3 Axis CNC MILLING MACHINE
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Date
2013
Authors
Ahmad M. Shayeb
Ahmad W. Odeh
Otrah Y. Al-Husseini
Shadi B. Hantouli
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Abstract
The machining or cutting of metals portion of manufacturing became important around thetime of the industrial revolution. In 1775, John Wilkinson invented a cannon-boringmachine (lathe) in England .He adapted that machine for boring the cylinders forBoulton & Watt's steam engines. His boring process was the only one of its kind to producethe smooth, tightly tolerance bores required of the cylinder of a steam engine.A bit later in the year 1818 Eli Whitney (inventor of the cotton gin) invented a millingmachine in New Haven Connecticut .Prior to the milling machine, a machinist's toolswere primarily files and required a highly skilled operator. The milling machine allowed aless skilled operator to make the same quality of parts as the skilled operator with the file.The spindle of Eli Whitney's milling machine was moved from being horizontal to beingvertical. This is commonly seen in the Bridgeport style knee-mill.In year 1952 John Parsons invented NC (Numeric Control) milling machine. Parsonsworked to attach servomotors to the x and y axis controlling them with a computer thatreads punch cards to give it positioning instructions .The reason for devising such asystem was to machine complex shapes like arcs that can be made into airfoils forairplanes.Today, modern machinery are CNC (Computer Numeric Control) milling machines andlathes. A microprocessor in each machine reads the G-Code program that the user createsand performs the programmed operations. Personal Computers are used to design the partsand are also used to write programs by either manual typing of G-Code or using CAM(Computer Aided Manufacturing) software that outputs G-Code from the users input ofcutters and tool path . CNC can be classified according work as lathes, milling machines,laser cutters and other industrial tools. The CNC term refers to a large group of thesemachines that utilize computer logic to control movements and perform themetalworking[2].Lathes are designed for the precise machining of relative hard materials. These rigidmachine tools remove material from a rotating work piece via the (typically linear)movements of various cutting tools, such as tool bits and drill bits.Rotating is the way that lathe shapes the material and with a rapid speed, this is done bypressing a fixed cutting or abrading tool. Now a days, lathes equipped with the CNC to helpfashion tool and products.The machine is controlled electronically via a computer menu style interface, the programmay be modified and displayed at the machine, along with a simulated view of the process.The operator needs a high level of skill to perform the process, however the knowledgebase is broader compared to the older production machines where intimate knowledge ofeach machine was considered essential. These machines are often set and operated by thesame person, where the operator will supervise a small number of machines (cell)[3].Milling is the process of cutting away material by feeding a workpiece past a rotatingmultiple tooth cutter. The cutting action of the many teeth around the milling cutterprovides a fast method of machining. Milling machines are classified to, peripheral milling,Another classification of milling according to the movement is the vertical and horizontalmilling. In the vertical mill, the spindle axis is vertically oriented. The horizontal mill hasthe same sort of xy table, but the cutters are mounted on a horizontal arbor across thetable[4].All CNC machine types share this commonality: They all have two or more programmabledirections of motion called axes. An axis of motion can be linear (along a straight line) orrotary (along a circular path). One of the first specifications that implies a CNC machine'scomplexity is how many axes it has. Generally, the more axes, the more complex the machine .