company news about Ultrasonic welding

Ultrasonic welding is the most common application of ultrasonic assembly. In welding, the horn is brought into contact with one of the workpieces, pressure is applied and vibrating ultrasonic energy travels through the material, generating frictional heat at the joint area between the two parts. The plastic material melts and flows
between the two part surfaces. When the vibrations stop, the plastic solidifies and the two workpieces are bonded together. Figure 1-1 shows the ultrasonic welding process in more detail.

Figure 1-1 Ultrasonic Welding

1. The two thermoplastic parts to be joined are placed together, one on top of the other, on a supportive

surface called a fixture.

2. A titanium or plated aluminum component called a horn is brought into contact with the upper plastic part.

3. A controlled pressure is applied to the horn, clamping the two plastic parts together against the fixture.

4. The horn is vibrated vertically 15,000 (15 kHz) or 30,000 (30kHz) times per second, at distances measured in thousandths of an inch (microns), for a predetermined amount of time called weld time. Through careful part design, this vibratory mechanical energy is directed to limited points of contact between the two parts. 

The mechanical vibrations are transmitted through the thermoplastic materials to the joint interface to create frictional heat. When the temperature at the joint interface reaches the melting point, plastic melts and flows, and the vibration is stopped. This allows the melted plastic to begin cooling.

5. The clamping force is maintained for a predetermined amount of time to allow the parts to fuse as the melted plastic cools and solidifies. This is known as hold time. (Note: Improved joint strength and hermeticity may be achieved by applying a higher force during the hold time.

6. Once the melted plastic has solidified, the clamping force is removed and the horn is retracted.
The two plastic parts are now joined as if molded together and are removed from the fixture as
one part.

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