Ultrasonic welding
- Fast cycle with no consumables
- Needs compatible resins, usually from the same family
- Joint geometry such as an energy director must be molded in
Decision guide
Ultrasonic Welding vs Adhesive Bonding for Molded Plastic Parts
Ultrasonic welding fuses compatible thermoplastics at a molded joint. Adhesive bonding joins dissimilar materials with a cured bead. The joint must be designed before steel.
Joining molded parts
Joining two molded halves
Joint design is part of the molded part, not an afterthought.
Ultrasonic welding melts an energy director at the joint with high frequency vibration and fuses the parts. Adhesive bonding joins parts with a cured adhesive and can join dissimilar materials.
Ultrasonic welding is one of NetProto's secondary operations. The joint has to be designed into both molded parts before steel is cut.
Side by side
What each joint needs
Material compatibility decides most programs.
Adhesive bonding
- Joins dissimilar materials and irregular joints
- Cure time, fixturing, and surface prep add steps
- Adhesive choice depends on resin surface energy
Routing table
Signals for each joint
Qualitative only.
| Factor | Ultrasonic welding tends to fit | Adhesive bonding tends to fit |
|---|---|---|
| Materials | Same or compatible thermoplastics | Dissimilar materials or metals |
| Volume | Steady production with fixtures | Low volume or large joints |
| Seal | Sealed joints with the right joint design | Seal depends on bead control |
| Rework | Welded parts are permanent | Some adhesives allow limited rework |
Quote inputs
Send this with your CAD
Include both halves of the assembly.
Both resins, including fillers and colorants
Sealing requirement at the joint
Where the joint sits relative to cosmetic surfaces
Whether the assembly must ever be opened
Continue exploring
Related comparisons
Decision guides and the pages that go deeper.
Compare hub
All comparison guides.
Compare hubPainting vs molded in color
Color from the resin or from a coating.
Painting vs molded in colorSingle vs multi cavity molds
How cavitation shifts tool and part cost.
Single vs multi cavity moldsSecondary operations
Post-mold steps before parts ship.
Secondary operationsAssembly features
DFM rules for features that join parts.
Assembly featuresFAQ
Common questions
Can filled resins be ultrasonically welded?
Often, but high filler content and some resins weld poorly. Confirm the resin before designing the joint.
Is adhesive bonding quoted with the parts?
Adhesive bonding scope is confirmed on the quote. Describe the joint and the adhesive if one is already specified.
Next step
Quote the parts and the joint together
Upload both halves of the assembly. NetProto manufacturing is ISO 9001 certified.