thedeadpoint Posted January 18, 2008 Report Share Posted January 18, 2008 So I was watching the History Channel. There was a show about welding. I've heard of some cool ways to weld metals together, but I never heard of explosion welding. Basically, two metals are placed in near proximity to each other. Think two gigantic sheets/slabs placed only a quarter inch apart. About 3 inches of explosive are placed across the surface of the top slab. Then BOOM! The top slab is rocketted downwards into the bottom slab and they are "zipped" together so fast that all air and oxides are expelled. The benefit of these two methods is that 2 incompatible metals (in other welding processes) can be joined. Many explosion welds are found in reactors, pressure vessels, and the like. They said that the process was developed in the early 1960's and was used to create clad coins for the US mint. But since it's such a crazy way to weld, why would they waste that much energy on making coin blanks using explosion welding?? So what method do they use to create clad coins? Quote Link to comment Share on other sites More sharing options...
Scottishmoney Posted January 18, 2008 Report Share Posted January 18, 2008 Pretty soon when all the coins are stainless steel and aluminium it will not matter. They should have made them from cupro-nickel from the get go instead of the clad coins. In a way they made it easier for people to distinguish the silver coins and remove them from circulation, adding to the then coin shortage. Quote Link to comment Share on other sites More sharing options...
rittenhouse Posted January 18, 2008 Report Share Posted January 18, 2008 Don't think The History Channel is correct on this point. While certain applications requiring a very tight bond still use explosive bonding, cupro-nickel/copper clad is produced by roll-bonding. See www.cladit.com If I recall correctly, the reason for the clad was to maintain the electromagnetic properties so coins would still work in vending machines. Quote Link to comment Share on other sites More sharing options...
thedeadpoint Posted January 18, 2008 Author Report Share Posted January 18, 2008 Don't think The History Channel is correct on this point. I wasn't fully paying attention at the time because i didn't expect them to mention coin cladding (though I was thinking of coin cladding earlier in the segment). But I heard them distinctly mention early use of this method for the 1960's coin cladding. Interesting, eh? Quote Link to comment Share on other sites More sharing options...
Spek Posted October 5, 2020 Report Share Posted October 5, 2020 Sorry to all the naysayers, but explosive bonding is indeed how the start of copperclad voins started with quarters and indeed explosive bonding process was used and I was personally involved with this process. (yes, I'm that old). I was 18 and basically a swamper. But it was the most amazing thing I saw. It was done in a cave like structure away from population. I didnt see the documentary you guys are talking about, but its as factual as you reading this. RH Quote Link to comment Share on other sites More sharing options...
cladking Posted November 5, 2020 Report Share Posted November 5, 2020 They were able to start transitioning away from explosion bonding pretty early and by about 1970 all clad was rolled rather than explosions bonded. My understanding though is the metals were forced together hydraulic and the dynamite completed the process? I used to kid people that these were guaranteed for 50 years and then they'd all start failing explosively. Quote Link to comment Share on other sites More sharing options...
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