How are the layers of a 40% silver-clad coin fused?

[Half-Hound]

I understand 40% silver-clad half-dollar coins consist of three separate layers of metal. The inner layer is 20.9% silver and 79.1% copper. The outer layers are each 80% silver and 20% copper. The 11.5 gram half-dollar coin has an average 40% silver and 60% copper content. Does anyone know how the three separate layers of metal are bonded together?

 

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[coinmojo]

Good question.

As far as i know they start out as sheets and the planchets are punched out. but the bonding process I'm not i the know.

I have had a cople of 40's that have seperated though. I would imagine that there is a heating and pressing process though.?

Mojo

 

[CHAINCHOMP]

they just lie, all 40%ers are really copper-nickel, or 90% silver, its one or the other, they just think its fun to lie to everyone to confuse them.

 

[TxTim]

The coin shaped planchets are punched from sheets of co-extruded metal which have been rolled to the proper thickness depending on denomination.

 

[obediah]

The coin shaped planchets are punched from sheets of co-extruded metal which have been rolled to the proper thickness depending on denomination.

I've had a couple of %40's rubbed almost smooth- saw not a hint of copper in them, and many that have been drilled thru again not a hint of copper in them.

 

[TxTim]

The coin shaped planchets are punched from sheets of co-extruded metal which have been rolled to the proper thickness depending on denomination.

I've had a couple of %40's rubbed almost smooth- saw not a hint of copper in them, and many that have been drilled thru again not a hint of copper in them.

I've seen the same with many modern clad coins too.
Drilling can produce heat, drag and melt the clad layers through the hole.

Check out this site:

http://www.cladmetal.com/overlay.htm