Tuesday, May 21, 2019
table of contents 1 ABSTRACT 2 ABBREVIATION 3 INTRODUCTION TO NC AND CNC 4 4 HISTORY 7 5 CNC SYSTEM ELEMENTS 10 6 WORING ON CNC MACHINES 7 BASIC CONCEPTS OF actuate PROGRAMMING 16 8 TYPES OF CNC MACHINES 18 9 PROPERTIES OF CNC MACHINES 20 10 DRILLING AND TAPPING ON CNC 35 11 APPLICATIONS OF CNC MACHINES 49 12 ADVANTAGES AND DISADVANTAGES OF CNC 51 13 CONCLUSION 52 LIST OF FIGURES PAGE NO 1 Hydrotel mill about gondola 5 2 Chiron CNC instrument 5 3 CNC Lathe political machine 6 CNC elements englut diagram 10 5 excite to Point putz caterpillar track 11 6 Contour asshole Path 12 7 Continuous path m different fucker black marketments 18 8 Continuous path conquerlers 19 9 Schematic Illustrations of comp unrivallednts(a)An open loop(b)A closed loop overtop 19 10 CNC Lathe 21 11 CNC Grinders 21 12 CNC oil production 22 13 CNC long-winded auto 22 14 Electrical turn Machines (EDM) 23 15 Laser recognizeting utensil putzs 23 16 forthwith bed CNC Lathe 25 7 Slant bed CNC Lathe 25 18 CNC marionette Turrent 26 28 Different diaphysiss in Drilling utensils 26 20 legal instrument Holders 27 21 CNC with Fanuc potency 28 22 CNC placeter 29 23 bowl over f number setter 31 24 CNC cringe 32 25 Sensitive Drilling utensil 37 26 Ra dial bore railroad car 38 27 Up-right Drilling simple form 38 28 Drill materials 39 29 legal document nomenclature 40 30 rotating shaft holding devices 41 31 Various exe chop offions of operationing automobiles 42 32 getting even Boring 43 33 Counter sunk 43 34 Spot Facing 43 35 collapses Taps 46 36 Holding Devices 48 7 Types of Clamps and C- Clamps 49 38 Products en pierce upd in Aerospace fabrication 49 39 5 bloc CNC Milling political forge 50 3. INTRODUCTION TO NC AND CNC Numerical escort(NC) refers to theautomationof implement appliancesthat argon operated by programmed didacticss encoded on a storage medium, instruction guide manual(a)ly via hand go arounds or levers, or mechanic completely in ally automated via cams alone. The premier NC machines were build in the 1940s and 1950s. These previous(predicate) servo machines were fastly augmented with analog and nameal estimators, creating the current ready reckoner quantitative control(CNC) machine tools that have revolutionized themachining mathematical operationes.The program is translated into the appropriate electrical signals for stimulation to motors that withdraw the machine. A CNC machine is an numerical control machine with the added feature of an on board computer. The computer is referred to as the machine control unit (MCU). In modern CNC bodys, component protrude is highly automated victimizationcomputer-aided intention( pawl) andcomputer-aided manufacturing (CAM) programs. The programs produce a computer file that extracts the commands compulsory to operate a graphemeicular pro amaze machine, and therefore steamed into the CNC machines for procedure.Since any component mogul hold the use of a result of diametrical tools- bores, saws, etc. , modern machines frequently combine multiple tools into a angiotensin converting enzyme cell. The Evolution of NC It was in 1947 when numerical control was born. It began when John C. Parsons of the Parsons Corporation, Traverse City, Michigan, a manufacturer of helicopter rotor blades, could not make his templates fast enough. So, he invented a counselling of coupling computer equipment with a jig borer. Mr. Parsons utilise punched cards to operate his digit Ron system. 1949 was the year of another Urgent invite. The U. S. transmit Material command realized that part for its planes and missiles were becoming to a greater extent complex. Also, as the designs were constantly being improved, interchanges in the drawing were frequently made. Thus, in their search for methods of faster production, an Air Force study contract was awarded to the Parsons Corporation. The servo mechanisms laboratory of the Massachus etts Institute of Technology (MIT) was the subcontractor. In 1951, MIT took all over the complete job, and in 1952, the prototype of todays NC machine, a modified Cincinnati Hydrotel Milling Machine, was success lavishy demonstrated.The numerical control was originated at MIT. chassis1 number2 CNC MACHINES CNC radixs for Computer Numerically get windled. CNC refers to how a machine operates, that is, its basic method of controlling prodment, e. g. , a CNC machine uses a stream of digital information (code) from a computer to execute motors and other billet systems in order to guide a capitulum or other tooling over raw material. A CNC machine uses mathematics and coordinate systems to understand and process information about what to decease, to where, and how fast.Most CNC machines ar able to move in collar controlled advocates at once. These directions argon called axes and ar ha smirchuated simple names such as X, Y and Z ( foundd on the Cartesian Co-ordinate System) . The X bloc is forever the longest surpass a machine or a part of a machine must travel. X whitethorn be the movement from front to back, Y the movement from left over(p) to right, and the Z is well-nigh always vertical movement (normally the pergolas positioning movement up and downhearted). Superior Machinery sells virtually types of CNC Machines, from CNC Horizontals, CNC Verticals to CNC Lathes they have over 182 CNC Machines to choose from.A CNC machine must be able to legislate with itself to operate. A computer numeric control unit s mop ups position commands to motors. The motors must talk back to the control that, indeed, they have acted correctly to move the machine a given up distance. The ability of CNC machines to move in three (or more) directions at once allows them to create al virtually any desired pattern or shape. All of this touch happens actually fast, accurately and consistently. 