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How Are Coins Made?
1. Remove the metal from the earth
2. Move the metal to the Mint
3. Mint the Coin
[None of this proves especially easy...]
Why do coins vary in appearance, even when made the same year by the same mint?
Coins start as blank pieces of metal called "planchets". These planchets are then struck by dies, metal objects with incuse design, to produce a coin.
The mint produces a master hub is used to make master dies, master dies are used to make working hubs, working hubs are used to make working dies, which in turn are used to strike the coins. This “hubbing” or "hobbing" process requires that the die stock be annealed between each impression and varies greatly for each series. For example, in the dollar series, Morgan Dollars (1878-1904) had hubbing performed 7-10 times whereas for Peace Dollars (1921-1935) it was done 3-5 times. That is why Peace dollars look soft or mushy compared to Morgans, their details/devices were simply not struck as sharply.
The master hub, which produced the first master die, which produced the first working hub, which made the first working die, which struck the first coins on the best planchet produced the highest quality coins. he mint typically used a working hub to produce 250 working dies. Now, depending on the standards set by each mint (they did vary, especially in the early part of the 19th century), the number of coins in the production run, and the number of available working dies, the average number of coins struck by each die would vary from between 125,000 to 250,000 coins. Each time the hub produced another die some metal wore off so the next die lost some detail. Therefore every coin struck by that die would increasingly lose even more detail as the die wore down. TThe first hubs and the first dies from each hub produced the best example of every coin design. Defects in dies or planchets can produce varying quality coins. Polishing of all or part of a die also effects the outcome of the coins struck. This explains the difference in strike on coins.
Mint production standard were driven by numerous factors such as the underlying social conditions of each year, the availability of materials and men, the chief engraver, designer and minter and political or economic parameters. The US has had eight different production mints over the years. Two mints were used to produce early gold issues. One mint has only been used to produce proof coins. Five mints produced larger silver coins that have provided much of the interest amongst the coin collecting fraternity. Each of these mints set their own standards and quality assurance/control methods for coin production.
Now, it takes extreme of pressure to strike a coin. The pressure actually turns the planchet into molten metal which flows through the devices (nooks and crannies) of the hub to produce the coins surface (design/devices). This pressure, in turn, puts much wear and tear on the dies. To prolong the life of the dies some mints used less striking pressure, varying from 50 tons per square inch (!) up 150 tons per square inch depending upon a myriad of production concerns. The less pressure used, the more soft or mushy the coin appears.
How were proof-like coins produced?
Many conditions and factors must simultaneously come together her to produce a proof-like (PL) coin. Higher quality coins with better 'strikes' (the clarity of the coin devices [details]) demand a premium from collectors. Those with a watery mirror like fields and finish (known as proof-like [PL], Deep Mirror proof-like [DMPL], or Cameo - the best) demand even higher premiums as they are the finest coins produced by the mint using standard minting techniques. Since DMPL and PL coins are the first few coins struck from new dies, they have the best strike, relief, and their details are truest to the mints original design. Their fine detailing and fields result from the use of brand new dies and planchets.
Annealing drum>upsetting mill
Milk Spots - These are distracting hazy areas on proof coins. In Q. David Bowers' book, Silver Dollar Encyclopedia, he provides an explanation from one Wayne Miller detailing what might be the most reasonable explanation for 'milk spots'. Namely: "The planchets were improperly washed and dried after they had emerged from the annealing ovens and subsequent acid bath. Also, an increase in the concentration of sulfuric acid and water solution used during this cleaning and polishing operation could have lightly etched the surface of the planchet in some places."
Basining - A step in the coin minting process where the die surfaces are set against a rotating zinc plate; polishing of the die. This process helps the coin properly strike.
Lamination - Laminations can occur are always possible when dealing with metal of any kind that has been melted. Lamination is predominantly a planchet problem where gas bubbles or other impurities in the melted metal are trapped in the molten planchet and then cool. They are then either elongated or smeared during the rolling process. Because of this the metal above the bubble is not attached to the metal below. When this rolled bubble breaks, like a squeezed zit, a damaged planchet results and surface flaking starts ('lamination peel').
Metals Used in Coinage
Here is a great resource for coin metallurgy:
Pouring a Bullion Bar
Here is a picture of a 1-ounce bullion bar shaped as the state of Nevada.
I paid like 30$/oz for those Nevada-shaped MetalRex bars (when the price of silver was lower than now), and was happy to do so. I also have a 5-oz bar of the same design
These bars are not common anymore, by a long shot.
So, I looked into what it would take to manufacture a few…
Cast method is the common and low tech method for producing bullion bars. The caster pours molten lava from a crucible into a fireproof mould. Some molds are graphite. Old graphite electrodes from electrical discharge machining that could be used for making individual molds. You must add the fourth side so that there is not a rough and uneven bottom to the bar.
Casting costs would be cheap but the quality low.
The other major method of producing rounds and bars is minting, by machine tools. The quality is high, but so is the price. Here is a company that mills and mints metal.
I imaging Englemark, Asarco, and the other big boys have the bullion bar production process down pat by now, but what about the second and tier producers?
Like these guys:
What software do they use?
I recognize that to start, one needs to produce CAD .tif and .dwg files, etc for takeoffs based upon a basic awareness of the standard construction estimating software packages.
After asking around, for commercially available sheet metal/pipefitter construction design software to develop design graphics for a mould, one smarter than I suggested the Solidworks design software program and associated add- ons.
Apparently there are some moderately expensive packages that will also allow engraving on the bullion bar.
What is the Market for Shaped Rounds and Bars?
Have you ever seen the picture of the gold-bar dispensing vending machines in Abu Dubai?
And how about the multitudes of Chinese now purchasing gold bullion individually.
For millennia the Indians have been purchasing simple rolls and chains.
And after scouring dozens of coin shows, hundreds of dealers web-pages, dozens of coin stores, and scanning ebay constantly for ten years straight, I have NEVER SEEN a simple silver bar shaped like Arizona or Montana or Utah.
Why the hell not?
If that rich guy in Arabia is purchasing gold ingots from a friggin soda dispenser machine, wouldn’t he shell out a few extra ducats for the gold bar shaped like Arabia? OF COURSE HE WOULD.
Imagine the point of pride in china for those that can purchase bullion bars shaped like their own province!
For the life of me, can’t understand why this hasn’t been tried by other manufacturers.
Metalrex did it with Nevada bars. And at the time of production in the late 1970s and early 80s, Nv had a lousy population of less than half a million souls! Not much of a customer base.
Imagine someone producing gold ingots shaped like the state of Maharashtra or Andrha Pradesh – what a market base!
How come I must do all the R&D and marketing around here!!!
Go ahead lurkers, take my idea. I am *convinced* there is a healthy profit stream in there.
I don’t mind - will be busy for the next five lifetimes with all the other pursuits already on by radar….
Explanation of Various Coin Errors
Cooper, Denis R. THE ART AND CRAFT OF COIN MAKING: A HISTORY OF MINTING TECHNOLOGY. London: Spink, 1988.
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