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How to Operate a CNC Milling Machine

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Operating a CNC milling machine takes quite a bit of knowledge and formal training. Information must be input into the machine's computer control for every aspect of the operation. This includes the tooling location and the dimensions that will be used to cut the raw material. You must watch each operation during the first machine cycle to make sure that none of the tools break as that may cause damage to the machine or the expensive raw material. With formal training or schooling on a CNC machine, you can operate a mill successfully.

You should set the machine to zero so that it can use the dimensions in the program to cut the raw material accurately. When a CNC machine is started, it does not have a reference point. Place the machine in manual mode by pressing the positive X axis traverse button for one second. You should follow that by pressing the Y axis button and the Z axis button. This will allow the machine to set a reference point based on a home position.

You should set the vise or work-holding device on the table. Place a dial indicator on the spindle and manually move it above the vise. Place the tip of the dial indicator on the front jaw and manually move the dial indicator along the X axis. If the indicator does not move, the vise is straight. Tap it in whichever direction to adjust it if the indicator moves and tighten when straight. Remove the dial indicator and send the spindle back to the home position.

Place all of the needed tools into the tool turret. Place the machine in tool teach mode and call up each tool individually. The tool teach mode can usually be found on the tool information screen. The machine will automatically bring each tool to the probe and you will hear a beep when the tool is taught.

Using any of the tools, touch the top of the raw material and set the Z zero point. The machine will use this location to determine any depth cuts. This dimension is crucial to machining and must be as accurate as possible.

Place an edge finder in the spindle and set to 1000 RPM. RPM stands for revolutions per minute. Place the tip of the edge finder very close to the right side of the material. Slowly bring the edge finder closer to the material. When it touches the side, you will see the tip of the edge finder line up with its body. Continue in that direction until the tip becomes misaligned again. That is the edge of the X axis, set the X zero to this point. Follow the same directions on the Y axis and set that point as Y zero.

Send the spindle to the home position and start the program. Set your rapids very low. Rapids dictate the speed of the spindle during tool changes and the approach it takes for cutting. You can make adjustments to the rapids with the override on the face of the control and set them anywhere between 0 and 100, which is full speed. Make sure it is coming in at the correct spot and watch the first piece closely to watch for any mistakes or errors in the setup.

About the Author

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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