364 SSCK20A數(shù)控車床主軸和箱體加工編程,ssck20a,數(shù)控車床,主軸,以及,箱體,加工,編程 產(chǎn)品型號(hào) 零件圖號(hào)第 1 頁共 2 頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注0 備料10 精鍛 立式精鍛機(jī)20 熱處理 正火30 鋸頭40 銑端面 專用機(jī)床50 粗車 車各外圓面 臥式車床60 熱處理 調(diào)質(zhì) 220～240HBS70 車大端面 臥式車床80 粗車 仿形車小端各部 仿形車床90 鉆 鉆打斷各孔 搖臂鉆床產(chǎn)品型號(hào) 零件圖號(hào)第 2 頁共 2 頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸工 藝 裝 備序號(hào) 工序 工 序 內(nèi) 容 車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注100 熱處理 高頻感應(yīng)加熱淬火110 數(shù)車 精車各外圓并車槽 數(shù)控車床 ′120 粗磨 粗磨個(gè)外圓 萬能外圓磨床130 精銑 銑鍵槽 銑床140 精車 加工三段螺紋 臥式車床150 粗精磨 粗精磨各外圓 萬能外圓磨床產(chǎn)品型號(hào) 零件圖號(hào)第 1頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱體工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注0 鑄造正火10 劃線 照顧毛坯各部劃立車加工線20 立車 車 465±0.2兩面,各面均留量 3mm30 劃線 劃鏜序加工線40 臥鏜 鏜銑 A面，B 面留量 3mm以 A面為基面,B 面為導(dǎo)向粗鏜 Φ150(-0.008,+0.002)Φ140(-0.007,+0.003)各孔留量半徑 3mm過孔留量半徑 3mm050 二次正火060 劃線 劃車序加工線產(chǎn)品型號(hào) 零件圖號(hào)第 2頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱工 藝 裝 備序號(hào) 工序 工 序 內(nèi) 容 車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注070 立車 車 465±0.2尺寸兩面,至 465±0.1mm,兩面平行 0.1mm′080 劃線 劃刨、鏜序加工線090 臥鏜 1）鏜銑 A面、B 面各留量 0.5—0.6mm銑 30尺寸下面達(dá)圖銑 5尺寸空刀至尺寸2）按線銑右視圖上部?jī)商?135度斜面達(dá)圖銑：150±0.2 尺寸上面留量 0.5mm鉆：2—M12 底孔 XΦ8(起吊孔)鉆：2—M12 底孔（右上圖局部剖）按線鉆攻：左、右視圖 4—M16（裝配起吊孔）3）以 A面為基面、 B 面導(dǎo)向粗鏜 Φ150(-0.008,+0.002)Φ140(-0.007,+0.003)各孔留量半徑 1—1.2 mm過孔留量半徑 1—1.2 mm產(chǎn)品型號(hào) 零件圖號(hào)第 3頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注100 數(shù)鏜 以 465尺寸左面為基面； 工件壓在工作臺(tái)一角位置， 找正 A面在 0.1以內(nèi)， 精銑 A、B 面（B 面精加工用 Φ30 立銑刀側(cè)刃加工，不許有接刀痕，吃刀深度 0.2mm)粗糙度達(dá) Ra3.2,平面度達(dá) 0.05mm ′110 臥鏜 1）以 465尺寸左面為基面；工件壓在工作臺(tái)一角位置找正 A面在 0.1以內(nèi)，銑 3X2空刀（根據(jù)刀具情況可加工至 5X3）2）工作太轉(zhuǎn) 90度，包拯 350尺寸，銑 350尺寸左面達(dá) Ra6.3。3）銑 320尺寸兩面：左面粗糙度達(dá)Ra3.2。4）銑 380尺寸右 6.3 面。5）鉆 4—M6、2—M8 底孔。120 臥鏜 以 A面為基面，B 面導(dǎo)向，上等高墊鐵、位置公差軍達(dá)圖紙要求產(chǎn)品型號(hào) 零件圖號(hào)第 4頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注半精鏜：Φ150(-0.008,+0.002)Φ140(-0.007,+0.003)、Φ141.5 孔留量，半徑 0.5—0.6mm。半精劃：底面留量 0.2mm精銑：Φ280 范圍內(nèi)，Φ240 范圍內(nèi)達(dá)Ra1.6465±0.2至 465（+0.2，+0.3）130 臥鏜 1、以 465尺寸左面為基面，找正 A面。在 0.05以內(nèi)實(shí)測(cè) Φ140 孔尺寸，按實(shí)際尺寸計(jì)算；精銑 150±0.2 尺寸上面。要求上面與 C、D 平行 0.03mm。鉆 4—M10底孔2、保證 25±0.2，80 尺寸自劃線，鉆劃 6—Φ22XΦ36140 裝配鉗 刮研 A、B 面。25MMX25MM范圍內(nèi)不少于 8個(gè)點(diǎn)。B ⊥A 達(dá) 0.02MM150 數(shù)鏜 以 A面為基面、B 面導(dǎo)向、產(chǎn)品型號(hào) 零件圖號(hào)第 5頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注保證 B面與主軸孔平行 0.02上等高墊鐵，300（0，+0.1）至 300（0，+0.05） 。50±0.1尺寸達(dá) 50±0.05mm。保證深度尺寸 115（-0.2，-0.1） 。精鏜 Φ141.5 過孔至尺寸，精鏜：Φ140、Φ150 孔?？讖焦畎摧S承尺寸配鏜；160 臥鏜 1）精劃 Ra1.6底面。精銑：Φ280、Φ240（檢查范圍） 。2）引窩：左視：6—M8。右視：6—M10。在右視圖 125度左側(cè)斜面打編號(hào)3） 三坐標(biāo)檢測(cè)：按圖紙技術(shù)要求檢測(cè)，孔徑用比較儀測(cè)量。170 鉆 按窩鉆攻：6—M8、6—M10180 鉗工 各銳角倒鈍、去刺產(chǎn)品型號(hào) 零件圖號(hào)第 6頁共 6頁 機(jī)械加工工藝卡片 產(chǎn)品名稱 SSCK20A 零件名稱 主軸箱工 藝 裝 備序號(hào)工序 工 序 內(nèi) 容車間設(shè)備 夾具 刃具 量具 輔具工等 工時(shí)單件 備注攻絲：4—M6、4—M12、2—M84—M10。190 噴漆′姓名： 任務(wù)下達(dá)日期： 年月日設(shè)計(jì)（論文）開始日期： 年 月 日設(shè)計(jì)（論文）完成日期： 年 月 日一、設(shè)計(jì)（論文）題目：SSCK20A 數(shù)控車床主軸及主軸箱的數(shù)控加工及數(shù)控編程 二、專題題目： 數(shù)控五軸技術(shù)及數(shù)控編程 三、設(shè)計(jì)的目的和意義：隨著社會(huì)的進(jìn)步，制造業(yè)的發(fā)展越來越迅速，數(shù)控技術(shù)和數(shù)控裝備是制造工業(yè)現(xiàn)代化的重要基礎(chǔ)。這個(gè)基礎(chǔ)是否牢固直接影響到一個(gè)國(guó)家的經(jīng)濟(jì)發(fā)展和綜合國(guó)力，關(guān)系到一個(gè)國(guó)家的戰(zhàn)略地位。因此，世界上各工業(yè)發(fā)達(dá)國(guó)家均采取重大措施來發(fā)展自己的數(shù)控技術(shù)及其產(chǎn)業(yè)。在我國(guó)，數(shù)控技術(shù)與裝備的發(fā)展亦得到了高度重視，近年來取得了相當(dāng)大的進(jìn)步。數(shù)控機(jī)床發(fā)展很快，作為數(shù)控機(jī)床的重要部分，主軸箱的設(shè)計(jì)更新也越來越快。四、設(shè)計(jì)（論文）主要內(nèi)容：（1）SSCK20A 數(shù)控車床的主軸箱展開圖（1 張 0號(hào)） 、主軸零件圖（1 張 1 號(hào)） 、箱體零件圖（1 張 0 號(hào)） 、帶輪零件圖（1 張 2號(hào)） 、前端蓋零件圖（1 張 2 號(hào)） ；（2）主軸及主軸箱的加工工藝規(guī)程；（3）主軸及主軸箱的部分加工工藝的數(shù)控程序；五、設(shè)計(jì)目標(biāo)：主要完成對(duì) SSCK20A 數(shù)控車床的主軸及主軸箱加工工藝規(guī)程設(shè)計(jì)以及部分加工工藝數(shù)控程序的編制。六、進(jìn)度計(jì)劃： 2007 年 3 月 13 日至 3 月 31 日進(jìn)行為期 3 周的生產(chǎn)實(shí)習(xí)；4月 1 日至 4 月 10 日完成對(duì)設(shè)計(jì)題目的資料收集與查詢；4 月 11 日至 5 月 10日完成對(duì)設(shè)計(jì)圖紙的繪制；5 月 11 日至 6 月 10 日完成畢業(yè)設(shè)計(jì)說明書的編寫；6 月 11 日至 6 月 20 日最后的審稿及說明書和圖紙的打印。 七、參考文獻(xiàn)資料：許鎮(zhèn)宇.機(jī)械零件.北京：高等教育出版社，1983；孔慶復(fù).