A zipper (British English: zip or (rarely) zip fastener) is a commonly used device for temporarily joining two edges of fabric. It is used in clothing (e.g., jackets and jeans), luggageand other bags, sporting goods, camping gear (e.g., tents and sleeping bags), and other daily use items.
Description
The bulk of a zipper consists of two strips of fabric tape, each affixed to one of the two pieces to be joined, carrying from tens to hundreds of specially shaped metal or plastic teeth. These teeth can be either individual or shaped from a continuous coil, and are also referred to aselements.[1] The slider, operated by hand, moves along the rows of teeth. Inside the slider is a Y-shaped channel that meshes together or separates the opposing rows of teeth, depending on the direction of the slider's movement.
Some zippers have two sliders, allowing variation in the opening's size and position. In most jackets and similar garments, the opening is closed entirely when one slider is at each end. In most baggage, the opening is closed entirely when the two sliders are next to each other at any point along the zipper.
Zippers may:
§ increase or decrease the size of an opening to allow or restrict the passage of objects, as in the fly of trousers or in a pocket.
§ join or separate two ends or sides of a single garment, as in the front of a jacket, dress or skirt.
§ attach or detach a separable part of the garment to or from another, as in the conversion between trousers and shorts or the connection / disconnection of a hood and a coat.
§ decorate an item.
These variations are achieved by sewing one end of the zipper together, sewing both ends together, or allowing both ends of the zipper to fall completely apart.
A zipper costs relatively little, but if it fails, the garment may be unusable until the zipper is repaired or replaced—which can be quite difficult and expensive. Problems often lie with the zipper slider; when it becomes worn it does not properly align and join the alternating teeth. If a zipper fails, it can either jam (i.e. get stuck) or partially break off.
History
Elias Howe, who invented the sewing machine, received a patent in 1851 for an "Automatic, Continuous Clothing Closure". Perhaps because of the success of his sewing machine, he did not try to seriously market it, and missed out on any recognition he might otherwise have received. Forty-two years later, Whitcomb Judson, who invented the pneumatic street railway, marketed a "Clasp Locker". The device was similar to Howe's patent, but actually served as a (more complicated) hook-and-eye shoe fastener. With the support of businessman Colonel Lewis Walker, Whitcomb launched the Universal Fastener Company to manufacture the new device. The clasp locker had its public debut at the 1893 Chicago World's Fair and met with little commercial success.
Gideon Sundbäck, a Swedish-American electrical engineer, was hired to work for the Universal Fastener Company in Hoboken, New Jerseyin 1906. Good technical skills and a marriage to the plant-manager's daughter Elvira Aronson led Sundbäck to the position of head designer. After his wife's death in 1911, he devoted himself to the worktable, and by December 1913 had designed the modern zipper.
Sundbäck increased the number of fastening elements from four per inch to ten or eleven, introduced two facing rows of teeth that pulled into a single piece by the slider, and increased the opening for the teeth guided by the slider. The patent for the "Separable Fastener" was issued in 1917. Sundbäck also created the manufacturing machine for the new device. The "S-L" or "scrapless" machine took a special Y-shaped wire and cut scoops from it, then punched the scoop dimple and nib, and clamped each scoop on a cloth tape to produce a continuous zipper chain. Within the first year of operation, Sundbäck's machinery was producing a few hundred feet of fastener per day.
Zipper slider brings together the two sides
The popular "zipper" name came from the B. F. Goodrich Company; they opted to use Sundbäck's fastener on a new type of rubber boots (or galoshes) and referred to it as the zipper, and the name stuck. The two chief uses of the zipper in its early years were for closing boots and tobaccopouches. However, it was almost twenty years before the fashion industry began seriously promoting the novel closure on garments.
In the 1930s, a sales campaign began for children's clothing featuring zippers. The campaign praised zippers for promoting self-reliance in young children by making it possible for them to dress in self-help clothing. The zipper beat the button in 1937 in the "Battle of the Fly", afterFrench fashion designers raved over zippers in men's trousers. Esquire declared the zipper the "Newest Tailoring Idea for Men" and among the zippered fly's many virtues was that it would exclude "The Possibility of Unintentional and Embarrassing Disarray."
The most recent innovation in the zipper's design was the introduction of models that could open on both ends, as on jackets. Today the zipper is by far the most widespread fastener, and is found on clothing, luggage, leather goods, and various other objects.[2]
Types
A coil zipper with its slider removed.
