Understanding CNC Have you ever asked yourself how machines in a factory know exactly when to stop making the parts they're supposed to make? Well, this is all because of Computer Numerical Control (CNC). But to understand CNC, you have to know what Numerical Control (NC) is. HISTORY NC machines were first introduced after the 2nd world war as mass production became the trend. These machines were given a set of instructions in punched cards. However, these machines were hard-wired and their parameters were difficult to change. These NC machines still required a great deal of human intervention. To illustrate this point, try to take a look at a drill press. A lot of actions have to be taken in order to manufacture a product. The process is actually so complicated that a person has to do something almost every step of the production process. This created an avenue for errors to take place as the likelihood of fatigue increased with the quantity growth. CNC then came into the picture when computers were introduced. Punched cards were replaced by floppy disks, cables, and other software transfer media. This made it easier to manage and edit data. Production and manufacturing were revolutionized by the increased automation of CNC machines. These machines allowed a degree of added control over the quality and consistency of the components that were manufactured without any additional strain on the operators. This reduced the frequency of errors and allowed the operators time to perform additional tasks. Furthermore, this automation allowed a greater degree of flexibility in the way components are held in the manufacturing process. With the advent of Computer Aided Manufacturing (CAM), even programming CNC machines is a snap. These programs actually take the bulk of the programming process to make the operation less tedious. However, to be an effective programmer of CNC machines, you have to know what the machine you're working on will be doing. That is why machinists are often the best people for the job. The ease that the machines provide is hinged heavily on the quality of the machine. Low-cost CNC machines oftentimes have many functions that have to be manually activated. High-cost machines, however, are almost fully automated. The operator only has to load or unload workpieces. Once the cycle has been initiated, the operator just has to sit back and watch for any malfunctions. The stress on the operator is so low that some even complain of boredom in the middle of a cycle. CODING The programming language that CNC uses is called a G-Code. These codes actually position the parts and do the work. To be able to have a machine work properly, you have to input the correct variables such as axes, reference points, the machine accessories, and whatnot. Every machine has a different set of variables so you have to be careful to take note of the differences. Aside from the G-Code, logical commands or parametric programming can be used to make the process more time-efficient. This type of programming language shortens lengthy programs with incremental passes. A loop can also be programmed thereby removing the need for coding repetitions. Because of these features, parametric programming is more efficient than CAM. It allows users to directly and efficiently make performance adjustments. It also allows extensions to the functionality of the machine it is running on. And that makes CNC. How CNC Helps Companies The advent of Computers lessened the need for human intervention in almost all aspects of our daily lives. This is especially true in the industrial sector now that production is virtually automated. Precision and accuracy Computer numerical control has been able to help companies in terms of precision. With the need for more complex designs and more complex operations, human workers could not cope with the required precision that comes with advancement. CNC machines were able to alter that idea by allowing increased precision and lesser error ratios with regards to production. Another important improvement that CNC has brought with it is the increased accuracy. The dimensions of components have to be very accurate. And since an increase in production speed also increases the error ratio, CNC has helped lower that ratio by the increased level of automation and the error detection capabilities that computers have. Speed In the industrial sector, speed is of the essence. With CNC technology, the normal production capacity has been increased exponentially. This means that effective and accurate production methods have been developed. Mass production requires more scrutiny for errors and mistakes. However, anomalies can also be corrected. The programming structures of CNC machines can be altered in a fast way. This means that mistakes do not have as serious an impact as they had before CNC was improved to this level. Machine versatility CNC machines have become very versatile with regards to the tools that they use. They can easily be assigned to different tasks and thus can be very productive. Tools and networks can be switched without compromising the speed of the production. Aside from this, one machine can do more than one task at a time. This exceeds the normal human capacities as it allows more tasks to be accomplished at a faster rate than before. Furthermore, when one machine tool breaks down, it can easily be pulled off the grid to prevent it from affecting the whole production cycle. It can then be replaced or repaired on the spot. Lesser human intervention Since component production is a very tedious and repetitive operation, human error skyrockets as time passes. This is due to fatigue and other factors. Furthermore, the ability of a person degrades due to psychological and emotional factors. This means that if a person works on the same job for a certain amount of time, the person may eventually get bored or tired or both. This increases the possibility for the human to commit an error and thus causes a drop in the efficiency rating of that person. A machine, however, does not get tired or bored. A machine does not have any concern at all. Therefore, a machine increases efficiency ratings by speeding up production and eliminating or reducing factors that threaten efficiency. In this case, one must simply program the machine to start a cycle. Furthermore, humans have to be fed, paid, and rested. Machines only have to be rested when failures occur to often and they do not need to be paid or fed. This brings us to the conclusion that companies will be able to save a lot in the long run. While investing in CNC machines is not cheap, maintenance will only cost a fraction of what will be paid to manual laborers. How To Effectively Consider CNC In the employment world, the phrase "manual labor" is often associated with jobs which are dirty, psychologically sickening, or worse, both. Small to medium-size manufacturing enterprises are moving towards using the CNC(Computer Numerical Control) in their major manufacturing processes because of its fame in accuracy, flexibility and automation. If you're one of these entrepreneurs, don't jump in the bandwagon just yet. Acquiring a CNC machine is more than just buying additional equipment; it also has a social aspect in it. Here is the low down: PEOPLE-WISE First, you have to consider the people who are working in your shop. How many people will be displaced if you buy a CNC machine? Keep in mind that a CNC machine is multi-operational; so it's possible that a couple of laborers will be erased from the production team. Experts say that the healthy ratio is at least one-sixth (1/6) of your whole labor force. You will be saving time and effort, yes, and that is the best thing about having a CNC machine. However, you might be worrying about actually terminating people because, to put it bluntly, you won't need them anymore. A CNC machine, just like any machine, will need an operator. Instructions used by a CNC machine for operational execution are composed of CNC "words/codes" and is in the form of a "sentence". Does one of your people ever have experience with a CNC machine before? Can s/he formulate CNC instructions? If the answer to both questions are "yes", then that's absolutely good news. However, if you answered "no" to at least one of the questions, then there are more things to evaluate. Are your people capable of fast-learning? If it pains you to terminate them because they have been good employees in the past, train them on how to use the CNC machine and how to compose instructions for it. There are plenty of free training kits online. COMPANY-WISE There's a corporate adage that goes: "Innovate or die". There's a lot of truth in that. A purchase of any CNC machine symbolizes a company's decision to innovate to increase productivity. However, there are a few things that you need to note. Review your company's history. How long should you innovate drastically in terms of production? CNC equipment is expensive. It is an investment. In the long run, you may be forced to buy new equipment more often. Consider CNC heavily if you feel that your company innovates faster than other companies in terms of the industry that you belong to. After all, you can easily alter designs and material when you have CNC powered operations. In most companies, "Innovation" is another word for "saving". It means saving time, effort and space. In using CNC machines, the first two factors are sure savings while the third is not. People doing the labor and CNC machines often occupy the same amount of space. Do not romanticize a "clearing of clutter" effect when you buy a CNC machine. You will keep up, in terms of production; but CNC equipment also occupies a lot of space. So in that aspect, it's pretty much the same thing. Another thing that you have to be reminded of is the level of accuracy that your company needs to produce. Intricate patterns on metal/wood will DEMAND CNC accuracy. So any time that you feel your company is ready for such innovation and accuracy, consider employing CNC in your manufacturing. At the end of the day, the last aspect that you need to evaluate is you, yourself. As the owner/head manager, you have to KNOW AND UNDERSTAND the CNC machine and the software well. This is the biggest battle that you have to face. The equation to improvement is simple a really good machine plus a really good operator (you). Do not easily be blinded by the salesmen's poetry. The CNC Family You might have not heard of the CNC before, or what it does, or how it makes lofty manufacturing operations a lot easier. However, CNC machining is dubbed as one of the most important factors of most production processes. The common tasks CNCs machines usually perform are drilling holes, tool changing, cooling and lubrication of separate factory machines at the same time. Let's start with a brief introduction. CNC stands for Computer