4. HISTORY common fig3 In 1775, John Wilkinson- preemptnon boring machine (lathe). In 1881, Eli Whitney- milling machine. In 1947, Mr.John Parsons began experimenting for employ 3-axis curvature data to control the machine tool doubtfulness for the production for aircraft components. In 1949, parsons- offset NC machine. In 1951, MIT was involved in the project. In 1955, after refinements NC became available in industry . Today, modern machineries are CNC milling machines and lathes. CNC technology was developed in the United States in the 1950? s for the US Air Force by metalworking machine tool builders. It was a major dab out in the ability of machines to faithfully reproduce complex part machining steps more accurately without homosexual intervention or variability.Numerical control (NC) refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to manually controlled via handwheels or levers, or mechanically automated via cams alone. The starting signal NC machin es were build in the 1940s and 1950s, based on alive tools that were modified with motors that moved the controls to follow points feed into the system on punched video splashe. These early servomechanisms were rapidly augmented with analog and digital computers, creating the modern computer numerical control (CNC) machine tools that have revolutionized the machining processes.In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine via a postprocessor, and then loaded into the CNC machines for production. Since any particular component might require the use of a payoff of different tools- performances, saws, etc. , modern machines often combine multiple tools into a single cell.In other cases, a number of different machines are apply with an external controller a nd gracious or robotic operators that move the component from machine to machine. In either case, the complex serial publication of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design. Proliferation of CNC The price of computer cycles fell drastically during the 1960s with the widespread introduction of useful minicomputers. Eventually it became slight expensive to worry the motor control and affordback with a computer program than it was with apply servo systems.Small computers were dedicated to a single mill, placing the entire process in a small box. PDP-8? s and Data worldwide Nova computers were rough-cut in these roles. The introduction of the microprocessor in the 1970s further reduced the cost of implementation, and today almost all CNC machines use some(prenominal) form of microprocessor to handle all trading operations. The introduction of lower-cost CNC machines radically changed the manufacturing industry. Curves are as flourishing to cut as straight disceptations, complex 3-D structures are relatively easy to produce, and the number f machining steps that required human action have been dramatically reduced. With the increased automation of manufacturing processes with CNC machining, goodish improvements in consistency and flavor have been achieved with no strain on the operator. CNC automation reduced the frequence of errors and admitd CNC operators with cartridge clip to carry through additional tasks. CNC automation to a fault allows for more flexibility in the way parts are held in the manufacturing process and the cartridge clip required to change the machine to produce different components.During the early 1970s the Western economies were mired in slow economic growth and rising employment costs, and NC machines started to pass more attractive. The major U. S. vendors were slow to respond to the demand for machines suitable for lower-cost NC systems, and int o this void stepped the Germans. In 1979, gross revenue of German machines surpassed the U. S. designs for the first judgment of conviction. This cycle quickly repeated itself, and by 1980 Japan had taken a soundership position, U. S. gross sales dropping all the time. Once sitting in the 1 position in terms of sales on a top-ten chart consisting entirely of U. S. ompanies in 1971, by 1987 Cincinnati Milacron was in 8th place on a chart heavily dominated by Japanese firms. Many researchers have commented that the U. S. focus on high-end applications left them in an uncompetitive situation when the economic downturn in the early 1970s led to greatly increased demand for low-cost NC systems. Unlike the U. S. companies, who had focuse on the highly profitable aerospace market, German and Japanese manufacturers targeted lower-profit segments from the start and were able to innovate the low-cost markets much more comfortably. As computing and ne bothrking evolved, so did direct nume rical control (DNC).Its long-term coexistence with less networked variants of NC and CNC is explained by the fact that individual firms tend to arrive with whatever is profitable and their time and money for trying out dislodgenatives is limited. This explains why machine tool models and tape storage media persist in grandfathered fashion even as the state of the art advances. 5. CNC SYSTEM ELEMENTS A typical CNC system consists of the following six elements. 1 Part program 2 Program input device 3 Machine control unit 4 Drive system 5 Machine tool 6 Feedback system Fig4 6. WORKING OF CNC MACHINESCNC machines are Controlled by G and M codes. These are number values and co-ordinates. Each number or code is assigned to a particular operation. Typed in manually to CAD by machine operators. G&M codes are automatically generated by the computer software. The tool or material moves. mechanisms mass operate in 1-5 axes. Larger machines have a machine control unit (MCU) which manages o perations. Movement is controlled by a motor (actuators). Feedback is provided by sensors (transducers) Closed loop. Tool magazines are apply to change tools automatically. Tool Paths and Cutting MotionsTool paths describe the route the crude tool takes. Motion give the gate be described as point to point, or contouring. Speeds are the rate at which the tool operates e. g. rpm. Feeds are the rate at which the wounding tool and work piece move