Vacuum Brazing Services
Vacuum Brazing Services for Strong, Clean, and Leak-Free Joints
Expert Vacuum Brazing Solutions
At Solar Atmospheres, we specialize in fluxless vacuum brazing services that join metals while keeping assemblies bright and clean. Unlike traditional soldering or welding, our vacuum brazing process allows even complex shapes to be brazed with minimal distortion. This method is ideal for both ferrous and non-ferrous metals, including:
- Stainless steel brazing
- Carbon steel brazing
- Copper brazing
- Nickel alloy brazing
- Tantalum brazing
- Titanium brazing
- Molybdenum brazing
Filler Metals for Vacuum Brazing
- Nickel Alloys
- Silver Alloys
- Titanium Alloys
- Pure Metals
- Copper Alloys
- Gold Alloys
- Other Precious Metals
- Active Metals
What is Vacuum Brazing?
Vacuum brazing is a metal-joining process that uses heat and a filler metal with a melting temperature above 840°F (450°C) but below the melting point of the base metals. The filler metal is distributed between close-fitting parts by capillary action. When cooled, it forms exceptionally strong, sealed joints due to grain structure interaction. The result is a metallurgical bond where the brazed joint becomes a sandwich of different layers, each linked at the grain level.
Why Choose Vacuum Brazing?
Unmatched Versatility in Metal Joining
- Exceptional Strength: Properly made brazed joints often exceed the tensile strength of the metals joined. For stainless steel, tensile strengths can reach up to 130,000 psi.
- High Ductility: Brazed joints can withstand considerable shock and vibration without failure.
- Ease and Efficiency: The brazing process is quick and requires minimal operator skill, making it highly efficient.
- Join Dissimilar Metals: Easily join ferrous and non-ferrous metals, even those with widely varying melting points.
- One-Step Process: Typically requires no additional grinding, filing, or finishing after the joint is completed.
- Low Distortion Risk: Performed at lower temperatures than welding, reducing the chances of warping or melting base metals.
- Cost-Effective: Offers a favorable cost-per-joint compared to other metal joining methods.
Industries We Serve
Our vacuum brazing services are trusted by various industries, including aerospace, defense, medical, and energy sectors. We adhere to strict quality standards to ensure reliable and durable joints for all applications.
Get Started with Solar Atmospheres
Ready to solve your metal joining challenges with our advanced vacuum brazing services? Contact Solar Atmospheres today to discuss your project requirements and discover how we can deliver strong, clean, and leak-free joints for your assemblies.
Vacuum Brazing Unique Capabilities at Solar Atmospheres
- State of the art vacuum furnaces from lab-sized to 48 feet long and 150,000 pound load capacity
- Pressure differential brazing (up to 6 bar)
- Prototype brazing
- Partial pressure: hydrogen, argon, nitrogen
- Testing services: flow, helium leak, ultrasonic
- Fixture and jig design services
- Vacuum levels 1 x 10-6 torr
- On-site Metallurgical Test Lab
- Metallurgical R & D Team
- Conformance to AMS, AWS and MIL Specifications
- Nadcap approved for brazing
Applications for Vacuum Brazing
- Assemblies for food and drug production
- Aircraft parts and equipment
- Pressure vessels
- Tube and block assemblies
- Heat exchangers
- Structural components
- Exhaust ducts
- Medical and dental tools
- Excavation and drilling components
- Cutting tools
- Honeycomb
Ask the Expert:
Solar Atmospheres Director of Sales Answers Questions About Vacuum Brazing
FAQs
Yes. Vacuum brazing is an excellent method for joining 304 stainless steel to copper. Depending on the application, gold-, silver-, or nickel-based brazing filler metals (BFMs) may be used to create a strong, reliable joint.
Because copper and stainless steel expand at different rates during heating, joint design is critical. An experienced vacuum brazing supplier can recommend the appropriate joint clearance, filler metal, and process parameters to ensure a high-quality brazed assembly with minimal distortion.
Yes. Multi-stage vacuum brazing is commonly used for complex, high-value assemblies that require multiple joining operations.
To successfully complete multiple brazing cycles, the brazing sequence, filler metal selection, and processing temperatures must be carefully planned so previously completed joints do not remelt during subsequent cycles. In many cases, progressively lower-temperature filler metals are used, while some brazing alloys become diffusion-stabilized and can withstand additional thermal cycles.
Multi-stage vacuum brazing is widely used in aerospace, medical, and other precision manufacturing applications.
Yes. Properly designed and manufactured vacuum brazed joints can perform reliably in extremely low-temperature environments, including cryogenic service approaching 4 Kelvin (-452°F / -269°C).
Gold- and silver-based brazing alloys are commonly selected for cryogenic applications because they maintain excellent joint integrity and mechanical performance at extremely low temperatures. Joint design, base material selection, and filler metal compatibility remain important considerations.
For critical brazed assemblies, the American Welding Society (AWS) publishes several industry-recognized standards that provide guidance for joint design, manufacturing, inspection, and qualification.
One of the primary design references is AWS C3.3 – Recommended Practices for Design, Manufacture, and Examination of Critical Brazed Components, along with the brazement design guidance contained in the AWS Brazing Handbook. These resources help engineers develop brazed joints that are both manufacturable and reliable.
The primary specification for vacuum furnace brazing is AWS C3.6M/C3.6 – Specification for Furnace Brazing.
