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How to Program CNC

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CNC, or computer numerical control, programming is a series of commands that tells the CNC machine what to do. Similar to sentences, each line has a series of commands that allow for the cutting and shaping of various materials, including metal, wood and plastic. G code is a universal CNC programming language understood by all CNC machines, but many manufacturers also offer a proprietary language that is often easier to work with and understand. This conversational programming is then converted to G code for the machine.

Enter the home commands, which set the home position point for the program when using G code to program a CNC machine. This first line sets the universal settings for the machine, including the maximum spindle speed and the designation for the material being cut in the machine whether it is a mill, lathe or CNC router.

Set the position for the entry of the first tool. First, designate a tool to be used from the turret. The machine will know which tool you are using, as you must set them up before starting the program. The first line will dictate the feed rate of the tool, RPMs and location of the actual cutting. If you are drilling, this line will indicate where to start drilling and how deep to drill as well as the feed rate and speed of the drill.

Designate a tool change for the next process. The machine will calculate the proper entry point and will cut the part to the specifications of the numbers next to the axis letters. Coolant off and on will also be designated in the line of programming. There are X, Y, Z, A and B designations. X, Y and Z are the most common on mills, while A and B are used on five axis models. For simple CNC lathes, X and Z will be commonly used in programming.

Continue in the same manner as in Steps 2 and 3 for the rest of the program, making sure that the numbers you enter are correct and that coolant codes are correct. Most tooling will require coolant, but some indexable tools run better without coolant, so you can turn it off in the program.

Place the end of the program at the bottom to let the machine know it is complete. Alternatively, you can place a hard stop at the end of the program to switch out the finished part for more raw material. When you hit the "Start" button, the program will pick up the first tool and start over once again.

Follow the preceding steps for conversational language, which is a proprietary way to program CNC machines. Every manufacturer has its own conversational language that converts particular commands into G code for you, making the programming easier and simpler to understand.