Dragkedjorna

Dragkedjorna, or zippers in English, are fastening devices used to join two edges of fabric or other flexible materials. They consist of two fabric tapes with interlocking teeth and a movable slider that opens or closes the teeth as it travels along the tapes.

History: The concept emerged in the late 19th and early 20th centuries. Whitcomb Judson invented an early "clasp locker" in the 1890s; Gideon Sundback improved the design in 1913, producing the first practical zipper. The modern zipper entered mass production in the 1920s–1930s; YKK, founded in 1934, became the leading manufacturer.

Construction and types: The device has two fabric tapes carrying interlocking teeth (metal or molded plastic). A slider engages or disengages the teeth; end stops prevent it from sliding off. Teeth materials include metal and plastic (nylon). Common types include coil or tape zippers (nylon coil teeth), molded-plastic zippers, and metal zippers; variants include invisible zippers and waterproof or water-repellent designs; separable zippers used in jackets.

Applications and maintenance: Zippers are ubiquitous in clothing, bags, tents and equipment. Proper care involves keeping the zipper clean, avoiding dirt ingress, occasionally lubricating the slider with graphite or silicone, and replacing worn or bent teeth or sliders. Do not force a zipper that sticks.

Impact: Dragkedjorna have become a standard fastening method worldwide, supporting a wide range of products and industries. Their simplicity, durability, and low cost have contributed to broad adoption and continuous development in materials and manufacturing.