ACCORDING to CAST CRC, Mig brazing is rising in popularity as an alternative to conventional welding processes.
While brazing is traditionally seen as an inferior alternative to welding, it is seeing a new-found respect due to the popularity of newer steels whose parent metal weaken when welded.
Brazing, like welding, is a joining technique. It was prized for its strength, durability and aesthetics, and can be carried out at lower temperatures than that needed for welding. The development of better welding techniques meant some applications moved away from brazing.
However, to save costs and weight, vehicle manufacturers have started using thinner grades of high strength steels. These advanced steels, with acronyms like AHSS, UHSS, DP, TRIP, and HSLA, are used in various structures of the vehicles.
However, the steels derive their advanced characteristics from heat treatment, meaning high-heat Mig welding could interfere drastically with the metal. Welding could also burn off the zinc coating on the steels, affecting joint strength and corrosion resistance.
Brazing, with its lower temperatures, avoids these problems and eliminates distortion and embrittlement. Additionally, the braze material forms strong metallurgical bonds with the parent metals, even if they are not the same grade or the same material.
Manufacturers are also using Mig equipment to apply the braze. Mig brazing uses similar if not identical power sources, controllers and torches to the welding process. Both automated and manual solutions are available.
Most automotive body repair shops, use copper-silicon alloy brazing wires which do not need a flux. Grooved wire feed rollers and a soft lining in the cable between the feeder and the torch enhance the brazing process, and pure argon is used as the shielding gas.
Brazing also differs from welding in its need for a small gap between the components being joined. The braze metal penetrates this gap with capillary action.
Add a comment