Weak strike

In the production of coins, a strong pressure of 35 to 200 tons is required for the upper die to transfer the design elements onto the planchet. The pressure required varies according to the denomination of the coin, the alloy used for production, and whether it is intended for circulation or testing purposes. Prior to production, a series of single-stroke tapping is performed to decide which tonnage will be used for the production cycle and to obtain the maximum yield from the dies. This single shot is known as a “die adjustment strike”.

Single-strike coins are rare in circulation as they are typically disposed of shortly after minting. These coins are characterized by ghost prints on both sides of the coin, with the outline being the only clearly visible portion. However, with the latest generation of money presses equipped with automatic pressure regulation systems, it is difficult to determine the cause of the error, making it practically impossible to assign a definitive cause. Weak strikes, on the other hand, are the result of inadequate piston pressure, insufficient approximation of the die, or spontaneous malfunctions of the monetary press.

Piston pressure refers to the tonnage applied to a normal thickness round bar, while the approximation of the die refers to the minimum distance between the dies in the absence of a planchet. Spontaneous malfunctions of the coin press can be due to multiple reasons, including hammer dies falling out of adjustment, a jam in the bowels of the press, a badly cut or broken cam (on which the anvil rests), a press frame loose or broken, or a broken circuit breaker.

Most weak strikes in the market are the result of spontaneous malfunctions of the money press, caused by an increase in the minimum clearance of the die. These strikes present as a circular fading near the plus or minus edge, which may vary in size depending on the tonnage applied. It is essential to understand the causes of weak strikes to avoid confusion with other types of errors and to accurately identify the reason behind the error.