Is Ultrasonic Welding The Same As Vibration Welding?

It is often misunderstood that ultrasonic welding and vibration welding are the same welding process because they both use vibrational energy to weld plastic components. In fact, the implementation process of these two welding methods is completely different. Let’s take a look at the differences between the two.

Difference 1: Vibration Direction

The vibration welding process vibrates one part linearly relative to the other, whereas ultrasonic welding vibrates in the opposite direction, vibrating one component perpendicular to the other.

Difference 2: Vibration Frequency

The vibration welding process vibrates at approximately 120-240Hz per second, depending on the size of the parts being welded. This frequency is in the range of human hearing, so vibrating equipment uses sound enclosures to protect machine operators from deafening fog-horn-like sound.
Most ultrasonic welding processes operate between 20 and 40 kHz frequency, some work at 15 kHz, which is technically outside the ultrasonic range, but is still considered ultrasonic welding. Ultrasonic welding at 20-40 kHz is quieter than vibration welding but does sometimes produce harsh sounds due to the lower resonant frequency of plastic parts.

Difference 3: Welding Time

Vibration welding is a very fast process, with typical cycle times in the range of 5-10 seconds, ultrasonic welding is faster than vibration welding, with typical cycle times between 1 and 3 seconds.