In the Viking Age, an upper die and a lower die were placed on either side of a piece of silver before hitting the dies against one another. This procedure was used through the Middle Ages. Mechanical coin presses were introduced in more recent times. Today, modern production methods using fully automated coin presses are used for minting coins. 
Here you can read more about the production of coins in the Viking Age and the Middle Ages
Stop here for a look at more recent minting methods.
This is the gateway to modern minting.

Here you can also find a video from the Royal Norwegian Mint at Kongsberg