Servomotors: Predictive maintenance

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Rockwell Automation does not publish predictive maintenance information for its range of servomotors. There are too many external factors that can influence the lifespan of a motor such as:

Radial load
Axial load
Duty cycle
Environmental pollution
Transmission type
Load type...etc

To maximise motor life, and to verify that a drive/motor combination is being operated with its capacity, an approach could be to monitor certain critical parameters, such as:

Current feedback
Position error
Motor capacity
Inverter capacity
Motor temperature
Drive temperature...etc

...and record these values as a baseline for a healthy system, with reference to the published specifications for the drive/motor. Once a healthy baseline has been established, any deviation could indicate an underlying problem such as

Change in application has occurred without a sizing review
Excess radial/axial loading due to damaged mounting
Excessive vibration
External condition or contamination (shock, vibration, heat, dust, water...)

With this approach, a problem could potentially be identified before any damage occurs. For installations with Kinetix 5700 and 5300 servo drives, the Virtual Torque Sensor feature may be useful. This feature estimates the motor air-gap torque which can be used to monitor machine operation, diagnose faults on the mechanical system, and assist in maintenance and commissioning. More information here: Application Technique: Virtual Torque Sensor, publication 2198-AT003

Additional considerations to maximise the life of a servo motor are detailed within the installation instructions for the particular motor family in question, such as:

Provide a drip loop in each cable to carry liquids away from the connection to the motor.
If possible, provide shields that helps protect the motor housing, shaft seals, and their junctions from contamination by foreign matter or fluids.
Shaft seals are subject to wear and require periodic inspection and replacement. Replacement is recommended every 3 months, not to exceed 12 months
Motor and seals should be inspected for damage or wear regularly. If damage or excessive wear is observed, replace the item.
Braked motors should not have their internal brakes used for stopping, as they are only rated for holding.