What effects might a mold release agent have on an ultrasonic assembly?
Mold release agents reduce surface friction between parts and contaminate the thermoplastic resin. Both are bad for ultrasonic assembly. A good ultrasonic bond depends on the plastic parts surface friction to create the frictional heat needed for assembly. Therefore, use of a mold release agent can cause uneven welds, inconsistent welds, or prevent welds completely. If you re using mold release and experiencing problems, clean the parts joint surfaces with solvent. Use a mold release agent that is a paintable/printable grade; those agents interfere the least with the ultrasonic process and they often require no pre-assembly cleaning. It s a good idea to stay away from mold releases such as zinc stearate, aluminum stearate, fluorocarbons, and silicones because they are particularly difficult to work with when using ultrasonics.
