Ben Lloyd, EA Product Manager, Festo, shares five ways machine builders and specifiers can avoid simple errors and optimise the performance of electric automation systems.
Electric automation can deliver enhanced efficiency, consistency and precision in many industrial automation applications. However, simple oversights during the design and specification process can cause serious problems, including poor machine performance and premature component failure, and result in higher energy consumption, increased maintenance costs and lower productivity. Here are five ways to avoid these errors and optimise performance:
- Check which way is up!
Always consider final axis orientation when selecting a drive for a linear axis. This may sound obvious, but it is often overlooked. In our experience, this omission becomes more common as the application becomes more complex. Every axis-motor combination is calculated separately but the orientation direction is frequently forgotten.
Orientation is crucial for optimal performance because a vertical axis requires more torque to lift the load than a horizontal one. Ensure the motor, gearbox, ball screw or toothed belt are not undersized by considering the orientation during the calculation phase.
- Select the correct gear ratio
For the control circuit in a servo system to be stable, the motor’s mass moment of inertia must be proportional to the load. Otherwise, it may lead to an imbalance. We like to compare it to a light vehicle towing a heavy trailer. The vehicle may have enough power to get the heavy trailer moving, but not enough mass to prevent it from swaying (in crosswinds, for example).
A gearbox is most often used to achieve a good inertia ratio. It reduces the inertia that the load effects on the motor with the gear ratio squared. The right gear ratio will depend on the application.
- Verify vibration risks
Vibration is one of the key environmental conditions that can significantly affect the service life of a linear axis. If not properly addressed, vibrations can cause additional stress and wear on the components, which may not be evident during initial calculations.
Applying a specific factor to the load during calculations will ensure the component achieves its predicted life cycle. This factor, which accounts for the expected vibration, typically ranges from 1³ to 23. Refer to the component’s manual or datasheet for further guidance.
- Don’t forget to lubricate
Electric automation components are sometimes required to make repeated, very short and precise movements. Concentrated cycles can lead to components’ grease being depleted in this focused area causing sticking or failing due to inadequate lubrication.
An extended stroke, or “lubrication stroke”, should be made periodically to spread the pre-applied grease along the whole length of the bearing. Ideally, this action would be programmed into the machine software: for instance, at the end of every shift or production series. Lubrication requirements must be considered during the design phase to ensure that all movements are smooth and consistent.
- Consider cooling cycles
Heating and cooling cycles are typically influenced by whether the electric drive must operate continuously or intermittently. Intermittent operation gives components time to cool down, improving service life and offering the potential to select a less powerful version.
Festo’s Electric Motion Sizing tool helps factor in thermal modelling. Simply enter the dwell times between movements alongside other requirements such as motion, mass and speed. The online tool provides manufacturer-independent suggestions to help find the right combination of servo drive, motor and actuator for the application.
More advice on improving an electronic drive’s performance and life cycle is available in Festo’s eGuide 10 Most Commonly Made Errors With Electric Axes, which is free to download:
