SST Shop Talk
More about CNCs!
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 us start with a brief introduction. CNC stands for Computer Numerical Control and it has been around since the early 1970 is. Before it was christened CNC, it was called NC, for Numerical Control. When computers were introduced during 1970 is, 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 is 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 is 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.
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 is your first time to read and learn about the CNC, it may sound so mighty and ubiquitous. It is 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.
The first person is the CNC programmer. He is like the "playmaker". 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 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 third person that will need is the CNC technician. Although this may still be the programmer, it is 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 is running right, how much more if it is 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 is 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.
The second person that you need is the CNC operator. 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 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.