Sep 15, 2026
How to Prevent Burn-Through in Handheld Laser Welding？
Burn-through is a common challenge when welding thin metal. Learn simple ways to control heat input and achieve a stable, clean weld.
Burn-through happens when the laser puts too much energy into the material, causing the molten pool to become unstable or penetrate completely through the sheet. It is especially common when welding thin metal.
1. What Does Burn-Through Look Like?
Typical signs include:
- A hole appears in the sheet
- The back side has excessive penetration
- The molten pool suddenly becomes larger
- The weld becomes difficult to control
If the problem appears only in some sections, check whether the material thickness or joint gap changes.
2. Check Welding Speed
Moving too slowly keeps the laser on one area for longer and increases heat input.
Try: Increase the welding speed slightly and make a short test weld.
If the hole disappears while the weld remains properly fused, the previous speed was likely too slow.
3. Check Laser Power
For thin sheet, excessive power can quickly create a deep and unstable molten pool.
Try: Reduce the power gradually rather than making a large adjustment at once.
The goal is to use enough energy for proper fusion without overheating the material.
4. Watch the Joint Gap
A larger gap means there is less material available to absorb the laser energy.
This can make burn-through more likely, especially on thin sheets.
Check: Keep the joint gap as consistent and as small as the application allows.
Quick Troubleshooting
Hole appears → Check material thickness and gap → Check welding speed → Adjust power slightly → Test again
Avoid changing several parameters at the same time.
Burn-through is mainly about controlling heat input.
For thin metal, use stable movement, suitable power, and consistent joint fit-up to keep the molten pool under control.
