Welding, Ultrasonic

a method of welding that uses ultrasound to transmit vibrations to a tool clamped to the surfaces of the materials being welded.

Metals are welded in the solid phase, without melting. A metal is heated to 200°–600°C by friction between the tool and the metal. The vibrations of the tool promote surface cleaning, and the resulting weld is therefore of good quality.

Ultrasonic welding is used primarily to join sheet metals (such as Al, Ti, and Cu), certain alloys, and plastics at individual spots or along continuous seams. The thickness of the sheets is 0.1–2 mm. The welding time for spot welding is 0.1–5.0 sec when the clamping force of the tool is 20–200 kilograms-force (0.2–2 kilonewtons).

When workpieces with different thicknesses are welded, one workpiece should be thin, that is, not thicker than 1 mm, but the other may be as thick as desired.

The equipment employed for ultrasonic welding includes a high-frequency electron-tube oscillator with a power output of 0.5–5 kilowatts and a magnetostrictive transducer with a core whose length may be varied. The core is coupled to a wave-guide acoustic intensifier that supports a force-application device with a hard-alloy tip. Ultrasonic welding is used primarily in the radio-engineering, electronic, and electrical-engineering industries.