in relation to each other. Expressed in IPM (inches per minute) Feeds and speeds are determined by irate depth, material and quality of finish needed. e. g . harder materials need slower scats and speeds. Rouging cuts remove larger amounts of material than finishing cuts. Rapid traversing allows the tool or work piece to move rapidly when no machining is taking place.Fig6 Point to Point Tool path Fig5Contour ToolPath 1. Point to Point tool paths cut following lines 2. Contour tool paths cut follow surfaces Linear intervention (Point to Point) Linear ejaculation consist of a programmed point associate together by straight line Fig7 Circular Interpolation (Contour) Circular interpolation is the process of programming arcs and circles. Circular interpolation requires endpoints, a hunt rate, a center, a radius, and a direction of movement. Block of Information When running, a part program is interpreted one command line at a time until all lines are completed.Fig8 N001 G01 X1. 2345 Y. 06789 MO3 N001Represents the sequence number of the operation G01 Represents linear operation (tool movement) X12345 Will move the tool or table 1. 2345 in. a positive direction along the X axis Y6789Will move the tool or table 0. 6789 in. along the Y axis M03Turns spike heel on clockwise Commands, which are likewise referred to as blocks, are made up of words which each begin with a letter get over and end with a numerical value. Each letter address relates to a specific machine attend to. G and M letter addresses O-Program numb er ( go ford for program identification)N-Sequence number (Used for line identification) G-Preparatory function X-X axis designation Y-Y axis designation Z-Z axis designation R-Radius designation F-Feed rate designation S- stiletto heel speed designation H-Tool aloofness offset designation D-Tool radius offset designation T-Tool Designation M-Miscellaneous function G- CODES (Preparatory Functions) which cause some movement of the machine table or wellspring. G00 Rapid Movement G01- Linear Interpolation (movement) G02- Circular Interpolation, CW G03- Circular Interpolation, CCW G17 -XY Plane,G18- XZ Plane,G19 -YZ Plane G20/G70 -Inch unitsG21/G71 -Metric Units G40- Cutter compensation cross off _or_ out G41 -Cutter compensation right G43- Tool length compensation (plus) G43- Tool length compensation (plus) G44- Tool length compensation (minus) G49-Tool length compensation dejectioncel G80-Cancel canned cycles G81-Drilling cycle G82-Counter boring cycle G83-Deep hole cut cycle G 90-Absolute positioning G91- Incremental positioning M-CODES (Miscellaneous) which turn ON or OFF different functions M00 -Program stop M01 -Optional program stop M02 -Program end M03- mandrel on clockwise M04 -Spindle on counterclockwise M05- Spindle stop M06- Tool change . BASIC CONCEPTS OF PART PROGRAMMING Part programming contains nonrepresentational data about the part and motion information to move the peachy tool with respect to the worpiece. Basically, the machine receives instructions as a sequence of blocks containing commands to set machine parameters speed, feed and other relevant information. A block is equivalent to a line of codes in a part program. N135 G01 X1. 0 Y1. 0 Z0. 125 T01 F5. 0 These define N135-Block number G01-G codes X1. 0, Y1. 0, Z0. 125-Coordinates T01-Tool number F5. 0-Special function computer programing Methods Automatically Programmed Tools (APT)A text based system in which a programmer defines a series of lines, arcs, and points which define th e overall part geometry repairs. These features are then use to generate a bid location (CL) file. Computer Aided Machining (CAM) Systems-Computer Aided Design (CAD) Systems CAD/CAM systems allow for rapid development and modifying of designs and enfranchisement. The 3D geometric model produced becomes a common element for engineering analysis (FEA), machining process planning (including CNC part programming, documentation (including engineering drawings), quality control, and so on.Drives of CNC machine tool Hydraulic actuator high power machine tool Stepping motor small machine due to limited power and torque DC motor pure speed regulation, high torque, most widely used. 8. PROPERTIES OF CNC MACHINES Based on Motion Type Motion control the heart of CNC Point-to-Point or Continuous path Based on Control Loops Open loop or Closed loop Based on Power Supply Electric or Hydraulic or Pneumatic Based on Positioning System Incremental or Absolute Point-to-Point Tool Movements Poi nt-to-point control systems cause the tool to that point only.The tool is not in continuous contact with the part charm it is moving. Examples oil production, reaming, punching, boring and tapping. Fig9 Continuous-Path Tool Movements Continuous-path controllers cause the tool to maintain continuous contact with the part as the tool cuts a contour shape. These operations include milling along any lines at any bung, milling Fig10 Arcs and lathe bit. Loop Systems for Controlling Tool Movement Schematic typification of the components of (a) an open-loop and (b) a closed-loop control system for a CNC machine. 