計(jì)算機(jī)輔助設(shè)計(jì)與制造.哈爾濱：哈爾濱工業(yè)大學(xué)出版社，1994；雷宏.機(jī)械工程基礎(chǔ).哈爾濱：黑龍江出版社 2002；王中發(fā).實(shí)用機(jī)械設(shè)計(jì).北京：北京理工大學(xué)出版社 1998； 唐宗軍.機(jī)械制造基礎(chǔ).大連：機(jī)械工業(yè)出版社 1997；吳祖育，秦鵬飛.數(shù)控機(jī)床.上海：上海科學(xué)技術(shù)出版社 2003；許翔泰，劉艷芳. 數(shù)控加工編程實(shí)用技術(shù).北京：機(jī)械工業(yè)出版社 2000；吳明友.數(shù)控機(jī)床加工技術(shù) 東南大學(xué)出版社.江蘇：2000；王寶成.現(xiàn)代數(shù)控機(jī)床.天津：天津科學(xué)技術(shù)出版社，2000；廖效果，朱啟俅.數(shù)字控制機(jī)床.江西：華中科技大學(xué)出版社，2002；王衛(wèi)兵.數(shù)控編程 100 例.機(jī)械工業(yè)出版社，2004；張樹森.機(jī)械工程學(xué).遼寧；東北大學(xué)出版社，2001；應(yīng)云天.俄文翻譯手冊(cè).北京：高等教育出版社，1999；金蓓.數(shù)控加工的編程技巧.《航空精密制造技術(shù)》.成都：2002，2；鄧星鐘. 機(jī)電傳動(dòng)控制(第三版). 武漢: 華中科技大學(xué)出版社, 2001； 指 導(dǎo) 教 師： 院（系）主管領(lǐng)導(dǎo)： 年 月 日1附錄 2 外文翻譯（外文部分）ADVANCED MACHINING PROCESSESAs the hardware of an advanced technology becomes more complex, new and visionary approaches to the processing of materials into useful products come into common use. This has been the trend in machining processes in recent years.. Advanced methods of machine control as well as completely different methods of shaping materials have permitted the mechanical designer to proceed in directions that would have been totally impossible only a few years ago.Parallel development in other technologies such as electronics and computers have made available to the machine tool designer methods and processes that can permit a machine tool to far exceed the capabilities of the most experienced machinist.In this section we will look at CNC machining using chip-making cutting tools. CNC controllers are used to drive and control a great variety of machines and mechanisms, Some examples would be routers in wood working; lasers, plasma-arc, flame cutting, and waterjets for cutting of steel plate; and controlling of robots in manufacturing and assembly. This section is only an overview and cannot take the place of a programming manual for a specific machine tool. Because of the tremendous growth in numbers and capability of computers ,changes in machine controls are rapidly and constantly taking place. The exciting part of this evolution in machine controls is that programming becomeseasier with each new advanced in this technology.2Advantages of Numerical ControlA manually operated machine tool may have the same physical characteristics as a CNC machine, such as size and horsepower. The principles of metal removal are the same. The big gain comes from the computer controlling the machining axes movements. CNC-controlled machine tools can be as simple as a 2-axis drilling machining center (Figure O-1). With a dual spindle machining center, the low RPM, high horsepower spindle gives high metal removal rates. The high RPM spindle allows the efficient use of high cutting speed tools such as diamonds and small diameter cutters (Figure O-2). The cutting tools that remove materials are standard tools such as milling cutters, drills, boring tools, or lathe tools depending on the type of machine used. Cutting speeds and feeds need to be correct as in any other machining operation. The greatest advantage in CNC machining comes from the unerring and rapid positioning movements possible. A CNC machine does dot stop at the end of a cut to plan its next move; it does not get fatigued; it is capable of uninterrupted machining error free, hour after hour. A machine tool is productive only while it is making chips.Since the chip-making process is controlled by the proper feeds and speeds, time savings can be achieved by faster rapid feed rates. Rapid feeds have increased from 60 to 200 to 400 and are now often approaching 1000 inches per minute (IPM). These high feed rates can pose a safety hazard to anyone within the working envelope of the machine tool.Complex contoured shapes were extremely difficult to product prior to CNC machining .CNC has made the machining of these shapes economically feasible. Design changes on a part are relatively easy to make by changing the program that directs the machine tool.A CNC machine produces parts with high dimensional accuracy and close tolerances without taking extra time or special precautions, CNC machines generally