Determining which booster to use for an ultrasonic application requires some planning. First you must understand the theoretical amplitude requirement for the material you are welding. Then you must determine the amplitude from the transducer. Transducer amplitude is fixed based on the frequency of the system.
To determine which ultrasonic booster ratio to use there are two formulas:
1) Transducer Amplitude X Booster Gain X Horn Gain = Amplitude.
2) Stack Amplitude > Resin Amplitude Requirement