Creating coin dies is a specialized craft that involves designing, engraving, and hardening steel rods to imprint a design onto metal blanks. The process can be broken down into these key steps:
- Conceptualization: The process starts with an initial concept for the coin design.
- Artistic Rendering: A medallic artist creates a detailed drawing or digital sculpture representing the desired coin design.
- Digitalization and Scaling: The design is then digitized using high-resolution scanners and processed with 3D design software to create a digital file for production.
- Master Hub Creation: A Computer Numerically Controlled (CNC) milling machine engraves the design onto a cone-shaped steel rod, creating the master hub, which features the design in its positive form.
- Master Die Creation: The master hub is then used in a hubbing press to transfer the positive design to a die blank (a steel rod), creating a master die that carries the negative, or inverse, image. This process requires significant pressure (up to 265 tons depending on the denomination), according to [the U.S. Mint].
- Working Hubs: Master dies are used to create working hubs, which are then used to create working dies.
- Working Dies: These working dies are the actual tools that will strike the coin blanks. The use of multiple hubs and dies protects the integrity of the original master hub and die.
- Heat Treatment: Working dies are heat-treated to make them durable enough to withstand the stress of striking hundreds of thousands of coins.
- Quenching: The dies are heated to high temperatures (up to 1,800 degrees Fahrenheit) and then rapidly cooled by quenching in a liquid, which hardens the steel but can also make it brittle.
- Tempering: To reduce brittleness, the dies undergo two cycles in a tempering oven at temperatures up to 450 degrees.
- Adjustments and Inspections: Final adjustments are made, including laser engraving serial numbers for tracking lifespan and use, and grinding the dies to their final shape.
- Cleaning and Polishing: Employees meticulously clean, polish, and examine the dies under a microscope to buff out imperfections.
- Special Finishing (Proof Coins): Proof dies undergo additional steps, such as applying diamond paste for polishing and using a laser to cut indents for a frosted texture.
- Chrome Plating: Proof dies are also plated with a thin layer of chrome using Physical Vapor Deposition (PVD) to protect them during striking.
It’s important to remember that die-making involves working with heavy machinery, high temperatures, and sharp tools. Following safety protocols and using appropriate personal protective equipment (PPE) is crucial.
Note: This process outlines modern die-making techniques. Ancient and medieval die-making relied more heavily on hand engraving and punching, often producing dies with shorter lifespans.
How to make a die for coins?
Step 1: Design. The process of making coin dies begins with a line drawing that represents a two or three-dimensional image. …
Step 2: Master Hubs & Dies. …
Step 3: Working Hubs & Dies. …
Step 4: Final Touches.
How to damage a coin?
Spit on Your Coins
These microscopic bits of saliva can cause spotting and discolorations that are difficult to remove. Collectors have ruined many uncirculated, Proof and Mint State coins this way. Say whatever you want about your coin collection, just make sure your coins are away from your mouth when you say it.
How to make a coin look antique?
And now for one of my favorite parts is dropping it in some brass. Black. This stuff will patina the coin. Really quickly and turn it black it’s such a cool reaction.
How were coin dies made?
The tools used to engrave the dies included iron or perhaps even steel burins and small chisels to remove metal from the face of the die, punches to impress an image into the face of the die, and perhaps simple bow drills, tipped with corundum or other abrasive, to drill into the die face.