In industry, only the profile for the die is given as an IGES file, and there is no IGS file for the punch. It is necessary to offset the die IGES file to obtain the geometry of the punchy.
When using LSDYNA, you have two choices to offset the punch, i.e. you can use some pre-processor to offset it, or you can let LSDYNA to offset it internally.
If you want to LSDYNA to offset it, you have to use negative value for the parameter of MST under the contact card: “CONTACT-xxxx”.
However, the users should always be encouraged to use the physical offset of the punch, because it is easy to check the model.