The perforation (from latin perforare literally for "pierce") or perforation is the piercing of hollow or flat objects. The regular arrangement, quantity, shape and size of the holes play a role, especially in technology.
In addition to the many areas of application mentioned below, special perforations can also be found in industrial applications. In the area of surface, filter and sieve technology, perforation is often the decisive factor. The perforation, in terms of size, shape and arrangement, results in particular from the goods to be processed or the behavior of the medium to be processed or used in a process. Solids generally behave completely differently here than liquid media. In the case of solids, it is usually a matter of sieving or separating the goods or the medium using different or adapted special perforations. Like there are flour, sand, dust, powder, small parts, grain, round vegetables and fruits, or the separation of soil, like with potatoes, or chaff with grain.
Surface technology is a special area. Here in particular the heat treatment of metals, coating and painting or in the area of electroplating.
In the beginning, wire mesh was used, later also with punched perforations. Here it was initially round hole perforations or slotted hole perforations. Some time later the Conidur perforation used in the food industry was added. These perforations, which are now commercially available, very quickly reached their limits. Physical effects severely limit these perforations. This results from the geometry of the perforation and the physical laws that work there, as well as the insufficient perforation area.
Here a company from Menden began to investigate the properties of the different perforation geometries in the mid-1990s. The result was the patented sickle and sinus perforation, which has been further developed to this day. In the meantime, these perforations, some of which are patented, have become the standard in the field of surface technology and heat treatment.
Photography and film
Dickson first used the perforation on roll films for his cinematograph in 1893, allowing 70 mm film, cut lengthways, to run horizontally in the apparatus. The Lumière brothers also used a perforating machine for their 35 mm film , but they let it run vertically through the machine.
Print / paper
Slit and hole punching in paper or cardboard for separating a sheet or part of a sheet. Manufacture in continuous printing (e.g. with dot matrix printers) also with letterpress (such as the Heidelberger Tiegel - platen printing presses) or generally perforating machines , sometimes also in offset printing machines by gluing the perforation lines to the impression cylinder and using the blanket as a counter-form. A perforation is measured in teeth (see also leaf shape: spreading edge ) or inches .
In philately (postage stamps), perforation refers to the teeth or piercing of a sheet of postage stamps for easier separation of the individual postage stamps . (Compare also postage stamp separation ).
In medicine , a perforation refers to the breakthrough or penetration of tissue that encases a body cavity. The term is used in a variety of ways:
- disease-related perforation
- Accident or gun impact
- therapeutic perforation
- iatrogenic perforation
In anatomy, for example, the veins that connect the deep and superficial venous system on the leg are called perforating veins . These vessels pierce (= perforate) the fasciae of the legs on their way .
Disease-related perforations occur
- in the gastrointestinal tract: esophagus , stomach , duodenum , small intestine , large intestine , biliary tract
- in the ENT area: eardrum
- in dentistry
- in gynecology : uterus and
- in urology: urinary bladder
A perforation of the esophagus is always life-threatening and can be triggered by a tumor. Ulcers of the stomach and duodenum can break through into the abdominal cavity and cause an acute abdomen . Gallstones can also cause perforation by applying pressure to the gallbladder wall. A perforation of the large intestine occurs, for example, in ulcerative colitis . In the ENT field, the facilities of a can otitis emptied by a perforation of the tympanic membrane in the ear canal. A perforation of the uterus can occur during a spontaneous birth after a caesarean section due to the rupture of the old scar. The urinary bladder can be perforated by a malignant tumor, causing urine to empty into the abdominal cavity.
Perforations can also occur in accidents involving sharp objects. Falling on a point is called a stake injury . Even after knife attacks or gunshot wounds, perforations must be ruled out or repaired.
Therapeutic perforations are e.g. B. used to drain pus to the outside. One example is perforation of the eardrum to drain the pus from an otitis media into the ear canal. In the case of abscesses, too, the surgeon will first perform a perforation to drain the pus.
Iatrogenic perforations are unintentionally created by the doctor during a therapeutic measure. When scraping the uterus, for example, there is occasional unwanted perforation of the uterine wall. This can spread germs into the abdominal cavity and cause peritonitis . The dentist speaks of a perforation if, for example, the maxillary sinus was opened during a root canal treatment .
The problem with chemical pressure impregnation is that the most important construction timber, spruce, is very difficult to impregnate. The shallow penetration depths of usually just a few millimeters are generally not sufficient for effective protection of wooden components. In order to improve the impregnation of spruce wood, perforation has been used since the 50s of the last century. This method consists in making slots or holes in the wood surface in a relatively narrow grid, that is, "perforating" the wood to a desired depth. The perforation of the wood increases the absorption of the wood preservative.
Oil and gas production
The perforation is the point at which the conveyed material (crude oil or natural gas) flows into the conveyor system.
Leather as a cover material for furniture is partially perforated for better ventilation.
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