9. TYPES OF CNC MACHINES * Lathe Machine * Milling Machine Drilling Machine -The judicature drill -The pillar drill * Boring Machine * Grinding Machine CNC Mills These machining centers use computer controls to cut different materials. They are able to translate programs consisting of specific number and letters to move the spindle to diverse locations and depths. Used to ma ke 3D prototypes, moulds, cutting dies, printing plates and sights. CNC Lathes They cut metal that is often turn of events at fast speeds. CNC lathes are able to make fast ,precision cuts using Indexable tools and drills with complicated programs. Normally, they cannot be cut on manual lathes.They often include 12 tool holder sand coolant pumps to cut down on tool wear. Fig11 CNC Grinders Grinding metal process uses a coated wheel that slowly removes metal to create a part. Through the years, grinding was foole on a manual machine, further with the advent of CNC technology, the grinding process has advanced . Fig12 CNC DRILLING Drilling is ordinarily used for mass production. The cut machine ( drill press) is used to create or enlarge holes. The bench drill For cut holes through raw materials such as wood, plastic and metal The pillar drill A larger version that stands upright on the floor.As the bench drill, it can be used to drill larger pieces of materials and produce bigge r holes. Fig13 CNC Boring Process of enlarging an existing hole or upcountry cylindirical surface. This can be accomplished on a lathe or a machine tool specifically designed for the process, such as a horizontal boring machine. Fig14 Electrical Discharge Machines (EDM) Wire EDM machines utilize a very thin conducting wire (. 0008 to . 012in. ) as an electrode. The wire is stretched between rhomb guides and carbide that conduct current to the wire and cuts the part like a band saw.Material is removed by the wear caused by a spark that moves horizontally with the wire. Fig15 Laser Cutting Machines The machine utilizes an uttermost(prenominal) beam of focused laser light to cut the part. Material under the beam experiences a rapid rise in temperature and is vaporized. Laser cuts with a minimum of distortion, no mechanical cutting forces. Specific tools to perform different trading operations Fig16Fig17 CNC lathe machine tool hired gun gun enclosure is part of the CNC machine where all tooling is mount. CNC lathe tool gun enclosure has an integral Disk like part (Tool turret disk) on which all the tools are mounted.CNC lathe tool turret is mounted on the x-axis carriage. Fig18 Slant whop CNC Lathe / Flat Bed CNC Lathe On some CNC lathe machines x-axis carriage with the tool turret is located behind the spindle (such cnc lathe machines are called shift bed cnc lathe machines) and on other cnc lathe it is located at the front (as normal lathe machines) such cnc lathe machines are calledflat bed cnc lathe machine. The below is a Slant Bed CNC Lathe Machine. Fig19 Fig20 CNC Lathe Tool Turret Tool Capacity Tool capacity for cnc lathe machines varies machine to machine.Small CNC lathe machines normally comes with a tool turret capacity of 4 or 8 tools stations. Bigger and plodding CNC lathe machines tool turrets are big and overweight and accordingly testament hold more tools such as 12 or more. Fig21 Tool Holder Tool holder is the actual part which faste ns the tool to the cnc lathe tool turret Disk. Tool holder size in addition depends upon the cnc lathe tool turret size, heavy CNC late machine tool turret comes with with big bore for tool holders such as 50 mm diameter. For the small tool turret this might be 40 mm diameter or, less to suit the tool to hold.Fig22 CNC Lathe Tool Turret Rotation CNC lathe tool turret rotates with the cnc program commands. Normally a letter T is used to call a tool in the working position. The tool rotation is dependent on cnc lathe machine. or so cnc lathe tool turret rotate in one direction (CW or CCW ). Some cnc lathe tool turret rotates both directions, such tool turret direction is optimized for the nearest tool station. Some cnc lathe give full control over tool call up, you can call by optimized direction or you can call tool by rotating tool turret by CW direction or CCW.Tool Offset in CNC Lathe with Fanuc Control Fig23 There are variety of cnc machines in the market, and almost every cnc m achine in acnc workshophas different affable of cnc machine controls if controls are not different they might have different versions of the same cnc machine control. As the operating of different cnc machines controls is very much different from one another the same wayTool Offsettingis very much different. Here I provide discuss the cnc tool cadencyment on Fanuc. Tool Offset Setting on Fanuc TCSome cnc machines has some kind of built-in mechanism of tool-offsetting, this built-in mechanisn of tool-offsetting makes adding peeled tools are changing existing tools a breeze, because you just bandstand the tool in the tool-post on thecnc machine tool-turretand just perform the agency the cnc machine manufacture has given in the cnc machine operating and setting manual. TheFanuccontrols such as Fanuc TC has this capability, Just tie up tool in the tool turret and perform a simple procedure and everything is done. The tool offsetting procedure might be different from version to ver sion, simply on Fanuc TC this procedure is simple as under.For tool offsetting of a new tool just tie up the tool in the tool post and inMDI (Manual Data Input) Modecall up the tool in the working position by entering the command T1, the T is for tool call up and 1 is tool number if you have your tool on another position you might change that with that tool number. Now change the cnc machine to Jog Mode and touch the tool cutting point to the finished component (already gripped in cnc machine jaws) face and bring the Tool-Geometry page and enter under the tool number the command MZ0 this command lead clear any previous values and will measure the current tools tool-offset in Z-axis.Now touch the tool to aknown-diameteron the component and again in the tool-geometry page enter the command MX50 you can enter the measured diameter value instead of 50. This way now we have calculated the tool-measurement on the Fanuc TC cnc machine control. CNC Dry Run Invaluable Tool for CNC Setter F ig24 It repoints the power and the flexibility the cnc machine manufacturers and cnc control manufacturers give acnc machine setterby integrating the Dry Runon cnc machines. On some cnc machines the Dry Run is added as aCNC Machine Modelike Fanuc.On Fanuc cnc control you just select the Dry Run mode and cnc machine is now in Dry Run Mode. Introduction of Dry Run for CNC Machines Setting a new component on a cnc machine is not an easy job. You have to go