What is Ultrasonic Welding?

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  • Written By: Michael Anissimov
  • Edited By: L. S. Wynn
  • Last Modified Date: 27 November 2019
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Ultrasonic welding is an industrial technique whereby two pieces of plastic or metal are joined together seamlessly through high-frequency acoustic vibrations. One component to be welded is placed upon a fixed anvil, with the second component being placed on top. An extension ("horn") connected to a transducer is lowered down onto the top component, and a very rapid (~20,000 KHz), low-amplitude acoustic vibration is applied to a small welding zone. The acoustic energy is converted into heat energy by friction, and the parts are welded together in less than a second.

Ultrasonic welding is unique in that no connective bolts, nails, soldering materials, or adhesives are necessary to bind the two parts together. This saves greatly on manufacturing costs and creates visually attractive (i.e., unnoticeable) seams in product domains where appearance is important. Because ultrasonic welding is a largely automated process, all a technician needs to do is pull a lever and the welding is complete. The downside of ultrasonic welding is that it only applies to small components - watches, cassettes, plastic products, toys, medical tools, and packaging. The chassis of an automobile, for example, cannot be assembled with ultrasonic welding because the energies involved in welding larger components would be prohibitive.


The technology of ultrasonic welding appeared in the early 90s and has been under rapid development since then. As the technology improves, the range of materials that can be joined together using this technique increases. At first only non-flexible plastics could be welded because their material properties allowed the efficient transmission of acoustic energy from part to part. Nowadays, less rigid plastics such as semicrystalline plastics can be welded because large amounts of acoustic energy can be applied to the welding zone. As the technology matures and becomes more versatile, it is likely to obsolete large classes of historical techniques for joining materials together.


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Post 8

I'm so confused. I always thought it was for welding unlike materials. Or is it not?

Post 7

I have seen dukane welding machines. In this machine's setup, you have to adjust amp, absolute distance, weld energy, and peak power. Anybody know what these attributes mean?

Post 6

Isn't ultrasonic welding for unlike materials?

Post 5

I have seen dukane welding machines. in this machine's setup, you have to adjust amp, absolute distance, weld energy, and peak power. anybody know what these attributes mean?

Post 4

15 kHz ultrasonic welding equipment is designed for welding medium to large-size parts at higher amplitudes. Plastics assembly at the15 kHz frequency permits the welding of many softer plastics with greater far field distances than is possible with conventional 20 kHz systems.

Post 3

Ultrasonic welding can be used to join dissimilar materials. This makes it an ideal process for joints that may not be able to be formed using traditional methods. However, ultrasonic welding can also be used to join the same material such as copper to copper. The main limit for ultrasonic welding is the thicknesses of the materials.

Post 2

I've seen ultrasonic horn assemblies advertised in the 15 through 40 kHz range, yet according to the above

article they supposedly operate in the 20,000 KHz

range. (40 kHz would be 40,000 Hz). Which is correct?

Post 1

i heard that ultrasonic welding should be used in dissimilar metals. But in some places, I found that it was used to weld copper and copper.

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