Welding and brazing are two of the most common metal-joining processes used in the manufacturing industry. When fasteners aren’t viable, manufacturers often use one of these techniques to join two metal surfaces together. But while brazing and welding both allow for the permanent joining of two metal surfaces, they work in different ways. Below is a comparison of brazing and welding, revealing how these common metal-joining processes vary.
The Basics of Welding
By definition, welding is a fabrication process that uses high heat — usually thousands of degrees Fahrenheit — to join two metal surfaces. When exposed to enough heat, metal will melt, and this is the basis on which welding works. An arc- or oxy-fuel welding tool is used to heat the two metal surfaces until they melt. Once melted, the two surfaces will mix together and harden after they’ve cooled.
The Basics of Brazing
Brazing differs from welding by using a lower temperature. The American Welding Society (AWS) states that brazing occurs above 840 degrees Fahrenheit, which is often several times lower than the temperature at which welding is performed. How does this lower temperature affect the joining of two metal surfaces exactly? With brazing, the metal surfaces don’t melt. Instead, brazing joins the two surfaces by establishing a metallurgical bond using a filler metal. To perform brazing, manufacturers add filler metal in a joint between the two metal surfaces to be joined. Next, a tool is used to heat the surfaces just enough to activate the filler metal and trigger a metallurgical bond.
Which Metal-Joining Process Works Best?
You may assume that, because brazing uses lower temperatures than welding, it’s less effective at joining metal surfaces. Most times, however, it’s just as effective if not more effective. Even though the metal surfaces are never melted, the metallurgical bond created through brazing allows for a strong and secure joint. And since it uses lower temperatures, it’s typically safer to perform than welding.
Furthermore, the metal surfaces joined with brazing are able to retain their original properties. When metal is welded, its physical properties change due to melting. Brazing doesn’t melt metal surfaces, though, so this isn’t an issue. The metal surfaces joined with brazing will have their same physical properties as before.
Brazing even allows for a cleaner and more finished-looking product. There’s only a single strip of filler metal used in brazing, whereas welding melts both metal surfaces to create a messy, unsightly appearance.