Numerical Control and it has been around since the early 1970's. Before it was christened CNC, it was called NC, for Numerical Control. When computers were introduced during 1070's, the name changed. It has stroked almost all manufacturing forms in almost all stages of production. CNC machines either substitute some existing manufacturing processes or combine work with them. A CNC program is just any other set of instructions. It's written like a sentence and the order of operation is chronological. The machine will then execute that set of instructions step-by-step. A special series of CNC words/codes are used to relay what the machine is supposed to do. CNC codes begin with letter addresses (like S for spindle speed, and X, Y & Z for common linear axis motions). When certain codes are arranged together in a coherent method, this group of CNC codes create a "command" that is like a sentence. A common CNC machine will only be needing around 40-50 words/codes to program different commands. See, it's not very difficult to learn. Although CNC sounds very independent and do-it-all, there are a few words that you need to know to fully understand CNC operations. THE CAM CAM stands for Computer Aided Manufacturing. It simplifies the programming processes which are new, and added to the CNC program regularly. Of course, the easy applications can be programmed with only the simplest machines around: the pen, paper and calculator. However, more complex programs are vital regularly. It is when composing these programs become much more tricky and (worse) tedious. The CAM is a program that runs on a computer that aids the CNC programmer with the programming. It also works hand-in-hand with the CAD (Computer Aided Design) design drawing (those designs engineers compose/nurture). With the CAM helping, redefinition of the work-piece configuration is not needed. What the CNC programmer is left to do is just to specify the machine operations to be executed and the CAM system will compose the CNC program automatically. Thanks to CAM, programming tediousness will not be a problem to the CNC programmer again. THE DNC SYSTEM DNC stands for Distributive Numerical Control. It is a computer that is connected with one or more CNC machines, forming a network. When a program is manually composed and ready to be loaded to the CNC control, it is being typed right into the control. However, this is like using the CNC machine as a luxurious keyboard. Moreover, if the CNC program is achieved with the help of CAM, it is already in text form and ready to be loaded to the CNC control. The DNC simply distributes the CNC program to more than one CNC machine. Lately, the newest controls are more advanced in terms of networking capabilities and can be networked with, say, the Ethernet. If it's your first time to read and learn about the CNC, it may sound so mighty and ubiquitous. It's about time you learn they also need help from some programming friends such as the CAM and the DNC. No man is an island; but hey, neither are CNC machines. Meet Your "Other" Employees: The Basic Parts of a CNC Machine If you carve your name on a wood using a very sophisticated font, you're lucky if you'll finish your first name in 24 hours perfectly. Years ago, wood crafting and metal crafting are very expensive massive- labor industries because every aspect of the manufacturing is done by hand. There was minimal machine intervention but the designs were still as intricate. Today, with the help of technology, wood carving, metal molding, cutting and even finishing can be done simultaneously with minimal hands involved. In fact, a company is deemed unproductive if it mass produces products every day BY HAND. CNC (Computer Numerical Control) machines are in demand in industries where hands are better off pushing buttons than doing actual labor. Businessmen are raving about this wonder-machine because it is accurate, speedy and flexible. The CNC machine is actually a factory of its own. There are different parts that have specific functions. Let's get to know the "factory workers". THE VICE The Vice is what holds the material which is to be cut or molded. It is important that the vice must be tight; so the material will be held securely. When the CNC machine starts to operate, the material will dash out of the vice if it is not secured. The vice usually works like a clamp that needs to hold the material not just securely but also in the right position. THE GUARD The Guard -- just like any other guard -- works like a "protection" to the person operating the CNC machine. Once the CNC starts working, scraps of the material can "shoot off" at high speed. This is very risky for the operator if a piece hits him/her. The guard completely covers all the hazardous sides of the CNC machine. THE CHUCK The chuck holds the cutting tool. Sophisticated designs require maximum chuck precision so the actual design can be realized. THE MOTOR The motor rotates the chuck at very high speed. It is hidden and protected inside the machine. You have to take care of this part very carefully. Nowadays, cooling and lubrication is automated in most CNC machines. Usually, if this part doesn't function well, it is the most difficult to treat. It is advised to have a CNC technician handy all the time. THE LATHE BED Like the sea bed, this is the sturdy base of the CNC machine. It is connected to the headstock and aids the carriage and tailstock to be parallel with the spindle's axis. It is securely bolted so it remains unshaken by the vibration of the machine when it starts operating. THE CUTTING TOOL/ CUTTER This is the where the first-level shaping occurs. The cutter is usually made from high quality steel so as to cut the specific material fed to the CNC machine. As a businessman, it is important that you get to know your employees, bond with them and earn their respect without scaring them. When you have CNC machines working for you, it is equally important that you understand them well. Do not be fooled by the CNC machine salesmen who court your interest because they are usually just after your purchase. You have to master what comprises these machines, what makes them dysfunctional and most of all, what makes them stay in your company. Just don't start talking to them. That would be really, really, dysfunctional. Data Transfer Methods of CNC A CNC machine cannot function without a program. And a program cannot make its way to the machine without an effective data transfer system. So, what are the methods of data transfer and how effective are they in conveying data from one point to the next? Punched tape The first data transfer method is the punched tape. It consists of a long strip of paper with holes punched in it to store data. The holes represent a set of data that tells the machine how to move and what to do. This method has proven to be very versatile and very useful. It has proven to withstand the test of time as numerous magnetic storage devices have deteriorated over time even to the extent of being unreadable while punched tape has been shown to be fine decades and perhaps even centuries later. Repair is also not a problem as specially designed splices can put two end together virtually unchanged. Furthermore, punched tape can be visually decoded should the need arise. This means that human accessibility is also not a problem. Floppy Disk While punched tape is quite a long roll of paper, a floppy disk is a small magnetic storage device that is more space efficient than punched tape. It can also be used to store simple programs. Floppy disks virtually revolutionized the way data could be stored and transferred from one point to another. It allowed users to store and transfer data faster than punched tape allowed. Furthermore, the data within a floppy could be easily edited at any point as long as you have the proper program to read it. However, this method has proven to be quite problematic in the long run as floppies have a tendency to degrade alarmingly fast. A floppy could be unreadable after only 3 years. RS232 This method is actually a set of standards for serial binary signals that connects between computers, terminals, and modems. This is a fast and efficient way to transfer data. This cable connects a CNC machine to a computer that has floppy disk support thus eliminating the need for punched tape. This allows the operator to input data remotely and even while accomplishing other tasks. However, it need to be used in conjunction with an effective data storage device so as to have backups in case of emergencies. Networks Networks are a set of computers that are linked together to make data sharing easier. In an industrial scenario, networks allow a number of different users to individually create a program for the machine to run on. This method allows multiple users to access and transfer data remotely. This allows for a faster and more efficient check-and-balance system for the programmer and the data verifier. Furthermore, different parts of the program can be completed by different programmers and then compiled by one user. This makes program creation a fast and easy process. Manual Data Input (MDI) MDI allows users to input commands directly into the CNC machine's memory. This may seem to be an effective way of telling the machine what to do but it actually has a lot of drawbacks to it. Despite it being the fastest way of telling the machine what to do, it is also a very risky and tedious operation as it requires the use of the machine's terminal. Furthermore, the construction of a program is not as fast as opposed to the network method. It only allows one user to access the machine thus making it a long and drawn-out process. Another disadvantage that comes with MDI is that it limits the operator to only one task at a time. However, MDI allows the most control over the machine compared to other methods. My Bestfriend's Name Is CNC: A Company's Perspective CNC machine tools are praised all over the world because of three major factors: automation, accuracy and versatility. Human (operator) intervention is reduced to minimal levels because CNC machines can run on its own after it is programmed. Also, when the program is perfected, the CNC machine can run the instructions perfectly on its own. Remember that any CNC machine can also be programmed to do special one-time tasks such as a dry-run, which will help the operator oversee what will happen when s/he leaves the CNC machine to do its tasks alone. Accuracy also goes hand in hand with repeatability. Again, once the program is perfected, the CNC machine can perform that task PERFECTLY even until 7 or 7000 times. Lastly, versatility also works in the form of "task memory" that these CNC machines have. Once a program has been performed even for just one production run, it can be easily recollected the next time that the company needs the program. This