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 Replies: 13 / Views: 1,874 |
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Valued Member
United States
119 Posts |
Hello all, not able to find info on the hardness test test they did on pennies. heard something about it the other week or so but cant find tha post not sure if it was on this site. Any help on tis would be great thank you
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Moderator
 United States
34423 Posts |
@BDC, an easy way to find old threads is to use the search box in the upper left hand part of your screen. When I use the keywords ROCKWELL HARDNESS, I see several candidates. Maybe this one? http://goccf.com/t/237597&whichpage=6"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz
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Valued Member
 United States
119 Posts |
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Pillar of the Community
United States
2775 Posts |
Edited by Halo1st
04/07/2018 6:55 pm
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Pillar of the Community
United States
2624 Posts |
ROCKWELL HARDNESS test would have been done to the die not the coin.
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Pillar of the Community
United States
2775 Posts |
Quote:
ROCKWELL HARDNESS test would have been done to the die not the coin. Au contraire. I'm thinking the metallurgists or research lab dept in the production plant could potentially have reason and the means to test both if needed. Thanks, Doug. Edited by Halo1st
04/07/2018 10:17 pm
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Pillar of the Community
United States
2624 Posts |
I was not aware there was a specific range of hardness for a finished cent that is different from the hardness specific for the planchet prior to minting.
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Rest in Peace
United States
233 Posts |
I used to sell hardness testing equipment, and I'm with DrDon: you might need to test the die at various stages, eg, after annealing.
But the coin? The alloy is the alloy. Stamp and go!
Cheers,
/s/ ikeyPikey
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Bedrock of the Community
United States
62064 Posts |
If the Rockwell tests were done on the dies, the there would not be an incuse mark on the coin. It would be raised. All I've ever seen these is an incuse mark on the coin. If they were done on the die before use, then would be a million extra examples with a raised mark on the coin on each one. I'm not seeing that anywhere on the coins.
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Pillar of the Community
7234 Posts |
When I was (much) younger I worked at SifCo bearings - we constantly had to do Rockwell hardness tests on the raw bearings that came in for machining so we knew what tool and speed to turn them at. It made a small "ping" into the metal the size of a .177 BB - the meter would test the hardness. Like stated about hardened dies - I can see the dies being hardened tested but NOT the coins coming off the striking machines! And the Mint would have test dies right through the process of heat treating and annealing that weren't tested next to the production ones - If the test dies pass the inspection process the rest of the dies in that production run will go into the stamping/minting machines
Edited by Mark1959
04/07/2018 8:55 pm
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Pillar of the Community
United States
2775 Posts |
Quote:
I was not aware there was a specific range of hardness for a finished cent that is different from the hardness specific for the planchet prior to minting. Guess I'll have to reread the articles. What I thought they proposed was materials (blanks and or die stock) being tested prior to strike. Though since mentioned, I suppose it could be done after the coining process and or anytime before, during or after the die making process as well. I can say for probably some lack of security clearance I was not asked to be present during any of the testing. Thanks, Doug. Edited by Halo1st
04/07/2018 10:25 pm
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Valued Member
United States
119 Posts |
yes some good reading, thanks all for the comments on this, and the links. like I said hear someone talking about this and thought I should know a bit on it and what to look for since I go thought pennies boxes all the time,
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Pillar of the Community
United States
2624 Posts |
Testing die stock and planchets make more sense. I would think the test pieces would kept for future reference or destroyed. this does not exclude the possibility of mistakes or " skull duggery"
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Rest in Peace
United States
233 Posts |
Quote:
... If the Rockwell tests were done on the dies, the there would not be an incuse mark on the coin. It would be raised. All I've ever seen these is an incuse mark on the coin. If they were done on the die before use, then would be a million extra examples with a raised mark on the coin on each one. I'm not seeing that anywhere on the coins ... This assumes that you need to test the hardness of the die on the working surface. That is the surface we care about, of course, but I am not sure that you could not learn everything you needed to know by testing the side of the die 1mm down from the working surface. This also assumes that you are using test equipment with a large probe. Nanoindentation equipment applies micro-newtons of pressure to achieve nanometers of penetration by very small diamond probes. The final polishing of the die might resolve any artifacts. Lastly, hardness testing can be pass/fail; a particular pressure is applied to a largish probe for a shortish amount of time and, if indentation is observed, the die fails; if not, the die passes. Cheers, /s/ ikeyPikey Edited by ikeyPikey
04/07/2018 11:42 pm
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Replies: 13 / Views: 1,874 |
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Posted 04/07/2018 6:13 pm
