After the outbreak of new crown pneumonia, due to insufficient reserves of masks, a mask appeared difficult to find. Many companies have turned into production masks to achieve high-speed production. Are you also interested in the technology of mask production? Now let's share a welding technology applied to the mask during the manufacturing process: ultrasonic welding.
Ultrasonic welding uses high-frequency vibration waves to transfer to the surfaces of two objects to be welded. Under pressure, the surfaces of the two objects are rubbed against each other to form a fusion between molecular layers.
Some indentations can be seen everywhere on the mask, such as edge welding, ear bands, and exhalation valves are all ultrasonic welded.
As shown in the figure above, during the production of masks, we can intuitively understand the welding of all-plastic nose bridges, welding after hemming, breathing valve welding, multi-layer roll welding, and ear band welding. These are actually obtained by ultrasonic welding Finished.
When the ultrasonic wave is applied to the thermoplastic plastic contact surface, it will generate tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration reaches a certain amplitude. The ultrasonic energy is transmitted to the welding area through the upper welding part. The welded interface has a large acoustic resistance, which can cause local high temperatures.
Also, due to the poor thermal conductivity of plastics, they could not be released in time, and gathered in the welding zone, which caused the contact surfaces of the two plastics to melt rapidly. After applying a certain pressure, they were merged into one.
When the ultrasonic wave stops working, let the pressure last for a few seconds to make it solidify and form, so that a strong molecular chain is formed to achieve the purpose of welding, and the welding strength can be close to the strength of the raw material.