through many important tasks like cnc machine zero offsetting (cnc machine shift value setting),tool offsetting of toolsused on cnc machine etc. Now if you have completed these all tasks, now comes the time to run the cnc program for the first time, A really crucial and time consuming cnc task. A small negligence might be cause of an accident on cnc machine (tool breakage etc. . To make the first run easy and safe the cnc machine manufacturers and cnc control manufacturers provide us a way by which we can slow control the tools fee d withfeed rescind. So now the cnc setter is a bit easy because he can now run all the tools with aSafe Feed. Now cnc setter easily can lower the tool feed when he feels the tool is entering a bit danger zone, and easily can increase the tool feed (to a rapid feed) when the tool is away from the component (so the time not go wasted with lower feed when tool is away from component).In Dry Run all the cnc blocks whether those are starting with G00 or G01 and otherG-codelike G02/G03 run with the same feed, which is controlled through Feed Override. On Fanuc the feed change by reversal is controlled throughHandwheelafter feed decree entirelyton press, and there as well exists a Rapid Feed Button which if pressed during Dry Run Mode the cnc machine program block will run with Rapid Feed. One point must be cleared for Fanuc control is that feed upset also works inAuto Mode and Single Block Modebut in such modes the feed override only controls G01/G02/G03 like G-code.But feed overrid e will not control the G00 (Rapid Traverse). But in Dry Run Mode all the cnc program will run with the feed which is controlled through Feed Override. An introduction to cnc machine speed override and feed override controls and rubber eraser instructions which must be adhere to while working with cnc machine feed and speed override. CNC Machine Speed Override / Feed Override Introduction Normally you program the speed and feed this way, N10 G97 S ascorbic acid0 G95 F0. 3 Fig25Now for one reason or other you want to increase or decrease the speed or feed of the cnc machinefor some time, you definitely have a way to just alter thecnc machine program, but there is one more suitable solution the Feed Override and Speed Override Controls. The feed override and speed override arethe most suitable and handy way to control thecnc machine feed and speed through cnc control panel. You control the speed and feed in percentage. When the feed overrideis 100% the actually feedwhich is programmed will be active.But if the feed overrideis 50% then the feedwill decrease by that ratio, now the machine tools will run with 50% of feed. So if youhave programmed 0. 5 mm/rev feed then with 100% the 0. 5 will be active, but for 50%feed override the actually tool feed will be 0. 25 mm/rev. The same rule applies for speed override, for 100% the actual programmed speed will be active and spindle will revolvewith the actual programmed speed. Butat 50% speedoverride the spindle speed will drop by 50%. Feed Override Speed Override Minimum Maximum Values Normally you can control speed override and feed override from 0% to 120%.At 0% speed override the spindle will stop rotating, and at 0% feed override the tool will stop working ( the tool will be stationary ). No doubt120% feedoverride and speed override is justsafe. But some cnc machines give even more flexibility Ihave worked on a cnc machine which has its feed override 0% to 200%. Normal cnc machine has just 0% to 120% feedoverride and speed override. Speed Override and Feed Override Safety Precautions Whenever handling the speed override and feed override always think about safety, safety of yourself, tool, machine, component and your surroundings.Never try to use the speed override and feed override if you dont need it. Because when cnc programs are made the speed and feed is properly set for the machined component. The increase in feed or speed might break insert or even tool. CNC backfire CNC Troubleshooting, In this category we will see the cnc machine from a different wad (cnc machine maintenance), your feedback will really matter, and I hope you will share you knowl marge and experience. I will talk about theCNC passwhich is found in cnc machine axis. * what is cnc funk, * cnc backlash causes, * when to worry about cnc backlash, how to measure backlash, * How to settle and compensate cnc backlash through hardware and cnc control software. Fig26 *What is CNC Backlash? CNC Backlash is any kind of play w hich is found in cnc machine axis. or you might say, CNC Backlashis non-movement of the cnc axis which occurs on axis reversal. *Causes of CNC Backlash? This play (backlash) might be due to * Clearance which is kept in mechanical parts to reduce friction. * As mechanical parts get loose with time. * As with time mechanical parts keep moving and rubbing each other and after long time they lose their actual shape and size. CNC Backlash Is already there A cnc machine axis move due to theirLead ScrewandLead Screw Nut. There is always kept a very minor backlash in the lead screw and lead screw nut to reduce hurt and wear. *CNC Backlash When to Worry It is good if your cnc machine axis backlash is near 0. 0001? but not always possible, so 0. 0003? to 0. 0004? is acceptable. But if the amount of play in the lead screw and nut crosses this limit then there is the time to worry, and call up you mechanical maintenance guys. CNC Backlash How to Measure?CNC machine backlash can be measure with aDial Indicatorattached to an Adjustable Stand. Put the stand on the cnc bed and direct the needle (plunger) of the dial indicator towards the axis which you want to measure. 1. Set the dial needle to 0. 0mm (zero). 2. Now move the axis in one direction 0. 5mm. Dial indicator should show 0. 5mm travel. 3. Now reverse the same axis 0. 5mm. If your dial indicator now goes back to 0. 