Perforations in a web.
Perforations in moving webs can be detected with a special detection bar and a high voltage generator. Perforations will be detected but not localised. A special HD Det electrode is mounted over a roller to create a strong electrical field. A perforation in the film will create a spark through the material and will generate an output signal on the charging generator. Due to the strong electrical field placement of anti-static bars after the perforation detection is mandatory.