The sudden stop of the workbench during CNC lathe work may be caused by many reasons. Here are some possible reasons:

1. Emergency stop button trigger: If the emergency stop button of the CNC lathe is pressed, the workbench will stop running immediately to ensure the safety of the operator. Check whether anyone pressed the emergency stop button during operation.

2. Power failure: CNC lathe power problems, such as power outage, unstable voltage, etc., may cause the CNC lathe to stop running. Check whether the power connection is normal and make sure the power supply is stable.

3. Overload protection: If the CNC lathe's CNC system or main drive system detects that the load is too large, the overload protection mechanism may be triggered, causing the workbench to stop running. This may be caused by improper workpiece clamping, incorrect cutting parameter settings, etc.

4. CNC system failure: Failure of the CNC lathe CNC system may cause the workbench to stop running. This includes software issues, control card failures, etc. Check the alarm information or error code of the CNC system to determine the specific cause of the failure.

5. Sensor failure: CNC lathes are usually equipped with various sensors to monitor motion status, temperature, pressure, etc. Sensor failure may cause the system to misjudge and trigger shutdown protection.

6. Mechanical failure: Failure of the mechanical components of the CNC lathe, such as bearing damage, transmission system problems, etc., may cause the workbench to stop running. Check whether the mechanical parts of the machine tool are functioning properly.

7. Program errors: If there are errors in the CNC program of the CNC lathe, such as endless loops, wrong motion instructions, etc., the workbench may stop running. Check whether the CNC program is correct and fix errors.

8. Coolant problem: If the CNC lathe uses cutting fluid for cooling, coolant supply problems may cause the workbench to stop running. Make sure the cooling system is functioning properly.

If the fault cannot be solved after troubleshooting simple problems (such as pressing the emergency stop button), it is recommended to contact professional CNC equipment maintenance personnel for diagnosis and repair. Note that before performing any maintenance operations, ensure that the equipment is powered off to ensure safety.