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About Ultrasonic Welding

Ultrasonic metal welding is ideal for the assembly of similar and dissimilar non-ferrous metals for electronic components and pipe sealing.

Parts to be joined are held together under pressure and ultrasonic vibrations of 20 to 40 kHz, depending upon application. One part is held by the ultrasonic horn and is vibrated onto the second part, which is held on an anvil. The vibration of the horn causes the parts to scrub together (in shear) that removes surface contaminants to expose bare metal areas. The materials’ atomic structures then co-mingle to create a strong, surface molecular, solid-state bond that is clean and has low electrical resistance.

No heat is applied in ultrasonic metal welding. This cold-process welding does not require connective bolts, nails, soldering materials or adhesives to bind the materials together. So it avoids problems common to traditional processes: messy solvents and adhesives or costly mechanical fasteners and consumables.

Ultrasonic welds are typically as strong or stronger than alternative processes. In many cases, ultrasonic welding is the only welding solution for a component because ultrasonic welding does not damage the metals involved and conductivity is retained.

The oxide skins of the metals are broken by applying intense friction to the weld and the two parts are then pressed together simultaneously. These processes bring the two materials into close contact for atomic bonding force. The relatively slight rise in temperature created by the friction is well below melting point and plays no essential part in the weld.

An ultrasonic welding system is composed of:

• A press to apply pressure to the two parts to be assembled
• A nest or anvil where the parts are placed, allowing the high frequency vibration to be directed to the interfaces
• An ultrasonic stack composed of:
  · Converter—converts the electrical energy into a mechanical vibration
  · Booster—modifies the amplitude of the vibration. It is also used in standard systems to clamp the stack in the press.
  · Sonotrode or Horn—applies mechanical vibration to the parts to be welded.
  These three elements are tuned to resonate at the same ultrasonic frequency (typically 20, 35 or 40 kHz)
• An electronic ultrasonic generator that controls the movement of the press and delivers the high power AC signal, matching the resonance frequency of the stack.