saves time for setting up and loading of different programs. The CNC sure simplifies the work of thousands of factories and machine shops worldwide. However, no matter how great CNC sounds like, it is something that doesn't fit in some industries. Like, perhaps, in the cosmetic industry, or in the show-business. Those examples are way too obvious. On the other hand, in these two major mechanical industries, CNC is almost synonymous to "hero". THE METAL INDUSTRY Think of Metal. Metal. Perhaps the easiest metal that you can imagine is that of: a spoon. Now, imagine ANY spoon done with bare hands. After that, imagine a thousand spoons done with bare hands. It's so tedious you might even consider suicide if you are assigned to such a job. The metal industry has been operating on CNC for ages. In fact, if you search CNC in the internet, you will instantly find metal companies topping the list. The major CNC centers that you will find in most metal machining processes are "CNC turning centers", "CNC machining centers", "CNC grinding centers" and "CNC drill and tap centers". Some of the CNC programs that are connected with the metal industry are milling, drilling, reaming, boring and tapping. Moreover, any metal that has any curved side have experienced some form of knurling, grooving, turning and/or threading. Fabrication, in manufacturing, refers to processes that are executed on thin plates/sheets. These sheets are cut, punched, and bent to form their finishing shapes. CNC also stars in almost every aspect of metal fabrication. THE WOODWORKING INDUSTRY While the most beautiful wood-worked products are most likely hand-made, you cannot deny that a wide array of tools and furniture HAVE to be NOT hand-made to save time and for mass production levels. There's just too much work and not to many hands. In light with this, CNC has worked wonders for this industry. Important woodworking processes include cutting, framing, carving and engraving. The most useful woodworking CNC product is the CNC router table. It is capable of carving elaborate 2D and 3D designs. Moreover, it is also capable of material change while repeating the same design. Since contemporary furniture is often a splash of different materials (e.g. Wood, aluminum and/or plastic), any CNC router is capable of reproducing the same design EVEN in different kinds of materials by just altering the router bit. Although many local, middle-sized enterprise owners are skeptical about using employing CNC in their manufacturing operations, there have been many success stories to sway them to using it anyway. In the Metal and Woodworking industries, CNC has proven itself time and again to be efficient. It saves time and efforts in production and (more importantly) back-jobs. If you're venturing to one of these industries, remember that the word "labor" isn't something social anymore -- it's technological. And start calling CNC your best friend. Pros and Cons in Sheet Metal Manipulation with CNC The advancement of technology allowed sheet metal designs to be more complicated. However, this level of complication has surpassed human capabilities (as far as mass production is concerned). The required accuracy for the intricacy of the designs can only be provided by Computer Numerical Controlled (CNC) machines. The Punch press An example of a CNC machine that is used in sheet metal manipulation is the punch press. This device uses hydraulic, pneumatic, or electrical power to exert immense pressure to shape the metal and cut it according to the designs. Being computer aided, this machine is capable of rapid positioning and therefore, fast production. Manual punch presses compromise speed for accuracy therefore lessening efficiency. The punch press works by receiving instructions from a program in a computer. This allows the operator to sit back and relax once the cycle (rapid positioning, punching, and switching of tools) has been initiated. These machines perform operations with accuracy that is measured by the thousandth of an inch. Introduction of these machines into the sheet metal industry sped up production significantly. And to stay competitive in the global market, such an edge would be needed. However, technology finds ways to improve on this. New devices Today, presses have newer versions. The turret punch press is capable of sorting sheet metal into their respective design classes. This means that the new punch presses can operate virtually unattended. Steel manufacturing companies invest in these machines should it mean streamlining of their jobs and increasing production capabilities. Newer CNC machines can even alert operators who are not in the area if a problem crops up during the sheet metal punching process. This happens by enabling the CNC machine to keep track of the operators' phones. Therefore, the workload of the operator is relaxed to the point that he/she does not even need to be in the area of operation. The drawback However, these machines do not come cheap. A lot of time, money, and effort have to be spent in order to operate the machine to its fullest capacity. Furthermore, there is a shortage of people who are skilled enough to operate such machines. An operator has to be knowledgeable with BASIC programming language, fundamental machining processes, design awareness, and accessory functions. Furthermore, knowledge of Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) is a big factor in being able to control such machinery. So the capital that you have to spend on understanding these machines have to be justified with the caliber of the operator that you have. Another drawback that is present is the compatibility of the machines with the current technology that the company has. If they are incompatible, it takes even more time and money to replace current facilities or to restructure the factory in order t accommodate such devices. The Conclusion so, if you're a big company and you want to stay in the race, you have to consider and reconsider investing into these things. The investment may be worth itself a hundred times over but it is a rather risky choice to step into something new. You have to restructure your work schedules, change the requirements for operators, and provide proper training to operators that you want to keep. These things will cost a lot and will take a while before they reflect what they really are worth. People You Will Need When You Already Have A CNC Machine If you think that you will just sit back and relax when you have a CNC machine in your shop, think again. CNC may help you speed up your operations and even make them more efficient. However, CNC is not a "wonder robot" which will make you disregard all your employees and expect your shop to run on auto-pilot. Though you will need more people without the CNC technology, you will need only three very, very skilled people. Call these people your friends, your team, whatever. In the long run, they might be just all you need to keep the shop in good shape. THE PROGRAMMER The first person is the CNC programmer. S/he is like the "playmaker". S/he will create the programs that the CNC machines are intended to execute. Since the programs are in the form of CNC codes fabricated like sentences, he should have mastered these codes because they work like a different language. The regular CNC machine can use up to 50 codes, so that's like learning 50 new words for the newbie. Also, the programmer should have at least and engineering or machining degree. Remember that the CNC machine will only execute WHAT IT IS PROGRAMMED TO DO. If the program is wrong, the whole operation goes down the drain with it. Moreover,s/he should also be flexible and have a fast turn-around because a CNC machine is often used to machine a huge selection of different work-pieces. THE OPERATOR The second person that you need is the CNC operator. S/he will simply recheck the programs loaded to the machine and push the right buttons to get the work done. However, thinking that a CNC operator can have little or NO SKILL AT ALL is wrong. A CNC machine operator must have at least basic machining skills and s/he should have undergone some form of training to run a CNC machine. These machines can produce very intricate motions, making it possible to make shapes that cannot be created on conventional machine tools. So, the operator should foresee this complexity and know how to cruise with it. The skills that an operator must have though, are lesser compared to the operators of conventional machine tools. THE TECHNICIAN The third person that will need is the CNC technician. Although this may still be the programmer, it's more convenient to always have a technical expert on-call because in the long run, you may have more than one CNC machine and you may need to prioritize over the other in case both gets crippled at the same time. Just like the programmer, the technician should also be flexible and articulate. CNC offers a lot of complexity when it's running right, how much more if it's behaving badly? So, if you are having job openings for positions that need to be handling a CNC machine, ask the applicants first to do a demo for you and make sure that during the demo, they know what they're doing. An exam may also do wonders too. If they have no experience with any kind of CNC machine, it is advisable that you encourage them to take short courses on CNC. Eighty-hour courses are available online and hey, it's better than nothing. Experts even encourage employers to hire CNC machinists who have finished AND PASSED the National Occupational Competency Testing Institute (NOCTI) assessment just so they could be sure that their CNC machines will go to good hands. After all, a CNC machine is still an asset. Motion Control -- The Heart of CNC What is Motion Control? Motion control can be applied in many categories such as robotics, CNC operated machine tools and Kinematics, wherein motion control in kinematics are usually simpler. It can be mainly used nowadays with packaging, textile, assembly industries, printing, and semiconductor production. The hardware of a motion controlled machine usually consists of drive systems, motors, a computer, a PLC or Programmable Logic Controller to run the programs, and an amplifier. The basic design of a motion control system would include a motion controller to produce a set of points including closing a position, a drive or amplifier to convert the control signal of the motion controller into a high power electrical current, an actuator, one or more feedback sensors, and mechanical components to convert the motion of the actuators to the desired motion. CNC machines use programmable commands to make inputting motion to the machine easier rather than using cranks or other conventional machine tools. Almost all CNC machine tools can have programmable motion type (whether it would be rapid, linear or