Common Servo Motor Failures

Servo motors, also known as AC synchronous motors, provide machine builders with versatile solutions. They combine incredible energy efficiency with compact size, producing up to 60% more torque capacity than comparable-sized induction motors.


Servos, like any tool, are not infallible: failures with these motors can have a negative impact on productivity and safety. This is why it is critical to understand the most common causes of servo motor failure. Keeping an eye on these largely preventable issues will help you limit downtime and get the best performance out of these motors throughout their lifespan.


1. Failure of a Bearing

Bearing failure in servo motors is extremely common and has a variety of causes. Naturally, bearings deteriorate over time as a result of repeated use. Incorrect motor installation or reinstallation can also cause these bearings to be misaligned. An abnormal sound, such as growling or screaming while the motor is running at high speeds, is a telltale sign of bearing failure.


Predictive maintenance is the most effective way to avoid bearing failure. Consistently checking the motor to replace bad bearings will significantly increase the motor’s lifespan—and allow you to schedule repairs at convenient times that will not disrupt productivity. To ensure proper bearing replacement, it is critical to collaborate with a reliable repair partner. Critical applications should also consider using motor-mounted vibration sensors to detect the failure early.


2. Inadequate Braking

When the drive is deactivated or shut down, servo motor brakes are used to keep the load in place. The majority of servo motor brakes are designed for holding only, not dynamic stopping. Repetitive stopping or multiple e-stops may cause the brake to wear to the point where it must be replaced.


Because many servo motors are designed with IP65 protection, the brake is frequently enclosed within the housing and is difficult to check or replace. At a standstill, it is best to always engage the motor brake. After the brake has been engaged, the motor’s drive current can be turned off.


If an e-stop and dynamic stopping are required on occasion, the machine should use a separate brake capable of repetitive dynamic stopping.


3. Cable and winding failures

A common cause of servo motor failure is faulty winding. These copper coils within the motor can be harmed by water contamination or, more slowly, by natural vibration as the motor runs. Similarly, the system’s power, control, or feedback cables can deteriorate over time, resulting in failure or voltage spikes that cause the motor to shut down. Servo motor repair helps to find the exact reason of servo motor. 


If the servo motor has been exposed to any contaminant, such as coolant or water, it is critical to check for winding failure. (We’ll go over this further below.) Even uncontaminated windings should be checked because they deteriorate over time. Rewinding the defunct coils will keep the motor running smoothly and extend its life.


Investing in dependable cables is one of the best ways to avoid cabling failures. A high-quality feedback cable will improve overall system performance by allowing for fast, error-free connections. Cables, regardless of quality, should be tested on a regular basis as part of your troubleshooting efforts.


4. Contamination

Contamination is a root cause of many of the motor issues we’ve discussed thus far. Despite their general toughness, servos can be severely damaged by certain substances such as coolant, oil, and even common debris such as dirt. The latter can clog system-critical components such as fans, causing overheating. Liquid contaminants can wreak havoc on the motor’s bearings, encoder, windings, and other components.


Regular inspections and cleanings, as well as diligence, are essential in avoiding servo contamination. Sealing the motor windings and fully closed motor systems can help prevent these harmful substances from entering and affecting the system, especially in harsh environmental conditions. Check out for Leroy somer repair.


5. Excessive heat

Most machines, including servo motors, are vulnerable to overheating. Excessive heat may cause parts of the motor and connected systems to fail, resulting in costly downtime. Heat damage in servos is frequently caused by motor blockage, high environmental temperatures, and extended operating times.


Old, worn-down parts are a common cause of overheating in older engines, and they can be easily replaced. To limit excessive heat, servo motors should ideally operate in climate-controlled environments, but this is not always possible. Proper ventilation will aid in the management of the threat of overheating servos, as will allowing the stressed system enough time to cool down before continuing operation.


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