A machine tool is a powered mechanical device， typically used to fabricate metal components of machines by machining， which is the selective removal of The term machine tool is usually reserved for tools that used a power source other than human movement， but they can be powered by people if appropriately set Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of The earliest lathe with direct mechanical control of the cutting tool was a screw-cutting lathe dating to about [1] This lathe "produced screw threads out of wood and employed a true compound slide rest"The first machine tools offered for sale ( commercially available) were constructed by one Matthew Murray in England around [2]Contents [hide]1 Overview 2 Examples 3 See also 4 References 5 Bibliography 6 Further reading 7 External links [edit] OverviewMachine tools can be powered from a variety of Human and animal power are options， as is energy captured through the use of However， modern machine tools began to develop only after the development of the steam engine， which led to the Industrial R Today， most machine tools are powered by Machine tools can be operated manually， or under automatic Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked Soon after World War II， the numerical control (NC) machine was NC machines used a series of numbers punched on paper tape or punch cards to control their In the 1960s， computers were added to give even more flexibility to the Such machines became known as computerized numerical control (CNC) NC and CNC machines could precisely repeat sequences over and over， and could produce much more complex pieces than even the most skilled tool Before long， the machines could automatically change the specific cutting and shaping tools that were being For example， a drill machine might contain a magazine with a variety of drill bits for producing holes of various Previously， either machine operators would usually have to manually change the bit or move the work piece to another station to perform these different The next logical step was to combine several different machine tools together， all under computer These are known as machining centers， and have dramatically changed the way parts are From the simplest to the most complex， most machine tools are capable of at least partial self-replication， and produce machine parts as their primary [edit] ExamplesExamples of machine tools are:Broaching machine Drill press Gear shaper Hobbing machine Hone Lathe Screw machines Milling machine Shaper Saws Planer Stewart platform mills Grinding machines When fabricating or shaping parts， several techniques are used to remove unwanted Among these are:Electrical discharge machining Grinding (abrasive cutting) Multiple edge cutting tools Single edge cutting tools Other techniques are used to add desired Devices that fabricate components by selective addition of material are called rapid prototyping Several regions of the United States became centers for machine tool development between 1800 and 1950， including Philadelphia， Pennsylvania; Cincinnati， Ohio; Rockford， Illinois; Providence， Rhode Island] Springfield， Vermont; Windsor， Vermont; Hartford， Connecticut; and Bridgeport， C
