In modern industrial automation production lines, servo motors act as the “motor nerves” of precision equipment, undertaking over 70% of positioning control tasks. However, a certain automotive parts enterprise recently encountered a thorny production halt – its welding robots experienced positioning drift for three consecutive days, causing the product qualification rate to plummet by 15%. After diagnosis, the root cause was found to be abnormal encoder signals from the servo motors. This case reveals the harsh reality of industrial equipment: even when using international brand servo systems such as Mitsubishi and Siemens, under harsh operating conditions like 24-hour continuous operation, high dust, and temperature fluctuations, sudden failures can still occur due to component aging or environmental erosion. According to statistics, in 2023, servo system issues accounted for 34.7% of manufacturing equipment failures, with over 65% of unplanned downtime resulting from the failure to implement preventive maintenance in a timely manner. When your equipment experiences positioning accuracy deviations, abnormal vibrations, or frequent alarms, should you choose emergency repairs or systematic troubleshooting? This article will decode the deep-seated causes and scientific handling solutions for servo motor failures through three typical maintenance cases.
The Secret Behind Abnormal Equipment Jitter – Encoder Calibration Failure
Periodic jitter occurred during the operation of the servo motor on a certain food packaging line, resulting in a decrease of 0.15mm in the positioning accuracy of the equipment. The technical team carried out the following steps to troubleshoot: Firstly, they used an oscilloscope to detect the feedback signal waveform and found a 0.8ms phase difference between the A and B phase pulses. Then, they disassembled the equipment and discovered that the buffer rubber ring of the encoder coupling was aged. The corresponding solution was to replace it with a metal elastic coupling with anti-twist design. Therefore, to maintain the stability of the equipment, we should regularly calibrate the encoder origin. It is recommended to use a laser interferometer to detect the positioning accuracy every 2000 hours to avoid signal distortion caused by the aging of the buffer components.
The Deep-seated Causes of Frequent Overload Alarms
The servo system of a certain injection molding machine continuously triggered the F790 overload code. The current and torque parameters were found to be normal during routine checks. However, upon further investigation, it was discovered that dust had accumulated on the cooling fan at the motor’s tail end, causing the winding temperature sensor to far exceed the rated temperature. Additionally, the grease had carbonized, significantly increasing the friction coefficient of the bearings. The maintenance personnel proposed a solution involving the use of ultrasonic cleaning technology for deep dust removal and upgrading the heat dissipation components to IP67 protection level. At the same time, MOLYKOTE HP-300 high-temperature grease was adopted. After the repair, the temperature rise was reduced by 28℃, and there were no alarms during continuous operation for 72 hours. Therefore, if an overload alarm occurs, these aspects can be checked.
Preventive Strategies for Power Module Burnout
A sudden failure of the servo driver occurred on a certain CNC machine tool. Inspection revealed that the capacity of the DC bus capacitor had declined to 67% of its rated value, and the gate resistance deviation of the IGBT module reached 15%. Four transient voltage spikes of 380V were recorded on the power grid. To prevent such incidents, all departments should install three-phase AC reactors, establish a quarterly inspection system for capacitor capacity, and be equipped with online UPS uninterruptible power supplies.
Summary
Through these three typical maintenance cases, it is clear that most servo system failures stem from daily maintenance oversights. More than 80% of sudden failures of servo motors (such as encoder failure, power module damage, and bearing overheating) are not accidental events but the inevitable result of accumulated blind spots in daily maintenance. It is best for enterprises to establish a three-level prevention system: daily inspection of operating noise/temperature rise, monthly cleaning of the cooling system, and annual professional deep maintenance, which can reduce unplanned downtime risks by more than 60%.