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Print ArticleHOW DOES A CNC WORK?
The movements of a CNC machine are simple but the programming, mechanical and electrical components are complex and need to be engineered so that all these elements will work together. I won't bore you with all the technology, but will explain in basic terms how the CNC machine works. In other words, how does it know to go to a certain position, pick up a tool, run in one direction, etc?
If you remember your basic geometry classes, you should know what the x and y axes are. In case you don't, let me explain. The x, y and z axes are called directions of motion — in other words, right and left, up and down for the x and y axis. The z axis is a little more difficult to explain but basically it is the near and away from you.
The x axis is the horizontal direction going both right and left. The y axis is the vertical line. Any motion going to the right and horizontally of the y axis is positive and any motion to the left horizontally of the y axis is negative. Any motion going up on the y axis above the x axis is positive. Any motion going down below the x axis is negative. If this were a 3-D diagram, the z axis would be coming straight out of the page or through the other side of the page. Imagine you are holding this page up and you push a pencil through the page. The line direction of the pencil would be the z axis.
The x, y and z axes are all linear or along a straight line, and
the bed of the CNC machine is nothing more than a big graph that the stone lays on.
Now, when you hear someone talking about a 3-axis CNC machine you should know what they are
talking about. But, what the heck is a 4-, 5- or 6-axis CNC machine? OK, you asked for it.
The x, y and z are all linear axes; however, there are also rotary axes motions commonly
named A, B and C.
CNC MACHINE PROGRAMMING
Programming a CNC machine requires a lot of computer experience, but fortunately one can learn to operate a machine with some good training. In other words, you don't have to be a computer nerd to operate one. Program it, maybe, but not to operate it. Let's take a look at how basic programming works.
A CNC machine will move only when it is told to move and where to move. Because of this, a set of instructions is needed to tell the spindle of the machine where to go, how fast to go, etc. This language uses a code or words to communicate with the machine's brain. There are only about 50 common words that tell a CNC what to do; for example, "S" would indicate spindle speed. Keep in mind that the language and programming are very complex and I am not trying to make light of this subject. This is just a basic explanation to help you understand the basics of how the machines work.
