Ultrasonic Welding: Principle, Working, Equipment, Applications, Advantages & Disadvantages

Today, we will explore the principle, working process, equipment, applications, and pros/cons of ultrasonic welding through diagrams. Ultrasonic welding is a welding process that uses ultrasonic vibrations to generate heat for joining materials. Ultrasonic waves refer to vibrations with frequencies above the normal hearing range, typically between 20,000 to 30,000 Hz. It is a solid-state welding process, meaning no external heat or filler metal is added.

Principle of Ultrasonic Welding

It operates based on the principle of ultrasonic energy. High-frequency vibrations create dynamic shear stress at the contact points between two workpieces. The resulting friction causes localized plastic deformation and heat, forming a bond at the interface.

![Ultrasonic Welding Diagram]

Equipment

1. Power Supply

   • Provides high-frequency, high-voltage electricity to the transducer.

2. Transducer

   • Converts electrical signals into high-frequency mechanical vibrations (using piezoelectric crystals).

3. Booster & Horn (Sonotrode)

   • The booster amplifies vibrations, and the horn transfers them to the welding plates.

4. Fixture/Clamping Device

   • Holds workpieces in place using pneumatic, hydraulic, or mechanical force.

Working Process

1. High-frequency current passes through the piezoelectric transducer, converting it into mechanical vibrations.

2. The booster amplifies these vibrations.

3. The horn delivers the vibrations to the workpieces under moderate pressure.

4. Shear forces and friction cause plastic deformation and localized heating at the interface.

5. A strong joint forms without melting the materials or using filler metal.

(Watch the video below for a visual explanation.)

Advantages & Disadvantages

✅ Advantages:

• Easily automated for fast production.

• Produces high-strength joints without external heat.

• Clean process with excellent surface finish.

• Suitable for dissimilar metals (e.g., copper-aluminum).

• No molten metal splatter.

❌ Disadvantages:

• Limited to thin, soft metals (e.g., max. ~2.5 mm for aluminum).

• High tooling cost for custom fixtures.

• Vibrations may damage electronic components.

Applications

• Nuclear reactors: Component fabrication.

• Automotive: Key fobs, headlight parts, switches.

• Electronics: Armature windings, circuit breakers.

• Medical: Filters, masks (clean, precise welding).

This covers ultrasonic welding’s principle, working, equipment, uses, and pros/cons. If you have questions, ask in the comments! Don’t forget to share this article on your social networks.