Alternative metals testing for us coinage

from another thread, I thought I would split this out for it's not buried in another thread. Just in case other folks are interested in it.

The US MINT has a few Alternative Metal testing documents which includes a few (many) things they did to the dies to increase longevity, etc over time. From die lifes of 300,000 to 1,000,000 with various coatings (to just expecting low quality) including chrome nitride PVD-coated circulating dies which did not increase longevity.

There's so much in these documents, the link below is 400 pages, so I can't even write a brief about it.

They reference Burnishing in there as only the Dollar coin is burnished now as of 2012.
Costs, metal tests and options for Cents including CPZ - Copper Plated Zincs which uses an 8 micron thick copper plating (now you can post that to all the damaged CPZ pictures you see).

400 pages of fun information for the Numismatic Geek
https://www.usmint.gov/wordpress/wp.../ctcr-alternative-metals-study-2012-08-31.pdf

I'll try to find the one that is even earlier than this one.
I have downloaded versions if it doesn't load. Their servers are slow.

just searching for burnish... here's one hit

which was done to an A190 strip to improve the metal planchets themselves, and not necessarily the die. As stuff added to the die wears out quickly, whereas to the planchets will keep "lubricating" it, which they picked up from the RCM test samples sent to them for some test.

Of course, then they figured out some other process which made burnishing not needed.

have fun reading ....

oh, they don't mention half dollars much as they are the same type of composition as dimes and quarters.

can someone find a prototype $1,000 coin ... hehehe .. go searching.

 

Log in or Sign up to hide this ad.

see the attached PDF

 

https://www.usmint.gov/about/reports/biennial-2012
is the landing spot for a few links for this information


United States Mint Releases Findings on Alternative Metals Study: Additional R&D Required Before Making Recommendations
The U.S. Mint is committed to pursuing potential cost savings—whether it be from the use of less costly alternative materials or through production efficiencies. As part of that commitment to reduce costs, the Mint—along with a research and development consultant—undertook a very thorough R&D study to identify potential changes to the metallic composition of circulating coinage and methods of production.

The study took nearly two years, researching 80 metals on the periodic table of elements that may work—and which ones will not, establishing an R&D lab, and testing hundreds of test pieces composed of nearly 30 alloy formulations. The study involved working closely with many stakeholders—the vending industry being the primary one—to assess impacts of any potential alternatives.

The Mint has made significant progress and, at this time, has concluded that additional R&D is necessary before it can recommend any changes to the current coin composition. Going forward, the Mint will continue R&D and testing of potential alternative materials; conduct production-scale runs to validate supply chains, manufacturability, and costs; and further verify the estimated costs to stakeholders that are associated with the change.

Two reports are available on this page—the U.S. Mint’s report and the report provided by the consultant under contract to the Mint.

 

that's 400 pages of small print reading material - you might add the specific relevant page #s

 

depending what you are interested in reading,
from pages 1. To 400.



there is an Table of Contents .. it starts on page ix

 

Thank you! This should be interesting.

3 posts to go

 

How many posts to go ?

 

Mint is chock full of information for those error hunters
https://www.usmint.gov/news/inside-the-mint/superior-manufacturing-reduces-errors


December 3, 2014


A 2012 Dime demonstrates a broad strike defect

The Mint currently produces billions of circulating coins a year. In the past, the sheer quantity of manufactured circulating coins produced an occasional mistake in the planchet, or blank, die or striking process and an “error” coin popped out of the press. These days, virtually all error coins and defects are found and recycled before they ever leave the United States Mint. The few that do make it into circulation, though, are often perceived to be collectibles. Unfortunately, for collectors, the quantity of error coins is getting to be fewer and fewer. The Mint has been steadily improving manufacturing processes that are resulting in fewer of these error coins.

The Mint Quality Index (MQI) describes the “measurable quality attributes that provides an objective measurement of performance in meeting high quality standards on finished coins.” What this means for the non-manufacturing crowd is that the Mint has developed a scoring system to rate its own coins.

The Mint monitors MQI results for both circulating, numismatic, and bullion coins. In a weighted scale that targets 100 as a perfect score and measures “minor,” “major” and “critical” defects, this number was 74.9 for circulating coins in 2007.Through zero-defect targeted efforts that include sampling, die inspections and yearly summits where Mint employees from each facility share knowledge and standardize approaches, 2014 saw the combined Denver and Philadelphia circulating MQI reach in excess of 99.3.

No matter who you talk to, circulating error coins carry value. For most people, this value is on the face of the coin. Numismatists find error coins to be interesting additions to their collection. The Mint sees an error as an opportunity to continue to improve as a world-leading manufacturer of coins.

