Welding amplitude is the peak-to-peak vertical motion at the horn face. Here is an example: A 20 kHz converter produces amplitude of .0008". A 1.5 (gold) gain booster coupled to the converter amplifies the vibration to .0012". An ultrasonic horn with a gain of 2.0 is coupled to the booster and the resulting welding amplitude is .0024". Substituting gain factors for the booster and horn results in welding amplitudes ranging from .001" to .006". The math is fairly simple, but the secret lies in understanding how much amplitude is required for any given application.
Here are some guidelines:
Easy to weld resins such as ABS, Acrylic, Polystyrene, Polycarbonate, SAN and related blends/families require low to medium amplitude. Welding amplitudes of .0012" to .0035" are typical with these materials. High temperature Amorphous and most Semi-Crystalline resins such as Acetal, LCP, Polyester, Polyamide, PE, PP, PPS, Polyetherimide and Polysulfone require medium to high amplitude. Typical values are .0025" - .005". Shear type weld joints almost always require higher amplitude than energy director designs. For ultrasonic spot welding, staking and swaging applications, medium to high amplitudes are used to generate instantaneous surface melt on horn contact. Low to medium amplitudes are used for ultrasonic insertion applications.
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