CNC Milling – A Quick Guide

Like other tasks performed in the machine shop, using a CNC (Computer Numeric Control) Milling machine takes a little time to set up, operate, and shut down. Due to the exacting nature of a CNC Mill’s operation, it’s imperative to understand what to do to avoid damaging or disabling a CNC Mill. Mill operators should familiarize themselves with the operating manual, maintenance schedule, and service points established for both routine maintenance as well as preventative maintenance.


Before beginning, a few questions should be answered to establish basic conditions:

  • Is the mill vertical or horizontal?
  • How many axes will be utilized?
  • What is the Tool Turret capacity?
  • How will the workpiece be positioned and held in place?

It may seem a little like CNC Milling 101, but it’s important to establish the working conditions before loading the machine and hitting the start button.


Assuming you’re not a newbie, some other preparations must be completed prior to commencing operations, such as:

  • Set up the edge finder.
  • Review machine operating instructions for the workpiece milling sequences.
  • Check tools, turret, and all hydraulic/pneumatic lines for leaks or damage.
  • Prepare cleaning and lubricating materials and have them readily available.
  • Download the CNC control command application or instructions.
  • Organize workpiece feeding, mounting, and dismounting protocols.

Just like a great chef preps all his ingredients ahead of time, so a professional CNC machine operator sets his workstation up before starting a production run.


It is a good idea to check, double-check, and, in some cases, triple-check everything before going full bore. Mistakes cost time, money, and can be easily avoided by consistently and diligently following the same routine with each machine start:

  • Clean all the machine surfaces before loading in parts or tools.
  • Load tool(s) to be used for processing workpiece.
  • Set the workpiece X and Y-axis offset using an edge finder or End Mill Cutter tool.
  • Set the workpiece Z-axis offset by loading a tool into the spindle.
  • Enter the tool length in the control application data set for cutter radius compensation.
  • Confirm coolant and cutting oil are filled and hooked up to the CNC machine.
  • Run a test piece to confirm dimensional results are correct per specification.

By establishing a consistent start-up routine, any machine abnormalities or anomalies will become evident and can be resolved before damaging workpieces or causing other issues.

Take Time and Make Time

Cutting corners may seem like a real time-saver, but when it comes to CNC milling and CNC machines, there are no shortcuts. Deliberate protocols are in place for safety, operating, and maintaining CNC machines and those protocols must remain inviolate. You don’t have to like it, you just have to do it, each and every time. Doing the right pre-start, start, and shut down routine will ensure CNC machine longevity and utility. Extending the life of a CNC machine while properly operating and maintaining it will ultimately save time, money, and frustration. For more information on CNC Milling guides, try contacting manufacturer service dealers or CNC equipment distributors.

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