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How to Operate a CNC Machine

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A computer numerical control (CNC) mill is capable of cutting and drilling many different types of material including steel, aluminum, wood and plastic. An CNC mill operator is in charge of making sure that the parts coming out are well within the specifications dictated by the print. By cleaning the contact surfaces and making sure that tools are in good shape, he can keep a production run going without any wasted raw material. This waste can cost a manufacturing company thousands of dollars, so a good, knowledgeable operator is essential.

Clean off the table and tooling after every cycle. It is important to make sure that the machine is clean and that the vise or fixture is free from chip build up. If a chip gets under a piece of raw material, the dimensions of that finished part may be compromised. Chips on the flutes of a drill may also cause breakage, so tooling must be blown off after the cycle is finished.

Check the tips of end mills and drills to make sure that they are still usable during the production run. A chipped end mill or drill can cause a machine overload. Overloads can damage the machine as well as the part that is being cut. To prevent these types of tooling failure, an operator must not only check the tooling when the machine is stooped, but they must pay careful attention to load meters to watch for overloads.

Adjust the tooling offsets for worn tools that do not need to be replaced. By stopping the run and checking a part, an operator can take control of sizing and assure that no pieces are off. The operator can also re-teach any tools that have been changed at this time and clean off the table and get the machine ready for the cycle.

Check the parts for size as they come out of the machine. After a part is done and another one is put in for machining, it is always best to check very third piece or so to make sure that are the key dimensions are on point and within the tolerances in the print. Certain dimensions can be fixed with tool offsets on the control of a CNC mill or lathe.

De-burr the parts to take off sharp edges. Operators must de-burr all cut edges so that the next person to handle the parts is not cut. In many cases, the machining of the part is the last process, so de-burring the parts will get them ready for powder-coating or assembly.


Christian Mullen is a graduate from the University of Central Florida with a bachelor's degree in finance. He has written content articles online since 2009, specializing in financial topics. A professional musician, Mullen also has expert knowledge of the music industry and all of its facets.

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