The metal mill is primarily used on stone wool boards. For polystyrene, the use of a plastic mill is recommended.

The mill removes a piece of thermal insulation material with:

• Diameter: 67mm
• Thickness: 10 millimeters

This ensures that the plastic supports used do not align with the thermal insulation material and can be covered with a cap made of the same material. This way, thermal bridges and the problems they bring, mainly unwanted condensation, are avoided.

Another advantage is that supports that are 2cm shorter are used.