Step 1: Confirm Safety Conditions and System Alarms — First Check "Whether It Is Allowed to Rotate"

When the spindle does not rotate, it is often not the spindle itself that is broken, but the safety conditions or system status that are not satisfied.

Key Checks:

• Whether the emergency stop button is pressed and whether the safety door is properly closed;
• Whether there are spindle alarms, servo alarms, drive alarms, hydraulic/pneumatic alarms on the operation panel;
• Whether the chuck is properly clamped and whether the chuck clamping signal is normal;
• Whether the hydraulic system pressure and lubrication system pressure meet the requirements;
• Whether the system is in an alarm not reset state.

Judgment Criteria: If there is an unreset alarm or missing safety signal, prioritize handling the alarm and signal. Do not continue to force the spindle to start.

Step 2: Check Operation Commands and Running Modes — Confirm "Whether the Command Has Been Issued"

If there is no alarm but the spindle does not rotate, confirm whether the system has actually received the spindle start command.

Key Checks:

• Whether the current mode is correct: spindle start methods differ in manual, MDI, automatic, and handwheel modes;
• Whether the correct M03/M04 command has been input and whether there is an S speed command;
• Whether the spindle override has been turned to 0%;
• Whether the program has set a spindle maximum speed limit or interlock condition;
• Whether the spindle forward/reverse button has been pressed during manual operation and whether the button is effective;
• Whether any spindle enable signal is not connected.

Judgment Criteria: If the command has been issued but the system has no spindle output, proceed to Step 3; if the command itself has not been issued, first check the program, mode, and operation panel.

Step 3: Check Spindle Drive and Electrical System — Determine "Whether Power Is Being Delivered"

The spindle drive chain includes the spindle motor, spindle drive/inverter, contactor, fuse, wiring, and encoder, etc.

Key Checks:

• Whether the spindle drive or inverter has an alarm code;
• Whether the spindle motor power cable and encoder cable are loose or broken;
• Whether the AC contactor is engaged and whether the thermal relay has tripped;
• Whether the fuse and circuit breaker are normal;
• Whether the input voltage is normal and whether the three-phase power phase sequence is correct;
• If it is a servo spindle, check the servo enable signal and drive status.

Judgment Criteria: When the drive has an alarm, first troubleshoot according to the drive manual; when the contactor does not engage, check the control circuit and PLC output; when the motor has abnormal noise but does not rotate, pay attention to the possibility of mechanical seizure.

Step 4: Check Mechanical Load and Transmission System — Rule Out "Stuck and Cannot Rotate"

If the electrical system is normal but the spindle still does not rotate, check whether the mechanical side is "locked" by the load.

Key Checks:

• Whether the chuck, workpiece, or tool interferes or is jammed;
• Whether the spindle cannot rotate due to bearing damage, gear seizure, or poor lubrication;
• Whether the spindle belt is broken, slipping, or insufficiently tensioned;
• Whether the gear shifting mechanism and clutch are normal;
• Whether the spindle brake device is not released;
• Whether the spindle can be rotated by manual turning (under the premise of safety).

Judgment Criteria: If manual turning is difficult or completely seized, prioritize handling the mechanical fault. Do not force power-on startup, to avoid burning the motor or drive.

Step 5: Verify System Parameters and PLC Signals — Troubleshoot "Hidden Interlock Conditions"

The last step is to check system parameters and PLC logic, especially suitable for difficult cases of "no alarm, no output, normal mechanics."

Key Checks:

• Whether spindle-related parameters have been mistakenly changed, such as spindle maximum speed, gear ratio, and spindle enable method;
• Whether the spindle override, analog output, and inverter communication parameters are normal;
• Check key input signals through the PLC diagnostic screen: chuck clamping, safety door, lubrication pressure, spindle enable, emergency stop circuit;
• Check whether there are interlock conditions not displayed or whether the external emergency stop circuit is disconnected;
• Whether the system has not been restarted or reset after parameter modification.

Judgment Criteria: If the PLC input signal is missing, troubleshoot upstream along the signal chain; if the parameters are abnormal, restore the correct parameters and keep a record.

Troubleshooting Quick-Reference Table

Frequently Asked Questions (FAQ)

Summary

The key to troubleshooting a spindle that does not rotate is to judge step by step along the signal chain and energy chain: first confirm whether the system allows rotation, then confirm whether the command has been issued, then confirm whether power is being delivered, then confirm whether the mechanics can rotate, and finally verify parameters and hidden interlocks. Following these 5 steps can avoid blind disassembly and reduce secondary damage caused by misjudgment.

Haishu Machinery specializes in the R&D, production, and sales of CNC lathes and has a comprehensive technical support system. If you encounter spindle faults or equipment alarm issues, welcome to contact the Haishu Machinery technical team for professional support.