During the epidemic, the demand for masks became very large, and some companies switched to producing masks. In medical masks, non-woven fabric is a relatively good material. Its main components are PET, PP, and PE, and these materials are very suitable for ultrasonic welding. What is the welding principle of making masks?

Some indentations can be seen everywhere on the mask, such as the edges, ear straps and exhalation valve are all ultrasonically welded.

In the production process of masks, we can intuitively understand the welding of all-plastic nose bridge, welding after hemming, breathing valve welding, multi-layer seam welding, and ear band welding. These are actually completed by ultrasonic welding.

When the ultrasonic wave acts on the thermoplastic plastic contact surface, it will generate tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration with a certain amplitude will transmit the ultrasonic energy to the welding area through the upper weldment. Because the welding area is two The acoustic resistance at the welding interface is large, so local high temperature will be generated.

Because of the poor thermal conductivity of the plastic, it cannot be distributed in time for a while, and it gathers in the welding area, causing the contact surface of the two plastics to melt rapidly, and after a certain pressure is applied, it merges into one.

When the ultrasonic stops, let the pressure continue for a few seconds to make it solidify and shape, 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.

Non-woven fabrics are the most used in the environmental protection, medical supplies industry. Like the liquid filter bag sealing and tail sealing are achieved by welding, after welding, it is waterproof and leak-proof, with high strength.