggestion are welcomed.

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  • $\begingroup$ aluminium foil is like paper... you don't need a press for bending it ... maybe you mean to say aluminium sheet $\endgroup$
    – jsotola
    Oct 18, 2023 at 16:43
  • $\begingroup$ Not just dies. Punches and dies. I think you are going to need to get a book. Design of punch and dies is a high-skill field, especially if you are going to stretch and form the material to get sealed edges without welding...which I am not even sure you can do on the press you have. $\endgroup$
    – DKNguyen
    Oct 18, 2023 at 22:07
  • $\begingroup$ @jstola. You're right. I meant sheet instead of foil $\endgroup$
    – v1nce
    Oct 19, 2023 at 7:21
  • $\begingroup$ @DKNguyen I'm not sure I'll need punches except for the very last step when I'll need to cut away the excess oif matter. $\endgroup$
    – v1nce
    Oct 19, 2023 at 7:27
  • $\begingroup$ You use punches to form against. They aren't just to cut. $\endgroup$
    – DKNguyen
    Oct 19, 2023 at 14:12

1 Answer 1

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One solution that might work well, even if you need a waterproof box is riveting (instead of welding). It's a lot easier and cheaper to do (if you don't mind the surface finish).

In any case, as mentioned before, to obtain the flat pattern layout is very difficult to do by hand. Many professional CAD software (e.g. Solidworks) have tools that take into account the K-factor, bend radius, and other material properties, in order to come up with the final flat pattern layout.

So the process would be:

  • Design the flat pattern taking into account the tools that will be used and their limitations (you might have trouble ending up with a complete box in one go)
  • cut the flat pattern in a water jet/plasma/laser
  • do the bending/punching
  • rivet the ends.

Another option (not economically sensible though), is deep drawing. However, you will need a big press and expensive tooling depending on the size of the box you want to make. So usually, it makes sense only for large quantities.


PS: I have worked with solidworks about 10 years ago, and even though you could get away with using some generic values, I vaguely remember that the best results are obtained when using the K-values which take into account also the tools that will be used.

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  • $\begingroup$ I think Solidworks would be out of budget. But I'll have to think twice about it because I think this is what I need (computational aided pattern design). I don't expect to obtain the box in one-go, I expect multiple bending/punching iterations $\endgroup$
    – v1nce
    Oct 23, 2023 at 7:46
  • $\begingroup$ Another option might be onshape, which is online and there is a free version (or at least there was because its been a while since I used it). I seem to (vaguely) recall that it had sheet forming capabilities. $\endgroup$
    – NMech
    Oct 23, 2023 at 8:15
  • $\begingroup$ @NMech i seem to have clicked downvote by mistake can you edit a bit so i can reverse it. In anycase you dont nesseserily need super presses for deep drawing ive done this with a 40ton press using several 3D printed dies (with steel inserts), what matters is the sheet material. Its possible to do, its just a bit tricky to get all the parts working correctly. $\endgroup$
    – joojaa
    Oct 23, 2023 at 15:16

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