14/12/2017 Press Forming

My mum has done press forming at her class with a bench top vice. 

However, we have a number of hydraulic presses, which are hopefully much easier.

Press forming is done using a number of layers of different materials. 

The metal sheet to be shaped is placed between a perspex die (a thick slab with the desired shape cut out of the centre) and thick flexible rubber.  Other materials can be used instead of perspex but it can be easily laser cut which is why it’s preferable (if you have the facilities).

When compressed, the metal sheet is pushed though the die by the rubber, forming a domed 3D shape. 
The metal may have to be reannealed several times to get the desired depth, and subjecting it to excessive pressure may cause the domed section to split away from the rest of the sheet. 
Press forming is only suitable for largeish, rounded shapes. 
Finer detail may be enhanced by placement of small pieces of rubber or blu-tack.

Using the Bonny Doon Press 

Turn the allen key anticlockwise to release the pressure and let the platform fall. 
Position the die-metal-rubber sandwich centrally and use the removable handle to pump up the platform. 

Pressure applied is read from the dial.  Up to 4000 is quite easy.  I can then get it up to 6000 with a bit of effort.

We didn’t to make our own samples but I tried using a Bonny Doon press with some patterned wire dies. 
The “sandwich” I used in this case was: bronze die, silver wire, steel sheet. 
I went up to 5000 and it worked perfectly.  Just a shame the dies aren’t long enough to do a full rings worth in one go.

Disk Cutting 

We were also shown the Jossi Press. 
This is a really useful disk cutting machine that unfortunately needs to be setup by a technician

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