Impression mold?

[Spinneyhill]

A while ago someone posted some pictures of forming a shape by pushing metal into a mold with a lump of gel and a press. What was the process called? I would like to find the thread and a bit more information.

 

I want to form flat elliptical aluminium name tags onto a cylinder. They are Delco-Remy generator and starter tags for The McKinnon Industries.

Edited October 21, 2017 by Spinneyhill (see edit history)

[Spinneyhill]

I have now found it is called hydroforming with fluid or rubber-pad forming with "rubber", probably urethane. Thank you. I have found Gary Ash's posts etc.

 

So if I use rubber pad forming and I want to fit 0.6 mm aluminium onto a 4.5" diameter cylinder, how much elastic rebound should I expect? i.e. how big should the cylinder be? I expect it would be a little less than 4.5" dia..

Edited October 21, 2017 by Spinneyhill (see edit history)

[Friartuck]

Please post the link to Gary's thread.

[Gary_Ash]

Here's a summary of the hydroforming process.  I made a rosette for a grille shell from 0.020" thick brass sheet (1/2 hard).  The embossed features were cut into an aluminum slug, along with a raised ring to center a piece of 4" diameter steel pipe.  The brass disk was placed on top of the die and a urethane pad about 1/2" thick was placed on top, followed by a thick steel slug that was loose slip fit in the steel pipe.  I used my 12 ton hydraulic press to push the brass into the recesses in the aluminum disk.  As I recall, I tried a couple of urethane disks of different durometers.  The amber one in the photo is 80 durometer.  The 12-ton press wasn't really enough to do the job to my satisfaction, so I eventually used a 50 ton press that I had access to.  The urethane really does behave like hydraulic fluid under pressure, which is why the steel pusher has to fit almost tight to keep the urethane from squeezing out.

 

I've also bent sheet steel pieces in the press using a 1" thick hard rubber pad and a body dolly or piece of pipe to get a smooth, round shape.  Sounds like that might be the way to go for Spinneyhill - use a piece of steel pipe of the same diameter (or just a bit smaller) as the starter/generator as a form tool or shape a piece of hard wood with a 2-2.5" radius.  With a pusher tool made from a piece of 2"x2"x1/8" angle iron, you can bend sheet metal by pressing the sheet metal into the rubber pad.  The pad thickness needs to be at least 2-3 times the depth you are trying to obtain.

Edited October 24, 2017 by Gary_Ash (see edit history)

[Spinneyhill]

Thank you very much Gary. That looks to be just what I need.

 

Friartuck, Gary's posts were in your topic on Hydroforming and elsewhere. "Rubber pad" forming terminology I found on the www.