Ultrasonic Welding Of Plastic Parts: Design Considerations

Ultrasonic Welding Of Plastic Parts: Design Considerations

Date:Sep 03, 2019

Ultrasonic Welding of Plastic Parts: Design Considerations

No fasteners, no adhesives, fewer components and simplified assembly – that’s the beauty of ultrasonic welding. A proven technique for joining plastic parts, it’s fast, cost-effective and reliable. However, as with any manufacturing process, getting the best from it means designing appropriately.

In the paragraphs below we’ll share some advice on ultrasonic welding of plastic parts. Consider these your ultrasonic welding plastic part design guidelines.


Ultrasonic Welding Basics

Ultrasonic welding uses friction to heat plastics to a temperature high enough that they’ll bond together. This frictional heat is applied through high speed vibration generated in a sonotrode and delivered by a welding “horn.”

Ultrasonic welding machines look similar to spot or resistance welders. A horn pushes against the parts being joined, applying pressure and energy until they fuse together. With modern industrial controls its a fast and repeatable process.

When and Why to Use Ultrasonic Welding

Consider ultrasonic welding whenever the design calls for joining separate plastic pieces. One common reason is because its not feasible to mold the pieces as one unitary part. Another is that the pieces must be assembled around another part or parts. (Think motor housings or enclosures.)


Ultrasonic welding can simplify part design. There’s no need for large flat areas or holes and it’s possible to create hermetically tight enclosures. By eliminating fasteners it reduces piece count and weight, saving time, money and factory space. It’s also cleaner than adhesives with none of the mixing, storing and dispensing challenges.

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