How the Denver Mint Makes Uncirculated Coin Sets


This fifth article in a series about our visit to the U.S. Mint at Denver, Colorado, describes how uncirculated coin sets are made.

It’s a blast watching numismatic coins coming to life in coining presses and then seeing how they’re packaged into sets by robots and other automated machines.

Most recently, we were lucky enough to discover how the tech teams from the U.S. Mint at Denver use robotics to build annual United States Mint Uncirculated Coin Sets. These popular sets, which most collectors call "Mint Sets," have annual sales of several hundred thousand units.

Numismatic Advent Line, Denver Mint
This machine uses robotics to place collector coins into blister packages. Donald Bush, seen toward the back, makes sure everything runs smoothly.

We observed probably several hundred sets made just in our short time there. We watched how smart robots pick up uncirculated coins, detect if they are upright, determine their orientation and then place them into opened blister packs. Then we saw how the packs get sealed, snapped inside a coin folder, and dropped off for inspection.

Here’s how it all happens…

Uncirculated Coins Get Placed into Blister Packs

Annually issued Mint Sets include 28 coins of the year with 14 uncirculated coins from Denver presented in a red folder and 14 uncirculated coins from Philadelphia displayed in a blue folder. Ironically, while we watched how Mint Sets were created from scratch and that’s what this article is about, we must have been dazed by the day’s events because we forgot to take photos of the finished folders. Here are U.S. Mint images of their set for 2013:

2013 United States Mint Uncirculated Coin Set
The 2013 United States Mint Uncirculated Coin Set and its 28 uncirculated coins that are split into two folders. The folder accented in red holds the 14 coins from the Denver Mint, and the folder accented in blue holds the 14 coins from the Philadelphia Mint.

Now that we’re hopefully on the same page, let’s see how the coins are packaged and get into these folders.

Clear blisters are used to hold coins in place and protect their surfaces. At the rate of about 850 per hour, empty blister packs are fed into a long packaging machine.

Beginning of Packaging Line for Uncirculated Coin Sets
This photo shows the beginning of the packaging line where empty blister packs are fed. The display panel at top includes information on speed, how many blisters have been packaged, and identifies locations of any problems.

A stop and go conveyor system moves the packs to coining stages that are identified by denomination, beginning with Kennedy halves and Jefferson nickels, rotating through the five America the Beautiful Quarters and five $1 coins, and ending with Lincoln cents and Roosevelt dimes.

Before jumping into the robotics of how uncirculated coins get plucked and placed, here are several photos and a video of the blister packaging machine.

Top and Back Section of Numismatic Advent Line, Denver Mint
This photo shows a top view of the blister packaging machine, as seen from a section of the Denver Mint’s Public Tour. It gives a better scope of the machine’s length and width. Overlaid at left is a closer view of a back section of the packaging machine. It shows boxes of uncirculated coins that get fed into the blister packs.

Inside Packaging Machine for Mint Sets, Denver Mint
Inside view of a very small section of the packaging machine

This video offers a look inside of the blister packaging machine. It was taken from the center of the machine while turned off, and pans from left to right.


Robots with Cameras Grab Uncirculated Coins

It’s all about the robotics now. Blister packs move down the line on conveyors, they stop at a coining stage and then a robot picks up an uncirculated coin and places it into a pre-programmed position on the blisters. Smart technology is in play here. The "head" of each robot arm has a camera that detects whether coins are upright and in proper rotation. If the robot senses a problem, it drops the coin into a holding bin instead of placing it on the blister pack.

Uncirculated Coins Placed Inside Blister Packages, Denver Mint
A small robotic arm is about to place one of the uncirculated coins on an open blister package.

Rejected Uncirculated Coins
Notice the two coin bins by the robot arm. They hold uncirculated coins that failed camera inspection. Usually, such failures are the result of coins that are wrong side up since the robots are not designed to flip them.

Robotic Arm Grabbing Theodore Roosevelt Presidential $1 Coin, Denver Mint
This photo shows a close-up view of a robot that is about to grab an uncirculated Theodore Roosevelt Presidential $1 Coin

In this video, a robot scoops up uncirculated coins and places them on blister packs.


Blister Packs Get Sealed

Blister packs must be flipped shut and sealed after all 14 uncirculated coins are set into position. This video shows the automated process of closing the packs.


Sealed Blister Pack of Uncirculated Coins from Denver Mint
Sealed blister pack of uncirculated coins produced at the Denver Mint

Blister Packs are Inserted into Red Folders of Mint Set

Now, each sealed blister pack with its uncirculated coins must get inserted into a red folder that includes artwork, Denver labeling, specification of the coins and a U.S. Mint Certification of Authenticity. This happens automatically.

Denver Mint folder for 2013 United States Mint Uncirculated Coin Set
Unassembled Denver Mint folder for United States Mint Uncirculated Coin Set

A robot picks up an unassembled folder, squeezes it through a frame so it bends at its scored seams, and then places it on a conveyor. The now partly bended folder is moved further down the line where it meets up with a six-fingered robot that has grabbed a package of blistered coins. The robot snaps the blister pack into the waiting folder. From that point, the folder with coins gets glued and moves down the conveyor to await manual inspection and boxing. The following video shows how blister packs and folders are combined.


Inspection of Uncirculated Coin Sets

Here, at the end of the line, Nathan Wittstruck and Bob Luethje inspect uncirculated coin sets and place them into boxes for temporary storage.

Nathan Wittstruck and Bob Luethje Inspecting Denver Mint Uncirculated Coin Sets
Nathan Wittstruck (left) and Bob Luethje (right) inspect completed folders of Denver uncirculated coins. They check to make sure that all the coins are all properly rotated, the artwork is centered on the blister pack, and everything is glued down well

Machine Combines Denver and Philadelphia Uncirculated Coin Sets

Finally, a fully automated boxing machine combines the Denver uncirculated coin sets in the red folders with the blue folders of the Philadelphia uncirculated coin sets. It’s quick and able to complete about of 2,100 sets per hour. The machine, not running during our visit, also boxes up the sets.

Advent Line Boxing, Denver Mint
The automated boxing machine combines the Denver and Philadelphia uncirculated coin sets.

How popular are the sets? Priced at $27.95 and released on June 4, 2013, just shy of 350,000 of the 2013 Mint Sets have sold to date. Sales of the 2012 Mint Sets topped 395,000 before they unexpectedly went off sale. This year’s 2014 Mint Sets are scheduled to launch in May.

Final Article in Series About the Denver Mint

Return Monday, Jan. 27, for the last article in our series about the Denver Mint. It offers final comments and includes all of the photos we’ve published. To catch up on any articles, there are links to them in the upper right column.

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Amazingly, nothing ever goes wrong.

Theodore Dzielski

Why can’t a person get a roll of pennies, nickels, or dimes from the P or D or s mint?

James Ashman

The place looks good, some day I will get too take a trip there hopefully.

Donald Wirts

Are these Uncirculated Coin Sets made by the US Mint themselves or some other company either working for the Mint or Government or themselves altogether? And is the US Mint part of the US Governmant or a private company? Thank You–Don Wirts