I need to create some form tools that create countersinks completely within the thickness of the material.

I think the best one to start with would be a 3/16" in 3mm sheet, this is formed on our turret punch by pre-punching a 7.4mm diameter hole and the using the c/sink tool to form the top edge of the hole down through the hole, creating the c/sink. The major diameter ends up being 11mm and the hole is 5mm dia

Simple form tools similar to any from the SW library tend to push the material through the sheet, creating a dimple

I've tried many different types of geometry to try and stop the material being pushed through, but nothing seems to be working.

Hopefully theres a simple solution that I've missed

Any help would be appreciated

Chris