need less complex work-holding fixtures, 3which saves time by getting the parts machined sooner. Once a program is ready and production parts, each part will take exactly the same amount of time as the previous one. This repeatability allows for a very precise control of production costs. Another advantage of CNC machining is the elimination of large inventories; parts can be machined as needs .In conventional production often a great number of parts must be made at the same time to be cost effective. With CNC even one piece can be machined economically .In many instances, a CNC machine can perform in one setup the same operations that would require several conventional machines.With modern CNC machine tools a trained machinist can program and product even a single part economically .CNC machine tools are used in small and large machining facilities and range in size from tabletop models to huge machining centers. In a facility with many CNC tools, programming is usually done by CNC programmers away from the CNC tools. The machine control unit (MCU) on the machine is then used mostly for small program changes or corrections. Manufacturing with CNC tools usually requires three categories of persons. The first is the programmer, who is responsible for developing machine-ready code. The next person involved is the setup person, who loads the raw stork into the MCU, checks that the correct tools are loaded, and makes the first part. The third person is the machine and unloads the finished parts. In a small company, one person is expected to perform all three of these tasks.CNC controls are generally divided into two basic categories. One uses a ward address format with coded inputs such as G and M codes. The other users a conversational input; conversational input is also called user-friendly or prompted input. Later in this section examples of each of these programming formats in machining applications will be describes.CAM and CNCCAM systems have changed the job of the CNC programmer from one 4manually producing CNC code to one maximizing the output of CNC machines. Since CNC machine tools are made by a great number of manufacturers, many different CNC control units are in use. Control units from different manufacturers use a variety of program formats and codes. Many CNC code words are identical for different controllers, but a great number vary from one to another.To produce an identical part on CNC machine tools with different controllers such as one by FANCU, OKUMA or DYNAPATH, would require completely different CNC codes. Each manufacturer is constantly improving and updating its CNC controllers. These improvements often include additional code words plus changes in how the existing code works.A CAM systems allows the CNC programmer to concentrate on the creation of an efficient machining process, rather then relearning changed code formats. A CNC programmer looks at the print of a part and then plans the sequence of machining operations necessary to make it (Figure O-3). This plan includes everything, from the selection of possible CNC machine tools, to which tooling to use, to how the part is held while machining takes place. The CNC programmer has to have a thorough understanding of all the capacities and limitations of the CNC machine tools that a program is to be made for. Machine specifications such as horsepower, maximum spindle speeds, workpiece weight and size limitations, and tool changer capacity are just some of the considerations that affect programming.Another area of major importance to the programmer is the knowledge of machining processes. An example would be the selection of the surface finish requirement specified in the part print. The sequence of machining processes is critical to obtain acceptable results. Cutting tool limitations have to be considered and this requires knowledge of cutting tool materials, tool types, and application recommendations.A good programmer will spend a considerable amount of time in 5researching the rapidly growing volume of new and improved tools and tool materials. Often the tool that was on the cutting