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A file is a metalworking, woodworking and plastic working tool used to cut fine amounts of material from a work piece. It most commonly refers to the hand tool style, which takes the form of a steel bar with a case hardened surface and a series of sharp, parallel teeth. Most files have a narrow, pointed tang at one end to which a handle can be fitted.〔.〕 A similar tool is the rasp. This is an older form, with simpler teeth. As they have larger clearance between teeth, these are usually used on softer, non-metallic materials. Related tools have been developed with abrasive surfaces, such as diamond abrasives or silicon carbide. Because of their similar form and function, these have also been termed 'files'. == History == Early filing or rasping (the distinction is emic, not etic) has prehistoric roots and grew naturally out of the blending of the twin inspirations of cutting with stone cutting tools (such as hand axes) and abrading using natural abrasives, such as well-suited types of stone (for example, sandstone).〔, (pp. 5–15 ).〕 Relatedly, lapping is also quite ancient, with wood and beach sand offering a natural pair of lap and lapping compound. The Disston authors state, "To abrade, or file, ancient man used sand, grit, coral, bone, fish skin, and gritty woods,—also stone of varying hardness in connection with sand and water."〔, (p. 5 ).〕 The Bronze Age and the Iron Age had various kinds of files and rasps. Archaeologists have discovered rasps made from bronze in Egypt, dating back to the years 1200–1000 BC. Archaeologists have also discovered rasps made of iron used by the Assyrians, dating back to the 7th Century BC. During the Middle Ages files were already quite advanced, thanks to the extensive talents of blacksmiths.〔, (pp. 16–17 ).〕 By the 11th century, there already existed hardened files that would seem quite modern even to today's eyes.〔 But although they existed, and could even have spread widely, in a geographical sense, via trade, they were not widespread in the cultural sense of the word—that is, most people, and even many smiths, did not have them. For example, in the 13th century, ornamental iron work at Paris was done skillfully with the aid of files, but the process was a secret known only to a master craftsman.〔 The Disston authors state, "It was not until the fourteenth century, however, that those who practiced art in ironwork began to use other tools, besides heat and the hammer, regularly."〔 This statement could mislead in the sense that stoning (with sandstone) and lapping (with wood, sand, and water) have never been rare activities among humans, or especially smiths. But the point is that modern iron or steel files, with teeth and hardening, and the material culture of intricate filing that would lead to locksmithing and gunsmithing, for example, are what took time to become common. But by the late Middle Ages, however, the transition was extensive. The Disston authors mention Nuremberg, Sheffield, and Remscheid (they use the ''Reimscheid'' spelling) as leading centers of production for files as well as tools in general. The activity in Remscheid reflects the metalworking spirit of the Rhine-Ruhr region in general (including Essen, Düsseldorf, and Cologne) rather than representing a single village of geniuses in isolation. (In fact, given the Disston authors' mention of the blacksmith guilds of 13th-century Florence and 15th-century England, coupled with their mention of Nuremberg, Sheffield, and Remscheid, it is interesting to trace a region that sweeps from Florence through Nuremberg, the Rhine-Ruhr, the Netherlands, and up to Sheffield, and to compare it with the modern economics notation of the Blue Banana.) Most files of the period were smithed by hand in a sequence in which the iron was forged (heated and hammered), then the teeth were cut with a chisel (some of this action was just as much upsetting/swaging as it was cutting), and then the piece was hardened (by heating and then quenching), followed sometimes by tempering. Among the drawings of Leonardo da Vinci is a sketch of a machine tool for the cutting of files (the chisel would make one strike, swaging a tooth, then automatically advance into position for the next tooth, and strike again). Prior to the industrialization of machining and the development of interchangeable parts during the 19th century, filing was much more important in the construction of mechanisms. Component parts were roughly shaped by forging, casting, and by primitive machining operations. These components were then individually hand-fit for assembly by careful and deliberate filing. The potential precision of such fitting is much higher than generally assumed, but the components of such hand-fit assemblies are decidedly not interchangeable with those from another assembly. Locks, clocks, and firearms (flintlocks and earlier) were manufactured in this way for centuries before the Industrial Revolution. Machining in the mid-19th century was heavily dependent on filing, because milling practice was slowly evolving out of its infancy. As late as the early 20th century, manufacturing often involved filing parts to precise shape and size. In today's manufacturing environment, milling and grinding have generally replaced this type of work, and filing (when it occurs at all) usually tends to be for deburring only. Skillful filing to shape and size is still a part of diemaking, moldmaking, toolmaking, etc., but even in those fields, the goal is usually to avoid handwork when possible. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「File (tool)」の詳細全文を読む スポンサード リンク
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