#Advanced manufacturing

Ultrasonic Welding

A strong bond is created when two or more materials of the same kind or two or more materials of different kinds are bonded together by ultrasonic welding. Ultrasonic welding works well especially for thermoplastic materials. Ultrasonic waves with a frequency range of 20 to 70 kHz are utilized to weld plastic. The oscillations, whose amplitudes range from 5 to 50 m, are introduced into the component by the sonotrodes. The heat created by friction causes melting.

The plastics are bonded after being put through further stress. To be precise, Ultrasonic Welding needs focused sound wave energy.

This is accomplished either by the geometry of the tools (sonotrode and anvil) or by the plastic itself (joint design). The seam's edges or points could be the center of the energy. For this reason, they are referred to as energy directors (ED).

Ultrasonic Welding Important Process Parameters

The perfect weld junction should be secure, robust, and attractive to the sight. The material, weld process, and welding instrument must all operate in unison to accomplish this. Die Settings are crucial: The right procedure parameters ensure superior and repeatable results.

Amplitude: The weld tool vibrates at a rate quicker than the eye can perceive, with an amplitude ranging from 5 to 50 meters. To provide the required power, the amplitude transformer adapts the mechanical vibration created in the converter.

Trigger point: The weld is initiated when the component is pressed on the mold with the trigger force at the trigger point. If this only fluctuates slightly over a predetermined period of time, the ultrasonics are triggered, and the trigger force transforms into a weld force. This ensures that the welding procedure always starts in the same position and that the final products are dependable of the highest quality.

Weld Force: to create consistent and dense weld connections, the sound waves impact force on the component is essential. The amount of force applied depends on the component size, connecting surface, and strength.

Weld time: The actual welding process, which starts as soon as the ultrasonics are turned on and the trigger point is achieved, lasts only a few moments. The weld time finishes when a previously determined switch-off condition is satisfied.

Hold time: After the weld period, the components are maintained under pressure for a short while. They are able to cool and solidify uniformly as a result. The weld tool doesn't heat up throughout the entire process, which supports the cooling process.

How Does Ultrasonic Welding Work?

When the ultrasonic vibrations make into contact with a substance (like plastic), the chemical chains start to oscillate. The molecules start to migrate and run into each other. This results in the production of friction heat. This process causes the thermoplastic materials it affects to start melting. This concept makes Ultrasonic Welding possible. After a brief hold period under increased pressure, the connecting the area enables molecular welding of various materials (components).

Ultrasonic Welding Plastics
Advantages

Ultrasonic Welding has a number of advantages. The most important as following:

Time Savings: The plastics are immediately welded, there are no start-up procedures or waiting intervals necessary for the tools to heat up and cool down while using Ultrasonic Welding.
Consistent Quality: Precision control methods ensure accurate and reproducible results.
Saving Costs and Being Environmentally Friendly: Less energy is used, and no tools or other support are required, like adhesives.

Plastic Materials for Ultrasonic Welding

There are a lot of ways to combine materials made of the same plastic as well as those made of different plastics. Welding is the most common method, particularly when adhesive bonding is unable to get a strong or durable connection. Plastic welding leads to a deep and strong bond betweeen materials. However, it only applies to so-called thermoplastic materials, which may get different shapes when heated.

Thermoplastic materials: Mostly made of linear molecular chainst. The plastic of thermoplastic material is bendable and weldable when heated. Thermoplastic materials include ABS, PS, PP, PE, PVC, PC, PMMA, etc.

Ultrasonic Welding