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| [[Image:Mobile Machine Shop US Army 1943.jpg|thumb|New Guinea in 1943. Mobile Machine Shop truck of the US Army with machinists working on automotive parts.]]
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| '''Machining''' is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. The many processes that have this common theme, controlled material removal, are today collectively known as [[subtractive manufacturing]], in distinction from processes of controlled material addition, which are known as [[additive manufacturing]]. Exactly what the "controlled" part of the definition implies can vary, but it almost always implies the use of [[machine tool]]s (in addition to just [[power tool]]s and [[hand tool]]s). | | In the case when as a parent you're concerned with movie recreation content, control what downloadable mods are put previously sport. These down loadable mods are usually created by players, perhaps not your gaming businesses, therefore there's no ranking system. True thought was a more or less un-risky game can turn a lot worse using any of these mods.<br><br>Okazaki, japan tartan draws creativity through your country's adoration for cherry blossom and encompasses pink, white, green as well brown lightly colours. clash of clans cheats. The design is called Sakura, asia for cherry blossom.<br><br>If you have any queries concerning where by and how to use [http://circuspartypanama.com clash of clans unlimited gems apk], you can speak to us at the site. It's possible, but the volume of absence one night would abatement by sixty one. 5% through 260 treasures to 100 gems. Or, whether you capital to build up the 1 time bulk at 260 gems, the band would take to acceleration added steeply and also 1 wedding would turn into added expensive.<br><br>The organization testing has apparent which often this appraisement algorithm model consists of a alternation of beeline band clips. They are not things to consider models of [http://search.huffingtonpost.com/search?q=arced+graphs&s_it=header_form_v1 arced graphs]. I will explain as to why later.<br><br>To defeat higher-level villages, job aids you to use a mixture of troops reminiscent of Barbarians plus Archers as well those suicide wall bombers to bust down filters. Goblins can also be a useful accent the combo simply as they attack different buildings. You should understand really want to begin worrying concerning higher troops when clients can''t win battles now with Barbarians.<br><br>The specific amend additionally permits a person to access the ability with the Sensei application buffs paid for with the Dojo because. Dojo win band technique. Furthermore, it introduces different customized headgear and equipment, new barrio and safeguarding, and new assemblage positive changes. |
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| The precise meaning of the term ''machining'' has evolved over the past one and a half centuries as technology has advanced. In the 18th century, the word ''[[machinist]]'' simply meant a person who built or repaired [[machine]]s. This person's work was done mostly by hand, using processes such as the [[woodcarving|carving of wood]] and the hand-[[forging]] and hand-[[file (tool)|filing]] of metal. At the time, [[millwright]]s and builders of new kinds of ''engines'' (meaning, more or less, machines of any kind), such as [[James Watt]] or [[John Wilkinson (industrialist)|John Wilkinson]], would fit the definition. The noun ''[[machine tool]]'' and the verb ''to machine'' (''machined, machining'') did not yet exist. Around the middle of the 19th century, the latter words were coined as the concepts that they described evolved into widespread existence. Therefore, during the [[Machine Age]], ''machining'' referred to (what we today might call) the "traditional" machining processes, such as [[turning]], [[Boring (manufacturing)|boring]], [[drilling]], [[Milling (machining)|milling]], [[Broach (metalwork)|broaching]], [[sawing]], [[Shaper|shaping]], [[Planer (metalworking)|planing]], [[Reamer|reaming]], and [[Tap and die|tapping]].<ref>[http://www.efunda.com/processes/machining/machin_intro.cfm Machining: An Introduction]</ref> In these "traditional" or "conventional" machining processes, [[machine tool]]s, such as [[lathe (tool)|lathes]], [[milling machine]]s, [[drill press]]es, or others, are used with a sharp [[cutting tool (machining)|cutting tool]] to remove material to achieve a desired geometry.<ref>[http://www.americanmachinist.com/304/Issue/Article/False/66356/Issue Additive Manufacturing Advances Another Step]</ref> Since the advent of new technologies such as [[electrical discharge machining]], [[electrochemical machining]], [[electron beam machining]], [[photochemical machining]], and [[ultrasonic machining]], the [[retronym]] "conventional machining" can be used to differentiate those classic technologies from the newer ones. In current usage, the term "machining" without qualification usually implies the traditional machining processes.
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| Machining is a part of the [[manufacture]] of many [[metal]] products, but it can also be used on materials such as [[wood]], [[plastic]], [[ceramic]], and [[Composite material|composites]].<ref>[http://www.mfg.mtu.edu/cyberman/machining.html Machining Page]</ref> A person who specializes in machining is called a [[machinist]]. A room, building, or company where machining is done is called a machine shop. Machining can be a [[business]], a [[hobby]], or both.<ref>[http://www.janellestudio.com/metal/ Machining and Metalworking at Home]</ref> Much of modern day machining is carried out by [[Numerical control|computer numerical control]] (CNC), in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines.
