Since the 1950s, ultrasonic metal welding has been a useful resource in many industries that employ the use of joining applications or methods that utilize thermally conductive materials. Ultrasonic welding is popular in the plastic-processing industry, in particular, due to its high process speeds and repeatable weld results. Still, it is preferred in major industries, including packaging, hygiene, automotive, electrical and medical. Despite some disadvantages, like thickness limitations, ultrasonic welding appears to have a promising future in the automotive and aerospace industries as the popularity of lightweight materials continues to grow.
What is Ultrasonic Welding?
Ultrasonic welding is a technology that uses high-frequency vibrations or sound waves, which typically exceed the limit of human hearing, to heat and bond two parts that are touching under pressure. The vibrations create heat at the joint interface of the components being welded, causing the thermoplastic materials to melt and weld formation results after cooling. This process is a major advancement from using fasteners such as nails, glues, screws or thread, and is the fastest known welding technique. There are two common ultrasonic methods for welding plastic components, namely longitudinal and torsional.
The General Process
In simple terms, the process involves:
- The materials to be welded are positioned between a nest, or anvil, or fixture.
- The sonotrode, or horn, connected to a transducer, comes in contact with the material to be welded, producing low amplitude acoustic vibrations that produce friction.
- The friction produces heat that creates a melt between the materials, bonding them together as it cools.
The ultrasonic welding process is controlled by a computer microprocessor fixed within the welding apparatus.
Torsional Ultrasonic Welding
The torsional ultrasonic welding method involves a high-frequency friction welding process, in which the vibrations are transferred tangentially. The horn activates the upper connecting piece of material and moves it horizontally in relation to the lower connecting piece. This method uses a high vibration frequency of 20 kHz, which creates friction and produces a melt between the materials, joining them together. It is ideal for delicate applications because it does not strain the materials in the process.
Longitudinal Ultrasonic Welding
In the longitudinal ultrasonic welding process, the welding system is arranged horizontally, and the vibrations are tangentially transferred. Like the torsional process, in the longitudinal process, the horn activates the upper piece of material and moves it horizontally in relation to the lower connecting piece of material. The frequency is the same, 20 kHz, and results in friction that connects the two parts. The appropriate pressure is created with the utilization of a press.
Contact Lee Plastics
If you are interested in premier industrial ultrasonic technology, Lee Plastics offers a wide range of ultrasonic products and services that can meet your industrial welding needs. Contact us today to learn more!