Most impressively, the wizardry that is ultrasonic welding uses high-frequency vibrations to seal two thermoplastic parts together, under precise pressure, in typically less than 0.2 seconds.
Custom injection molders such as European-based specialist firm NS-K use ultrasonic welding as a secondary operation when two thermoplastic parts need to be joined together. Determined early in the Design for Manufacturing phase (DFM) stage of the production of new parts, when a specific requirement calls for parts that are so complex that it is impossible to mold them as a single unit, the bonding and assembly of two parts into one may be specified instead.
Explained simply, an oscillating plate vibrates at tens of thousands of pulses per second, creating ultrasonic waves which transfer from the contact surface to the plastic itself. As this happens, high temperatures are created at the touchpoint, and this heat turns the plastic from solid to liquid in much the same way in other injection molding practices. As the plastic liquifies, pressure is applied and the two sections bond hermetically. Once the ultrasonic waves are stopped, the plastic returns to its solid state and the result is one single molded component.
This fast and effortless process creates an extremely strong seal, and is often used in the auto world in situations where enclosures and engine parts need to be molded around, or where there is a need to seal two parts but without the weakness or fiddliness of fastenings or tapes.
Obviously, some resins or plastic types are more weldable than others, and there are limitations to the size of such joints, and the mix of materials which can be connected if they are of different material, however the molecular way that the join works, once bonded the structure is strong and durable.
As just one of numerous plastic techniques offered by NS-K, if you have a requirement for any format of molding, regardless of complexity, get in touch with the team via the contact button above who can advise on the best approach for your custom project.