Printing on coins is an extremely complex and challenging task. Even the smallest and most detailed photoprints must come out richly coloured and exact. Usually the coins are minted with a relief which means that the printing is on fine structures instead of an even surface. Considering the quality of the workpiece misprints involve high costs. Printing on coins can involve various methods, including pad printing and digital printing, both of which are suitable for different applications. Here’s an overview of these two methods and how they are best suited for you:

1. Pad Printing On Coins

Pad printing is a very popular method for printing on awkward and complex surfaces like coins. It uses a silicone pad to transfer ink from an etched plate (cliché) onto the surface of the coin. Here is how pad printing works for coins:

Process

1. Cliché Preparation: A plate (cliché) is etched with an engraved image or design.
2. Ink Application: Ink is applied to the plate, and excess ink is removed with a blade, leaving ink only in the engraved areas.
3. Ink Pickup: A soft, silicone pad presses onto the plate, picking up the inked design.
4. Ink Transfer: The pad is then pressed onto the surface of the coin, transferring the design.
5. Curing: The ink on the coin is cured or dried using UV light or air drying, depending on the type of ink used.

Advantages

• Flexibility: The silicone pad conforms to the shape of the coin, making it possible to print on flat, curved, or irregular surfaces.
• Precision: Offers high resolution and fine detail, suitable for intricate designs.
• Versatility: Can print on various materials, such as metals, plastics, and coated surfaces.
• Durability: The printed design is durable and resistant to wear.

Limitations

• Limited Colour Range: While pad printing can handle multiple colours, each colour requires a separate plate and run, making the process time-consuming and costlier for complex, multi-colour designs.
• Setup Time: Requires initial setup and plate preparation, which may not be cost-effective for small production runs

Our Recommendation

For pad printing we recommend the bespoke Teca-Print TPX-301 Mint Workstation I. It is specially designed and built to meet the needs of the mint industry. The electromechanical machine with an integrated camera system fulfils the highest expectations and results in extremely fine and detailed prints. 

Read up about Teca-Prints coin printing application

Enquire here!

2. Digital Printing On Coins

Digital printing is a more recent method used for printing directly onto coins using digital inkjet technology. It is similar to how a home printer works but on a much more sophisticated level. Here is how digital printing works for coins:

Process

1. Design Preparation: A digital design file is prepared using graphic design software.
2. Inkjet Printing: The coin is placed under an inkjet printer, which applies the ink directly onto the coin’s surface.
3. UV Curing: The ink is cured instantly using ultraviolet (UV) light, providing a durable finish.
4. Clear Coating (Optional): A protective clear coat may be applied for additional durability and gloss.

Advantages:

• Cost-Effective for Short Runs: No need for plate preparation, making it ideal for small production runs or prototypes.
• Full Colour and Gradients: Digital printing can produce full-colour images, gradients, and photographic quality designs.
• Quick Turnaround: Faster setup and printing process compared to traditional methods.
• Customization: Allows for easy customization, such as variable data printing (unique serial numbers or names).

Limitations:

• Durability: Digital prints may not be as durable as pad prints, especially if not coated with a protective layer.
• Material Restrictions: Works best on flat surfaces and may not adhere well to all types of metal without special coatings or primers.
• Cost for Long Runs: Digital printing can be more expensive for large production runs due to the cost of inks and potential wear on printing heads.

Our Recommendation

We recommend the Mimaki UJF 7151 plus II digital printer. One of Mimaki’s larger digital printing machines with a 710mm x 510mm bed size and a staggered head array gives the capability to produce approximately 6 beds per hour. The precise cutting edge technology allows for full colour extremely high resolution finishes that can bring your coins to life!

Check it out here!

 

Comparison Between Pad Printing and Digital Printing for Coins

Feature	Pad Printing	Digital Printing
Surface Adaptability	Good for curved or uneven surfaces	Better for flat surfaces
Colour Range	Limited to fewer colours per pass	Full-colour and gradients possible
Setup Time	Longer (requires plates)	Shorter (direct digital input)
Cost Efficiency	Cost-effective for large runs	Cost-effective for small runs
Durability	Highly durable	Durable with protective coating
Detail and Resolution	High precision and detail	High resolution, photographic quality
Customization	Limited to design on plates	High level of customisation

 

What printing application is best suited for you?

• Pad Printing is best for large production runs, especially for designs with fewer colours and when printing on curved or irregular surfaces.
• Digital Printing is ideal for short runs, custom designs, and where full-colour prints or complex images are needed.

Here at KayeDee we sell both digital and pad printing machines suitable for coin printing. Please email us on sales@kayedee.co.uk or call us on 0114 256 0222 for more information