Auto Tool Zero, also known as Automatic Tool Length Offset, is a feature in CNC (Computer Numerical Control) machines that automates the process of setting the length offset for cutting tools. This procedure ensures that the tool tip is precisely positioned at the correct distance from the workpiece surface, enabling accurate machining operations.

Here's how Auto Tool Zero generally works:

1. Probe Setup: The CNC machine is equipped with a probe or sensor that detects the tool's contact with a predefined surface or reference point on the workpiece.
2. Tool Measurement: When activated, the machine moves the tool to a designated position above the probing area.
3. Probe Contact: The tool makes contact with the surface or reference point, triggering the probe to send a signal indicating the exact position where the tool tip touches the workpiece.
4. Offset Calculation: Based on the probe signal and pre-programmed parameters, the machine calculates the difference between the actual tool length and the desired length, known as the tool length offset.
5. Offset Adjustment: The CNC controller automatically adjusts the tool length offset in the machine's control software to compensate for any variations, ensuring precise tool positioning during machining.

By automating the tool length offset setting process, Auto Tool Zero eliminates manual measurement errors and reduces setup time, leading to improved machining accuracy and efficiency in CNC operations.