Laser power, welding speed, focal position and weld geometry decide whether a battery welding process is stable. Here is what each parameter does — and how to verify it in production.
Laser welding is taking on an increasingly important role in modern industry, and several trends are converging to push it there.
On the commercial side, growing demand generates supply: new manufacturers enter the market, competition intensifies, and equipment becomes progressively more accessible to acquire and commission.
On the technical side, advances in beam quality — dual-beam infrared lasers, green lasers, blue lasers — are opening application areas previously closed: welding of very thin materials, and materials considered difficult or impossible to join by conventional methods. These lasers are gaining ground quickly in battery manufacturing, where materials with very different properties are joined at thicknesses of 250–300 µm — copper, aluminium and stainless steel.
A handful of fundamental parameters have a decisive impact on the stability of the production process:
Alongside these, a second group of factors is equally critical: material cleanliness, accurate targeting of the weld location, zero gap between the joined materials, and precise determination of the distance between the joint and the welding head optics.
Every laser source has its own accuracy characteristics, which can create discrepancies between programmed and delivered output. Laser power should therefore be measured both before a process is set up and periodically throughout production, using a simple industrial power meter that converts the heat of a short pulse into a power value. Periodic checks also confirm that no contamination has appeared in the beam's optical path.
In battery welding, 2D, 2.5D and 3D scanners built around galvanometer drives are the most common solution, chosen for the precision and speed these processes demand. They offer exceptional velocity stability and geometry reproduction, and do not require additional monitoring.
The last key parameter — the position of the laser beam focal point — actually covers two distinct problems.
The first is measuring the workpiece's physical distance from the welding head: relatively straightforward, given tools accurate enough for the required precision and repeatability.
The second is determining the actual distance from the welding head to the laser beam focal point — locating the point along the beam axis where the diameter reaches its minimum. This is considerably more complex, and it is where most of the difficulty in setting up a battery welding process is concentrated.
That second problem is the subject of the next article in this series.
Based on the technical article "RMA FocusFinder — A Reliable Method for Determining the Focal Point of a Single-Mode Laser" by Rajmund Pobereżny, Project Manager, RMA.
Send us the basics — laser type, material, thickness — and our engineering team will get back to you directly.
Thank you — our engineering team will be in touch shortly.