Perforation

In more brittle films, cold perforation can cause slitting rather than creating a round hole, which can jeopardize the material's integrity under pressure.

The middle section of the workpiece is scrap; commonly known as the chad in paper and similar materials.

Perforation frequently refers to the practice of creating a long series of holes or slits so that paper or plastics can be torn more easily along a given line: this is used in easy-open packaging.

Postage stamps are one common application of this, where small round holes are cut in lines to create individual pieces.

It is common for cheque-books, notebooks and legal pads to have perforations making it easier to tear out individual pages or leaves.

Perforation is used in ways to separate loose leaf (or even a form of graph paper from a ringed binder).

Screwcaps on glass or plastic bottles are sealed with a ring at the bottom of the cap attached by perforation.

Twisting the cap has the effect of rupturing the material between the perforations and indicating that the original seal has been broken.

The edges of film stock are perforated to allow it to be moved precise distances at a time continuously.

A series of patents had been issued in the late 19th century for perforation machines to be used on rail lines for ticketing.