circular), the amount of motion, the feedback rate, and the axes to move. Motion control is the simplest function of any Computer Numerical Control (CNC) machine. It is precise, consistent, and automatic system of control. CNC equipments need two or more modes of direction to which they are called axes. There are two common axis types and they are called linear and rotary. The linear axis type of motion control is driven along a straight path while the rotary axis type is driven along a circular path. The operator of the motion controlled machine counting the number of revolutions made on the handwheel, added the generations of the dial would accomplish accurate positioning. The drive motor of the machine would be rotated to a resulting amount, which would then drive the ball screw, which would cause the linear motion of the axis. The feedback device at the end of the ball screw would confirm its revolutions. The same linear motion can be found on a table vise. When you rotate the vise crank, it would also rotate a lead screw, which would then be able to drive the movable jaw in the table vise. In comparison to a motor controlled CNC machine, the linear axis in it is extremely precise compared to that of a table vise. This is because the number of revolutions of the axis drive motor in the CNC machine accurately controls the amount of linear motion along the axis. A CNC command programmed and executed within a control of a machine would tell the drive motor of the machine as to how many number of precise times it would rotate. This in turn would rotate the ball screw then the ball screw would drive the linear axis. After the process has started, a feedback device located at the end of the ball screw would confirm the programmed number of rotations that the machine would run has taken in effect. How would axis motion be controlled? Utilizing a form of coordinate system would make axis controlling a whole lot simpler and more logical to the CNC control. Two coordinate systems that are being used in CNC machines that have been popular are rectangular and polar coordinate system, to which the more popular of the two is the rectangular coordinate system. Graphing is a common application for the rectangular coordinate system and is needed to cause movement in a CNC machine. CNC Machine Setup and Operation Computer Numerical Control Machines are sophisticated instruments that only trained CNC operators should operate them. There are certain rules and guidelines to consider if you are planning to use a CNC machine by yourself. CNC checklist before startup Before starting up the Computer Numerical Control Machine, there are safety rules that must be considered first. First important aspect before starting up the CNC machine is to ensure your own safety, therefore wearing protective gear, such as eye glasses and short sleeved shirts is an important dress code during CNC operation. You should also be careful whenever you are handling tools and sharp edged work pieces to avoid any accidents. You must also ensure that the cutting tools are fastened in the machine spindle to avoid any movement during the cutting operation. Actual Startup, Operation and Machine Setup of the CNC The Computer Numerical Machine startup procedure varies depending with the type of machine being used but usually there is a main power switch or a circuit breaker to turn it on. Some machines also require hydraulics or air pressure before it starts up. When the Computer Numerical Machine starts up, the machine usually starts at its Machine Home Position. The Machine Home Position allows the control and the machine to have a preset starting position for all its axes. After startup, the CNC machine must be sent to this position before the work begins. This position will later be changed to an appropriate location whenever you are machining a particular part of a product. The Tool Length Offset Value or TLO is the distance from the tip of the tool from the spindle in the Home Position. The TLO must be set for each tool in the current job. The TLO can be set using a height gage, fixture location, as well as the reference tool. When these values are determined, they are stored in the Controller to be used during the program operation. After setting the Tool Length Offset Value it is time to setup a part origin of a CNC machine. Setting up the part origin on a CNC machine is the same as setting up a conventional machine. It usually involves positioning the axes to a point where the plan designates as its origin. There are many ways to locate the position on the reference point, it is by using edge finders, wigglers or magnifying glasses. After setting up the whole system for the Computer Numerical Control, it is time to Load the program to the machine. Program loading is different for each machine. Some machines have tape readers to input the program into the Computer Numerical Control Machine's memory. Newer machines have internal or external floppy devices to input the program to the machine. After the program is loaded to the machine, the CNC machine is now ready to use. There are certain instances when you have to change the tools in the Computer Numerical Control manually during machine operations. When a certain machining operation is complete, the program will move the aces to the tool change position and display the next tool needed. It is now the job of the Machine operator to remove and replace it with the next tool. Extra Care must be taken whenever you are starting operations with the CNC machine, any mistake taken during the part of the operation may lead to serious injuries from the machine operator. Pad Printing with CNC Pad printing is a process where a 2-D object is transferred into a 3-D object. It is done by using an indirect offset printing process that involves an image being transferred from the printing plate via silicone pad over a surface that is to be printed. Pad printing is used on a lot of industries that includes medical, automotive, promotional, apparel, electronics, appliances, sport equipment and toys. Pads are three dimensional objects typically molded of silicone rubber. They function as a transfer vehicle that picks up ink from the printing plate, and then transferring to the thing to be printed upon. Examples of pad printing are the printing of labels on the keys on a keyboard or the logo of a toy manufacturer on a Frisbee. The unique properties of a silicone pad allow it to pick the image up in a variety of surfaces such as a flat, cylindrical, spherical, compound angle, textures, concave surfaces or a convex surface. In presses that uses pad printing with Computer Numeric Control (CNC), the substrate or a material that can be printed on, such as paper, film, plastic, fabric, cellophane, or steel, is stationary and the silicone pads are programmed to print one image at a time. With a press that uses Computer Numeric Control, the substrate is stationary and the pads are all programmed to one image at a time to achieve a multicolor print. Though the robotic actions of these presses that uses Computer Numeric Control seems rather complicated, it allows simple setting procedures that enable several programs to be inputted into the machine. All actions are controlled by servo-motor drives giving a very smooth and highly controllable printing action, also giving stroke lengths to be infinitely variable to the dimensions of the machine. Manufacturers even claim that using presses with pad printing capability that uses Computer Numeric Control gives considerable energy savings to the industry. The Computer Numeric system of control can be built on standard machines or modular assemblies that can be produced to suit any application. The degree of complexity is regulated only by the imagination of the designer of the product/s and the number of modules he wishes to use to complete his desired quota. All of the elements of component manipulation can be achieved by combining with multiple closed cups, pad cleaning, varying pad-stroke lengths, alternative pad shapes and a lot more. This type of system is often used where items must be printed in line with other assembly processes, or for complex multiple prints on different surfaces. The flexibility of a Computer Numeric Controlled press comes close to producing the ideal machine for a particular application. Although a CNC press is substantially more expensive than that of a conventional pneumatic press. If the workload can justify the use of a CNC press for the increase in investment, then the CNC press is well worth considering. Although it is wise to not be carried away by the current technology at hand, it still must be a capable printer. Programming 101: CNC After World War II, people realized that they have to manufacture goods at a faster rate and at a lower cost. Hence, mass production trending came to be. Those events led to the development of the Numerical Control (NC) machines which in turn led to the Computer Numerical Control (CNC). HOW TO PROGRAM A CNC MACHINE CNC programming uses a code similar in structure to BASIC. So, if you know how to construct a simple counting program, chances are, you already know what a G-Code looks like. However, there a few other things you have to consider before you start encoding instructions. The first thing that you have to do is to assign values for each of the variables. These variables include the programmable motion directions (axes), and the reference point for the axes. The values that you assign to these variables dictate the movement of the machine. The next thing that you have to do is to take into account the accessories of the machine. Many machines have accessories that are designed to enhance the capabilities of the basic device. However, using these accessories requires you to include them in the coding system. This means that if you want a more efficient machine, you will have to know the machine inside out. READING CODES After those steps, you have to create a subprogram that will deal with the math. This step will then allow your machine to compute the necessary variables and effectively operate without stopping to ask the operator what the limitations are. To show you what these codes look like, here's an example from Wikipedia: #100=3 (bolt circle radius) #101=10 (how many holes) #102=0 (x position of ctr of bolthole) #103=0 (y position of ctr of bolthole) #104=0 (angle of first hole Tool call, spindle speed,and offset pickup,etc G43 in some cases (tool length pickup) G81(drill cycle) call sub program N50 G80 M30 Subprogram N100 #105=((COS#104)*#100) (x location) #106=((SIN#104)*#100) (y location) x#105 y#106 (remember your G81 code is modal) If #100 GT 360 goto N50 #100=(#100+(360/#101)) Goto 100 In the code above, the machine is a drill. The operator utilized a loop in order to keep the machine from stopping. The subprogram then governs the cycle of the machine. This code is still quite a simple code. Other machines require the inclusion of the maximum RPM in the coding. An easier way of programming CNC machines would be the use of Computer Aided Manufacturing (CAM). This system takes on the brunt of programming so that it doesn't seem so tedious and frustrating. It is still similar to BASIC. Another programming enhancement that was developed was the parametric programs or the logical commands. These programs were designed to shorten lengthy codes in order to make them user friendly. However, these codes do not always use the same language with every machine. The language and sequence often varies depending on the typ of machine you will be working on. The operator has to know what the machine can do or what it was made to do before attempting to program it. You should be able to visualize the machine doing what you want it to do. But, you don't have to be a math wizard or a programming genius. You just have to know what your machine does and what you want it to do.
