Philadelphia Mint enters into contract with Seco/Warwick

The small letter at the nape of George Washington’s neck in the image above is a mint mark. The “P” indicates that the coin was struck at the Philadelphia Mint. (Courtesy: Seco/Warwick)

The Philadelphia Mint has asked for furnace upgrades from Seco/Warwick, the partner with proven experience and cooperation with national mints.

The Philadelphia Mint was established by the Coinage Act of 1792, when Philadelphia was the nation’s capital. It was the first public building constructed under the direction of the recently formed United States government. The machinery was powered by a horse walking circles in the basement. The minting technology has seen a few upgrades since then.

Seco/Warwick Group’s American subsidiary, located in Meadville, Pennsylvania, recently began the current round of upgrades, a refurbishment of all five of the Mint’s heat-treating furnaces, one furnace per year.

The heat-treating furnaces were installed there by Seco/Warwick USA from 1994 through 2000. Their function in the minting process is to anneal, clean, and dry the coin blanks to soften the metal prior to striking into coins, extending the service life of the striking dies.

All five furnaces are 4,000 pound-per-hour rotary retort furnaces outfitted with Seco/Warwick’s patented Whirl-A-Way Quench™ system, as well as a hopper feeder, a batch burnish barrel, and a batch/continuous drum drier. The furnaces are showing their age after a quarter century and the Mint opted for a comprehensive refurbishment.

“Our partner has plenty of coin to heat-treat, but they don’t have any to burn,” said Marcus Lord, Seco/Warwick USA managing director. “These waste-heat recovery and combustion efficiency upgrades are going to save them a mint while cutting carbon and NOx emissions nearly in half.”

To reduce energy consumption, Seco/Warwick is replacing insulation, roof panels, and radiant tubes as well as upgrading the loading systems with an improved, more user-friendly design. New, more energy-efficient burners are being installed, along with recuperators to preheat the combustion air to improve energy efficiency and use less natural gas.

Mechanical improvements include replacing drive motors and two-speed gear boxes. The retort can over-heat and warp if the rotary retort unexpectedly stops before the cool-down cycle. As a failsafe, Seco/Warwick added a pneumatic backup motor that can run the gearbox off the Mint’s compressed air reservoir during a power outage.

Beyond upgrades to legacy systems, mints around the world are also upgrading their heat-treating capabilities to improve the strength and longevity of their stamping dies by installing Vector® high-pressure gas quench vacuum furnaces. Many of these newer systems include options of high vacuum, convection heating, as well as Seco/Warwick’s patented PreNITLPC® technology, which makes thin layer nitriding possible.