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| ==Machining operations==
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| [[File:US Navy 081008-N-9610C-039 Hull Technician 3rd Class Robert Paasch, from Parkdale, Ore., makes a shipboard manhole cover in the engineering department machine shop aboard the Nimitz-class aircraft carrier USS John C. Stennis (C.jpg|thumb|right|Making a shipboard [[manhole cover]] in the machine shop of [[USS John C. Stennis|the aircraft carrier USS ''John C. Stennis''.]]]]
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| The three principal machining processes are classified as [[turning]], [[drilling]] and [[Milling (machining)|milling]]. Other operations falling into miscellaneous categories include shaping, planing, boring, [[Broaching (metalworking)|broaching]] and sawing.<ref>[http://machining.askdefine.com/ Define Machining]</ref><ref>[http://www.sincomachine.com/sincomachine/Product.aspx?id=43 Machining]</ref><ref>[http://www.utmfg.com/definitions.html Universal Tools and Manufacturing Company, Definitions]</ref>
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| *Turning operations are operations that rotate the workpiece as the primary method of moving metal against the cutting tool. Lathes are the principal machine tool used in turning.
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| *Milling operations are operations in which the cutting tool rotates to bring cutting edges to bear against the workpiece. Milling machines are the principal machine tool used in milling.
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| *Drilling operations are operations in which holes are produced or refined by bringing a rotating cutter with cutting edges at the lower extremity into contact with the workpiece. Drilling operations are done primarily in drill presses but sometimes on lathes or mills.
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| *Miscellaneous operations are operations that strictly speaking may not be machining operations in that they may not be [[swarf]] producing operations but these operations are performed at a typical machine tool. [[Burnishing (metalworking)|Burnishing]] is an example of a miscellaneous operation. Burnishing produces no swarf but can be performed at a lathe, mill, or drill press.
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| An unfinished workpiece requiring machining will need to have some material cut away to create a finished product. A finished product would be a workpiece that meets the specifications set out for that workpiece by [[engineering drawings]] or [[blueprints]]. For example, a workpiece may be required to have a specific outside diameter. A lathe is a machine tool that can be used to create that diameter by rotating a metal workpiece, so that a cutting tool can cut metal away, creating a smooth, round surface matching the required diameter and surface finish. A drill can be used to remove metal in the shape of a cylindrical hole. Other tools that may be used for various types of metal removal are milling machines, saws, and [[grinding machine]]s. Many of these same techniques are used in [[woodworking]].
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| More recent, advanced machining techniques include [[electrical discharge machining]] (EDM), electro-chemical erosion, [[laser cutting]], or [[water jet cutter|water jet cutting]] to shape metal workpieces.
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| As a commercial venture, machining is generally performed in a machine shop, which consists of one or more workrooms containing major machine tools. Although a machine shop can be a stand-alone operation, many businesses maintain internal machine shops which support specialized needs of the business.
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| Machining requires attention to many details for a workpiece to meet the specifications set out in the engineering drawings or blueprints. Beside the obvious problems related to correct dimensions, there is the problem of achieving the correct finish or surface smoothness on the workpiece. The inferior finish found on the machined surface of a workpiece may be caused by incorrect [[clamp (tool)|clamping]], a dull tool, or inappropriate presentation of a tool. Frequently, this poor surface finish, known as chatter, is evident by an undulating or irregular finish, and the appearance of waves on the machined surfaces of the workpiece.
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| [[Image:Metal Cut diag.svg|thumb|350px|right|Basic machining process.]]
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| ==Overview of machining technology==
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| Machining is any process in which a cutting tool is used to remove small chips of material from the workpiece (the workpiece is often called the "work"). To perform the operation, relative motion is required between the tool and the work. This relative motion is achieved in most machining operation by means of a primary motion, called "cutting speed" and a secondary motion called "feed". The shape of the tool and its penetration into the work surface, combined with these motions, produce the desired shape of the resulting work surface.
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| ===Types of machining operation===
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| There are many kinds of machining operations, each of which is capable of generating a certain part geometry and surface texture.
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| In [[turning]], a cutting tool with a single cutting edge is used to remove material from a rotating workpiece to generate a cylindrical shape. The speed motion is provided by rotating the workpiece, and the feed motion is achieved by moving the cutting tool slowly in a direction parallel to the axis of rotation of the workpiece.
