Laser welding is usually done without filler metals so parts need to have good fit with a gap that's less than 15% of the thickness of the thinnest component. Parts should be relatively clean since welding is very fast with no time to burn-out contaminants. Shield gas is required for more reactive metals but many alloys can be welded in air.
Weld heat input and weld shape can be controlled with laser parameters and optics to generate conduction-mode, penetration-mode and keyhole welds. Conduction-mode welds are rather shallow penetration and wide welds, similar to a GTAW or TIG weld shape.
Penetration-mode welds have a weld penetration that is equal to, or slightly deeper than, the weld width. When using penetration-mode laser welding the heat input is reduced due to the lower melt volume, thus creating deep penetration low heat input welding from even low average power lasers.
Laser welding offers numerous advantages over tradition welding techniques such as resistance spot and arc welding.
- Minimum heat input, resulting in minimal distortion of the component;
- Consistent, repeatable welds;
- Small heat affected zone (HAZ);
- Narrow weld bead with good cosmetic appearance;
- High strength welds;
- Easily automated;
- High degree of accuracy and control;
- Ability to weld dissimilar materials;
- Generally no flus or filler material required;
- Flexibility of beam manipulation, including fiber-optic delivery;
- Ability to weld in areas difficult to reach with other techniques;
- Often faster than other techniques with greater throughput;
- Versatile (the same tool can be used for laser cutting and drilling).