![Perforations US1940 issues-2c](https://upload.wikimedia.org/wikipedia/commons/2/2c/Perforations_US1940_issues-2c.jpg)
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 collectively are called a ''perforation''. The process of creating perforations is called perforating, which involves puncturing the workpiece with a
tool
A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ba ...
.
Perforations are usually used to allow easy separation of two sections of the material, such as allowing
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
to be torn easily along the line.
Packaging
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a co ...
with perforations in
paperboard
Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 Inch#equivalences, points) than paper and has certain ...
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 film
Plastic film is a thin continuous polymeric material. Thicker plastic material is often called a "sheet". These thin plastic membranes are used to separate areas or volumes, to hold items, to act as barriers, or as printable surfaces.
Plas ...
s to allow the packages to breathe, medical films,
micro perforated plate A micro perforated plate (MPP) is a device used to absorb sound, reducing its intensity. It consists of a thin flat plate, made from one of several different materials, with small holes punched in it. An MPP offers an alternative to traditional so ...
and
sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
and
vapor
In physics, a vapor (American English) or vapour (British English and Canadian English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critic ...
barriers.
Processes
Pins and needles
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
Elasticity often refers to:
*Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress
Elasticity may also refer to:
Information technology
* Elasticity (data store), the flexibility of the data model and the cl ...
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
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
,
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
, and
aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
.
In more
brittle
A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Bre ...
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
Die and punch sets can be used for thicker materials or materials that require large holes; this process is the most common for
metalworking
Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale ...
. The workpiece is
sheared by pressing (either by machine or hand tool) the
punch
Punch commonly refers to:
* Punch (combat), a strike made using the hand closed into a fist
* Punch (drink), a wide assortment of drinks, non-alcoholic or alcoholic, generally containing fruit or fruit juice
Punch may also refer to:
Places
* Pun ...
through the workpiece and into the
die
Die, as a verb, refers to death, the cessation of life.
Die may also refer to:
Games
* Die, singular of dice, small throwable objects used for producing random numbers
Manufacturing
* Die (integrated circuit), a rectangular piece of a semicondu ...
. The middle section of the workpiece is scrap; commonly known as the
chad
Chad (; ar, تشاد , ; french: Tchad, ), officially the Republic of Chad, '; ) is a landlocked country at the crossroads of North and Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic ...
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.
Common applications are fruit and vegetable bags,
hole punch
A hole punch, also known as hole puncher, or paper puncher, is an office tool that is used to create holes in sheets of paper, often for the purpose of collecting the sheets in a binder or folder. A ''hole punch'' can also refer to similar t ...
ing and
ticket punch
A ticket punch (or control nippers) is a hand tool for permanently marking admission tickets and similar items of paper or card stock. It makes a perforation and a corresponding chad. A ticket punch resembles a hole punch, differing in that the t ...
ing.
Laser perforation
Laser cutting
Laser cutting is a technology that uses a laser to vaporize materials, resulting in a cut edge. While typically used for industrial manufacturing applications, it is now used by schools, small businesses, architecture, and hobbyists. Laser cutt ...
can place many precise holes in a web. Laser perforations look similar in many respects to hot needle perforations. However, laser systems are expensive. The big advantage of laser perforation is the consistency of the hole size, compared to mechanical perforation. This is very important in
modified atmosphere packaging
Modified atmosphere packaging (MAP) is the practice of modifying the composition of the internal atmosphere of a package (commonly food packages, drugs, etc.) in order to improve the shelf life. The need for this technology for food arises from t ...
for fresh produce. The laser perforation is often carried out on
roll slitting
Roll slitting is a shearing operation that cuts a large roll of material into narrower rolls. There are two types of slitting: log slitting and rewind slitting. In log slitting the roll of material is treated as a whole (the 'log') and one or mo ...
machines (slitter rewinder) as the printed material is slit down to the finished roll size.
Applications
![Paper perforator](https://upload.wikimedia.org/wikipedia/commons/2/2d/Paper_perforator.jpg)
Perforation frequently refers to the practice of creating a long series of holes or slits so that
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
or
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s can be torn more easily along a given line: this is used in easy-open
packaging
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a co ...
. Since the creation of perforation devices in the 1840s and 1850s, it has seen use in several areas.
