2031JG24N00003 - New Chemical Development - RFI.docx

The United States Mint (USM) uses a third-party proprietary compound to protect and lubricate blanks during the coin-stamping process. For any reason, if production of this proprietary compound was reduced or ceased, it would greatly impact the USM operations. The USM wishes to develop a similar or alternate solution that will perform equally or better than the current mixture. Development of an alternate solution will require in-depth knowledge of corrosion protection, lubrication, and self-assembled monolayers, exploration of relevant chemicals and/or processes, as well as small-scale and large-scale formulation and testing. The following narrative describes the current state of USM coin production as it relates to the chemical treatment of blanks and their use in the stamping process. Also provided is a list of requirements desired by the USM.

Current Process Sheets of thin metal are cold rolled by our suppliers and sent to the USM. The coil is fed through a press that punches out small circular blanks. To soften the metal and remove the residual stress, the blanks are annealed. Despite a protective atmosphere in the furnace, an unwanted thin oxide layer forms on the surface of the blank. The blanks are cooled in a water-surfactant solution. They are conveyed to a rotary barrel to be washed. The first chemical mixture is citric acid plus surfactant which removes the oxide and is then rinsed off. The next addition is the chemical to be replaced, which provides corrosion protection and lubrication for the stamping operation. The blanks are then lightly rinsed and dried.

The key properties of the chemical of interest are:

1. The chemical is a self-assembled monolayer that adheres well to the surface of a blank to survive the subsequent stamping process and is thin enough that it does not leave residue on the stamping tooling.

2. A protective layer impedes corrosive elements over a period of time.

3. The blanks shed rinse water easily to avoid forming water stains.

4. The layer provides a lubrication function during stamping reducing the friction at the die–blank interface and mitigates wear.

Alternate Solution Requirements Performance:

· Provide superior corrosion protection and lubrication for stamping coinage.

· Ability to apply during in-line operations at full-scale production to millions of metal blanks per day, water soluble.

· Compatible with all circulating coinage alloys except for copper plated zinc (CPZ) penny planchets, see “United States Circulating Coin Specifications” table below for details Supply:

· Uses readily available, non-proprietary precursors and/or processes to manufacture.

· The major and critical components of the solution are reported to the Mint.

· Able to be produced at more than one location

· Can be produced in large quantities

· Have a shelf-life of at least 1 year

· Transportable to any Mint without needing heated or cooled transportation Health and Safety:

· Allow for safe storage and handling in an industrial setting

· Maximize compliance with applicable environmental regulations

United States Circulating Coin Specifications

Denomination

5-Cent

Dime Quarter Dollar

Half Dollar

$1

Bulk Composition (weight percent [%])

Monolithic Cupronickel (75% Cu- 25% Ni)

Cupronickel- Clad Copper (91.67% Cu- 8.33% Ni)

Cupronickel- Clad Copper (91.67% Cu- 8.33% Ni)

Cupronickel- Clad Copper (91.67% Cu- 8.33% Ni) Clad Manganese- Brass (88.5% Cu-6% Zn-3.5% Mn- 2% Ni)

Surface thickness and composition

0.175 mm 75%Cu, 25% Ni

0.226 mm 75%Cu, 25%Ni

0.289 mm 75%Cu, 25%Ni

0.413 mm 77%Cu, 12%Zn, 7%Mn, 4%Ni