Dual Servo Spin Welder User’s Manual
Material filler and surface contaminants (e.g. mold release agent) are two factors that will affect consistency and weld repeatability. Spin welding is more tolerant of contaminants than ultrasonic welding. Spin welding is also less affected by hygroscopic polymers, although they may still require special handling for critical applications. The moisture content can lead to bubble formation in the joint resulting in decreased weld strength.
Control Parameters
There are several primary process control parameters that affect weld quality. They are the surface velocity of the weld joint, press (axial) speed, weld depth, and hold distance and time.
Thefollowingsectionsarepresentedforinformational purposes only and are in no way meant to serve as a rule or formula. The information is collected from publicly available books and papers. It is presented here to provide you with a general guideline for setting the initial parameters.
Surface Speed
For a fixed rotational spin speed (RPM), linear surface speed increases with weld joint diameter. For a fixed weld joint diameter, surface speed increases with motor RPM. Smaller diameter parts therefore usually require more RPM than larger parts of the same material. If the surface speed is too low, an adequate amount of heat will not be generated to cause sufficient melting. If the speed is too high, excessive heat in the joint could result in material degradation or reduction in viscosity leading to material flow away from the joint.
The selection of the proper surface speed depends to a large degree on the material and joint geometry of the parts being welded. Some materials, such as PVC, can be readily welded for a wide range of values, while others require a narrow range. Commonly quoted values in the literature recommend using
NOTE
Common hygroscopic thermoplatics: ABS/Polycarbonate (Cycoloy) Polyoxymethylene (Acetal, Delrin) Polyamides (Nylon, Zytel) Polycarbonate (Lexan) Polycarbonate/Polyester (Xenoy) Polysulfone (Udel)
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