Technical Standards

6. Wavy edge

The tension that arises during the perforating may cause a deviation in the flatness of the edges, the so-called "wavy edge", especially where perforated sheets and coils have wide unperforated margins, or where there are unperforated margins of different widths on either side.

Deviation within the permissible tolerances of the flatness, as stipulated in point 5, will be guaranteed for perforated sheets with standard perforation and narrow unperforated margins, of equal width, on the long side (i.e. margins narrower than approx. 2,5 % of the sheet width up to a maximum of 10 mm).

Perforated sheets and coils with wider unperforated margins or with unperforated margins of different widths on the long side, or special perforations, such as countersunk perforation, upper die etc. tend to have considerably higher flatness deviations, especially when using soft materials (Al, Cu, CuZn). The acceptable tolerances then need to be agreed separately.