High mechanical stability, minimal heat affected zones and smooth surfaces
Brazing is a joining process whereby a filler metal or alloy is heated to melting temperatures above 450°C and distributed between two or more close-fitting parts, without actually melting the base material. The laser is used to heat up the wire material, which will then flow in between the two closely fitted joining materials. In contrast to welding, the joint materials are held together due to wetting by the molten wire (filler) material. Therefore, the joint materials do not necessarily need to be of the same material. Brazing also allows joining of dissimilar materials with considerable strength. For laser brazing applications diode lasers with higher output powers are required.
Applications for brazing are mainly found in the automotive industry, where the filler material is used to bridge the gap between two parts. During the brazing process the corrosion protection stays intact. Often, the filler material is galvanized afterwards together with the joined materials.
The brazing process produces especially smooth surfaces and therefore is often used in the outer car skin areas, when the joints have to be invisible to the eye. This is often the case in areas such as tailgates, roof joints and C columns. Besides the requirement for a high degree of mechanical stability, these seams must also have minimal heat affected zone.
The diode laser can achieve large spot sizes as well as line foci very easily which is essential for applications like brazing. The homogeneous beam profile with a “top-hat” energy distribution leads to a particularly calm melt pool, and thus results in a very stable brazing process.
Using the laser as heat source in the brazing process allows achieving high precision as well as low part distortion.
Benefits for laser brazing in comparison to common heat sources such as soldering iron tip, soldering burners, hot air or steam, thermal radiation or induction:
- Non plasma process
- High process speed
- Processing of brass and zinc coated steel
- Significant reduction of splatters
- Corrosion protection (e.g. zinc coating) stays intact
- Smooth surfaces and joints that are nearly invisible to the eye
- Lower heat input
- Low part distortion
- Because of the high quality of the laser joints, laser brazing is often used in the outer skin area for body-in-white applications within the automotive industry.
- For this application we recommend: High-power diode laser