Galvanized steel + EPDM washer
Steel with GreyCoat anti-corrosion coating
The self-tapping screws for sandwich panels are optimized for attaching sandwich panels to steel or wooden substrates. They are capable of drilling metal up to 12 mm.
Both self-tapping and self-drilling screws have a top thread that grips the outer shell of the sandwich panel so that the sealing washer is pressed against it at the appropriate pressure, avoiding damage or local deformation of the sheet metal. This is why the upper thread has a larger diameter than the lower thread, which is driven into the support structure.
The self-tapping screws for sandwich panels are made of carbon steel with a galvanized coating or with a protective anti-corrosion coating GreyCoat.