FAQ: : How to evaluate test results of ultrasonic welding horns? Mr. W.G.
The frequency and the mechanical quality factor Qm are the pillars of the acoustic stack performance.
When testing an ultrasonic horn, you should judge the results based on two main parameters: antiresonance frequency (Fa) and mechanical quality factor (Qm). The TRZ Software judges the results with regards to preset criteria; these criteria are based on our experience and may be refined by you (they are not optimum for every manufacturer because we calculate them from averages).
The horn frequency should be the nominal one ±0.25% (±50 Hz for 20 kHz welders), this tolerance may be wider depending on the manufacturer, but not more than ±0.5% (100 Hz for 20 kHz welders). The mechanical quality factor should be higher than 1000, if it is lower than that you may have a cracked horn. The frequency increases when the horn wears out and decreases when the joints interfaces are damaged or have parts cracked (horn, booster, ceramics, studs). The mechanical quality factor tells you about the horn and acoustic stack efficiency in vibrating. It is not enough to be at the right frequency, the part also needs to be efficient, otherwise it will heat up during the operation.
Learn more about testing converters and acoustic stacks.