During the epidemic, the demand for masks became great, and some enterprises turned to masks. In mask medical products, non-woven fabric is a good material, its main components are PET, PP and PE, and these materials are very suitable for ultrasonic welding. What is the welding principle for making masks?

    Some indentations can be seen everywhere on the mask, such as edge sealing, ear band and exhalation valve, which are all welded by ultrasonic.  In the production process of masks, we can intuitively understand the welding of all-plastic nose bridge, welding after folding, welding of respiratory valve, multi-layer rolling welding and ear band welding, all of which are actually completed by ultrasonic welding process.

   When ultrasonic wave acts on the contact surface of thermoplastic plastics, it will produce tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration with a certain amplitude will transmit ultrasonic energy to the welding area through the upper welding piece. Because the welding area, that is, the interface between two welds, has a large acoustic resistance, it will produce local high temperature. Because of the poor thermal conductivity of plastics, they can't be distributed in time and gather in the welding area for a while, resulting in the rapid melting of the contact surfaces of the two plastics, and after a certain pressure is applied, they can be integrated into a whole. When the ultrasonic wave stops acting, let the pressure last for a few seconds to solidify and form, thus forming a firm molecular chain to achieve the purpose of welding, and the welding strength can be close to that of raw materials.

 Non-woven fabrics are widely used in filtration and environmental protection, and medical supplies industry. For example, the sealing and tail sealing of liquid filter bags are achieved by welding, which is waterproof and leakproof after welding and has high strength.