edge of technology just two years ago is now obsolete. Information on new tools can come from catalogs or tool manufacturers' tooling engineers. Help in tool selection or optimum tool working conditions can also be obtained from tool manufacturer software. Examples would be Kennametal's "TOOLPRO", software designed to help select the best tool grade, speed, and feed rates for different work materials in turning application. Another very important feature of "TOOLPRO" is the display of the horsepower requirement for each machining selection. This allow the programmer to select a combination of cutting speed, feed rate, and depth of cut that equals the machine's maximum horsepower for roughing cuts. For a finishing cut, the smallest diameter of the part being machined is selected and then the cutting speed varied until the RPM is equal to the maximum RPM of the machine. This helps in maximizing machining efficiency. Knowing the horsepower requirement for a cut is critical if more than one tool is cutting at the same time.Software for a machining center application would be Ingersoll Tool Company's "Actual Chip Thickness", a program used to calculate the chip thickness in relation to feed-per-tooth for a milling cutter, especially during a shallow finishing cut. Ingersoll's "Rigidity Analysis" software ealculates tool deflection for end mills as a function of tool stiffness and tool force.To this point we looked at some general qualifications that a programmer should possess. Now we examine how a CAM system works. Point Control Company's SmartCam system uses the following approach. First, the programmer makes a mental model of the part to be machined. This includes the kind of machining to be performed-turning or milling. Then the part print is studied to develop a machining sequence, roughing and finishing cuts, drilling, tapping, and boring operations. What work-holding device is to be used, a vise or fixture or clamps? After these considerations, computer 6input can be started. First comes the creation of a JOBPLAN. This JOBPLAN consists of entries such as inch or metric units, machine type, part ID, type of workpiece material, setup notes, and a description of the required tools. This line of information describes the tool by number, type, and size and includes the appropriate cutting speed and feed rate. After all the selected tools are entered, the file is saved.The second programming step is the making of the part. This represents a graphic modeling of the projected machining operation. After selecting a tool from the prepared JOBPLAN, parameters for the cutting operation are entered. For a drill, once the coordinate location of the hole and the depth are given, a circle appears on that spot. If the location is incorrect, the UNDO command erases this entry and allows you to give new values for this operation. When an end mill is being used, cutting movements (toolpath) are usually defined as lines and arcs. As a line is programmed, the toolpath is graphically displayed and errors can be corrected instantly.At any time during programming, the command SHOWPATH will show the actual toolpath for each of the programmed tools. The tools will be displayed in the sequence in which they will be used during actual machining. If the sequence of a tool movement needs to be changed, a few keystrokes will to that.Sometimes in CAM the programming sequence is different from the actual machining order. An example would be the machining of a pocket in a part. With CAM, the finished pocket outline is programmed first, then this outline is used to define the roughing cuts to machine the pocket. The roughing cuts are computer generated from inputs such as depth and width of cut and how much material to leave for the finish cut. Different roughing patterns can be tried out to allow the programmer to select the most efllcient one for the actual machining cuts. Since each tool is represented by a different color, it is easy to observe the 7toolpath made by each one.A CAM system lets the programmer view the graphics model from varying angles, such as a top, front, side, or