lb load with a bracket arm 12 in. from the actuator’s load carrier would be subjected to a 600 lb-in. moment load.
Environmental considerations. Failing to factor in environmental considerations can lead to catastrophic results. Extreme heat or cold, external abrasives, dirty or wet conditions, caustic fluids, and air quality are just a few of the conditions that affect cylinder life. Frictional wear (abrasive, pitting, adhesive, and corrosive) due to particulates or fluids hitting the cylinder can cause premature wear or failure and increase maintenance.
Most manufacturers specify cylinder performance based on normal operating conditions. If the cylinder must operate in adverse environments, it is best to discuss this with the manufacturer to determine if the cylinder can deliver the expected performance.
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Software to the rescue
Designers need to consider many important points when sizing rodless cylinders. Determining the available air pressure, proper working stroke, and overall length are relatively simple. But determining the effects of moment loads, dynamic loading, inertia, and breakaway pressure can be more complex. Some leading manufacturers offer sizing and selection software that makes it easier to specify the right cylinder.
For instance, programs such as Tolomatic’s Tol-o-motion sizing and selection software (available for download at tolomatic.com) factor in breakaway force and calculate bending moments based on values of the speed entered. And they use travel distance and speed values to determine the effects of inertia on a moving load.
When using a manufacturer’s software or manually sizing a cylinder, it is always best to discuss sizing results and application requirements with the manufacturer. Determining the right pneumatic rodless actuator can be an in-depth process because there are many different styles to consider. But in many applications, the space saving features and load-bearing systems of rodless cylinders make them an ideal choice for linear motion.