How to fit countersunk (CSK) buttons and bolt liners

1. Cut the fixing hole through the full plate thickness (plasma or water jet). Precision countersinks can also be produced by EDM.
2. Insert a CSK weld button / countersunk washer so its face sits at or just below the overlay surface.
3. Fillet weld the button to the mild steel backing from the face side using a low-hydrogen electrode — the weld must bond to backing steel, never rely on the overlay.
4. Fit the countersunk bolt from the wear face; torque from behind.
5. Cap the button face and any exposed weld with QARC™ hardfacing wire so the fixing wears at the same rate as the plate.

For applications needing machined features, weld a pre-machined mild steel insert into a cut-out and machine conventionally.