Perforation

A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes are called a perforation. The process of creating perforations is called perforating, which involves puncturing the workpiece with a tool.

Perforations are usually used to allow easy separation of two sections of the material, such as allowing paper to be torn easily along the line. Packaging with perforations in paperboard or plastic film is easy for consumers to open. Other purposes include filtrating fluids, sound deadening, allowing light or fluids to pass through, and to create an aesthetic design.

Various applications include plastic films to allow the packages to breathe, medical films, micro perforated plate and sound and vapor barriers.

Perforation can be created by pins, needles, die and punch or laser.

Rotary pinned perforation rollers are precision tools that can be used to perforate a wide variety of materials. The pins or needles can be used cold or heated. Cold perforation tools include needle punches.

There are a handful of manufacturers that specialize in hot and cold needle perforation tooling and equipment. In materials that have elasticity this can result in a "volcano" hole that is preferred in many applications.

Pinned rollers can be made from a variety of materials, including plastic, steel, and aluminum.

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 solution to this is often heating the pin; i.e. hot pin perforation. Hot perforation melts a hole in the material, causing a reinforced ring around the hole. Hot needle perforation also assists when high density pin patterns are utilized, as the heat aids the perforation of the material.

Die and punch sets can be used for thicker materials or materials that require large holes; this process is the most common for metalworking. The workpiece is sheared by pressing (either by machine or hand tool) the punch through the workpiece and into the die. The middle section of the workpiece is scrap; commonly known as the chad in paper and similar materials. The punch and die are shaped to produce the desired shaped hole. The clearance (the distance between the outside circumference of the punch and the inner circumference of the die) must be properly maintained to ensure a clean cut. Burrs are produced on the side of the workpiece that is against the die.

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Wikipedia