0mm, then everything is okay. But other than, if on reversal the dial lags behind, then the amount the dial lags behind is the backlash.CNC Backlash How to Resolve? ( Backlash Compensation ) Now you have two choices the hardware way and software way to resolve cnc backlash. You first better choose the hardware way, because normally backlash is due to lead screw or lead screw nut wear, so better resolve the issue by tightening them a bit if they are loose than required, there are plenty of other hardware ways to cope with backlash. CNC controls also give us the ability to control (compensate) cnc backlash through their parameters. CNC Backlash Compensation through CNC Control Parameters How Much Successful?The better advice is that you resolve the issue by changing the lead screw (if possible) or lead screw nut, or just tightening them if they are loose might work, but otherwise CNC control parameters can be changed to compensate backlash, the cnc lathe machine I work on with fanuc control has the 0. 012mm set in its parameters as the backlash compensation for x-axis and z-axis. So such values can be changed to resolve the backlash issue. 10. DRILLING AND TAPPING ON CNC MACHINES Drilling is the operation of producing circular hole in the work-piece by using a rotating cutter called DRILL.The machine used for drilling is called drilling machine. The drilling operation can also be accomplished in lathe, in which the drill is held in tailstock and the work is held by the chuck. The most common drill used is the become drill. Drilling Machine It is the simplest and accurate machine use d in production shop. The work piece is held stationary ie. Clamped in position and the drill rotates to make a hole. Types 1) Based on construction Portable, Sensitive, Radial, up-right, Gang, Multi-spindle 2) Based on Feed Hand driven ,Power driven Components of drilling machineSpindle The spindle holds the drill or cutting tools and revolves in a fixed position in a sleeve. Sleeve The sleeve or quill assembly does not revolve but may slue in its bearing in a direction parallel to its axis. When the sleeve carrying the spindle with a cutting tool is lowered, the cutting tool is fed into the work and when its moved upward, the cutting tool is pull back from the work. Feed pressure applied to the sleeve by hand or power causes the revolving drill to cut its way into the work a fraction of an mm per revolution. ColumnThe editorial is cylindrical in shape and built rugged and solid. The column supports the head and the sleeve or quill assembly. Head The head of the drilling machine is composed of the sleeve, a spindle, an electric motor and feed mechanism. The head is bolted to the column. Worktable The worktable is supported on an arm mounted to the column. The worktable can be adjusted vertically to accommodate different senior high school of work or it can be swung completely out of the way. It may be tilted up to 90 degree in either direction, to allow long pieces to be end or angle drilled. BaseThe base of the drilling machine supports the entire machine and when bolted to the floor, provides for vibration-free operation and best machining accuracy. The top of the base is same to the worktable and may be equipped with t- slot for mounting work too larger for the table. Hand Feed The hand- feed drilling machines are the simplest and most common type of drilling machines in use today. These are light duty machine that are operated by the operator, using a feed handled, so that the operator is able to feel the action of the cutting tool as it cuts through the work piece. These drilling machines can be bench or floor mounted.Power feed The power feed drilling machine are unremarkably larger and heavier than the hand feed ones they are equipped with the ability to feed the cutting tool in to the work automatically, at preset depth of cut per revolution of the spindle these machines are used in maintenance for medium duty work or the work that uses large drills that require power feed larger work pieces are ordinaryly clamped directly to the table or base using t bolts and clamps by a small work places are held in a vise. A depth stop mechanism is located on the head, near the spindle, to aid in drilling to a precise depth.Sensitive or Bench Drilling Machine * This type of drill machine is used for very light works. Fig. 1 illustrates the sketch of sensitive drilling machine. * The vertical column carries a turning table the natural elevation of which can be adjusted according to the work piece height. * The table can also be swung to any desired position. * At the top of the column there are two pulleys connected by a belt, one pulley is mounted on the motor shaft and other on the machine spindle. * Vertical movement to the spindle is given by the feed handle by the operator. * Operator senses the cutting action so sensitive drilling machine.Fig27 Up-Right Drilling Machine * These are medium heavy duty machines. * It specifically differs from sensitive drill in its weight, rigidity, application of power feed and wider range of spindle speed. Fig. 2 shows the line sketch of up-right drilling machine. * This machine usually has a gear driven mechanism for different spindle speed and an automatic or power feed device. * Table can move vertically and radially. * Drill holes up to 50mm Fig28 Radial Drilling Machine * It the largest and most versatile used for drilling medium to large and heavy work pieces. Radial drilling machine blend to power feed type. * The column and radial drilling machine supports the rad ial arm, drill head and motor. Fig. 3 shows the line sketch of radial drilling machine. * The radial arm slides up and down on the column with the help of elevating screw provided on the side of the column, which is driven by a motor. * The drill head is mounted on the radial arm and moves on the guide ways provided the radial arm can also be swiveled around the column. * The drill head is equipped with a separate motor to drive