In ultrasonic welding, there are typically four phases of welding:
- Contact phase: During this phase, the horn contacts the plastic parts with a low amplitude and high frequency vibration. This helps to remove any surface contaminants and achieve initial plastic deformation.
- Plasticization phase: In this phase, the horn applies more force and amplitude to create enough heat to melt the plastic at the joint interface, creating a molten layer between the parts.
- Hold phase: In this phase, the horn maintains a high force on the parts while the molten plastic cools and solidifies to form a strong bond.
- Cooling phase: The final phase is the cooling phase, where the horn retracts from the parts and they are allowed to cool to room temperature.
The parameters such as amplitude, pressure, and time can be varied during each phase to optimize the welding process for a particular application.
