For the design parameters of the ultrasonic weld line and the materials of two welding pieces are the same, then it is the distance between the ultrasonic weld line and the ultrasonic horn-- near welding and far welding that impact the ultrasonic welding quality.
       Then what is near welding and far welding? Generally speaking, when the distance between the ultrasonic weld line and the welding head is less than 6.3mm, it is near welding; and if the distance is over 6.3mm, it is far welding.
       In general, for ordinary plastic materials, the smaller distance between the ultrasonic weld line and the welding head, the easier for welding. But some special materials like glass, amorphous materials, etc.can only be carried out by far welding, since near welding can easily cause the part cracks or other damage.