CNC milling machine tool setting is the process of ensuring that the relative position between the tool and the workpiece is correct in order to perform effective milling processing. Its principle mainly includes the following steps:

1. Determine the reference point: First, the CNC milling machine needs to determine one or more reference points, usually a specific position or edge on the workpiece. These reference points serve as the basis for the CNC system to calculate the coordinates.

2. Install the tool: The CNC milling machine installs the tool to be used on the spindle of the milling machine, ensuring that the tool is firmly installed and the tool tip maintains a certain positional relationship with the spindle axis.

3. Move the spindle: The CNC milling machine controls the movement of the spindle through the CNC system so that the tool moves near the workpiece but does not touch the workpiece surface.

4. Adjust the coordinates: The CNC milling machine uses the coordinate adjustment function in the CNC system to adjust the origin and axial coordinates of the workpiece coordinate system according to the position of the tool relative to the workpiece.

5. Contact detection: The CNC milling machine uses contact or non-contact sensors to detect the distance between the tool and the workpiece surface. Usually when using a contact sensor, the tool will lightly touch the workpiece surface.

6. Coordinate correction: According to the contact detection results, the origin and axial coordinates of the workpiece coordinate system are adjusted through the CNC system so that the distance between the tool and the workpiece surface meets the set requirements.

7. Tool setting: After the CNC milling machine confirms that the relative position between the tool and the workpiece is correct and meets the processing requirements, it completes the tool setting process and prepares for milling.

During the entire tool setting process, the CNC system will control the relative position of the tool and the workpiece according to the preset parameters and programs to ensure that the tool is in safe and accurate contact with the workpiece surface, thereby ensuring the accuracy and quality of the milling process.