Explore our frequently asked questions about brazing and its applications. For any additional enquiries, please don’t hesitate to reach out to us at sales@solprobrazing.co.uk. We are here to assist you!
1) General
What is brazing?
Brazing is a metal-joining process that uses a filler metal (braze alloy) melted above 450°C (842°F) but below the melting point of the base metals, allowing it to flow into the joint by capillary action.
How is brazing different from welding?
In brazing, the base metals do not melt—only the filler does. In welding, both the base metal and filler (if used) melt and fuse.
What is the difference between brazing and soldering?
Both processes are similar, but soldering is done below 450°C, while brazing occurs above 450 °C and generally produces stronger joints.
What are the advantages of brazing?
- Joins dissimilar metals
- Strong, leak-tight joints
- Minimal thermal distortion
- Good for complex assemblies
- No melting of base materials
Are brazed joints strong?
Yes. Properly brazed joints can be as strong as or stronger than the base materials, depending on joint design and filler alloy.
2) Materials & Equipment
What metals can be brazed with our products?
Commonly brazed metals include:
- Steel, stainless steel
- Copper and brass
- Aluminium
- Tungsten carbide
What filler materials are used in brazing?
Common alloys include:
- Silver-based (high strength, low temperature) typically between 20% & 70% Silver content
- Copper-phosphorus (for copper components) typically between 0% & 18% Silver content
What are the different methods of brazing our products?
Torch Brazing
- A gas flame (usually oxy-acetylene, air-acetylene, or propane-air) is used to heat the joint area directly.
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Types:
- Manual torch brazing: Operator controls the flame and applies filler metal manually.
- Machine torch brazing: Semi-automated, used for repetitive work.
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Advantages:
- Simple, low-cost setup.
Furnace Brazing
- Workpieces and filler metal are placed in a controlled atmosphere or vacuum furnace and heated together, typically using rings or preforms
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Types:
- Atmosphere furnace brazing (uses inert or reducing gases like hydrogen or nitrogen)
- Vacuum brazing (no flux needed; produces very clean joints).
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Advantages:
- Excellent control of temperature and cleanliness.
- Can braze multiple parts simultaneously, ideal for mass production
Induction Brazing
- Normally with a coil for electromagnetic induction to heat the joint area rapidly and locally.
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Advantages:
- Fast, clean, and easily automated.
- Ideal for localized heating without affecting the rest of the assembly.
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Applications:
- Electrical connectors, carbide tool tips, automotive parts.
What are the common forms of brazing alloys?
Rods
- Most widely used form
- Ideal for manual torch brazing
- Available in flux-coated and bare varieties
Wires
- Used in automatic or semi-automatic brazing
- Supplied on spools or coils for continuous feeding
- Common in induction and furnace brazing
Strips / Foils / Shim
- Thin, flat material placed directly in the joint
- Provides consistent alloy volume and uniform gaps
- Ideal for furnace brazing and large surface joints
Rings
- Pre-formed to fit around tube, pipe, or round joints
- Ensures precise alloy placement and repeatability
- Widely used in HVAC, refrigeration, and automotive components
Preforms
- Custom shapes (washers, discs, frames, profiles)
- Designed for exact joint geometry
- Minimizes waste and improves consistency in mass production
Why is flux used in brazing?
Flux removes oxide layers, prevents oxidation during heating, and helps filler metal flow properly for a clean bond.
Can brazing be done without flux?
Yes, in controlled atmospheres such as vacuum or inert gas environments, or when using some self-fluxing filler metals such as copper-phosphorus on copper.
What are the advantages of using a Flux Coated Rod?
- The flux coating eliminates the need to apply additional flux manually, simplifying the process and reducing preparation time.
- With flux built into the rod, operators experience smoother workflow, fewer steps, and less mess compared to using paste or powdered flux.
- The integrated flux promotes excellent capillary action, helping the molten silver filler spread evenly and penetrate tight joints for strong bonding.
- The flux coating shields the joint from oxidation during heating, resulting in cleaner joints and reducing the risk of contamination or weak bonds.
3) Processes & Techniques
Why is joint clearance important in brazing?
Because brazing relies on capillary action, the gap must be small and uniform (typically 0.02–0.2 mm) to allow proper filler flow.
What are the defects to be aware of in the brazing process?
- Poor wetting
- Voids or gaps
- Cracking
- Overheating / base metal erosion
- Oxidation or contamination
4) Applications
What industries commonly use brazing?
- HVAC & refrigeration
- Automotive and aerospace
- Electronics and electrical systems
- Plumbing
- Medical devices
- Tool manufacturing
What are typical real-world applications?
- Heat exchangers and radiators
- AC and refrigeration tubing
- Fuel and brake lines
- Electrical connectors
- Cutting tool tips (carbide brazing)
Can brazing be used for pressure systems?
Yes, brazed joints are commonly used in high-pressure applications such as refrigeration compressors, hydraulic lines, and gas systems when performed to standards.
Is brazing suitable for dissimilar metals?
Yes, one of brazing’s biggest advantages is joining different metals (e.g., copper to steel, carbide to steel, aluminium to copper with proper alloys).
5) Quality & Safety
How can brazed joint quality be tested?
Common tests include:
- Visual inspection
- Leak testing
- X-ray or ultrasonic testing
- Tensile and shear strength testing
What safety precautions are important in brazing?
- Adequate ventilation
- Protective eyewear and gloves
- Fire safety measures
- Correct handling of gas cylinders and hot materials