U.S. Mint, Uncicirculated Mint Sets

boston

Has anyone else noticed the U.S. Mints' description on the 2004 uncirculted mints sets? (This may have been the same in the past. I just noticed.)

"These coins are minted on special presses and are struck with greater force than circulating coins..."

This statement is only included on the "Subscriptions" service, not with the "Annual Coin Sets".

The question: Are uncirculated mint set coins actually struck differently than the rest?

Bob

Bikingnut

I always understood that they were no different than the circulating issues.

AJ2525

I thought a couple of years ago the mint came out with something along the lines of "uncirculated mint sets will be struck with brand new dies and the dies will only be used for a short period of time for the mint sets." Obviously I don't remember the exact quote but I do think the mint sets get better treatment.

IMHO the philly coins still seem to have been sandblasted a bit, the fields don't seem as mirrorlike to me as most of the fields in the Dnever coins.

Artist

<<"These coins are minted on special presses and are struck with greater force than circulating coins...">>

This is true. Though the dies and manufacturing techniques are about the same as for circulating issues, there is a special room where coins for all Mint Sets are struck. The press in that room is newer than those on the floor, and it is set to strike with more force than what is used for standard coins. As such, the dies do need to be changed more often. Additionally, the operator of the press inspects for quality the coins that come of it almost continuously, whereas the coins coming off the floor presses are inspected more periodically.

DeepCoin

There is no special "room" where Mint State coins for the Unc sets are made. It is true that new dies are typically used for these coins. The coining process is a flow process, thus having a special "room" is pretty much out of the question.

Steve27

"The question: Are uncirculated mint set coins actually struck differently than the rest?"

Yes, they are actually NCLT now. This is also why all the MS68/69 coins come from mint sets and not rolls or bags.

cladking

There's little known about the mint sets and how they are coined and assembled. The mint
has long made seemingly contradictory statements about this and visitors are very rarely al-
lowed near the equipment. I believe I've seen only a single picture of the packaging equip-
ment and no others.

Much of what is known has to be pieced together from looking at the sets and comparing it
to information which has been released. There was an apparently accurate listing of the
differences released last year by the mint. In it thet said that most mint set coins are mint-
ed on vertical single presses rather than the horizontal quad presses. The latter have eight
dies which strike four planchets simultaneously at very high speed. The single presses have
only two dies and a single coin is struck on each strike. These run at lower speeds and at
higher pressure than the others. Dies are used for only around 30,000 strikes and then are
removed from the press and replaced. Coins are tumbled with corn meal after washing in
order to dry them.

While this process in no way assures all these coins are gems, they mostly do all have nice
strikes from new dies. It is hardly unusual for to see coins in the mint sets struck from dies
which weren't aligned perfectly. And the lion' share of the coins will have marking ranging
from minimal to severe. There will be very few coins struck from worn dies and there will be
very few coins that didn't recieve a good impression from the dies.

Apparently many of these changes started with the Special Mint Sets. After these were dis-
continued the mint simply continued with most of the steps for the regular mint sets. The SMS's
did have specially prepared dies which for the main part are absent in the later mint set coins.
souvenir sets contain nicer coins but there's no evidence that these get special treatment.

Many of the post-'65 coins do not appea as gems in the coins made for circulation! While it's
not impossible that some were made or even that they survive, after you look at several thou-
sand of the same coin and there aren't even very choice coins there are simply, in effect, no
gems. In some cases there are in effect no coins to check also.

DeepCoin

Well put Cladking. That is exactly what the current process is.

It should be noted that there are no "special" presses or rooms for these coins. They just get some extra care in the coining process. A couple of million coins out of billions minted is a drop in the bucket.