the spindle, which carries the drill bit.A drill head may be moved on the arm manually or by power. * Feed can be either manual or automatic with reversal mechanism. Drill Materials The two most common types are 1. HSS drill- Low cost 2. Carbide- tipped drills high production and in CNC machines different types are Solid Carbide drill, TiN coated drills, carbide coated masonry drills, parabolic drills, split point drill. Fig. 4 shows various types of drills. Drill fixed to the spindle Fig30 Tool Nomenclature Fig. 31 Nomenclature of thingumabob drill Tool holding devices Fig. 7 and Fig. 8 shows the different work holding and drill browse device.The different methods used for holding drill in a drill spindle are * By directly fitting in the spindle hole. * By using drill sleeve * By using drill socket * By using drill chuck Fig32 Drilling operations Operations that can be performed in a drilling machine are * Drilling * Reaming * Boring * Counter boring * Countersinking * Tapping Drilling It is an operation by which holes are produced in solid metal by core of revolving tool called Drill. Fig. 9 shows the various operations on drilling machine. Reaming Reaming is accurate way of size and finishing the pre-existing hole.Multi tooth cutting tool. Accuracy of 0. 005mm can be achieved. Boring Boring is a process of enlarging an existing hole by a single point cutting tool. Boring operation is often preferred because we can correct hole size, or alignment and can produce smooth finish. Boring tool is held in the boring bar which has the shank. Accuracy of 0. 005mm can be achieved. Fig. 33 Various operations on drilling machine Counter Bore - This operation uses a pilot to guide the cutting action to accommodate the heads of bolts. Fig. 10 illustrates the counter boring, countersunk and spot facing processes. Countersink-Special angled cone mold enlargement at the end of the hole to accommodate the screws. Cone angles of 60, 82, 90, 100, 110, 120 Fig. 34 Counter boring, countersunk and spot facing Drillingmachines are tools that have a rotating, cutting component at one end that bores holes into different materials. There are several types ofdrillingmachines that may be used for a wide variety of purposes, including woodworking, construction,masonry, metalworking, medicine, oildrilling, and many other fields. putting surface drills include the hand drill, push drill, pistol-grip drill, hammer drill, anddrill press.In addition to making holes, drills are often used to push screws into wood, metal, plastic, rock, o r composites. The hand drill and push drill are both manually operateddrillingmachines that have been largely replaced by power drills. A hand drill works by turning a crank that rotates gears, which cause the chuck to turn. The chuck is the component of thedrillingmachinethat holds the bit, or the end cutting piece. The push drill is a skinny tool resembling a screwdriver with a handle that can be pushed down on a yarned shaft, or a pole with helical ridging.As the handle is pushed down along threading, the shaft, chuck, and bit spins downward, much like pumping a toy metal top. Pistol-grip drills are the most commonly useddrillingmachines. These are corded electric drills that are typically shaped virtually like a pistol, with a trigger switch that starts a motor inside the drill. The motor causes the chuck and bit to spin in continuous revolutions. These drillingmachines may be used to make holes for bolts or other purposes, to push screws into wood, plastic, or other materials , and to bore countersinks.Acountersinkis a screw-shaped hole that is made beforehand the screw is drilled in, preventing splintering or pulling of the plastic or wood around the head of the screw. A pistol-grip drill is also available in a battery-powered, cordless version, though they are usually more expensive. There are many different types of this drill and several indications for use. It is also possible to admit the drill with an attachment, such as sanding or sawing components. A hammer drill, also called a rotary hammer, is sympathetic to a pistol-grip drill, but also applies a punching motion to complement the rotational action of the bit.This hammering, forward force makes it useful for tougher materials, such as concrete or stone, that standard electric drills cannot cut through. For softer materials, however, the hammer drill may apply excessive force and a standard drill may be a better choice. A drill press is a type of drill that may stand on the floor or be mount ed on a workbench. The base of themachineis bolted to the table or floor and a column rises up from the base to support the back of the head of the drill. The column also supports a table that can be adjusted in height between the head and the base.The spindle, a metal component that holds the chuck and drill bit, extends downward from the front of the head, parallel to the column. A larger distance between the spindle and column allows wood with a larger width to be drilled. An on switch triggers the spindle to spin and levers attached to the head of the drill press move the spindle and chuck to move up or down. Thesedrillingmachines are suited for accuratedrilling, because the bit is fixed and the work can be secured to the table with clamps or a vise. - Types Of Drill BitsDrill bits are tools used in making cylindrical holes. Various types of drill bits are designed for different uses. Drill bits are equipments or tools that are used in making cylindrical holes. Drill bits can al so be referred to as a drilling machine. Drill bits are available in various drill types such as metal drills, gun drills, screw machine drills, core drills, step drills, spade drills, forstner drills, masonry drills, dental or surgical drills, wood bits, twist drills, drill blank taper drills and much more. They are designed to cut while doing a clockwise rotating motion. Several drill bits are coolant fed.They contain a channel or hole for directing the coolant fed near to the cutting edges. The split point drill heads of drill bits are used for chip clearance and for excellent centering. Drill bits can also be used in cutting aluminum, general-purpose metals, brass, copper, bronze, ceramic, and plastic, virtuous steel, steel, wood, titanium and hardened materials. Various types of drill bits are designed for different uses. Listed below are some types of Drill Bits. Twist Drill It drills holes in plastic, metal and wood. This drill is currently produced with a width covert a r ange from 0. 