Laser brazing is a joining method whereby the laser is used to melt a metal filler material, which “wets” the parts to be joined along the seam. The wetting process is facilitated by a flux that removes surface oxides and enables a metallurgical bond between the filler alloy and the parts. Typically, the melting temperature of the filler alloy is considerably lower than the melting temperature of the materials to be joined. Compared to laser welding, the brazing process has better gap bridging capabilities due to the use of the filler metal and less effort is needed to maintain tight part tolerance and fit-ups with minimum gap. Furthermore, the lower heat input minimizes part distortion.
Laser brazed joints have smooth surfaces and minimal heat affected zones. These advantages are significant when meeting demanding visual finish requirements. For example, laser brazing is increasingly used for critical body-in-white assembly applications. Diode laser brazing is also a quality-assured process because the key process variables are measurable, predictable, controllable and repeatable.
Diode lasers offer a clear advantage over other solid state lasers because of their lower investment costs, high efficiency and reliable operation. They are also nearly maintenance-free and have a long service life presenting a good case even for the replacement of older, existing equipment such as Nd:YAG lasers.