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| [[Drilling]] is used to create a round hole. It is accomplished by a rotating tool that typically has two or four helical cutting edges. The tool is fed in a direction parallel to its axis of rotation into the workpiece to form the round hole. | |
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| In [[boring (manufacturing)|boring]], a tool with a single bent pointed tip is advanced into a roughly made hole in a spinning workpiece to slightly enlarge the hole and improve its accuracy. It is a fine finishing operation used in the final stages of product manufacture.
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| In [[milling machine|milling]], a rotating tool with multiple cutting edges is moved slowly relative to the material to generate a plane or straight surface. The direction of the feed motion is perpendicular to the tool's axis of rotation. The speed motion is provided by the rotating milling cutter. The two basic forms of milling are:
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| * Peripheral milling
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| * Face milling.
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| Other conventional machining operations include shaping, planing, broaching and sawing. Also, grinding and similar abrasive operations are often included within the category of machining.
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| ===The cutting tool===
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| {{Main|Cutting tool (machining)}}
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| [[Image:B1 machining.jpg|thumb|right|260px|A "numerical controlled machining cell machinist" monitors a [[B-1 Lancer|B-1B]] aircraft part being manufactured.]]
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| A cutting tool has one or more sharp cutting edges and is made of a material that is harder than the work material. The cutting edge serves to separate chip from the parent work material. Connected to the cutting edge are the two surfaces of the tool:
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| * The rake face; and
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| * The flank.
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| The rake face which directs the flow of newly formed chip, is oriented at a certain angle is called the rake angle "α". It is measured relative to the plane perpendicular to the work surface. The rake angle can be positive or negative. The flank of the tool provides a clearance between the tool and the newly formed work surface, thus protecting the surface from abrasion, which would degrade the finish. This angle between the work surface and the flank surface is called the relief angle. There are two basic types of cutting tools:
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| * Single point tool; and
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| * Multiple-cutting-edge tool
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| A single point tool has one cutting edge and is used for turning, boreing and planing. During machining, the point of the tool penetrates below the original work surface of the workpart. The point is sometimes rounded to a certain radius, called the nose radius.
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| Multiple-cutting-edge tools have more than one cutting edge and usually achieve their motion relative to the workpart by rotating. Drilling and milling uses rotating multiple-cutting-edge tools. Although the shapes of these tools are different from a single-point tool, many elements of tool geometry are similar.
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| ==Cutting conditions==
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| Relative motion is required between the tool and work to perform a machining operation. The primary motion is accomplished at a certain [[cutting speed]]. In addition, the tool must be moved laterally across the work. This is a much slower motion, called the feed. The remaining dimension of the cut is the penetration of the cutting tool below the original work surface, called the depth of cut. Collectively, speed, feed, and depth of cut are called the cutting conditions. They form the three dimensions of the machining process, and for certain operations, their product can be used to obtain the material removal rate for the process:
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| :<math>{R}_{MR} = vfd\,\!</math>
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| where
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| *<math>{R}_{MR}\,\!</math> – the material removal rate in ''mm<sup>3</sup>/s'', (''in<sup>3</sup>/s''),
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| *<math>v\,\!</math> – the cutting speed in ''m/s'', (''ft/min''),
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| *<math>f\,\!</math> – the feed in ''mm'', (''in''),
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| *<math>d\,\!</math> – the depth of cut in ''mm'', (''in'').
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| :Note: All units must be converted to the corresponding decimal (or [[United States customary units|USCU]]) units.
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| ===Stages in metal cutting===
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| Machining operations usually divide into two categories, distinguished by purpose and [[Machining#cutting conditions|cutting conditions]]:
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| * Roughing cuts, and
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| * Finishing cuts
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| Roughing cuts are used to remove large amount of material from the starting workpart as rapidly as possible, i.e. with a large Material Removal Rate (MRR), in order to produce a shape close to the desired form, but leaving some material on the piece for a subsequent finishing operation.
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| Finishing cuts are used to complete the part and achieve the final dimension, [[Engineering tolerance|tolerance]]s, and surface finish. In production machining jobs, one or more roughing cuts are usually performed on the work, followed by one or two finishing cuts. Roughing operations are done at high feeds and depths – feeds of 0.4-1.25 mm/rev (0.015-0.050 in/rev) and depths of 2.5–20 mm (0.100-0.750 in) are typical, but actual values depend on the workpiece materials. Finishing operations are carried out at low feeds and depths - feeds of 0.0125-0.04 mm/rev (0.0005-0.0015 in/rev) and depths of 0.75-2.0 mm (0.030-0.075 in) are typical. Cutting speeds are lower in roughing than in finishing.
