Robots invade San Francisco Mint for assembling plastic lenses for Proof coin sets

New equipment triples number of components put together before final packaging
By , Coin World
Published : 08/12/15
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The San Francisco Mint has completed installation of a robotic loop assembly system that triples the speed of packaging Proof coins into plastic lenses for special collector sets.

The system, developed by the Mint’s engineering team in conjunction with the manufacturer, Farason Corp., Coatsville, Pa., gives the San Francisco Mint the ability to fill coin lenses at the rate of 1,800 lenses per hour, versus the previous 600 per hour, a Mint official said.

The system replaces a labor-intensive system installed in 1999 that required significant manual inspection of coins and plastic lenses, checking for damage that would prompt removing the coins or lens from the assembly system.

The new robotically controlled digital inspection assembly inspects each coin and lens at each phase of the assembly operation. Coins and lenses can be rejected if they fail to meet quality control specifications. If defects are found, the system will shut off for the defective item’s removal, and then restart.

(Each lens is composed of a top and bottom plastic enclosure and a cardboard insert with openings sized for the respective coins, which are robotically placed into them.)

Once the multistep operation is complete, the finished lenses are moved by automated trolleys to the next station where they are loaded for placement into the full-color cardboard storage boxes before final shipment in delivery boxes.

Don Penning, the San Francisco Mint’s industrial manager for packaging, said the digital visual detection equipment will, at every entry interval, inspect the coins and lenses for defects. A final quality control inspection is conducted at the end of the line when the finished lenses exit the assembly loop.

Where the previous assembly system required three full-time operators, the new system requires only two workers to keep the system stocked with sufficient top and bottom plastic lenses, cardboard inserts, and coins. The system will shut down if any station from which coins or lenses are fed runs out.

Penning said the system has eight feed points that operators must stock with coins, lenses or inserts. Five feed points are for coins, two are for lenses, and one is for inserts.

The cardboard inserts are first in line on the conveyor. The insert is robotically selected and robotic arms are programmed to retrieve the proper coins from the correct coin trays and place them into their proper positions in the cardboard inserts. The inserts with the coins are then placed into the bottom lens.

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