When using ultrasonic welding technique to achieve allegation, product’s welding quality can be assured by adopting the following points:
① material;
② structure of plastic parts;
③ position and design of welding line;
④ welding area;
⑤ position and elasticity of upper and down surfaces;
⑥ contact surface of horn and plastic parts;
⑦ smooth welding path;
⑧ bed die’s support.
First of all ,the following points must be taken into account during the structure design of plastic parts:
① size of welding line;
② whether water tightness and air tightness needed;
③ whether perfect appearance needed;
④ avoid plastic melting or compound overflowing;
⑤ whether be suitable for horn processing demand.
 Then, in order to achieve perfect welding , three major design directions must be followed:
① two surfaces contacted initial must small, so as to focus energy, furthermore can decrease total energy to finish welding as far as possible;
② to find the proper method of fixture and alignment, such as plastic parts’ interface, step or tongue-and-groove , etc.;
③ welding area revolving around joint interfaces must uniform and contact intimately, furthermore, contact surfaces should be at the same plane as far as possible so as to stay the same during energy transformation, if possible.