Questions For Coppercoins And Foundinrolls?

I have a link to the manufacturer of the US Mint's presses that might help you- they are Schuler horizontal presses http://www.schulergroup.com/us/10_A...e/index.html

I am not a mechanically inclined person, thus my knowledge of the presses themselves is limited. I am more a statistical bean counter and can add this much regarding die wear:

Dies wear in patterns. The patterns in which dies wear are dependent on the design on the die. To a much lesser extent, although still important, are the impurities in the steel and the alignment of the molecules both from heat and pressure during the die making process. Through the years the mint has improved the process of making dies through both purifying the steel better and through lowering the relief on the designs to extend die life.

Back in 1989 a gentleman by the name of Delma K. Romines conducted an in-depth study of die life. He published his study in spiral snapshot albums, four to a 'set' and made about two dozen sets. I own one of those sets, probably the rarest piece of numismatic literature I could ever hope to own. I have been all the way through that set over a thousand times, and, in brief, this is what it says:

Dies wear with every strike they perform. All dies go through a life cycle as they wear, and the steps of this life cycle, eight in all, are called 'die states'. Every die that sees a full life expectancy goes through the complete cycle of die life, or die states. The measured major steps are:

VEDS (Very Early Die State) - about 0.21% of a full-life die's strikes.
EDS (Early Die State) - about 2.63% of a full-life die's strikes.
MDS (Mid Die State) - about 9.13% of a full-life die's strikes.
LDS (Late Die State) - about 35% of a full-life die's strikes.
VLDS (Very Late Die State) - about 53% of a full-life die's strikes.

A cent die created by the multiple hubbing technique (ended in 1997) could live up to about 600,000 strikes. Prior to zinc, they lived for about 750,000 strikes. Nickel, dime, quarter, and half dollar dies striking clad coins (for the dimes, quarters, and half dollars) each lived through roughly 450,000 strikes. Of course all of these numbers are dependent on the steel itself and whether or not it cracked or broke early, whether it turned out too soft and wore more quickly, machine failure, the hubbing technique used, etc.

Die state can be further broken down into medial steps. These are die states that are in-between major die states. Mr. Romines did not break his study down into these more contemporary descriptions. They are:

EMDS (Early Mid Die State) - fits between EDS and MDS.
LMDS (Late Mid Die State) - fits between MDS and LDS.

The die state of a coin can be determined by examining the lines that spider outward in the die as strikes are made. These lines are the result of misaligned molecules of steel spreading outward from the pressure of each strike. They cause two major things on coins; luster, and the loss of detail as they break away from the outer edges of devices. A coin struck with dies that have no flow lines or limited flow lines (VEDS or EDS) will appear more prooflike, while coins struck with dies exhibiting pronounced flow lines (LDS or VLDS) will have a much softer, lustrous appearance.

The essential element in defining die state is the loss of detail (or lack of loss) on the outer edges of the devices closest to the rim (outer edge) of the design. These definitions are:

VEDS - No flow lines, no loss of design. Extremely sharp outer edges to the design.
EDS - No flow lines, minimal loss of design. Sharp outer edges to the design with very light rounding.
MDS - Minor to moderate flow lines, some loss of design. Outer edges will not be sharp, yet will be present.
LDS - Moderate to heavy flow lines, moderate loss of design. Outer edges will be microscopically gone, but will still be definable on a macro level.
VLDS - Heavy to extreme flow lines, heavy loss of design. Elements will be completely missing from the design, outer edges will be visibly diminished.

This element of collecting coins is a fine art and is not observed by a large voice of the community, except indirectly. Coins of earlier die states are generally more desirable, even though the collectors often don't understand exactly WHY they are more desirable. Often they will mistake strength of design with strength of strike - two completely unrelated concepts. A sharply struck coin can exist in any die state, and a weakly struck coin can exist in any die state. The most desirable coins are those in earlier die states with strong strikes. All details are fully present and filled in properly.

