66 Soldering vs Brazing Cast Aluminum
Cast aluminum is a durable, strong alloy created by melting together a minimum of 50% aluminum with other metals such as tin and steel. The resulting alloy is then poured into molds and cast into parts such as cookware, patio furniture, and automobile parts like exhaust manifolds and transmission cases.
While both Super Alloy 1 and Super Alloy 5 can be used to repair pure aluminum, only Super Alloy 5 is specially formulated to bond with cast aluminum. (oxyacetylene torch required for cast aluminum brazing)
So what’s the difference between soldering and brazing? Essentially they are very similar: both join metals by bonding to the parent metal at a molecular level. However, soldering can be broken into soft soldering and hard soldering based on the composition and melting temperature of the alloy, and brazing is performed at a higher temperature with a stronger bonding rate than soft solder. Super Alloy 1 would be considered a soft solder, Super Alloy 5 would be considered a brazing alloy (which can also be used to weld with a TIG machine) and SSF-6 would be considered a hard solder. A good rule of thumb is the higher the melting temperature, the stronger the bond.
In addition to choosing the right alloy rod for your application, it’s important to choose the correct diameter. Super Alloy 1 is available in 1/8″ and 3/32″ diameter, Super Alloy 5 is available in 1/16″ and 3/32″ diameter. 1/16″ is the smallest diameter rod, 3/32″ is the medium diameter rod, and 1/8″ is the thickest diameter rod. The thinner or smaller the parent metal, the smaller the rod you should utilize to avoid overheating the parent metal. For thicker parent metal, it’s important to choose a larger diameter rod to avoid burning through large quantities of alloy.
Brazing cast aluminum parts successfully is dependent on choosing the correct torch and the correct diameter: Super Alloy 5 3/32 diameter and an oxygen fueled torch is our recommendation for this application.