How to tune an ultrasonic welding horn

There are several methods available for tuning an ultrasonic welding horn.  Ultrasonic horn manufactures rely upon frequency analyzers to measure the frequency of the ultrasonic horns during the manufacturing process.

CAUTION: Because multiple modes of vibration are present in all tooling, it is very important that the ultrasonic horn is tuned to operate on the correct axial frequency.  Tuning an ultrasonic horn to an incorrect non-axial frequency can result in catastrophic failure of the ultrasonic horn and/or damage to another component of the ultrasonic system (booster, converter/transducer, power supply, etc).

The most common method for tuning an ultrasonic horn is to build a "blank" horn with a tuned length that is .250"-.500" longer than the expected final tuned length (this results in a frequency which is lower than your target frequency).  Material is then removed from the working face of the horn, thus raising the frequency of the ultrasonic horn until the proper frequency is achieved.  The anticipated tuned length of an ultrasonic horn can usually be accurately achieved with proper use of FEA software.

Another common method for tuning an ultrasonic horn is to adjust the location of the radius "step" that is present on many ultrasonic horns, both circular and rectangular.  This method is commonly used when building multiple ultrasonic horns which require the same final tuned length.

Although not as common, the frequency can also be raised by removing material from the surface of the horn on which the stud is located.

On slotted horns, adjusting the slots will also affect the frequency of the horn but this is typically reserved for optimizing the performance of the ultrasonic horn rather than trying to simply adjust the frequency.

One of Industrial Ultrasonics, Inc cost saving services includes re-facing and re-tuning our customers' existing ultrasonic horns once the working surface has become worn or damaged.  If you are a customer with in-house machining capabilities, we can further increase your savings by advising you as to how much material can be removed from the face of the ultrasonic horn before it would need to be returned to Industrial Ultrasonics, Inc for re-tuning.

Disclaimer: Keith Anderson of Industrial Ultrasonics, Inc designs and manufactures ultrasonic welding horns for use on all brands of ultrasonic welders including, but not limited to, Branson, Dukane, Forward Technologies, Herrmann, Rinco, Sonobond, and Stapla.