Ultrasonic Insert
Threaded Inserts · ultrasonic threaded insert · sonic weld insert · press insert
Definition: An ultrasonic insert is a brass or aluminum threaded bushing vibrated into a pre-formed plastic hole by an ultrasonic welder — melting the plastic around its knurls for a strong thread.
Anatomy & Schematic
■ Body■ Internal thread
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 4-40 | M3 | — | — |
| 8-32 | M4 | — | — |
| 1/4-20 | M6 | — | — |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Brass | brass | — | None |
| Aluminum / stainless | varies | — | None |
Materials
- Brass
- Aluminum
- Stainless steel
Pros & Cons
Pros
- Fast in production
- Strong plastic bond
- No glue or screws
Cons
- Needs an ultrasonic welder
- Hole must be molded or machined precisely
- Only for thermoplastics
Typical Uses
- Injection-molded parts
- Production plastics
- Consumer electronics
- Medical devices
Alternatives & Related
- Heat-Set Insert — Hand-install with a soldering iron for prototypes
- Molded-In Insert — Insert placed in the mold before molding
Where to Buy
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FAQ
What is an ultrasonic insert?
A knurled brass bushing vibrated into a plastic hole by an ultrasonic welder — the plastic melts around the knurls to lock it in.
Ultrasonic vs heat-set insert?
Ultrasonic inserts use high-frequency vibration for fast production; heat-set inserts use a hot tip and suit prototyping and short runs.