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Interchangeable parts are parts (components) that are, for practical purposes, identical. They are made to specifications that ensure that they are so nearly identical that they will fit into any assembly of the same type. One such part can freely replace another, without any custom fitting (such as filing). This interchangeability allows easy assembly of new devices, and easier repair of existing devices, while minimizing both the time and skill required of the person doing the assembly or repair. The concept of interchangeability was crucial to the introduction of the assembly line at the beginning of the 20th century, and has become an important element of some modern manufacturing but is missing from other important industries. Interchangeability of parts was achieved by combining a number of innovations and improvements in machining operations and the invention of several machine tools, such as the slide rest lathe, screw-cutting lathe, turret lathe, milling machine and metal planer. Additional innovations included jigs for guiding the machine tools, fixtures for holding the workpiece in the proper position, and blocks and gauges to check the accuracy of the finished parts. Electrification allowed individual machine tools to be powered by electric motors, eliminating line shaft drives from steam engines or water power and allowing higher speeds, making modern large scale manufacturing possible. Modern machine tools often have numerical control (NC) which evolved into CNC (computerized numeric control) when microprocessors became available. Methods for industrial production of interchangeable parts in the United States were first developed in the nineteenth century. The term ''American system of manufacturing'' was sometimes applied to them at the time, in distinction from earlier methods. Within a few decades such methods were in use in various countries, so ''American system'' is now a term of historical reference rather than current industrial nomenclature. == First Use == Evidence of the use of interchangeable parts can be traced back over two thousand years to Carthage in the First Punic War. Carthaginian ships had standardized, interchangeable parts that even came with assembly instructions akin to "tab a into slot b" marked on them.〔(Rome, Carthage, and the Punic Wars ) Meanwhile Carthage was mass producing warships. And that's not an exaggeration either about numbers or about shipbuilding methods; Carthaginian warships were built up of standard interchangeable parts. We know this not only from contemporary accounts, but also from recovered Carthaginian ships like the half of a Carthaginian ship shown in (c), above, that was recovered off the coast of Marsala at the western tip of Sicily; it was brand new when it was sunk by the Romans, and it still retains marks giving assembly instructions ("tab a into slot b", etc.) Other recovered ships had identical parts.〕 In East Asia during the Warring States period and later the Qin Dynasty, bronze crossbow triggers and locking mechanisms were mass-produced and made to be interchangeable. Bi Sheng later employed the concept in the 11th century by using moveable type. Before the 18th century, devices such as guns were made one at a time by gunsmiths, and each gun was unique. If one single component of a firearm needed a replacement, the entire firearm either had to be sent to an expert gunsmith for custom repairs, or discarded and replaced by another firearm. During the 18th and early 19th centuries, the idea of replacing these methods with a system of interchangeable manufacture was gradually developed.〔, (p. 4 ).〕〔.〕 The development took decades and involved many people.〔〔 In the late 18th century, French General Jean-Baptiste Vaquette de Gribeauval promoted standardized weapons in what became known as the ''Système Gribeauval'' after it was issued as a royal order in 1765. (Its focus at the time was artillery more than muskets or handguns.) One of the accomplishments of the system was that solid cast cannons were bored to precise tolerances, which allowed the walls to be thinner than cannons poured with hollow cores. However, because cores were often off center, the wall thickness determined the size of the bore. Standardized boring allowed cannon to be shorter without sacrificing accuracy and range because of the tighter fit of the shells. It also allowed standardization of the shells. Gribeauval provided patronage to Honoré Blanc, who attempted to implement the ''Système Gribeauval'' at the musket level. By around 1778, Honoré Blanc began producing some of the first firearms with interchangeable flint locks, although they were carefully made by craftsmen. Blanc demonstrated in front of a committee of scientists that his muskets could be fitted with flint locks picked at random from a pile of parts. 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「interchangeable parts」の詳細全文を読む スポンサード リンク
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