Ultrasonic welding: Types and applications

26 February 2025
René Vetjens

Previously, we have written blogs about ultrasonic welding: Ultrasonic welding, our new technique and Ultrasonic welding, its operation. Therefore, to conclude this small series, in this blog we give an impression about the main types and their applications.

To refresh the memory: Ultrasonic welding is a joining technique in which high-frequency vibrations connect materials. This method is popular in the plastics and metals industries because of its fast processing times, strong connections and lack of glue or additives.

1. Ultrasonic plastic welding

When welding plastics (thermoplastics), ultrasonic vibration generates heat through friction. This melts the plastic and fuses it to the plastic counterpart. Ultrasonic welding is efficient, fast and requires no additives such as adhesives or chemicals. There are several methods of welding plastics:

Butt Welding (Butt Welding): During welding, the system presses two plastic parts tightly together. The ultrasonic vibrations generate frictional heat, causing the surfaces to fuse together. Butt welding is often used for products with flat weld surfaces, such as pipes and housings.
Shear Welding: These methods are created by placing the surfaces of the plastic parts at an angle. This provides additional molecular bonding and a stronger weld. Shear welding is preferred for joints that must withstand high forces.
Near-field and Far-field Welding:
- Near-field welding Near- is suitable for hard plastics where the ultrasonic energy acts directly on the welding zone. This leads to fast and controlled melting, which is important for precision applications.
- Far-field welding is suitable for softer or thicker materials, where the vibrations move through the material to the welding zone. This is useful for complex shapes or larger parts.
Spot Welding: This method creates small welding spots without fusing the entire edge. Spot welding is useful, for example, for products such as plastic containers, medical filters and thin films.
Ring Welding: Connecting round objects, such as bottles and tubes, with a circular weld seam creates ring welding. You often see this method in the food packaging and medical industries for making sterile seals.

2. Ultrasonic metal welding

By combining pressure with ultrasonic vibration in ultrasonic metal welding, a solid-state joint is created without deforming or melting the metal. This creates a strong and durable welded joint with minimal material change. Common techniques include:

Parallel Welding: During welding, the system places two metal surfaces in parallel and connects them by pressure and vibration…. You see this technique a lot in the automotive and electronics industries, where precise and strong connections are essential.
Cross Wire Welding: This technique is used to weld thin metal wires or strips together. It is often used in the production of batteries, sensors and other electronic components.
Foil Welding: A method for welding very thin metal foils. This is important in the semiconductor industry and in producing energy-efficient batteries.
Tab Welding: Applied in the production of lithium-ion batteries, where metal tabs are welded to the battery cells. This process ensures low electrical resistance and reliable performance.

3. Ultrasonic lamination and sealing

Companies use ultrasonic technology not only for welding, but also for laminating and sealing. This makes the method especially valuable in the packaging and textile industries.

Laminating: The joining of multiple layers of material together without the use of adhesives. This process is used in the production of protective packaging, textiles for the medical sector and technical films.
Sealing: Widely used in food packaging and sterile medical packaging. During welding, ultrasonic energy seals the layers tightly and airtight. This keeps products longer shelf life and protected from outside influences.

4. Ultrasonic micro-welding

Micro-welding is a specialized form of ultrasonic welding used for very small and delicate components. This process is used in:

Microelectronics: Welding of miniature components such as circuits and circuit boards without thermal damage.
Medical Devices: Processing small plastic and metal parts for applications such as pacemakers, blood pressure monitors and surgical instruments.
Nanotechnology: Nanometer-scale compounds for research and advanced electronic applications.

5. Ultrasonic hybrid welding

Sometimes ultrasonic welding is combined with other techniques to create stronger and more durable joints. This is used in:

Aerospace industry: Where lightweight and extremely strong joints are needed in aircraft structures.
Automotive industry: Here, producers apply hybrid welding to structural components that must withstand high loads and vibrations.
Precision Technology: As in sensors and advanced microelectronics where multiple welding methods are required for optimal performance.

Advantages of ultrasonic welding

All in all, ultrasonic welding has many advantages such as:

Fast and efficient: Welding is done in seconds without long cooling times.
Environmentally friendly: No glue or additives required, reducing waste and chemical use.
Strong joints: The welded joint is durable and resistant to mechanical loads.
Wide Application: Suitable for a variety of materials and industries, from packaging to high-tech electronics.
Energy efficient: Uses less energy than traditional welding methods and minimizes material loss.

Conclusion

Ultrasonic welding is a versatile and efficient method of joining materials. Many industries use this technique, from packaging to high-tech manufacturing environments. This makes it a popular choice for projects where speed and precision are important. The right welding method depends on the material, the application and the desired strength of the joint.

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