CAM: A Vital Component of CNC Computer Aided Manufacturing started being used by automotive and aerospace component manufacturing companies. This sped up the manufacturing process and thus increased efficiency ratings. However, the introduction of CAD into the industrial sector did not eliminate the need for skilled professionals. In fact, the operation of this program requires a higher degree of skill in terms of being computer literate. Flaws The CAM system is a flawless solution. However speedy the system becomes, it still has faults that may hamper production. Since CAM generates a code for the least capable machine, an improperly set CAM software required heavy manual editing. In this case, editing such a code is a tedious and drawn-out process that takes a lot of time and effort (something that big-time companies cannot spare). Another problem that you have to face is the data exchange that has to take place when integrating CAM with other components (CAD/CAM/CAE PLM). It becomes necessary for the CAM operator to export the data in a more compatible data format. And since the output stack of CAM is a G-code text file -- sometimes containing thousands of commands -- the operator is then faced with a very serious time problem. CAM cannot reason. In this case, it cannot figure out the right toolpath for mass production. Operators would still have to select the type of tool to be used, the machining process that should be followed, and the path to be used. This means that the CAM cannot adjust to wear issues and sudden changes. It needs to be reprogrammed to be able to work efficiently. Furthermore, mass production increases the likelihood of errors to occur in the production cycle. PROS CAM can cut cycle time significantly. This means that with the proper people and the proper tools, a more efficient production method can be obtained. A lower cycle time means that you can produce more components in a lesser time. And since the main users of CAM and CNC are big manufacturers with deadlines, it is of the utmost priority to cut cycle time. Another advantage that could be gained by CAM software is the increase in machine life. Since the process is automated, the system can keep track of certain variables that allow it to adjust to the conditions of the machine that is operating under it. This means that the life of the machine can be extended by adjusting the performance of the machine in order to avoid overworking it. Quality can also be taken into account in this scenario. It is because the system also monitors slight differences in the production environment. Furthermore, the intricate designs that cannot be achieved by human engineers can be achieved by the machines. Also, these designs can be completed at a faster rate compared to manual operations. Another factor that should be considered would be the error ratio of the production of any components. Conclusion So, CAM is a very important aspect of production. However, the need for skilled operators still exists as programming and setting up these machines decide the fate of the manufacturing process. However, the increased automation and efficiency provided by such a system makes programming and setting up of these systems the only jobs of the operators. This also allows operators to be more productive as they do not have to watch any single machine for more than the required amount of time. What It Takes to be a CNC Operator Being a CNC operator may seem a little too easy but take a look at the requirements from companies and you'll think twice about the difficulty level of being a CNC operator. Being a CNC operator takes a lot more than just being able to handle long hours of staring at the monitor or creating an input stack for the programs. What it means is that you have to have outstanding programming capabilities and at least basic machining knowledge. Job Requirements A CNC operator has to be knowledgeable about blueprint reading. This is because, basic design concepts and construction is hinged heavily on blueprints. Furthermore, the components that are being manufactured by companies that have CNC machines are based on blueprints of a whole structure. Therefore, if you do not know how to read blueprints, you won't know what to program the machine to do. Another thing that a CNC operator has to have is familiarization with machine operations. If the operator does not know which machine tools are for which job, or how fast the machine can work, or what the rate of feed is for the machine, or even the depth of the cut needed for the operation, then you wouldn't be productive and the operation would be a failure. The most obvious thing that an operator would have to know would be the general operating characteristics of the machine. He/she would have to know what the machine runs on -- tape, network data input, or floppy. Furthermore, proper data input procedures have to be observed to lower the error ratio. A faulty data input procedure could cause the entire cycle to collapse therefore lowering the level of efficiency. Working with CNC machines means that you will also be dealing with a lot of computer work. This means that you have to be familiar with basic computer operations. In addition to that, you will have to know how to interpret data in the program output stack. The company's requirements and the benefits. some companies require a lot more than what is written above. Oftentimes, they require applicants to be familiar with the system that they use. Other times, they want the applicants to have no less than five years of experience working in a factory or at least working with a CNC machine. Also, some companies require applicants to undertake a specific training program to ensure the employers that the material they are getting is worth the money they will be shelling out. However, the benefits that can be reaped is quite solid. Salaries and insurances are often negotiable. Working hours are also a snap! All you would have to do is initiate the cycle and then sit back and occasionally check for glitches. Furthermore, these companies often takes care of their operators as there is always a shortage of skilled enough people to take hold of the position. So, what does it take to be a CNC operator? To synthesize the requirements, you have to be amazingly determined to pass the requirements of the company you are applying for. And then, you have to be able to quickly restructure the program in case of any glitch that the computer might encounter during the process. The benefits are solid, but passing the requirements is like surviving the gauntlet. Think about this career. 3 Basic Motion Types in a CNC Machine A Computer Numerical Controlled (CNC) machine may have more than one motion type that it uses, but there are three most common motion types that are easy to remember. These are the Rapid Motion, the Straight Line Motion, and the Circular Motion. All of these motion types may seem different but they share two things in common, which would be that they are all modal and the endpoint of each motion is specified in motion command. By being modal it means that the motion type would be in effect until changed otherwise. 3 common motion types: 1.) Rapid Motion Type Rapid motion type is also called Positioning. The way this motion type is used is through utilizing the fastest rate possible of the command motion of the machine. Example uses of rapid motion are moving to clear obstructions, placing cutting tools to and from the desired position, and any program that provides non-cutting in their schemes. The command that is usually programmed to a CNC machine is G00 because in this command, the end point for the rapid motion would be specified. The CNC machine, with most controls given, will be able to move as fast as possible in all commanded axes. In the case of rapid motion, one axis may be able to reach its end point before other axes. Straight line movement will not occur with type of rapid command function and the programmer of the machine must take into account that there are no obstructions to avoid. Straight line motion will happen even during rapid motion commands when done with other controls. 2.) Straight Line Motion This type of motion would allow the programmer of the machine to command perfectly straight line movements within the machine. Unlike the rapid motion type, the straight line motion would allow the programmer to vary the rate of the motion or feed rate to be used during the movement. Examples of using straight line motion would be turning a straight diameter, taper, when milling straight surfaces, and when drilling for this is because these examples require straight cutting movement. The common word to specify a straight line motion into a machine would be G01, for within this command the programmer will include the preferred end point within each of the axes. 3.) Circular Motion This motion type would cause the machine to move in the direction of a circular path and is used to generate the radii in machining. When talking about points on circular motion feed rate, it is equal to that of straight line motion. Other than that of straight line motion and rapid motion, there are two G codes that are commonly used when programming a circular motion into a machine. These are G02 and G03. G02 is used when the programmer desires a clockwise motion into the machine while G03 is used to make an anti-clockwise motion. To know which of the commands to use, the programmer must view the movement with the same perspective as to what the motion of the machine will be, may it be clockwise or anti-clockwise. Another requirement that would be programmed into a machine that would be using circular motion is that the programmer must specify the radius of the arc that is to be generated. With brand new technological advances in CNC, an "R" word