Ultrasonic plastic welding machine theory knowledge

The principle of ultrasonic welding is to convert the 50/60 Hz current into 15, 20, 30 or 40 kilohertz electrical energy by means of an ultrasonic generator. The converted high-frequency electrical energy is converted again into a mechanical motion of the same frequency through a transducer, which is then transmitted to the welding head through a set of amplitude modulator devices that can change the amplitude. The welding head transfers the received vibration energy to the joint area of the workpiece to be welded, where the vibration energy is converted by friction into heat energy that melts the plastic. Ultrasound can be used to weld not only hard thermoplastics, but also fabrics and membranes.

The main components of an ultrasonic welding system include an ultrasonic generator, transducer/amplifier/head triplex, mold and frame.

How does linear friction vibration work?

Linear friction welding utilizes frictional heat generated at the contact surfaces of the two parts to be welded to melt the plastic. The heat energy is generated by moving one workpiece back and forth across the other surface at a certain displacement or amplitude under pressure. Once the desired degree of welding has been achieved, the vibration stops while a certain amount of pressure is still applied to the two workpieces, causing the newly welded parts to cool and solidify, resulting in a tight bond.

How does orbital friction vibration work?

Orbital vibratory friction welding is a method of welding that utilizes frictional heat energy. In orbital friction welding, the upper workpiece moves in an orbital motion - a circular motion in all directions - at a fixed speed. The motion generates heat energy that brings the welded portion of the two plastic parts to the melting point. Once the plastic begins to melt, the motion stops and the welded portions of the two workpieces will solidify and join together securely. Small clamping forces will result in a small degree of distortion of the workpiece, and workpieces up to 10 inches in diameter can be welded with Applied Orbital Vibratory Friction.