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density of metal
Posted by Andrew on 10/8/2003, 7:41 pm
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Re: density of metal
Posted by Bert Hickman on 10/10/2003, 1:29 pm, in reply to "density of metal" Hi Andrew, To my knowledge, there is no coil configuration (or any other process for that matter) that could be used to make the material in the coins permanently denser. This is due to the inherent physical properties of the metals and alloys used in coins. The coins do get tougher from work hardening and the surfaces show signs of plastic flow (radiating Luder's Lines), but the metals and alloys will not retain a permanently higher density state. Best regards, -- Bert --
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Re: density of metal
Posted by Lloyd Davis on 10/13/2003, 9:20 pm, in reply to "Re: density of metal" --Previous Message--
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Re: density of metal
Posted by Bert Hickman on 10/13/2003, 9:58 pm, in reply to "Re: density of metal" Hi Lloyd, That's a relatively common first impression. In reality, as the coin's diameter is reduced, its thickness correspondingly increases in such a manner that the coin's total volume remains the same. Even though the work coil explodes and portions of the coil vaporize, there's no ablation of the coin. It has been demonstrated numerous times that the coin's mass remains the same. Thus the density and specific gravity of the coin also remain the same. See Figure 4 in the following MintErrorNews article to see the thickening effect: Other more in-depth explanations of the process can be found here: Although it may be hard to believe, it's only the invisible, but extremely powerful, magnetic fields interacting between the coin and the work coil that cause the coin to shrink as the work coil simultaneously explodes: action and reaction. On more valuable coins I sometimes use a thin plastic sleeve between the work coil and the coin to prevent vaporized copper and copper oxide from condensing onto the surfaces of the coin. This delicate plastic sleeve remains intact after the explosion, demonstrating that any compressive forces from the hot gases and plasma of the exploding coil are quite small. The powerful magnetic fields pass through the plastic sleeve as though it wasn't there. It's only the invisible, but irresistably strong, magnetic fields that do all the work to reshape the coin. Best regards, -- Bert --
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Re: density of metal
Posted by Lloyd Davis on 10/14/2003, 5:00 pm, in reply to "Re: density of metal" --Previous Message--
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