22 Unit 5: CNC Operation


After completing this unit, you should be able to:

  • Understand the CNC Operation.
  • List the steps to set up and operate a CNC mill.
  • Identify the location and purpose of the operating controls on the Haas CNC Mill control.
  • Start and home a CNC machine.
  • Load tools into tool carousel.
  • Set Tool Length Offsets.
  • Set Part Offsets.
  • Load a CNC program into the machine control.
  • Dry run
  • Safely run a new CNC program.
  • Adjust offsets to account for tool wear and deflection.
  • Shut down a CNC machine correctly.

Overview of CNC Setup and Operation

CNC machine setup and operation follows the process below:

  1. Pre-Start
  2. Start/Home
  3. Load Tools
  4. Mount Remove Part into the vise
  5. Set Tool Length Offsets Z
  6. Set Part Offset XY
  7. Load CNC Program
  8. Dry Run
  9. Run Program
  10. Adjust Offsets as Needed
  11. Shut Down

1. Pre-Start

Before starting the machine, check to ensure oil and coolant levels are full. Check the machine maintenance manual if you are unsure about how to service it. Ensure the work area is clear of any loose tools or equipment. If the machine requires an air supply, ensure the compressor is on and pressure meets the machine requirements.

2. Start/Home

Turn power on the machine and control. The main breaker is located at the back of the machine. The machine power button is located in the upper-left corner on the control face.

3. Load Tools

Load  all tools into the tool carousel in the order listed in the CNC program tool list.

4. Mount the Part in the Vise

Place the Part to be machine in the vise and tighten.

5. Set Tool Length Offsets

Set Tool Length Offsets For each tool used in the order listed in the CNC program, jog the Tools to the top of the part and then set the TLO.

6. Set Part Offset XY

Once the vise or other Part is properly installed and aligned on the machine, set the fixture offset to locate the part XY datum.

7. Load CNC Program

Load your CNC program into CNC machine control using USB flash memory, or floppy disk.

8.  Dry Run

Run the program in the air about 2.00 in. above the part .

9. Run Program

Run the program, using extra caution until the program is proven to be error-free.

10. Adjust Offsets as Required

Check the part features and adjust the CDC or TLO registers as needed to ensure the part is within design specifications.

11. Shut Down

Remove part from the vise and tools from the spindle, clean the work area, and properly shut down the machine. Be sure to clean the work area and leave the machine and tools in the location and condition you found them.


1. Please list the CNC setup and operation process steps.

2. Describe each process.


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Manufacturing Processes 4-5 Copyright © by LamNgeun Virasak is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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