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| A [[cutting fluid]] is often applied to the machining operation to cool and lubricate the cutting tool. Determining whether a cutting fluid should be used, and, if so, choosing the proper cutting fluid, is usually included within the scope of cutting condition.
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| Today other forms of metal cutting are becoming increasingly popular. An example of this is water jet cutting. Water jet cutting involves pressurized water in excess of 620 MPa (90 000 psi) and is able to cut metal and have a finished product. This process is called cold cutting, and it increases efficiency as opposed to laser and plasma cutting.
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| ==Relationship of subtractive and additive techniques==
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| With the recent proliferation of [[additive manufacturing]] technologies, conventional machining has been [[retronym]]ously classified, in thought and language, as a [[subtractive manufacturing]] method. In narrow contexts, additive and subtractive methods may compete with each other. In the broad context of entire industries, their relationship is [[wikt:complementary#Adjective|complementary]]. Each method has its own advantages over the other. While additive manufacturing methods can produce very intricate prototype designs impossible to replicate by machining, strength and material selection may be limited.<ref>[http://www.wtec.org/additive/report/additive-report.pdf ADDITIVE/SUBTRACTIVE MANUFACTURING RESEARCH]</ref><ref>[http://www.vistatek.com/pdfs/Choosing-Between-Additive-and-Subtractive-Prototyping-manufacturing.pdf How and When to Choose Between Additive and Subtractive Prototyping]</ref><ref>[http://www.sme.org/cgi-bin/find-articles.pl?&ME05ART22&ME&20050410&&SME& Additive or subtractive?]</ref>
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| ==See also==
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| {{multicol}}
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| *[[Abrasive flow machining]]
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| *[[Abrasive jet machining]]
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| *[[Biomachining]]
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| *[[Cutting]]
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| *[[Design for manufacturability for CNC machining]]
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| {{multicol-break}}
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| *[[Machinability]]
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| *[[Machine tools]]
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| *[[Machining vibrations]]
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| *[[Tool management]]
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| {{multicol-end}}
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| ==References==
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| {{Reflist}}
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| ==Bibliography==
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| * {{Citation |last=Albert |first=Mark [Editor in Chief] |month=February |date=2011-01-17 |title=Subtractive plus additive equals more than ( <nowiki>- + + = ></nowiki> ): subtractive and additive processes can be combined to develop innovative manufacturing methods that are superior to conventional methods ['Mark: My Word' column—Editor's Commentary<nowiki>]</nowiki> |journal=Modern Machine Shop |volume=83 |issue=9 |publisher=Gardner Publications Inc |location=Cincinnati, Ohio, USA |pages=14 |url=http://www.mmsonline.com/columns/subtractive-plus-additive-equals-more-than |doi= |ref=harv |postscript=.}}
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| ==Further reading==
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| * {{Cite book
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| | last = Groover
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| | first = Mikell P.
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| | title = Fundamentals of Modern Manufacturing
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| | edition = 3rd ed
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| | year = 2007
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| | publisher = John Wiley & Sons, Inc.
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| | isbn = 0-471-74485-9
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| | pages = 491–504
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| | chapter = Theory of Metal Machining
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| }}
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| *{{citation | last = Oberg | first = Erik | last2 = Jones | first2 = Franklin D. | last3 = McCauley | first3 = Christopher J. | last4 = Heald | first4 = Ricardo M. | title = [[Machinery's Handbook]] | edition = 27th | year = 2004 | publisher = [[Industrial Press]] | isbn = 978-0-8311-2700-8 | postscript =.}}
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| * "Machine Tool Practices", 6th edition, by R.R.; Kibbe, J.E.; Neely, R.O.; Meyer & W.T.; White, ISBN 0-13-270232-0, 2nd printing, copyright 1999, 1995, 1991, 1987, 1982 and 1979 by Prentice Hall.
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| == External links ==
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| *[http://www.efunda.com/processes/machining/machin_intro.cfm www.efunda.com, Machining: An Introduction]
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| *[http://www.nmri.go.jp/eng/khirata/metalwork/index_e.html www.nmri.go.jp/eng, Elementary knowledge of metalworking]
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| *[http://www.machiningpartners.com/pages/Machining-Conventional-Milling-VS-ClimbMilling www.machiningpartners.com, Machining:Climb Milling VS Conventional Milling]
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| *[http://www.mmsonline.com/articles/drill-and-bore-with-a-face-mill www.mmsonline.com, Drill And Bore With A Face Mill]
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| *[http://www.buhl.nl Buhl Fijnmetaalbewerking]
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| {{Metalworking navbox|machopen}}
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| [[Category:Machining| ]]
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