isometric view. A toolpath that looks correct from a top view, may show from a front view that the depth of the cutting tool is incorrect. Changes can easily be made and seen immediately.When the toolpath and the sequence of operations are satisfactory, machine ready code has to be made. This is as easy as specifying the CNC machine that is to be used to machine the part. The code generator for that specific CNC machine during processing accesses four different files. The JOBPLAN file for the tool information and the GRAPHICE file for the toolpath and cutting sequence. It also uses the MACHINE DEFINE file which defines the CNC code words for that specific machine. This file also supplies data for maximum feed rates, RPM, toolchange times, and so on. The fourth file taking part in the code generating process is the TEMPLATE file. This file acts like a ruler that produces the CNC code with all of its parts in the right place and sequence. When the code generation is complete, a projected machining time is displayed. This time is calculated from values such as feed rates and distances traveled, noncutting movements at maximum feed rates between points, tool change times, and so on. The projected machining time can be revised by changing tooling to allow for higher metal removal rates or creating a more efficient toolpath. This display of total time required can also be used to estimate production costs. If more then one CNC machine tool is available to machine this part, making code and comparing the machining time may show that one machine is more efficient than the others.CAD/CAMAnother method of creating toolpath is with the use of a Computer-aided Drafting (CAD) file. Most machine drawings are created using computers with the description and part geometry 8stored in the computer database. SmartCAM, though its CAM CONNECTION, will read a CAD file and transfer its geometry represents the part profile, holes, and so on. The programmer still needs to prepare a JOBPLAN with all the necessary tools, but instead of programming a profile line by line, now only a tool has to be assigned to an existing profile. Again, using the SHOWPATH function will display the toolpath for each tool and their sequence. Constant research and developments in CAD/CAM interaction will change how they work with each other. Some CAD and CAM programs, if loaded on the same computer, make it possible to switch between the two with a few keystrokes, designing and programming at the same time.The work area around the machine needs to be kept clean and clear of obstructions to prevent slipping or tripping. Machine surfaces should not be used as worktables. Use proper lifting methods to handle heavy workpieces, fixtures, or heavy cutting tools. Make measurements only when the spindle has come to a complete standstill. Chips should never be handled with bare hands.Before starting the machine make sure that the work-holding device and the workpiece are securely fastened. When changing cutting tools, protect the workpiece being machined from damage, and protect your hands from sharp cutting edges. Use only sharp cutting tools. Check that cutting tools are installed correctly and securely.Do not operate any machine controls unless you understand their function and what they will do.The Early Development Of Numerically Controlled Machine ToolsThe highly sophisticated CNC machine tools of today, in the vast and diverse range found throughout the field of manufacturing processing, started from very humble beginnings in a number of the 9major industrialized countries. Some of the earliest research and development work in this field was completed in USA and a mention will be made of the UK's contribution to this numerical control development.A major problem occurred just after the Second World War, in that progress in all areas of military and commercial development had been so rapid that the levels of automation and accuracy required by the modern industrialized world could not be attained from the lab our intensive machines in use at that time. The question was how to overcome the disadvantages