Considering Laser Welding? 5 Key Evaluation Points You Must Test

1

Choice of Laser Type
Different materials absorb laser wavelengths differently. For example, steel has low absorption for CO₂ lasers (10600 nm) but significantly higher for fiber lasers (1064 nm), so fiber lasers are recommended for welding steel. Similarly, for soldering tin or plastics, diode lasers with wavelengths of 808 or 915 nm are preferred; for glass, CO₂ lasers are used. Most welding lasers on the market are fiber lasers due to their mature technology and flexibility. CO₂ laser welding systems are gradually being phased out.
2

Joint Type and Seam Gap
This involves the placement of workpieces, welding angles, and weld path design. Common joint types such as butt, lap, and corner joints are all applicable to laser welding (as shown below). Since the laser beam is very small (usually under 1 mm), the gap size directly affects weld quality. For butt joints, the allowable gap is typically less than half of the beam diameter to ensure proper melting of both sides. If filler material is used, slightly larger gaps can be accommodated. The laser spot size is another key factor — larger spots allow wider gaps but reduce penetration depth. In lap joints, the laser must penetrate both plates; weld depth should reach 20–50% of the bottom plate thickness to ensure strength. Gaps between the plates reduce joint strength and may require higher laser power.

▲ Joint types used in laser welding
3

Thickness of Plates or Workpieces
Thicker plates require higher laser power. You must also consider beam focus size, beam quality, and material absorption. For example, a 2 mm thick 316 stainless steel plate can be fully welded with 1 kW laser power. For 4 mm thickness or 2 mm lap joints, 1.5 kW is needed. A 16 mm steel plate may need 15 kW, as shown below. Highly reflective materials like aluminum and copper also require higher power for effective welding.

▲ 16 mm thick plate laser welding. Source: ewi.org
4
Laser Mode

Continuous or Pulsed Mode
Continuous lasers emit a steady beam, while pulsed lasers emit energy in bursts. Continuous mode provides consistent energy input, deeper penetration, and is ideal for thick materials or general metal welding where precision is less critical. Pulsed lasers offer high peak power with low total heat input, ideal for thin sheets (<1 mm), reflective materials (aluminum, copper), or fine parts like battery electrodes.
▲ Differences between continuous and pulsed laser welding
5
Laser Spot Pattern

Wobble Mode for More Flexibility
Wobble welding moves the laser beam in circular, C-shaped, or lateral motions to cover a wider weld area. Compared to linear welding, wobble mode spreads energy across a larger zone, resulting in shallower penetration. However, adjusting the wobble width allows bridging larger gaps and reduces pore formation in the weld seam.

▲ Different wobble spot welding forms. Source: Guang-Yao Huang et al., Laser Wobble Welding Development and Application Trends, Laser Valley Promotion Network

▲ Comparison of weld seams: wobble vs linear mode

Choice of Laser Type

Joint Type and Seam Gap

Thickness of Plates or Workpieces

Laser Mode

Continuous or Pulsed Mode

Laser Spot Pattern

Wobble Mode for More Flexibility