# Ultrasonic metal welding

Solid-state metal joining: material and tooling compatibility, force and vibration controls, process monitoring, electrical performance and joint acceptance.

Reviewed: 2026-11-01

Tags: processes, welding, ultrasonic-welding, solid-state

A hypothetical controller reports **600 J over 0.30 s**, averaging **2,000 W on its energy basis**. A **2.0 s** station cycle including loading, clamping, welding and release gives **30 assemblies/min**. At **98% first-pass yield**, expect **29.4 assemblies/min** before downtime or rework. Verify the controller's energy definition, bonded area and strength independently.

A sonotrode vibrates parallel to the metal interface under force, with an anvil supporting the lower part. Relative motion disrupts oxide and plastically deforms the interface during solid-state bonding. [Herrmann, metal-welding mechanism](https://www.herrmannultrasonics.com/en-us/welding-using-ultrasonics/metal-welding)

“Solid-state” does not mean zero local heating, zero deformation or automatic compatibility. Specify the actual alloy, temper, surface condition, joint geometry and equipment. A successfully welded copper wire bundle does not establish capability for an arbitrary thick structural joint.

## Identify the joint and process variant

Common enquiries include wire-to-wire splices, wire-to-terminal connections, overlapping battery foils and localized sheet contacts. Schunk's application brochure describes wire-harness, battery and power-electronics connections, and separately identifies specialized tube-closing applications. Those examples establish application families, not a universal thickness range or a hermeticity guarantee for every ultrasonic weld. [Schunk Sonosystems, Ultra What brochure](https://backend.schunk-group.com/Schunk/BU-Sonosystems/Redesign-Web/Documents/Brochures/Schunk-Sonosystems-Ultra-What-EN.pdf)

Define whether the proposed route makes an individual spot, a compacted wire splice or a continuous joint, and obtain the corresponding tooling concept. Access is required for the vibrating tool and its reaction support. Resolve the overlap, tool footprint, edge distances, nearby bends and allowable tool impressions before treating the connection as manufacturable.

| Enquiry input | Why it matters |
| --- | --- |
| Alloy, temper, coating and surface history | Defines the actual joining partners |
| Foil count/thickness or wire strand construction | Defines the stack the tool must grip and consolidate |
| Overlap, access and support | Determines whether motion reaches the intended interface |
| Electrical and mechanical duty | Determines which joint properties need qualification |
| Adjacent components and cleanliness limits | Defines permitted deformation, vibration and debris |

A drawing should distinguish nominal overlap from the required effective bonded region. Tool contact area, apparent imprint and bonded area are different quantities.

## Material and surface compatibility

Herrmann identifies copper, aluminum, nickel and silver among its nonferrous applications and emphasizes determining a process window for each application. Treat alloy combinations, layer sequence and thickness changes as engineering inputs rather than assuming that similar electrical conductivity means similar weldability. [Herrmann, weldable metals and application-specific process windows](https://www.herrmannultrasonics.com/en-us/welding-using-ultrasonics/metal-welding/weldable-metals)

Coatings require particularly careful interpretation. Sonobond states that its **SpliceRite Wedge-Reed** wire-splicing system can join tinned and oxidized nonferrous wires without pre-cleaning. This is a named supplier/system claim, not permission to omit surface preparation on another machine or to accept uncontrolled oil, oxide or coating thickness. Qualify representative incoming material and define what changes require a new trial. [Sonobond, SpliceRite](https://sonobondultrasonics.com/products/splicerite-ultrasonic-wire-welder-and-splicer/)

Preserve the specified surface state through storage, stripping, handling and loading. Include damaged strands, insulation residue, plating changes and mixed incoming lots in the preparation review. For sensitive assemblies, define collection and inspection of displaced particles as well as the finished joint's appearance.

## Tooling and controlled variables

The sonotrode, anvil, fixture and workpiece form a coupled system. Specify tool identity and revision, contact texture, alignment, reaction support and the allowed wear condition. An unsupported terminal or slipping upper layer can redirect motion away from the intended interface. Tool replacement therefore needs a defined setup verification rather than assuming an identical machine program guarantees an identical joint.

Document frequency, amplitude convention, force profile, trigger/contact condition, weld endpoint and any hold stage. Record whether the controller terminates on time, energy, displacement or another enabled mode. Percentage amplitude, micrometers of displacement and generator power are not interchangeable specifications; confirm whether a stated amplitude is peak or peak-to-peak and where it applies.

As a bounded equipment example, Herrmann lists the **HiS VARIO S 20** at **20 kHz**, with generator options **2,400 / 4,800 / 6,200 W** and maximum weld force **3,500 N at 6 bar**. These are listed system ratings, not a recommended weld force, actual delivered interface power or guaranteed capacity for a particular stack. The same page describes VARIO Control visualization and application data storage. [Herrmann, HiS systems technical data](https://www.herrmannultrasonics.com/en-us/products/ultrasonic-systems-modules/his-system)

## Original energy and production example

Assume a hypothetical controller reports **600 J over 0.30 s** for one weld:

- Average power on that controller's energy basis = 600 / 0.30 = **2,000 W**.
- If loading, clamping, welding and release together take **2.0 s**, ideal station output is **30 assemblies/min**.
- The vibration interval occupies **15%** of that cycle; it does not establish the equipment's permitted duty cycle.
- At an assumed **98% first-pass yield**, expected conforming output is **29.4 assemblies/min**, before downtime or rework.

Compare machines using the controller’s measurement definition. Identical displayed energy can come from different power histories and leave different bonded area, deformation and strength.

## Monitoring and acceptance

Use production signals to identify departures from a qualified process, while testing whether those signals actually predict the required joint properties. Herrmann describes visualizing amplitude, energy, weld depth and force and balancing material and production tolerances within a determined process window. A trace inside its limits is evidence of process consistency; it does not independently prove every interface is bonded. [Herrmann, process visualization](https://www.herrmannultrasonics.com/en-us/welding-using-ultrasonics/metal-welding/weldable-metals)

Define the test configuration and acceptance criteria before trials. Mechanical requirements may need specified pull, shear or peel tests with controlled fixturing and failure-location reporting. Electrical connections may require resistance measurements with a defined probe arrangement, current and temperature, followed by application-relevant aging or cycling. A low initial resistance alone does not establish fatigue life, corrosion resistance or long-term current capability.

Inspect the product features that matter: strand retention, cracks or tearing, excessive thinning, terminal distortion, insulation clearance and permitted imprint. Sectioning or other destructive evaluation may be needed to investigate an unexplained process change. Set sampling, test timing and disposition rules under the governing product requirements; this page supplies no universal strength or resistance threshold.

## Production handoff and source limits

Provide the controlled joint drawing, incoming-material specification, tooling/fixture revisions, approved settings and monitoring limits, representative qualification results, maintenance checks and finished-part acceptance plan. Address tool wear, alignment changes, material substitutions and restart after maintenance explicitly. Use the machine's guarding, acoustic protection and safe setup instructions; absence of a welding arc does not remove pinch or vibration hazards.

Reviewed **2026-11-01**. The cited live manufacturer pages and Schunk brochure did not expose a separately verified technical issue date in the retrieved content; no publication year is inferred from crawl dates or URL paths. Supplier application descriptions and equipment ratings remain bounded to their named systems. The calculation, enquiry checklist and handoff recommendations are original engineering guidance, not a qualified welding procedure.

## Related reference

[Welding methods](index.md)