While many people use “welding” and “fabricating” interchangeably, others confuse “welding” and “brazing”. However, neither is quite the case.
Both are individual metal-joining sheet metal techniques within the overall sheet metal fabrication process, but each operation differs slightly. In short, welding is a technique that joins metals by melting the base metal and causing fusion, while brazing joins metals by melting and flowing a filler metal into the joint.
The Big Difference
In brazing and welding, fabricators add a filler metal into the joint. The filler metal can be aluminum-silicon, brass, bronze, copper, copper-silver, gold-silver, nickel alloy, or silver.
However, the major differences are the following:
- In brazing, the filler metal has a lower melting point than the adjoining metal. In welding, the filler metal has a higher melting point, like soldering.
- In brazing, fabricators don’t melt the base metal. In welding, fabricators melt the base metal and each workpiece together.
- Brazing uses capillary action, and welding uses fusion.
In the welding process, fusion is caused. Fusion is the generic fabrication term for joining together metals of similar compositions and melting points. A pool of molten material called the weld pool is formed due to the high melting points of the workpieces.
This pool cools to form a joint that’s stronger than the base metal, and pressure in the form of heat might be used to assist in weld production.
Welding also requires a form of shield to protect the filler metal from being contaminated or oxidized, which is the loss of electrons and causes iron oxide (better known as rust) to form on the metal.
In the brazing process, the filler metal flows into the joint between close-fitting parts by capillary action, which is the ability of a liquid to flow in narrow spaces without the assistance of or in opposition to external forces like gravity.
The filler metal is then brought slightly above its melting point while protected by a flux, a chemical cleaning and purifying agent. It then flows over the base metal (also known as wetting) and is subsequently cooled to join the work pieces together.
Welding and brazing are sheet metal techniques, but sub-techniques of each operation exist. Types of brazing include the following:
- Torch brazing
- Furnace brazing
- Silver brazing
- Braze welding
- Cast-iron welding
- Vacuum brazing
- Dip brazing
Types of welding include the following:
- Electric resistance welding
- Electroslag welding
- Flux-cored arc welding
- Gas metal arc welding
- Gas tungsten arc welding
- Glass welding
- Oxy-fuel welding
- Plastic welding
- Shielded metal arc welding
- Submerged arc welding
The Benefits Of Brazing
Welding is a more common sheet metal technique, but brazing shouldn’t be discounted as a reliable process.
The biggest benefit to brazing is that sheet metal fabricators can join together similar or different metals and still produce a strong joint. In welding, metals of similar temperatures and compositions must be used for a finished product, which does produce stronger joints.
Brazing also allows for tighter control, produces a cleaner joint than welding without the need for secondary finishing, and produces less thermal distortion than welding. In brazing, a uniform temperature is used, unlike welding which uses different temperatures.
Brazing is also easily adaptable for mass production. The sheet metal technique allows for easy automation because the project parameters are rarely varied.
You can also download our newest Welding Cheat Sheet if you’d rather focus on this specific technique: