How to Select a Standard Sorbothane® Isolator

November 30, 2015

Sorbothane, Inc. offers an extensive line of standard Sorbothane® parts. These parts are featured in the Standard Products Guide have been selected for their specific shock absorbing and vibration isolating applications.

  1. Determine the load (weight) of the unit that requires isolation. Divide the weight of the system by the number of isolators to be used. This is the load per isolator.
  2. Determine the lowest critical frequency (excitation frequency) of the system. For example: RPM of the motor, rate at which a cylinder strokes, output speed of a speed reducer. Divide minute-based information, such as RPM, by 60 to convert to Hertz (cycles per second).
  3. Select an appropriate isolator by using the information charts supplied with each product. Generally, an appropriate isolator will create a system natural frequency at least one-third lower than the excitation frequency. For instance, if the source of the vibration is an 1800 RPM motor, then the excitation frequency is 1800/60 = 30 Hertz. The resultant, (damped) system natural frequency should be 20 Hertz or less.
  4. Select the isolator that meets the technical and physical requirements of your system. In addition to a part number, you must also specify the durometer of the Sorbothane part required to get the specified load rating. Do not oversize isolators. Oversized isolators raise the natural frequency and reduce the effectiveness. Sorbothane’s standard colors are black, gray and royal blue. Other colors are available for large quantity special orders. 
  5. Remember: A bad design can actually make things worse for vibration damping. Consult the factory if you are having problems.
  6. Sorbothane works best in compression. If you have a tension application, bushings or a custom variation of the bushings are your best options. 

Sorbothane, Inc. produces a wide range of Standard Sorbothane® parts that can be found here. Sorbothane, Inc. also provides custom engineered solutions. Please contact Sorbothane, Inc. with any questions or ideas.