What Does Coin "Upsetting" Mean?

By GovMint :

In coin minting, "upsetting" refers to a technique where the edge of a coin is raised or thickened before striking. This process imparts strength and durability to the coin's edge, reducing wear and preventing premature deterioration. By upsetting the edge of a coin, mints can create a more secure and robust boundary that increases the quality and longevity of the coin. This method is particularly crucial for coins that will undergo heavy circulation, ensuring they maintain their integrity over time.

Sources Used:

https://www.usmint.gov/learn/production-process/coin-production