La energy transition and the increasing spread of electric mobility are redefining the European and Italian production landscape. Our country, thanks to public and private investments, is becoming a strategic hub for the production of modules and battery packswith projects related to gigafactoryrecycling and material innovation. In this scenario, the ultrasonic welding is a key technology for ensuring reliable, lightweight and sustainable assemblies at all stages of the production of lithium-ion batteries and related thermoplastic components.
What is ultrasonic welding for thermoplastics
La ultrasonic welding is a process that uses high-frequency mechanical vibrations (usually 20-40 kHz) to fuse, through locally generated heat by molecular friction, the surfaces of two thermoplastic elements. It does not require external materials (adhesives, screws, solvents) or high ambient temperatures.
In the battery and electric mobility sector, ultrasonic welding is used for:
- Sealing plastic wrappings and containers of cells, modules and battery packs.
- Assembling safety valvesbushings and seals.
- Apply insulating sleeves and dielectric barriers on cables and busbars.
- Cutting films, foils and protective membranes with precision in multilayer plastic materials.
How the process works
The process consists of three main steps:
- Initial pressure: the two components are placed in contact and compressed through a sonotroda.
- Ultrasonic vibrationThe sonotrode emits high-frequency vibrations, generating localised heat and surface melting.
- Cooling under pressureWhen the vibration is over, the pressure is maintained for a few moments to allow the solidification of the joint.
In the case of the ultrasonic cuttingvibration is directed to an edge to separate the material cleanly, without fraying or overheating.
Advantages over other methods
Ultrasonic technology offers several specific advantages for the production of battery and electric vehicle components:
- High precision and repeatability.
- Reduced cycle times (fractions of a second).
- Clean, contamination-free joints chemical or thermal.
- Compatibility with high-performance plastics.
- Easy integration into automated and robotic lines.
- Comprehensive monitoring of process parameters for traceability.
Compared to laser, heat or adhesive welding, the ultrasonic process is more sustainable, economical and safer for plastic components.
Typical industrial applications
The most common applications of ultrasonic welding in the battery and e-mobility sector include:
- Battery pack cases and modular containment systems.
- Safety valves and membranes for cylindrical or prismatic cells.
- Insulating connectors and plastic supports for wiring.
- Composite plastic thermal and acoustic barriers.
- Protective sleeves for BMS (Battery Management Systems).
- Cutting separators and multilayer protective films.
Technical requirements: frequencies, powers and equipment
For welding and cutting thermoplastic materials used in battery applications, the machines must guarantee:
- Operating frequenciesfrom 20 kHz (robust joints and high thicknesses) to 35 kHz (precision components and complex geometries).
- Generator powerbetween 1000 W and 3000 W, digitally modulated.
- Customised sonotrodes in titanium or hardened steel, suitable for restricted access and complex profiles.
- Control and diagnostic systems for continuous parameter analysis (time, force, amplitude, energy).
- Compatibility with Industry 4.0 interfacesfor traceability, predictive maintenance and software integration.
The Sonomax solution for the battery industry
Sonomax Srlwith over 20 years of experience in the design of ultrasonic welders for thermoplasticsis a partner of choice for OEMs, system integrators and first-tier suppliers in the battery industry. Our table-top, automatic or integrable machines are designed for productivity, accuracy and traceability.
From rapid prototyping at mass productionour technical team supports the customer in the selection of frequencies, sonotrode geometries and optimised work cycles.
Discover:
- Automatic welding machines
- Manual welding machines
- Digital ultrasonic generators
- Ultrasonic cutting
Frequently asked questions (FAQ)
Which thermoplastics weld best with ultrasonics in battery packs?
Polypropylene (PP), polyethylene (PE-HD and PE-LD), ABS, polycarbonate (PC), nylon (PA), often in filled versions.
Is it possible to weld components with irregular shapes or complex geometries?
Yes. Sonomax realises customised sonotrodes based on the geometry of the part and offers CAD/CAM support to validate the feasibility of the joint.
What is the average ROI in adopting ultrasonic welding compared to traditional methods?
The investment in an ultrasonic welding machine pays for itself within a few months thanks to reduction of cycle times, absence of consumables e minimum maintenance.
Are the machines adaptable to modular or constantly changing production?
Yes. Our machines support memorable recipes, rapid format changes and are suitable for flexible contexts or small lots.
Is it possible to guarantee the traceability of each individual weld?
Absolutely. Sonomax machines allow the key parameters of each cycle to be recorded and exported.
What tests are recommended to validate the integrity of welds on battery cases?
Evidence of pressure seal, thermal cyclic testing, tensile test on joint, IP testing are common practice in the industry.
For technical assistance, customised requests or practical demonstrations, please visit the Contact Us section or request a trial at our application laboratory.