Ultrasonic plastic welding

1.    Ultrasonic welding mechanism

(1) Mechanical fitting: In the ultrasonic welding joint, a plastic flow layer is formed at the contact of the two weldments, and the mechanical fitting of the dog teeth is presented.

(2) Chemical bond bonding: After the polymer is heated, the molecular chain is broken, the interface is fused, and the molecular chain is reconnected after cooling to form a chemical bond.

2.Plastic properties and welding relationship

Most commonly used injectable polymers can be ultrasonically welded, but the difficulty of soldering is closely related to the properties of the plastic itself.

(1) The greater the friction coefficient of plastic, the worse the thermal conductivity, and the easier the interface is to form a molten shape, the better the weldability;

(2) The harder the plastic is, the smaller the vibration transmission loss is, the better the weldability is when the plane is welded. On the contrary, the soft material is difficult to weld;

(3) The crystalline material has a poor solderability due to the temperature range from solid to molten state being too narrow;

(4) Soft plastics are easier to harden when riveting and insert welding.