While there are volumes of information online about the duty cycle, it’s really a relatively simple concept. Duty cycle is simply the ratio of time a circuit is on compared to the time that the circuit is off. Our products, as with most electronic devices, have a maximum recommended duty cycle. Choosing an actuator (or any motor) that has a duty cycle appropriate for your application is an important consideration.
Why is duty cycle important?
Ensuring that you run the device at or below the max recommended duty cycle ensures that you will get the longest life possible out of your actuator. When a manufacturer rates a product for a maximum duty cycle, it is typically based on lifespan testing. If you run an actuator or electric motor at a higher than rated duty cycle, you are likely to experience premature failure. There are a number of reasons that this can happen including but not limited to:
- Premature component failure due to heat
- Premature lubricant failure
- High levels of stress on mechanical components
- Motor will reach the natural end of its life sooner
As with most electronic devices, when linear actuators run, they produce heat. If the temperature of the unit is allowed to rise beyond a certain threshold, damage to the unit is likely. If the actuator has a maximum duty cycle of 20% and you are constantly running it at 25%, you will increase the likelihood of component failure. This could be the motor, circuitry or gearbox. Duty cycles are set low enough that the temperature will not rise to the point of causing damage.
Related article: Stepper Motors vs. Servo Motors - What's the Difference?
How is duty cycle calculated?
Calculating the duty cycle is straightforward, especially when your application requires the device to operate at a consistent pace. For example, if an actuator runs for 30 seconds and then rests for 30 seconds, its duty cycle is 50%, as it is running half the time. Essentially, the duty cycle represents the percentage of time the actuator is actively operating.
We calculate duty cycles based on the peak efficiency of each product. However, as the load on the actuator increases or the speed rises, the duty cycle tends to decrease due to heat generation. On the other hand, operating at a lower load or slower speed than the peak efficiency point can lead to a higher duty cycle.
What factors can affect duty cycle?
As mentioned, duty cycle ratings are calculated at peak efficiency. If you’re operating your device at peak efficiency, the rated duty cycle will be appropriate. There are however a number of environmental and other factors that can affect the duty cycle, and these factors, combined with application testing, should be used to determine the appropriate duty cycle in your application.
Some key factors to consider that can affect the duty cycle of your device are.
- Load
- Voltage
- Temperature
Other operating conditions can affect the duty cycle as well. Humidity levels and side load will also have an impact on the duty cycle of any electric motor or actuator. If you need a higher-duty cycle, you can buy a device with a higher peak efficiency point. This means that even if the duty cycle is the same, you'll be running below that number and you will get more life out of your device.
What happens if a device is run past its duty cycle?
Running any electronic component at a higher duty cycle than it is rated for is not recommended, and linear actuators are no exception. While it might be tempting to push your actuator beyond its rated limits to achieve faster or more frequent movement, doing so can significantly reduce the overall lifespan of the device. This is primarily due to the excess heat generated during prolonged operation. When an actuator is not given adequate time to rest between cycles, the motor and gearbox assembly can overheat. Over time, this excess heat can degrade internal components such as brushes, windings, and lubricants, ultimately leading to premature failure.
In addition to thermal stress, operating beyond the rated duty cycle can increase mechanical wear. Bearings, gears, and lead screws may experience accelerated degradation, especially if the actuator is also operating under high loads. This wear not only shortens the actuator’s useful life but can also lead to reduced performance, including slower speeds, increased backlash, or diminished precision.
Duty Cycle Conclusion
Understanding the concept of a duty cycle is essential for anyone working with actuators and electronics. By grasping the duty cycle, you can make informed decisions about design, maintenance, and performance.
If you need help choosing a product that will work in your application, please contact our sales team for assistance. Actuonix can create custom designs for all OEMs.
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