is now used to specify the radius. For older controls in CNC machinery, an "I", "J", and "K" are used to specify location of the center point of the arc. When To Shove People Out To Make Way For CNC The normal businessman's mind is always geared towards profit, profit, profit. No matter how much the company spends, at the end of the day, the revenues should exceed the expenses (including tax). Although innovation is a major requirement to a business' growth, many small-time businesses just lie back in comfort. They think that as long as they're earning and they have a steady market, it's all right. This holds true for businessmen who are contented with being small-time (though it's hard to find one). However, for businesses that are aggressive towards getting ahead, acquiring a CNC machine seems to top their list of priorities. CNC stands for Computer Numerical Control. A CNC machine is a computer "director" which is composed of machine tools that read a specific set of instructions (in G-code) and is able to "direct" certain manufacturing tasks repetitively. The top industries that use the CNC technology are the Metal and Woodworking industries. If you are a regular member of a techie forum for entrepreneurs, CNC may be showered with praises because of its performance. Most businessmen also swear by saving a lot of money and time when they started employing CNC technology in their production processes. However, if you are still considering CNC at the expense of the jobs of your employees, it is best that you prefer CNC at two levels: the logical level and the emotional level. LOGIC-WISE CNC machines do specific instructions. They will never assume anything, nor rebel against the program loaded to them. Imagine the security of knowing that you will "reap" exactly what you "sowed". Let's say, something goes wrong during the process. Assuming the machine is in perfect condition, you CANNOT put the blame on it because it just performed what you told it to do so. Secondly, there is the blanket of consistency. It provides a certain level of safety and ease to the head supervisor. If you have overseen the operations today, most likely, it will be exactly the same tomorrow. The feeling of knowing what to expect is always a good thing, especially when there's money involved. Lastly, there's speed. CNC machines do not stop to think. After you do the thinking, they do the power-jobs that they need to do. It's that simple. There is a minimized set-up time and back-job time pocket. What you will find a flaw about CNC though, is that logic-wise, CNC machines cannot think of better ways to perform a task (IF there is a better way). A CNC machine is purely mechanical; when it was sold to you; the salesmen never mentioned the word "creative" or "innovative". I hope you did not miss that. EMOTION-WISE CNC machines are also assets of the company. When assets like this are purchased, there is little or no emotional investment that goes with it. You won't even train it! It is expected to do certain tasks and that's saving you a lot of time from all the explaining, demonstration and reminding. Also, when a CNC machine is performing its task, it is void of any emotion. So no matter how hot the weather is, or how noisy the workplace is, the CNC machine will do its job just like any other day. It is different as compared to people -- who have the tendency to space-out when doing very mechanical and tedious jobs. Although the CNC may want to, it also cannot complain. That's really convenient. What you will need to note now is your electric bill. Beware, for when getting CNC machines, it may betray you in the form of lofty bills. All the emotions you've saved might just be unleashed. Weighing Technology's Offers: The Pros and Cons of a CNC Job Are you good with computers and looking for a job? Well then, consider being a CNC machine operator. It's usually easy, full-time and the name isn't intimidating, right? If you think that being a Computer Numerical Control (CNC) machine operator may be a bit out of your reach, think again. You don't have to be a math wizard or a programming genius to get that position. But don't jump in just yet! There are a few things that you have to know (and consider! ) before applying for the job. The first thing that you have to understand is the abbreviation CNC. According to an online encyclopedia, CNC stands for Computer Numerical Control, and refers specifically to a computer "controller" that reads G-code instructions and drives a machine tool, a powered mechanical device typically used to fabricate components by the selective removal of material. CNC does numerically directed interpolation of a cutting tool in the work envelope of a machine. The operating parameters of the CNC can be altered via a software load program. THE PROS The good thing about being in this job is that the workload is actually light. Operators even complain of boredom because the cycles of CNC machines are all automated. All they have to do is initiate the sequence, sit back, watch for malfunctions, adjust the performance of each machine, and turn them off. If your boss is kind enough to let you use an MP3 player while working, then you sure are lucky. Another good thing about this job is that job openings for this position will always rise. Technology is moving forward. CNC machining will certainly lead the demand because in CNC, a group of machines can be controlled at the same time. That is exactly what big-time companies want, right? To reduced manual overseeing and just leave it to the machines. Advantage in this job arena is easy too. Statistics show that you will need only a high school diploma and (more importantly) an experience in CNC operations to gain an edge. THE CONS The thing is, when you're in this line of work, it is repetitive. One gets bored after doing the same mechanical thing over and over again. As time withers, you will reach a point where you will breathlessly wait for the next paycheck and not actually care about the job. It's emotionally exhausting. Furthermore, programming and operating these machines can be tedious. So, add that up to boredom and you get disproductivity. Another thing that you should think about is the work environment. You're going to be working in a factory. And factories are located away from town. If you're not comfortable with being away from the hustle and bustle of the city, this might not be for you. It can get pretty dangerous. Reports show that although most CNC operators work in a well-lit and smoothly ventilated environment, the high-power machinery poses dangers for them in the form of flying particles of metal and plastic. Also, though most modern machines produce less noise, ear plugs are still recommended by experts. Lastly, this may not sound like a biggie, but most CNC operators are on their feet all day. They can only sit when the programs are being loaded into the computer. It's pretty comforting that they receive salaries waaaay bigger than those salesladies. Practical Applications of CNC Manufacturing anything that requires exact measurements requires cutting edge precision and nimbleness from the worker. Most of the time manufacturing these kinds of products requires weeks or months to finish therefore slowing down productivity as well as consistency of the manufacturers. Computer Numerical Control or more commonly called as CNC's are the new trend in machine shop manufacturing and practice. Any manufacturing environment owns one or is basically acquainted to this kind of device because of its capability to increase productivity as well as consistency on the products being produced. Benchmarked from Numerical Control (NC) during the late 50's, Computer Numerical Control incorporate the functionality of a Programmable Logic Controller (PLC), meaning you could program it to execute different functions depending on the type of manufacturing that the industry needs. Given this kind of quality what does the Computer Numerical Control do in the practical application concept? CNC can do a variety of things depending on how the machine operator would program the system. The more acquainted the machine operator is to the CNC machine the more complex applications as well as programming can be made. Practical applications of CNC range from drilling, lathes, multi-axis spindles, milling machines, laser cutting machines, and wire electrical discharge machines. Let's discuss some of these common applications further. In Metal fabrication, Computer Numerical controlled Lathe's are used to fabricate metal sheet by shearing, flame or plasma cutting, punching, laser cutting, forming and welding. Most CNC Lathe's are used for designing modern carbide tooling. The design could be created with the Computer Aided Manufacturing (CAM) process, and when done, the CNC could start creating the product automatically with little supervision from the machine operator. Electrical discharge machining (EDM) is the process of removing metal with the use of electrical sparks to take away the metal. These Electrical Discharge Machine has two types, the vertical EDM and wire EDM. Vertical EDM uses an electrode that is the shape of the cavity to be machined into a work piece. Wire EDM is used to create punch and die combinations in the fabrication industry. Computer Numerical Control EDM's are not usually known because it is mostly incorporated to other CNC process. Drilling is the most common machine process. Computer Numerical Controlled Drilling is used to create precise right circular cylinders over a certain material, the CNC could be programmed to create holes on different standards, most of the time this is the gaps between these holes. Drilling is commonly used in wood working manufacturing process in which other process is also involved such as milling, turning and grinding. Several tools for creating holes with CNC's involve varied hole sizes as well as drill press for creating different depths on its holes. CNC drills are equipped depending on the type of hole that the machine operator is drilling. Applications stated above are just a few examples on what the Computer Numerical Control could execute. Depending on how you want it to perform, more complex designs can be made and a lot of things can be made in a shorter period of time, therefore the key concept for the proper use of CNC's is that the machine operator must know what he or she wants to do. This makes the CNC an indispensable tool for the Manufacturing Industry nowadays. CNC Programming Tips the Professional Way When a program is completed and sent to the Computer Numerical Control Machine, the programming process is over. All calculations were made and the algorithm fully written. But the question is the programmer's job really finished? When is the programmer's responsibility really over? And how can we evaluate the type of program that the Computer Numerical Control Machine programmer did? The fairest and reasonable answer to those questions would basically when a part has been machined under the most optimized working conditions. Therefore the Programmer's responsibility does not end after he or she finishes the program. We could say that the program at this stage is still very much in the development process, because most of the programming considerations were based on certain assumptions and there are a lot of external factors that may affect the outcome of the product. Every Computer Numerical Control programmer should have an effort to be in the touch with the actual production. In the field of software development, Constant communication with your colleagues as well as actual machine operators of the CNC will help you to improve your own program. Because most of the time the CNC machine operators are a good source of constructive ideas, improvements and suggestions. A good CNC programmer should talk, ask questions to them and most importantly listen to what they have to say. Programmers who never put their foot in the actual machining process and think they are always right are all on the wrong track. Exchanging ideas with CNC machine operators, asking questions and seeking answers is the only way to be fully aware of what is going on in the machine. Whenever you start a Computer Numerical Control Program the first time it is important to check its Program Integrity. A new and unproved program is a potential source of problems. During Manual Programming in CNC, mistakes are more common than when the program is made in a CAM program. A good way to look at a new program is through the machine operator's perspective. Experienced Machine Operators take a direct approach when running a program for the first time. That means that they wont take any chances of mistakes with the actual running of a program therefore a good programmer must take note of any comments that the Machine operator will say about the program. What does an experienced Machine Operator look for in a new part of a program? Most of the Machine operators would say that the first and most important thing to be checked on a Computer Numerical Control Program is its consistency. Therefore a machine operator looks at how a CNC programmer does its own programming, is the way you create your own algorithms the same as the other ones. Machine Operators take note with this kind of Information. Upgrading your CNC Program Whenever you upgrade your own program, it means that you are strengthening or enriching it, therefore making it better than it was before. Upgrading would be based on this standard, It is to decrease the production cost without compromising the quality of the part being manufactured or the safety of the Computer Numerical Control Machine Operator. One of the Most Common forms of Program Optimization is doing some minor changes to the spindle as well as the feed rates of the machines. This process is called cycle time optimization, slightly increasing the spindle speed and feed rates of these machines will decrease the time it takes to finish the part. And when we compare it to mass production, saving one second for each part in a batch of 3600 pieces would mean an hour saved. Efficiency in the rate of production is a very important aspect in Mass Production. Industries That Constantly Define CNC Precision Since the dawn of the CNC (Computer Numerical Control) machines introduction in the machining sector, they have been praised for being accurate, fast, consistent and flexible. Although CNC machines are not totally independent, a lot of major industries depend on these wonder machines. Common CNC-dependent industries include the metal industry and the woodworking industry. However, these industries, when small-time, can be operated by hands. In this article, you will learn about the industries which are CNC dependent not because they have grown big in time but because they have to. It can be also that they are CNC dependent because their industries demand a low level of tolerance and a high level of sophistication. There are no "small-time" members of this industry. Let's start discussing. THE AEROSPACE INDUSTRY First off, this is already a very sophisticated industry. An engineering degree (solely) will not get you anywhere in the Aerospace industry. Not even within striking range. This industry demands so high from their members so machine shops that belong to this industry trust only the best of the best of CNC machining. In fact, sources say that the term "Precision Machining" has been coined from this industry. In the materials they use, the aerospace industry already demands a lot. CNC machines which are used here are mostly capable of handling Inconel, Titanium, Magnesium, Stainless Steel and so much more. From parts of the landing gear, to shuttle seats, to housings, and even oxygen generation, CNC machines play a big part in their manufacturing. It's not just that. Every CNC machine used in this industry also has to be approved AND RATED by the Federal Aviation Administration (FAA) to be safe and to be surely capable of "Precision Machining". A NASA experience is highly praised too. THE MEDICAL INDUSTRY If the Aerospace Industry demanded precision above all, the Medical Industry demands sterility as much as precision. That's something that you may have known since you got your first vaccine. Most CNC machines which work for this industry are multi-spindle and contain multi-turret lathes. These special features allow the company to turn out components for hospital equipment, pulse meters, blood purification systems and mother medical devices. They are also useful in the mass production of disposable items and non-embeddable components. High-torque milling and turning spindles are heavily demanded in this industry to enable users to process all substrates currently used in the medical device and orthopedic implant markets. Moreover, CNC machines recommended in the medical industry are those which can properly handle Titanium, Cobalt Chromium, Nitinol and others. THE MILITARY INDUSTRY This industry's main concern aside from precision is security. In fact, if you try to search online the CNC-manufactured materials or CNC machines used in this industry, no matter how famous their reputation is, the manufacturer cannot display (pictures of) the materials that they have produced for their clients. They can only display products which they are used in. This industry deals heavily with Inconel, Titanium, Kevlar, Monel and Hastealloy; so most CNC machines recommended in the Military industry must be able to handle those. Famous CNC standards evaluators in this industry include the Department of Defense (DOD), the Mil Spec (Military Specifications) and other selected military sectors. The top managers of these industries also demand their CNC machines to be purchased from CNC machine suppliers which adhere to the International Standards Organization (ISO). And because these industries are CNC-dependent, their shops can occupy a vast amount of space. Basically, that makes no room for old school methods and errors. Programming CNC Machines With G-Codes Ever since the industrial revolution started, the demand to create precise instruments and products is an important factor in large scale manufacturing. Belts, screws, Drills and all movable parts needed to create other products in the assembly line must all be exact and compatible, thus extra care must be taken in order to ensure that all moving parts match perfectly. Computer Numerical Controlled programming has become an extremely important part of this process. Computer Numerical Controlled Machines are useless without any programming. CNC's rely on pure hard codes in order to execute commands that the Machine Operator wants to do, therefore not only is it needed to learn the mechanics of the whole Computer Numerical Controlled Machine but it is also at the utmost importance that the Machine operator knows how to communicate with the machine, and that is by using G-codes. Preparatory code/ functions or much commonly called as G-codes are functions in the Computer Numerical Control programming language. The G-codes job is to manage the position of the tool as well as control the step by step commands during the actual work. Basically the G-codes are the most important part of the Computer Numerical Control Programming algorithm. There are other codes involved in the programming of CNC's such as M-codes that manages the machine, T-codes for managing the tools, and F-codes for the tool feed and tool speed controls. All of these codes are created in a Computer Aided Manufacturing (CAM) software. G codes as well as the others use the RS-274D as the recommended standard for the Computer Numerical Controlled Machines. This standard was developed by the Electronic Industry association during the 1960's. These standards provide a basis for the creation of Computer Numerical Controlled Programs. First designs of these standards came from punched paper tapes as the medium standard for data interchange, but now ASCII character bit patterns are the standard for the representation. G-Codes Lets discuss the g-codes further, as what I have said earlier G- codes constitute only a part of the Computer Numerical Control Program, in the whole programming algorithm, they are denoted by the letter G, Basically it is a code telling the machine what kinds of actions to perform in a step by step basis, examples of these actions would be rapid move, controlled feed moves that would bore holes, a work piece cut routed to a specific dimension, change a pallet, and set a tool information such as offset. After creating each part of the codes, the algorithm is compiled in the Computer Aided Manufacturing (CAM) software. The CAM software basically use translators called post processors to output the code optimized for a certain machine type. Often times, post-processors are often used to allow users to enable further customization. G-codes can also be used to create outputs for Computer Aided Design systems used to design printed circuit boards (PCB). Any software must be customized for each type of machine tool that it will be used to program. Some G-codes are written by hand for volume production jobs. Some Computer Numerical Controlled machines use conversational programming. Conversational programming is an easier way to program CNC machines because it is more "user friendly" because it uses a wizard like program that hides the G-codes into plain view. Some Popular examples of this kind of CNC machines are the Southwestern Industries' Proto TRAK, Mazak's Mazatrol, and Mori Seiki's CAPS conversational software. Conclusion With these kinds of further sophistication in programming Computer Numerical Controlled Machines, it is expected in the future that programming would be much easier