In addition, due to the poor thermal conductivity of the plastic, it could not be distributed in time for a while, and gathered in the welding area, which caused the contact surface of the two plastics to melt rapidly, and after a certain pressure, they merged into one.
When the ultrasonic stops, let the pressure continue for a few seconds to make it solidify and shape, thus forming a strong molecular chain, achieving the purpose of welding, and the welding strength can be close to the strength of the raw material.