Finding circulating error coins was never easy to begin with and, thanks to the talented people at our Philadelphia and Denver facilities, finding these coins has gotten even harder.

 

some excerpts from the alternative metals document ...

· The Philadelphia and Denver facilities frequently have different production experiences with the same coin design.

· Currently, all coin designs are modeled and digitized, or produced digitally.

· Master dies are prepared on digitally controlled milling machines at the Philadelphia facility.

· After heat treatment the master dies are used to impress an inverse of the design into another piece of heated die steel, the hub.

· After additional heat treatment, the hub is pressed into another steel piece to produce a working die that will be used in a coining press.


· Master dies are distributed to the Denver facility, which produces its own working hubs and dies.

· Despite using the same masters, the crown heights of dies and design heights of relief produced at the two facilities differ,

· 138 which has a measureable effect on coin fill. Further research into the reasons for this difference and its impact on die life, coin quality and production costs is warranted.


· Consistently high one-cent coin die failure rates significantly affect overall production costs.

· Average die life in 2009 reached a low of approximately 300k strikes at both the Philadelphia and Denver facilities.

· Since one press produces roughly 300k coins in one 8-hour shift, this failure rate reduced production efficiencies and costs from historical trends.


· Note that one-cent coin die life from 2000 to 2008 averaged 1 million (M) hits, but that has fallen to under 500k from 2009 through 2011.


· In the Philadelphia facility there are seven presses in one production cell for one-cent coins, and a single operator manages six or more presses at one time.


· Desired production rates rely on any six of the presses being in operation at any given time. Therefore, if one press is down for a die change or for some other reason, these production rates are not impacted. At the Denver facility,

· however, the production rates rely on all presses to be operational at all times; therefore, an increase in the frequency of die changes can be more disruptive. An average die life of 600k or more strikes (1M strikes or more for one-cent dies) would be beneficial for both sites.

 

· Denver facility engineers calculated that doubling the one-cent coin die life would save $2660/day for production rates equivalent to the monthly average at the Denver facility during 2011, i.e., 200M one-cent coins per month.


· Longer die life for other denominations was of lower importance to the production staff. The die life (as measured by the number of die strikes) is shorter for the other denominations; however, due to the smaller annual quantities produced, die life improvements for these other denominations would have less overall impact on production rates and production costs.

· One area of potential future die research is the use of optimized physical vapor deposition (PVD) coatings for coining dies. Both the Royal Mint and the Royal Canadian Mint have developed such coatings; both of these mints contend that the coating improves die life in their operations.


Chrome nitride PVD coatings have been used in the United States Mint since 2009 to improve die life of numismatic dies where wear is the major failure mode. A number of coining tests were conducted in 2010–2011 with chrome nitride PVD-coated circulating dies that demonstrated no significant improvement where fatigue is the primary mode of failure. Coining tests of specially formulated low coefficient of friction PVD coatings are scheduled for 2012, with the goal of improving fatigue die life. This is another area where better understanding of design features and die stresses could be used to develop a more scientific approach to improving production practices.

 

There's info hidden in the above link I provided. There was one section I cannot find where it was stated that error rate has been reduced dramatically and gave percentages.

here's some alternative stuff about it.
There's info on page 304

 

if you deep dive into the document you can get some neat specific information
coil weight of 3-10k lbs
annealing temp between 680-720 C / 165-1320 F for dime, quarter and half dollar, etc.
There's also final bag weight which is handled differently between mints with one accepting a low % error weight and another not accepting it and being more picky.

View attachment 901247

 

Many thanks for all your info, @Clawcoins. It surely is hard work digging up all these. With the improving Mint Quality Index (MQI), I can see why there are so few errors since 2007.

On the other hand, I noticed a number of 2015-2017 minor errors showing up in the market recently. Mostly misaligned die strikes (shield pennies), partial collars and planchet clips (ATB quarters). Maybe its because the Mint loosens the quality criteria for acceptable coinage, as your attached information indicates. Just my thoughts.

 

DIE LIFE

 

more interesting info

 

Cents AND nickels. End them. Quick, before some bright spark decides we need cupronickel-plated-zinc five-cent pieces...

 

Very interesting reading, @Clawcoins. Many thanks for posting.

 

The NEW PHONE BOOK is HERE !!

okay, not really but the US MINT released the 2018 edition (ie, April 2019 release) of the Alternative Metals report

just a few items from that report ...
The below costs include (a) Costs of goods sold, (b) Selling, General & Administration costs, (c) Distirbutions costs to FRB


POSSIBLE alternative metals for lower cost coinage


PRODUCTION IMPROVEMENTS


these are just excerpts. The full copy is here
https://www.usmint.gov/wordpress/wp-content/uploads/2019/05/2018-Mint-Biennial-Report.pdf