Technical Standards

10. Missing holes

During the perforating process punches may break partially or totally. The risk of imperfect or missing holes is higher with certain difficult perforation specifications: where the size of hole/thickness of plate ratio = 1; where the width of bridge/thickness of plate ratio = 1; for small holes; with special materials; when there is maximum open area.

The normal tolerance of about 2 % incomplete or missing holes, relating to the perforated area, is according the background art. For the more difficult perforation specifications and tighter requirements, especially for plates used for decoration, other tolerances need to be agreed separately.