Pressure welding is a welding method in which a certain amount of pressure is applied during the welding process. There are two forms of this type of welding, which can be heated pressure or direct cold pressure welding, and its pressure joints are relatively strong. Forging welding, contact welding, friction welding, pneumatic welding, cold-pressure welding, and explosion welding belong to pressure welding.
Resistance welding is commonly used to weld auto parts, stamping parts, ultrasonic welding polymer and plastic parts. Pressure welding is a typical solid-phase welding method. In the solid phase welding process, the pressure must bring the surfaces of the parts to be welded into direct, close contact in the solid state and raise the temperature of the parts to be welded by adjusting the temperature, pressure and time.
The following factors affect the welding quality of plastic ultrasonic welding：
1. The welding performance of the base material
2. Geometry and tolerance range of the welded workpiece
3. Geometry and tolerance range of the weld seam design
4. geometry and tolerance range of the welding tool (ultrasonic vibration head)
5. Adjustment and stable control of welding pressure, welding power (amplitude), welding time, cooling time and tool press-in depth.