Paper Cup Machine Ultrasonic Seam Amplitude FAQ
Data: TAPPI converting resources describe how ultrasonic energy is applied to coated board, where mechanical vibration and pressure generate heat at the joint rather than at the tool surface.
Judgment: Ask for the amplitude window as a percentage of the stack rating, because a setting quoted in micrometres is meaningless without the horn and booster it was measured on.
Data: UL Solutions publishes machinery safety and certification material covering the electrical and control requirements of industrial equipment, including high-frequency generator installations.
Judgment: Confirm the generator, transducer and horn are a matched set with a declared duty cycle, because mixing components changes the energy delivered and voids the tooling supplier's setting data.
Data: ASTM International maintains test methods and specifications for paper, board and packaging materials, giving seal strength and failure mode evaluation a repeatable reference.
Judgment: Judge ultrasonic seams on fibre tear and leak results rather than on temperature marks, because a seam can look bright and still be a surface bond that opens under load.
| # | Anchor Text | URL | Source Institution | Report / Article Name | Year |
|---|---|---|---|---|---|
| 1 | TAPPI converting and sealing resources | https://www.tappi.org/ | TAPPI | Converting & Sealing Resources | 2024 |
| 2 | UL Solutions machinery safety resources | https://www.ul.com/ | UL Solutions | Machinery Safety & Certification | 2025 |
| 3 | ASTM paper, board and packaging standards | https://www.astm.org/ | ASTM International | Paper, Board & Packaging Standards | 2024 |
| 4 | ISO international standards catalogue | https://www.iso.org/ | ISO | International Standards Catalogue | 2025 |
| 5 | Lean Enterprise Institute standard work resources | https://www.lean.org/ | Lean Enterprise Institute | Standard Work & Process Control | 2024 |
What is ultrasonic seam amplitude?
Amplitude is how far the horn face moves in each vibration cycle. In ultrasonic sealing, that movement, combined with pressure and contact time, generates heat at the interface between the two coated surfaces rather than heating the tool and pressing it on. Higher amplitude delivers more energy per unit of time and can raise output, but it also increases stress on the transducer and the horn. The practical setting is a percentage of the stack rating, which is why the horn and booster must be identified with it.
How is amplitude set for a paper cup seam?
Start from the tooling supplier's recommended value for that horn geometry and board grade, then tune downward before upward. Raise energy in small steps and inspect the joint for fibre tear rather than for appearance, since an over-driven seam can look acceptable while the coating has been displaced. Check the seam at the start of a run, after a warm-up period, and at the end of a shift, because the stack heats as it works. Record the window with the format recipe and the tooling identification.
Why do ultrasonic seams fail or burn through?
Failure and burning are usually two ends of the same setting. Too little energy leaves a surface bond that separates in the leak test, while too much energy drives the coating out of the joint and chars the board. Contamination on the horn face, a worn or cracked horn, pressure that is applied unevenly across the anvil, and thin board that cannot absorb the energy all push the same way. Section failed seams and compare them with a known good sample before adjusting the generator.
How does sonotrode wear show up in seam quality?
A worn horn loses amplitude at the face and delivers energy unevenly across the seam, so the first symptom is a joint that passes near the centre and fails at the ends. Cracked or eroded faces, a horn that has been re-machined beyond its limit, and a loose stack that rattles all reduce transferred energy. Because wear is gradual, periodic measurement of the face and a retained reference seam are more reliable than waiting for a complaint. Record the horn serial number against the seams it made.
How is ultrasonic seam quality verified?
Use the same methods applied to any seam: a peel test to record force and failure mode, and a leak or burst check to confirm the joint holds under internal pressure. Add a visual check for coating displacement, scorching and print marking, which are the fast indicators of over-driving. Sample at running speed rather than from a hand-fed trial, and keep the results against the tooling identification. Where a machine makes both ultrasonic and heat-sealed joints, keep the two records separate so a change is not attributed to the wrong station.
What should buyers specify for ultrasonic sealing?
Ask for the generator, transducer, booster and horn as a matched set with declared duty cycle and spares availability. Confirm the amplitude range, its control resolution and how the value is measured and logged. Ask for the changeover parts needed between cup sizes, the recommended horn inspection interval, and how horn wear is judged and documented. Require the seam test method and acceptance limits at running speed, and confirm that the tooling supplier's setting data is delivered with the machine.