…an industrial technique whereby high-frequency ultrasonic
acoustic vibrations are locally applied to workpieces being held together under pressure to create a solid-state weld. It is commonly used for plastics, and especially for joining dissimilar materials. In ultrasonic welding, there are no connective bolts, nails, soldering materials, or adhesives necessary to bind the materials together.
This technology goes back and was patented in the 1960s by two people, one of whom:
…was a lab manager at Branson Instruments where thin plastic films were welded into bags and tubes using ultrasonic probes.
Today, the Branson brand of material joining and cleaning solutions is part of Emerson.
In a Medical Design & Outsourcing article, 5 tips for ultrasonic plastic welding success, Emerson’s Tarick Walton and Mike Diker highlight considerations where ultrasonic welding technology is an effective solution.
The five considerations include:
- Part design (e.g. geometry, joint design, wall thickness)
- Material selection
- Actuation technology
- Equipment adaptability
- Global support
I’ll highlight a few of these tips and invite you to read the article for the rest.
For the part design consideration:
Avoid design pitfalls by engaging early with application experts about the details of part design. Among the most critical aspects of design for ultrasonically welded parts are part geometry and joint style. For example, if hermetic sealing is essential for product performance, consider using tongue-and-groove joints rather than chisel-step or other joints.
Understand the compatibility/incompatibility of the thermoplastics to be welded:
Once you’ve selected material types for part design, ensure that your supply chain can manufacture (e.g. injection mold) tight-tolerance parts consistently. In the event that a material is adapted or changed, it’s good to reevaluate the process with the help of your ultrasonic supplier, since weld parameter changes or even equipment changes may be required. Because weld quality and strength tie closely to part design and materials, recognize that even small changes can have significant effects on the joining process.