Furthermore, die wear (die state) and Machine Doubling have little to do with one another. Machine Doubling is the simple result of mechanical adjustment (loose dies, timing problems, etc.) and can happen at any time (or through the entire period) of a die's life. The only relationship they share is that a loose die is more likely to wear faster than one that is tightly in place on the press.

The small voice of the community--those who have studied die state for many years now--are the die variety collectors. Naturally if you are collecting coins on a microscopic level, you want the details to be as sharp as possible. You want an early die state coin. These coins show the anomaly on the die much more sharply. They are the most desired for photography, and are the rarest of the rare. The die varieties in themselves are scarce in comparison to 'normal' coins, then the early die state coins are the rare examples of those dies.

To date very few die varieties are actaully valued differently from die state to die state, and most of those are valued differently simply because the dies were mated with opposite side die varieties at some stage in their life. For the most part, die state has a bearing on the coin's desirability as a die variety, however as of yet has little to do with value. This could be changing as die variety collectors become more selective in what they buy, keep, get rid of, or toss altogether.

It is my belief that one of these days the third party grading companies will begin including the coin's die state on the label, and that detailed specialist collectors in all coin series will begin to pay hefty premiums to obtain coins in not only high grade, but early die state. It's a marketing concept that has to come to pass at some point, as they begin to run out of excuses to continue reholdering the same coins over again and again. Some day collectors will need to send in their coins to have them reholdered because the die state isn't on the label, and the coin is an early die state worth two times the late die state price. Cherrypicking at shows will take on a whole new level. This concept could, in fact, breathe new life into the market as a whole. And you heard it here first.

----------------------------------------------------------

Of course this subject is only partially related to the original poster's questions. Bill answered most of them quite adequately, no need to repeat him. Only change I would make is that it actually takes 39 tons of force to strike a cent, not 35.

The subject I expounded on answers the third question, in my opinion, completely.

Great info Bill&Chuck!

I found this interesting although it is for Canadian coins. It is a fairly nice study of die life from 1935 to 1962.


http://www.coinscan.com/technical/dieu.html

Bill

Thanks Bill and Chuck. Great info. You guys covered a lot of bases. As a cad designer and having worked with presses I'll throw some things out probably tomorrow night as I have to get up by 5:00 AM.

As a CAD, computer aided design, Designer here's what I can throw into the works. No two batches of steel are exactly alike. The steel manufacturers do have limits as to how far they can very, such as how hard or soft they can be. This applies to heat treating to harden also. It can apply to things like resistance to stains, how well it will perform under, etc. The steel manufacturers will send along the characteristics for each batch that they make to the facility that's going to use it. They will have checked it before it leaves the mill. These are usually known as certs. More than likely the Mint will also test the steel as they hub the dies. There are tolerances to the making of the dies lengthwise and will be compensated for in the setup of the presses. With the type of product you want to produce at the mint you cannot have an honest sharp edge between the field and device, you need a radius. The die could crack from the stress on the first strike without the radius. Heat treating isn't an exact science either. The hardness is achieved by doing calculations as to the characteristics of the steel, size of the die temp of the oven, oil hardened, water hardened or air hardened steel as an example. As to all the hush-hush, it mat be that the steel supplier is offering a different steel just for the mint. It's also possible that the mint is using one of the specialty platings that really handles the wear problems or a combination of both. The laser forming of the dies sounds like anything to do with the government, old dogs-new tricks. The computer aided manufacturing CAM used to guide the laser has been around for maybe 30 years. Although yes they are a machine shop, I would say that the double dies and the Machine Doubling are being looked upon as dereliction and is being addressed to eliminate them.
Tonnage isn't a very accurate way to stop the travel of the ram of a press without a mechanical stop being involved. However with die clash being evident it's safe to say they aren't incorporating them. The computers and the sensors that they use are probably automatically adjusting for the variations in the hardness of the planchet material or materials. A hydraulic press is slow by nature and this characteristic makes it ideal for forming coins, the metal flowing from the fields to the devices. That takes tonnage.
The things I spoke of for the mint are conjecture but the things about the manufacture o0f dies and steel are experience. This has been really informative and fun. Thanks again Bill and Chuck. Keep up the good work.