Using plastic?

[ZipSnipe]

Do you think if I,m just punching out a flat part (.0196 copper) that I would be able to use that white plastic(forgot what its called) for the female . I was going to make the punch part out of copper using a punch made from heavy hardened steel and the bottom out of that plastic if possible any ideas?

[MrWild]

Are you forming, or shearing? How many parts and how deep a draw? Lots of things are possible for one time. More than once, no. Any shearing, no. Forming with a shallow draw? Possible. I've seen some interestingly dangerous things done with plastic and dies though. Saw a die "blow up" one time. Plastic was used for the stripper but there wasn't enough room in the stripper pocket for the plastic when the die was fully closed. A corner of the die literally blew up off the die set and flew across the room just missing another worker. Yes, it made one heck of a BANG too.

.020 copper is getting up there though. I have a lot of experence with brass and copper forming/punch dies. Copper sheet can be annealed so it draws easier, but mostly your plastic will deform with thicker stocks. With no experience trying what you're attempting to do but knowing forming properties, I'd say it is possible with copper foils (not over .005) but when you start to get thicker the plastic will start to either deform or break.

[Bill8]

Depending on the dia of your male punch you could use mild steel for the female to produce a few pieces. The male punch has to be very sharp and can be contoured for a slight shear.

[planebuilder]

I have used a trick that was developed during WW2. Make a male steel die with sharp edges and bandsaw out a female from aluminum. Bandsaw close to the line but make the female a little too tight, about 10 to 20 thou. Use the press to force the male through the female, thus cutting it to an exact match with the male. I used 1/2" aluminum, and had to press 1/8" into it and withdraw. Then I cleaned off the shear scrap and repeated untill I got through. I was suprised how well this worked. I have punched over 100 parts, .025" 6061T6 aluminum, no burr on the edge and no visible wear on the female yet. I don't see why it wont work for copper??
P.S. During the war they used a female made from an alloy called "Wood's Metal". It had a low pelting point and when the female got dull they melted it down and re poured a slab for a new female.

[Bill8]

The procedure you describe in the war is still used today. It's a great way to make tooling for cutting paper products as the tolerances are very tight. Punching aluminum is one of the easiest metals to work, and that is why your procedure has worked. But copper is a totally differenent material. It is much tougher to cut. Generally, the male punch must be harder than the female. And this is true for cutting copper. In high production runs we would use high grade carbide tooling for copper.

For the female die you will have to use a material that is harder than copper. Why not try to find an old female die from an iron worker?