5 millimeters to 100 millimeters while its length is around 1000 millimeters. The most usual twist drill has a tip angle of 118 degrees. This is a proper angle for an extensive set up of job. It also has a long series drill for extended length twist drills. It is not well(predicate) to drill deep holes using this twist drill. Diamond Drill Bit This particular drill is used in the bathroom for updating or remodeling. It is also used in redesigning your kitchen decoration. Furthermore, it is used on ceramic, glass, tile, limestone, dye glass, marble, fibreglass, porcelain, stone, slate and porcelain tile.When using this drill, the main concern is to obtain water at the edge of the drill bit. Drilling fiberglass may be done with or without water but make sure that the fiberglass has ample amount of water just to get the drill wet. Indexable Drill Bit This provides an excellent performance in making short-hole drillings. Stainless steel is drilled 3x in diameter and only a short-hole must be done. Listed below are some other types of drill bits Adjustable Bit This is built with a changeable cutter blade to bore holes of various sizes. It is also used for drilling gaps for wiring or piping.Around-the-corner bit It is used to cut arched holes that are stretched in corners with a diagonal cutting surface. plumbers snake Bits This drill creates drill holes in wooden materials. The drill ends have a screw head so that the bits may be self fed. Brad-point drill This drill looks almost the same as the usual bits but it has sharpened point to make wood drilling a lot easier. This drill has cleaner holes other than spade bits. Counterbore The drill allows a screw to be driven under the wood outside. The holes that are drilled may be filled with a plug or wire.Drill Saw Bit It is used to cut holes such as wood and metal and can enlarge current holes. Countersink A drill that has an angled tip design that forms a slump in the screw head. Fly cutter This one is often used to cut circles in wood and other soft metals. The diameter of circles may be adjusted by changing the cutter blade setting. Hole saw It cut holes from one to six centimeters in diameter and has a center bit for directing the cutting blade edge of the saw. Reamer bit The tapered bit of reamer may be used on existing holes rather than to enlarge holes.Screw pilot bit This beautiful bit is used for drilling body holes. A pilot hole is used along with the countersink. Wire Brushes It use to remove rust and to clean up metal and is available either as a wheel or a cup with wire brush. Plastic bit This is designed with a tip so as to prevent splintering when drilling plastic. It is important to reduce the speed and slowly drill the other side of the plastic. Plug cutter Use this to remove cylindrical shapes from the wood. It covers the screw using a small cylindrical plate. Tapping- Tapping is the process by which congenital threads are formed.It is performed either by hand or by machine. Minor diameter of the thread is drilled and then tapping is done. Fig. 11 show the tapping processes. Fig. 35 Hand taps and tapping process using tap wrench Fig. 36 Various operations performed on drilling machine Work Holding Devices 1. Machine Table Vice The machine vice is equipped with jaws which clamps the work piece. The vice can be bolted to the drilling table or the tail can be swung around swung around. Fig. 13 shows the standard and swivel vice. The swivel vice is a machine wise that can be swivel through 360 on a horizontal plane. Fig37 1.Step Blocks These are built to allow height adjustment for mounting the drilling jobs and are used with strap clamps and long T-slot bolts. 2. Clamps These are small, portable vises , which bears against the work piece and holding devices. prevalent types of clamps are C-clamp, Parallel clamp, machine strap clamp, U-clamp etc.. Fig. 14 shows the correct and incorrect methods of mounting the work piece. Fig38 11. APPLICAT ION OF CNC MACHINES ? cutting ? drilling ? milling ? welding ? boring ? bending ? s pin ? pinning ? gluing ? sewing ? routing Its application in some industries like -Automotive Industry Aerospace Industry -Machinery Industry -Electrical Industry -Instrumentation Industry Automotive Industry Different Products Fig39 Aerospace Industry Aircraft Turbine Machined by 5-Axis CNC Milling Machine Fig40 12. ADVANTAGES AND DISADVANTAGES OF CNC -Ease of Use ? CNC machines are easier for beginners ? Operation of several CNC machines at same time ? Some CNC machines dont need any operator indeed call their operator in case of the emergencies. heights Efficiency ? operate almost continuously 24 hours a day, 365 days a year. Expanding Options ? Expand the machines capabilities with SoftwareChanges and updates. No Prototyping ? new programmers provide elimination build a prototype, save time and money. Precision ? Parts are identical to each other. Reduce Waste ? Reduce waste as errors allows min imize wasted Material. evil of CNC Machines Cost CNC machinery ? costs quite a lot more than conventional machinery. ? Does not eliminate the need for expensive tools. ? Expensive to repair. 13. CONCLUSION CNC machines which are applicable any type of processing. manufacturing anything is identical in shorter time. CNC machines provide many advantages. Many industries prefer using CNC machines.