for its machine operators. Cycle Time Reduction Principles for CNC Machining Equipment What is the definition of cycle time? Cycle time is defined to be the time that happens from the time a task or series of tasks is initiated to the time a task is completed. Example, the cycle time is the time a shipping order is printed to the time it is loaded on the truck and the system is updated. An alternate definition would be is the time it takes to load, run, and unload on workpiece. Cycle time of a machine can be simply measured by timing how long it takes from pressing the button to start the cycle for the first workpiece to the pressing the next button for the next workpiece. Production quantities in an industry dictate that the more workpieces you run, the more important it is to achieve the goal of lowering the cycle time. Everything and anything that happens in a Computer Numerical Control (CNC) machining equipment can be divided into four categories: 1.) On-line, productive tasks: These are the actual machining operations that occur during a CNC cycle. These are the milling, drilling, tapping, reaming, and any other machining operation that in some way furthers the completion of the workpiece. To minimize the cycle time in these areas, there are two ways in which this can be achieved. One would be through careful process planning. The process engineer must select an appropriate machine tool, cutting tools, fixturing, and machining order in a way that it matches the number of workpieces to be machined that will be based on the production quantity. The cycle time will be a reflection of the processes being used to machine workpieces. If in the many times that your company's processes have already been developed and implemented before you begin your cycle time reduction program, then your second alternative is to optimize cutting operations for this would involve properly selecting cutting tool materials, feeds, and speeds to machine workpieces as efficiently as possible with the current process. 2.) On-line, non-productive tasks: These are tasks that occur during the machining cycle that do not actually further the completion of the workpiece. The first thing Computer Numerical Control people often target for improvement is wasted program execution time. These are the things like rapid movements, tool changes, M-code execution and spindle acceleration/deceleration. Reducing program execution time in this area is usually easy. It often takes nothing more than carefully monitoring the production run for a few workpieces to find those times when the program can be modified to eliminate noticeable pauses during the cycle. Although keep in mind that the worker for these machines must not overlook other processes for they may be so concerned with minimizing program execution that they overlook other operations, resulting in severe wastes of cycle time. 3.) Off-line, non-productive tasks: These are the tasks performed in the machining cycle that do nothing to further the completion of the workpiece. Since these types of tasks are done while the machine is producing workpieces, they do not actually add to the cycle time. It is possible to free the operator of the machines of performing off-line productive tasks if they have little, or nothing to do during lengthy machine cycles. 4.) Off-line, productive tasks: These are the tasks done away by the CNC machine, while the machine is producing workpieces, which would further the completion of the workpiece. This is extremely helpful during lengthy CNC cycles, tasks in this category can reduce the time it takes to complete the production run dramatically, which would effectively reduce cycle time. In Depth Discussion In Planning CNC Programs Understanding the Computer Numerical Control Machine as well as learning the method of programming these machines is not enough to maximize the capability of these devices. Even if you are proficient on those two stated above, proper understanding of the step by step procedures is still important. In this article we would talk about the step by step procedures of programming Computer Numerical Control Machines which is recommended by the most experienced CNC Machine Operators and progammers. Step by Step procedures in planning of a CNC program Whenever we try to program a Computer Numerical Control Machine the first thing that the Machine operator should consider is the blueprint of the part we are trying to manufacture. Proper understanding and reading of a blueprint is a basic and the most important skill in the manufacturing Industry that engineers, managers, CNC machine operators as well as CNC programmers should know about. Proper understanding of these blueprints should help the CNC machine operator as well as the programmer to use the appropriate CNC machine to be used. The second step on the proper programming of a Computer Numerical Control Machine is by selecting the appropriate type of Machine that will be used. This is where the proper understanding of each machine type comes into play. Knowing the type of design, specifications as well as features of a machine will help you on choosing the appropriate one. The third step would be the analysis of the operations or the setup sheet. The setup sheet is used to describe the necessary processes needed to create the parts on a CNC machine. The setup sheet includes the proper machine sequence and also the tools and cutting data to be used. Specifications written on the setup sheet aids the programmer on the proper algorithm needed by the Computer Numerical Control Machine. The fourth step on the step by step requirements would be the proper selection of the tools required to create the parts. This step is important on the industry manufacturing practices, basically the tools to be chosen is based on the common sense and Good CNC operators and programmers should be aware of them. Usually there is a certain checklist on this step, the most important point of this checklist would be knowing the material to be machined as well as its characteristics. Fifth step would be the calculation of the cutting data. Proper calculation is one of the important steps in the planning process. This is where the spindle speed, federate value, cutting speed and the depth of cut is calculated to fit to the specifications in the blueprint. Sixth step would be the actual programming process, this is also the step where the proper Units are inserted into the programming algorithm of the Computer Numerical Control Machine. This is where we incorporate all the codes that are needed to run the whole CNC machines in the CAD software. Programming Considerations In order for other programmers to analyze and append your algorithm, it is important to have certain programming considerations. These program considerations were suggested by experienced Computer Numerical Control Machine Programmers and Operators. First it is important that you develop a programming technique that will be readily understood by other developers, with a good programming technique programs could easily be appended if there are any errors. Second, it is also important to proofread all programs for typographical errors before being executed in the CAM software, this is to ensure that the CNC machine would operate its desired operation. And most important of all is to keep your programs as simple as possible in order for the machine to process the instructions faster. The Different CNC Machines CNC has different applications depending on the machines that operate on it. So if you're a budding operator, you should know the most common machines that can operate on CNC. Milling Milling machines are common CNC machines. These devices are used in the shaping of metal and other solid materials. It is basically a rotating cutter and a table. Milling machines are capable of complex toolpaths as the cutter is not limited to a sideways movement but allows for an "in and out" motion. This movement is precisely controlled by moving the table and the cutter relative to each other. Cutting fluid is then pumped in to lubricate and cool the cut and to remove any swarth that is generated by the cut. Lathes Lathes are machines that perform different operations such as sanding, cutting, knurling, deformation, or even drilling. These machines work by spinning various solid objects and then using tools that are symmetric to the axis of rotation. A lathe machine has a single tool in which the workpiece is worked against the tool. The tool is then worked alongside or into the workpiece in order to generate the feed. Lathes can be used for different operations. Machining Centers These are more complex CNC machines that combine milling and turning. As milling was described earlier, turning will be the focus of this section. Turning is the process by which a central lathe is used in conjunction with the rotation of the material to be turned. The cutting tool is then moved along the two axes of motions to produce accurate dimensions. Combining turning and milling can produce extremely precise components. And that is what these machines are used for. However, due to the complexity of these machines, operators have to be specialists in order to be able to operate with maximum efficiency. Electrical discharge machine An electrical discharge machine (EDM) creates cavities in metals by emitting electric sparks. This process requires an electrode, coolant, a power source, and a tank. The cycle is accomplished by connecting the workpiece to one side of the power supply and then placing it in the tank. An electrode (made in the shape of the cavity required) is then connected to the other side of the power supply. The tanks is then filled with coolant and the electrode is lowered until a spark jumps between the work and the electrode. As the coolant is a dielectric substance (resists electric currents), it requires a smaller difference in distance in order for a spark to jump through. This means that when the spark appears, the dielectric property has been overcome. The spark then dislodges material thereby creating a cavity in the shape of the electrode. CNC systems CNC systems are complex machines that transfer and store data regarding the operation mechanism of the machines. Motion programs include point to point control, straight cut control, and contouring control. Point to point control means the control of the tools from one point to another in the coordinate plane. This method of control is commonly used in drilling and boring operations. Straight cut control is the method by which a tool is moved in all axes of the machine. The tool also has the ability to move in a 45 degree angle. Contouring control is the means to create a toolpath. It moves the tools by interpolating points or coordinates that make up the path for the tool to follow.
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