Power battery tab ultrasonic welding is the process of joining the multi-layer metal foils of a cell's positive and negative electrodes to tab leads using ultrasonic metal welding; the ultrasonic power battery welder is equipment designed specifically for tabs, busbars and similar battery components, and the tab welder is the most common type.
1. What makes tab welding difficult
Tabs typically stack a dozen to dozens of metal foils, each very thin. Too little energy leaves inner layers unwelded (weak welds); too much burns through or cuts the foils. Copper and aluminum foils differ in thermal conductivity and hardness, so one parameter set never fits both — this is where tab welding tests process skill most.
2. Horn and anvil selection
The knurl pattern on the horn face directly affects energy transfer: teeth that are too sharp cut the foil, teeth that are too dull don't generate enough friction. Thinner foils and higher layer counts demand a better-matched pattern. Anvil support matters equally — poor support lets foils shift under vibration and produces weak welds.
3. Matching pressure, energy and amplitude
The three work together: pressure ensures contact, amplitude sets friction intensity, energy (time) determines penetration. A practical approach is to fix two and fine-tune the third, converging on the best process window step by step. Copper tabs generally need more energy than aluminum; nickel-plated composite tabs should be set for the hardest-to-weld layer.
4. Common defects and fixes
Weak welds: usually insufficient energy or low pressure — increase weld energy appropriately and check that horn and anvil are parallel and unworn.
Burn-through or cut foil: excessive energy or overly sharp knurl — reduce energy, inspect the horn, and switch to a better-matched knurl pattern if needed.
Splayed foils: inadequate anvil support or side restraint — improve fixture clamping and retry.
5. Tab welder selection advice
Choose power by total stacked tab thickness, with some margin; high-volume lines can consider multi-station machines with automatic feeding; for strict consistency requirements, pick models with weld quality monitoring. Always verify with trials on your actual tab samples before selecting — never order on catalog specs alone.
6. In-production process control
Tab welding is a volume process — in-production control matters as much as the initial trial: verify pull force and appearance on first articles each shift; inspect horn knurl wear regularly, since worn horns are the most common root cause of weak welds; re-confirm parameters when foil coils or batches change; keep weld parameter records for traceability when batch anomalies occur. These details determine yield stability.
If you are selecting a tab welder for a power battery line, contact us for guidance. Jingjin offers tab weld trials to help confirm your process window and machine choice.