This specification establishes requirements for furnace brazing procedures and defines three joint classifications:
- Class A – Critical service applications requiring the highest quality standards
- Class B – Intermediate service applications
- Class C – General service applications
Engineers should clearly specify the required joint classification on engineering drawings. If no classification is identified, Class A requirements typically apply by default.
For brazing filler metals, AWS A5.8 – Specification for Filler Metals for Brazing and Braze Welding provides alloy classifications, chemical compositions, and recommended brazing temperature ranges.
Yes. AWS B2.2/B2.2M – Specification for Brazing Procedure and Performance Qualification provides requirements for qualifying both brazing procedures and brazing personnel.
These standards establish documentation, testing, and qualification requirements that help ensure consistent, repeatable, and high-quality brazed joints for critical applications.
No. AWS C3.6 recognizes AMS2750 and other accepted pyrometry standards for furnace temperature uniformity, instrumentation, and calibration. Facilities that maintain AMS2750-compliant furnace controls can satisfy the temperature control requirements necessary for high-quality vacuum brazing.
Vacuum brazing is suitable for joining a wide variety of engineering materials, including:
- Stainless steels
- Titanium and titanium alloys
- Nickel-based superalloys
- Copper and copper alloys
- Cobalt alloys
- Refractory metals
- Tool steels
- Dissimilar metal combinations
Material compatibility and filler metal selection should always be evaluated based on the intended service conditions.
Vacuum brazing offers numerous benefits compared to conventional brazing methods, including:
- Bright, clean, flux-free joints
- Excellent joint strength and reliability
- Minimal oxidation and contamination
- Superior cosmetic appearance
- Ability to join complex or dissimilar materials
- Uniform heating with minimal distortion
- Ideal for aerospace, medical, defense, and high-performance industrial applications
Solar Atmospheres combines decades of vacuum brazing experience with advanced vacuum furnace technology and metallurgical expertise to support everything from prototype development to high-volume production. Our engineering team works closely with customers to optimize joint design, filler metal selection, and processing parameters, delivering repeatable, high-quality brazed assemblies for the world’s most demanding industries.
The importance of correct procedures
Brazing, as we’ve seen, uses the principle of capillary action to distribute the molten filler metal between the surfaces of the base metals. Therefore, during the brazing operation, you should take care to maintain a clearance between the base metals to allow capillary action to work most effectively. This means, in almost all cases – a close clearance. The following chart is a general guide.
If the gap is wider than necessary, the strength of the joint will be reduced almost to that of the filler metal itself. Also, capillary action is reduced, so the filler metal may fail to fill the joint completely – again lowering joint strength.
Remember, brazed joints are made at brazing temperatures, not at room temperature. So you must take into account the “coefficient of thermal expansion” of the metals being joined. This is particularly true when dissimilar metals are being joined.
| BAISi Group | 0.000-0.002 Vacuum Furnace Brazing |
| BAg Group | 0.000-0.002 Vacuum Furnace Brazing |
| BAu Group | 0.000-0.002 Vacuum Furnace Brazing |
| BCu Group | 0.000-0.002 Vacuum Furnace Brazing |
| BNi Group | 0.000-0.002 Vacuum Furnace Brazing |
The importance of cleaning metal surfaces
One of the important steps is to ensure metals are clean from any impurities. Since Capillary action is needed when fitting parts, metal surfaces face difficulty during this fitting process if they are contaminated. For example, if they are coated with oil, grease, rust, scale or just plain dirt, those contaminants will form a barrier between the base metal surfaces and the brazing materials.
Cleaning the metal parts is seldom a complicated job, but it has to be done in the right sequence. Oil and grease should be removed first, because an acid pickle solution aimed to remove rust and scale won’t work on a greasy surface. (If you try to remove rust or scale by abrasive cleaning, before getting rid of the oil, you’ll wind up scrubbing the oil, as well as fine abrasive powder, more deeply into the surface).
Perfect positioning for brazing
The parts of the assembly are cleaned. Now you have to hold them in position for brazing. And you want to be sure they remain in correct alignment during the heating and cooling cycles, so that capillary action can do its job.
If the shape and weight of the parts permit, the simplest way to hold them together is by gravity. Or you can give gravity a helping hand by adding additional weight.
If you have a number of assemblies to braze and their configuration is too complex for self-support or clamping, use a brazing support fixture. In planning such a fixture, design it for the least possible mass, and the least contact with the parts of the assembly. Use pin-point and knife-edge design to reduce contact to the minimum.
Try to use materials in your fixture that are poor heat conductors, such as stainless steel, Inconel or ceramics. Since these are poor conductors, they draw the least heat away from the joint. Choose materials with compatible expansion rates so you won’t get alterations in assembly alignment during the heating cycle. However, if you’re planning to braze hundreds of identical assemblies, then you should think in terms of designing the parts themselves for self-support during the brazing process.
At the initial planning stage, design mechanical devices that will accomplish this purpose, and that can be incorporated in the fabricating operation. Typical devices include crimping, tacking, interlocking seams, swaging, peening, riveting, pinning, dimpling or knurling. Sharp corners should be minimized in these mechanically held assemblies, as such corners can impede capillary action. Corners should be slightly rounded to aid the flow of filler metal.
Perfect Positioning for Brazing
This is the actual accomplishment of the brazing joint. It involves heating the assembly to brazing temperature, and flowing the filler metal through the joint.