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furnace brazing

Differences Between Soldering & Furnace Brazing

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What’s the Difference Between Soldering and Furnace Brazing?

Furnace brazing joins metals by melting a filler metal developing a metallurgical bond between substrates. This process works well in mass production applications because it produces strong joins without requiring a high degree of precision. It is also very flexible.

The metallurgical bond developed between substrates has a tensile strength higher than the substrates.  The metallurgical bond developed between substrates has a tensile strength higher than either substrate being joined together.  This strong bond allows for higher current carrying capacity applications.

Furnace brazing operates with different types of furnaces:

  • Controlled atmosphere furnaces
  • Continuous or mesh belt furnaces

Norstan specializes in furnace brazing, which we believe achieves the strongest welds in the most cost-effective manner.

Soldering vs. Furnace Brazing

Furnace brazing operates similarly to soldering. Both joining types use filler metals to create the metallurgical bond between workpieces together, which allows for increased versatility and ease of use. However, a few key differences distinguish these techniques from each other.

 

Each technique uses different filler material. Soldering typically operates at much lower temperatures than brazing, using fillers that melt at or below 840°F (450°C). Therefore, soldering primarily works with gold, silver, copper, brass, iron, and other soft metals.

 

Because they possess lower melting points, soldered metals’ bonds aren’t as strong as those of as brazed or welded metals. Therefore, soldering is great for creating precision welds in applications with sensitive environments, such as electronics or medical devices. But furnace brazing creates durable welds at higher production volumes and with stronger metals.

Furnace Brazing Creates Stronger Welds

The American Welding Society (AWS) defines furnace brazing as welding that operates with filler metals with melting points higher than 842°F (450°C). Brazing also requires the use of a protective atmosphere to reduce the risk of impurities negatively affecting the bond.

Furnace brazing can take place in either flux or vacuum environments, and it develops stronger bonds than soldering. Brazed joints have shear strength five times as strong as that of soldered joints.

Brazing also allows for the use of a wide variety of filler metals, such as:

  • Aluminum-silicon alloy
  • Copper
  • Copper alloys with silver, zinc, and tin
  • Gold alloys
  • Silver
  • Silver alloys
  • Nickel alloys
  • Amorphous brazing foil

Welders often prize brazing specifically for its efficiency and reliability. Because it operates in environments with no airborne particles or contamination, brazing creates extremely clean welds and prevents impurities from affecting the metals.

Additionally, brazing mitigates many of the difficulties of working with flux, such as corrosion, excess porosity, crack formation, weld deformation, slag inclusions, irregular wire feed, and high levels of smoke and fumes. Flux-free braze joints tend to feature increased strength and integrity.  

Furnace Brazing at Norstan

Ultimately, choosing between brazing and soldering depends on what metals you want to join, where they’re located, and whether you want to work with flux. Some systems, like HVAC systems, rely on smooth, clean welds, rendering excess flux residue problematic.

With a 100% satisfaction guarantee and an innovative, knowledgeable, and responsive team, Norstan can help you make the right call for your situation. Reach out to us today to request a free quote, and let’s help you ace your next welding project.


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