of conventional plant and current manning levels. It is generally ackonwledged that the earliest work into numerical control was the study commissioned in 1947 by the US government. The study's conclusion was that the metal cutting industry throughout the entire country could not copy with the demands of the American Air Force, let alone the rest of industry! As a direct result of the survey, the US Air Force contracted the Persons Corporation to see if they could develop a flexible, dynamic, manufacturing system which would maximize productivity. The Massachusetts Institute of Technology (MIT) was sub-contracted into this research and development by the Parsons Corporation, during the period 1949-1951,and jointly they developed the first control system which could be adapted to a wide range of machine tools. The Cincinnati Machine Tool Company converted one of their standard 28 inch "Hydro-Tel" milling machines or a three-axis automatic milling made use of a servo-mechanism for the drive system on the axes. This machine made use of a servomechanism for the drive system on the axes, which controlled the table positioning, cross-slide and spindle head. The machine cab be classified as the first truly three axis continuous path machine tool and it was able to generate a required shape, or curve, by simultaneous slide way motions, if necessary.At about the same times as these American advances in machine tool control were taking Place, Alfred Herbert Limited in the 10United Kingdom had their first Mutinous path control system which became available in 1956.Over the next few years in both the USA and Europe, further development work occurred. These early numerical control developments were principally for the aerospace industry, where it was necessary to cut complex geometric shapes such as airframe components and turbine blades. In parallel with this development of sophisticated control systems for aerospace requirements, a point-to-point controller was developed for more general machining applications. These less sophisticated point-to-point machines were considerably cheaper than their more complex continuous path cousins and were used when only positional accuracy was necessary. As an example of point-to-point motion on a machine tool for drilling operations, the typical movement might be fast traverse of the work piece under the drill's position-after drilling the hole, anther rapid move takes place to the next hole's position-after retraction of the drill. Of course, the rapid motion of the slideways could be achieved by each axis in a sequential and independent manner, or simultaneously. If a separate control was utilisec for each axis, the former method of table travel was less essential to avoid any backlash in the system to obtain the required degree of positional accuracy and so it was necessary that the approach direction to the next point was always the same. The earliest examples of these cheaper point-to-point machines usually did not use recalculating ball screws; this meant that the motions would be sluggish, and sliderways would inevitably suffer from backlash, but more will be said about this topic later in the chapter.The early NC machines were, in the main, based upon a modified milling machine with this concept of control being utilized on turning, punching, grinding and a whole host of other machine tools later. Towards the end of the 1950s,hydrostatic slideways were often incorporated for machine tools of highly precision, which to sonic extent overcame the section problem associated with 11conventional slideway response, whiles averaging-out slideway inaccuracy brought about a much increased preasion in the machine tool and improved their control characteristics allows "concept of the machining center" was the product of this early work, as it allowed the machine to manufacture a range of components using a wide variety of machining processes at a single set-up, without transfer of workpieces to other variety machine tools. A machining center differed conceptually in its design from that of a milling machine, In that the cutting tool