The machining of the rough shape is done with the steel in soft condition. But when a die is soft it cannot be used for production. Therefore the dies are hardened before they move to the next step in production.
To make sure that the tools have the right hardness they are hardened. This is done by a thermohardening process. A process that is closely monitored. As soon as the dies are hardened they are checked to make sure that they have reached the specifications that they should have.