Features of Ultrasonic Welding

Semi-crystalline polymers have a sharp change in melting point, and when heated, the polymer transitions from a solid to a liquid phase instantaneously. Therefore, in the ultrasonic welding of semi-crystalline plastics, it is best to use shear welding. Since amorphous plastics have a softening range, the welding design of amorphous plastics is relatively minor. Schematic diagrams of near-field and far-field welding methods are given. Depending on the distance between the contact points, the ultrasonic waves transmit the vibrations into the workpiece and bond the contact surfaces together. In general, near-sound welding will work well with all plastics. For the welding of plastics with low elastic modulus, it is best to use the near-sound field welding method.