There is no distinction between the quality of ultrasonic plastic welding machines at 15kHz and 20kHz, it is only applicable to different product scenarios.

The common frequencies for ultrasonic welding machines are 15kHz and 20kHz ultrasonic plastic welding machines. The higher the ultrasonic frequency, the better the welding accuracy, but the smaller the relative power, the smaller the amplitude. Below is the difference between ultrasonic plastic welding machines at 15kHz and 20kHz:

When the frequency of the ultrasonic welding machine is low, it will produce noise. When the frequency is below 20kHz, the noise during ultrasonic welding becomes very loud. For plastic products with higher welding accuracy and relatively smaller plastic parts, the higher the frequency, the better. Therefore, ultrasonic welding machines with a frequency of 20kHz or higher are suitable for precision, ultra-thin, and very fragile plastic components, such as SD cards or products with crystal oscillators inside;

The 15kHz ultrasonic welding machine is easier to increase in power and has a larger amplitude, making it suitable for welding larger, difficult to weld, and rough plastic products;

From the appearance, the transducers of 15khz and 20khz ultrasonic plastic welding machines can be distinguished. The transducers of 15khz ultrasonic machines are generally inverted conical, with a screw hole specification of M16X1.0 teeth, while the transducers of 20khz ultrasonic welding machines are generally cylindrical, with a smaller diameter and a screw hole specification of 3/8 inch 24 teeth in the British system.