Edit: See this article for a noise comparison of pneumatic, electric, and HASEL actuator technologies.
In many applications, linear actuators need to be small, discrete, and quiet. In healthcare settings, silent actuators are important because increased noise can distract workers or patients, or the sound of the actuator can distract from the purpose of the product.
This also goes for home automation as well. Most of us enjoy a quiet home, and as we add more mechanical devices into our lives, the need for silent actuators goes up.
How Quiet are Silent Actuators
When it comes to measuring the sound output of an actuator, volume is measured in decibels. Put simply, a decibel is a unit used to measure the intensity of the sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.
For example, a decibel range of 20-30 is akin to a ticking watch or a bedroom at night, while something at 40-50 is a refrigerator sound or speech. 80-90 dB is a piano or symphony concert. 130-140 dB is the noise of a screaming child, thunderclap, jet plane, or gunshot. Finally, 180-190 dB would be like a rocket launch.
Servos (motor-driven) and pneumatic (compressed air or gas powered) actuators are the loudest due to the driving mechanisms. Other electric actuators are rated below 65 dB, which is fairly quiet, or the same level as a sewing machine, shower, or rainfall. Silent actuators, however, are generally quieter than this. The best-selling silent actuators on the market have a decibel rating of less than 45, meaning they sound like a quiet whisper, but they aren’t completely silent. Some of the quietest electric actuators available are offered by Artimus Robotics and they actuate with only a slight, barely-noticeable noise as the plastic film changes shape. This is a dramatic difference from the traditional but loud electric servo and pneumatic actuators.
When looking into a silent actuator, it is important to consider the way the manufacturer took the measurement. Don’t hesitate to ask them what the testing standards are and how far they were from the device when they took them. However, be realistic with the results that you find. While silent actuators are very quiet, you will likely never find an actuator with a decibel rating of less than 30.
Written by Chris Glover