NexBot Drives STP113-006 Stepper Motor on S-5 Robot is Overheating and Stalling

Description

We have a NexBot S-5 robot on our assembly line, used for component placement. For the past 48 hours, the Joint 4 axis motor has been exhibiting problems. During the operational cycle, the motor runs noticeably hotter than the other axes, reaching temperatures we believe are outside of the normal operating range. This is causing intermittent stalling, especially when the arm is fully extended and carrying a payload. The movement has become jerky, leading to positioning errors and dropped parts. We have checked the drive parameters in the controller, and they match the factory settings. We also verified the 24VDC supply is stable. The issue persists after a full system reboot. The controller is logging a recurring axis drive fault, which forces us to reset the cycle and is causing significant downtime. We suspect the motor itself may be failing internally.

Symptoms

• Motor casing is excessively hot to the touch
• Axis movement is jerky and inconsistent
• Robot arm stalls during operation
• Controller logs a persistent axis drive fault

Resolution

Support analysis confirmed the symptoms were consistent with an internal winding failure in the stepper motor. Resistance checks performed by the on-site technician showed a significant deviation on one phase of the Joint 4 motor compared to a new unit. The overheating under load combined with the inconsistent torque output pointed to a component failure rather than a configuration or drive issue. The recommended course of action was to replace the faulty motor. The customer was instructed to replace the affected NXB-SRV-STP113-006 Stepper Motor and perform a post-replacement axis calibration. The issue was resolved after the new motor was installed.

Resolution Steps

1. Perform a full power-down and lockout/tagout procedure on the S-5 robot controller.
2. Carefully disconnect the power and encoder cables from the Joint 4 stepper motor.
3. Remove the four mounting bolts and detach the faulty STP113-006 motor from the robot arm.
4. Mount the new replacement motor, SKU: NXB-SRV-STP113-006, ensuring proper alignment.
5. Secure the mounting bolts to the manufacturer's specified torque.
6. Reconnect the motor power and encoder cables securely.
7. Remove the lockout/tagout and power on the robot system.
8. Perform a Joint 4 axis calibration and zeroing procedure using the teach pendant.
9. Run the robot through several operational cycles without payload, then with payload, to verify smooth movement and confirm the issue is resolved.