Postage stamp
A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...
s are one common application of this, where small round holes are cut in lines to
create individual pieces. Perforations on stamps are rather large, in the order of a millimeter, in comparison other perforated materials often have smaller holes.
It is common for
cheque-book
A cheque, or check (American English; see spelling differences) is a document that orders a bank (or credit union) to pay a specific amount of money from a person's account to the person in whose name the cheque has been issued. The pers ...
s,
notebook
A notebook (also known as a notepad, writing pad, drawing pad, or legal pad) is a book or stack of paper pages that are often ruled and used for purposes such as note-taking, journaling or other writing, drawing, or scrapbooking.
History
...
s and
legal pads to have perforations making it easier to tear out individual pages or
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
. Perforation is used in ways to separate
loose leaf
A loose leaf is a piece of paper of any kind that is not bound in place, or available on a continuous roll, and may be punched so as to be organized in a ring binder. Loose leaf paper may be sold as free sheets, or made up into notepads, where ...
(or even a form of
graph paper
Graph paper, coordinate paper, grid paper, or squared paper is writing paper that is printed with fine lines making up a regular grid. The lines are often used as guides for plotting graphs of functions or experimental data and drawing curves. I ...
from a
ringed binder). A fine perforation next to the rings allows the page to be separated from the book with no
confetti
Confetti are small pieces or streamers of paper, mylar, or metallic material which are usually thrown at celebrations, especially parades and weddings. The origins are from the Latin ''confectum'', with ''confetti'' the plural of Italian ''con ...
.
Screwcap A screw cap or closure is a common type of closure for bottles, jars, and tubes.
Usage
A screw closure is a mechanical device which is screwed on and off of a "finish" on a container. Either continuous threads or lugs are used. It must be engi ...
s on glass or
plastic bottle
A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft drinks, motor oil, cooking oil, medicine, shampoo, milk, and ink. The size ranges from v ...
s 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.
![FortranCardPROJ039](https://upload.wikimedia.org/wikipedia/commons/5/58/FortranCardPROJ039.agr.jpg)
The edges of
film stock
Film stock is an analog medium that is used for recording motion pictures or animation. It is recorded on by a movie camera, developed,
edited, and projected onto a screen using a movie projector. It is a strip or sheet of transparent p ...
are perforated to allow it to be moved precise distances at a time continuously. Similarly,
punched card
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
s for use in
loom
A loom is a device used to weave cloth and tapestry. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads. The precise shape of the loom and its mechanics may vary, but th ...
s and later in
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s input and output devices in some cases were perforated to ensure correct positioning of the card in the device, and to encode information.
Perforation of steel strips is used in the manufacture of some
zester
A zester (also, citrus zester or lemon zester) is a kitchen utensil for obtaining zest from lemons and other citrus fruit. A kitchen zester is approximately long, with a handle and a curved metal end, the top of which is perforated with a row of ...
s and
rasp
A rasp is a coarse form of file used for coarsely shaping wood or other material. Typically a hand tool, it consists of a generally tapered rectangular, round, or half-round sectioned bar of case hardened steel with distinct, individually cut ...
s.
Historically, perforation patterns other than linear were used to
mark stamps. A series of patents had been issued in the late 19th century for perforation machines to be used on rail lines for ticketing. Libraries and private collections used similar perforating stamps to mark ownership of books. End sheets, title pages, and image plates were punched with the namesake of the collection. Today, similarly elaborate perforation patterns continue to be used in
orienteering
Orienteering is a group of sports that require navigational skills using a map and compass to navigate from point to point in diverse and usually unfamiliar terrain whilst moving at speed. Participants are given a topographical map, usually a s ...
.
Bread bags for some bread often have micro-perforations in the plastic, which is supposed to keep the bread fresh by releasing excess moisture. Similarly, bags of concrete use small perforations to allow air to escape while they are being filled.
See also
*
Film perforations
Film perforations, also known as perfs and sprocket holes, are the holes placed in the film stock during manufacturing and used for transporting (by sprockets and claws) and steadying (by pin registration) the film. Films may have different types ...
*
Punched tape
Five- and eight-hole punched paper tape
Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop
Punched tape or perforated paper tape is a form of data storage ...
References
{{Reflist
Fabrication (metal)
Industrial processes
Braille