§ Coil zippers now form the bulk of sales of zippers worldwide. The slider runs on two coils on each side; the "teeth" are the coils. Two basic types of coils are used: one with coils in spiral form, usually with a cord running inside the coils; the other with coils in ladder form, also called the Ruhrmann type. This second type is now used only in a few parts of the world, mainly in South Asia. Coil zippers are made of polyester coil and are thus also known as polyester zippers. Nylon was formerly used and though only polyester is used now, the type is still known as a nylon zipper.
§ Invisible zippers' teeth are behind the tape. The tape's color matches the garment's, as does the slider, so that, except the slider, the zipper is "invisible". This kind of a zipper is common in skirts and dresses. Invisible zippers are usually coil zippers. They are also seeing increased use by the military and emergency services because the appearance of a button down shirt can be maintained, while providing a quick and easy fastening system.
§ Metallic zippers are the classic zipper type, found mostly in jeans today. The teeth are not a coil, but are individual pieces of metal moulded into shape and set on the zipper tape at regular intervals. Metal zippers are made in brass, aluminum and nickel, according to the metal used for teeth making. All these zippers are basically made from flat wire. A special type of metal zipper is made from pre-formed wire, usually brass but sometimes other metals too. Only a few companies in the world have the technology. This type of pre-formed metal zippers is mainly used in high grade jeanswear, workwear, etc., where high strength is required and zippers need to withstand tough washing.
§ Plastic-molded zippers are identical to metallic zippers, except that the teeth are plastic instead of metal. Metal zippers can be painted to match the surrounding fabric; plastic zippers can be made in any color of plastic. Plastic zippers mostly use polyacetal resin though other resins are used as well, such as polyethylene.
§ Open-ended zippers use a "box and pin" mechanism to lock the two sides of the zipper into place, often in jackets. Open-ended zippers can be of any of the above specified types.
Waterproof zipper on a diving dry suit. The exterior metal segments clamp the waterproof sheeting over the individual zipper teeth. The zipper teeth are not visible in this image.
Airtight zippers were first developed by NASA for making high-altitude pressure suitsand later space suits, capable of retaining air pressure inside the suit in the vacuumof space.
The airtight zipper is built like a standard toothed zipper, but with the zipper teeth wrapped in a fabric-reinforced polyethylene sheeting. The sheeting is then crimped around each zipper tooth using a C-shaped metal clip. As the zipper is closed, the facing edges of the plastic sheeting are pressed together between the C-shaped clips, both above and below the zipper teeth.
This double-mated surface is good at retaining both vacuum and pressure, but the fit must be very tight to press the surfaces together firmly. Consequently these zippers are typically very stiff when zipped shut and have very minimal flex or stretch. They are hard to open and close because the zipper anvil must bend apart teeth that are being held together by the tough plastic sheeting. They can also be derailed and damage the sealing surfaces if the teeth are misaligned while straining to pull the zipper shut.
These zippers are very common where airtight or watertight seals are needed, such as on scuba diving dry suits, ocean survival suits andhazmat suits.
A second, less common water-resistant zipper is similar in construction to a standard toothed zipper, but includes a molded plastic ridge seal similar to the mating surfaces on a ziploc bag. Such a zipper is much easier to open and close than a clipped version, and the slider has a gap above the zipper teeth for separating the ridge seal. However, this ridge seal is structurally weak against internal pressure, and can be separated by pressure within the sealed container pushing outward on the ridges, which will simply flex and spread apart, potentially allowing air or liquid entry through the spread-open ridges. Ridge-sealed zippers are sometimes seen on lower cost surface dry suits.
Components of a zipper
The components of a zipper are:
§ 1 - top tape extension
§ 2 - top stop
§ 3 - slider
§ 4 - pull tab
§ 5 - tape
§ 6 - chain width
§ 7 - bottom stop
§ 8 - bottom tape extension
§ 9 - single tape width
§ 10 - insertion pin
§ 11 - retainer box
§ 12 - reinforcement film
One large manufacturer is YKK, which has production facilities in 68 countries and the world’s largest zipper manufacturing center in Macon, Georgia, USA, with 900 employees[citation needed]. Almost all of the rest are made in South Asia and East Asia[citation needed]. Major zipper manufacturing countries in South Asia are now Bangladesh, India and Pakistan
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