Controlled Atmosphere Oven Brazing FAQs

Controlled Atmosphere Oven Brazing (CAB) is a process that joins different metal components. It is ideal where strong, intricately designed components are required, such as in the automotive sector.

This FAQ guide will answer several questions about CAB. We cover everything, including how it differs from other joining techniques and the materials best suited for this process.

1. What Is Controlled Atmosphere Oven Brazing?

Controlled Atmosphere Oven Brazing is a metal-joining process that takes place in an oven filled with inert or reducing gases. The process allows for precise control of temperature and atmosphere, which prevents oxidation and ensures clean, strong joints between metal components.

In CAB, metals are joined using a filler material that melts at a lower temperature than the base materials. This creates a secure bond without melting the base metals themselves.

2. What’s the Difference Between Oven Brazing and Welding?

Both oven brazing and welding are metal-joining techniques. However, they differ significantly in how they achieve the joint.

Welding

Welding typically involves melting the base metals to fuse them together. It is generally used for low-complexity structural applications.

Brazing

Brazing uses a filler material that melts at a lower temperature than the base metals. In brazing, the base metals remain solid while only the filler melts. This allows for the joining of dissimilar metals, more precise temperature control, and less distortion of the parts.

Brazing offers superior versatility, making it ideal for applications where strength, minimal distortion, and aesthetics are priorities.

3. What Gases Are Used in Controlled Atmosphere Brazing?

• Nitrogen
• Hydrogen
• Oxygen-free blend of Nitrogen and Hydrogen

The gases used in CAB typically include nitrogen, hydrogen, or a mixture of both. Nitrogen is commonly used because it creates an inert atmosphere that prevents oxidation of the metal components.

Hydrogen, being a reducing gas, can also be used in certain cases to remove oxide layers and improve the quality of the braze. The specific gas mixture depends on the materials being brazed and the desired results.

4. What Is the Controlled Atmosphere Brazing Process?

The CAB process typically follows these steps:

• Prep and Assembly
• Brazing
• Heating
• Cooling

Preparation: The parts to be brazed are cleaned to remove oils, oxides, and other contaminants.

Assembly: The parts are assembled with the filler metal in place. Filler materials typically come in the form of pastes, foils, or preforms.

Brazing: The assembly is placed in a brazing oven. The temperature is precisely controlled, and the atmosphere is typically filled with a mix of oxygen-free gases—usually nitrogen and hydrogen.

Heating: The oven gradually heats up to the brazing temperature. This causes the filler metal to melt and flow into the joint.

Cooling: Once the brazing temperature is reached, the assembly is cooled down under controlled conditions. This solidifies the filler and completes the joint.

5. What Are the Advantages of Controlled Atmosphere Oven Brazing?

CAB offers several advantages over other joining techniques:

• Oxidation Prevention: By using inert or reducing gases, CAB eliminates oxidation. This ensures cleaner and more reliable joints.
• Consistent Results: The precise control of temperature and atmosphere ensures uniform heating and produces a consistent braze quality.
• Minimal Distortion: Since the base metals do not melt, there’s less risk of distortion or warping during the brazing process.
• Versatility: CAB can be used to join a wide variety of metals, including dissimilar metals. This is often not possible with traditional welding.
• Cost-Effectiveness: It allows for the mass production of complex assemblies. This reduces labor costs and improves efficiency. CAB uses fluxless brazing. This removes an extra cleaning step, reducing costs.

6. What Are the Best Materials or Alloys to Use in Oven Brazing?

The metal brazing choice depends on your specific requirements. Anything from stainless steel to brass, copper, aluminum alloys, and nickel alloys can be brazed together. Titanium, metals with a natural oxide coating, and alloys with very similar melting points are unsuitable for brazing.

There are several desirable characteristics that the brazing filler metal needs to have to make a strong and lasting bond:

• Base metal compatibility – The filler must be able to form a strong bond with the base metal.
• Melting point – the filler metal needs to have a lower melting point than the base metals
• Wettability – the ability to spread over surfaces allows the filler metal to form a uniform bond
• Strength – Fillers should be of the right strength and flexibility
• Corrosion properties – Brazing requires an oxygen-free bond for a strong and long-lasting joint.
• Thermal properties – High thermal conductivity is preferable. Especially when efficient heat transfer between materials is required.

Intran uses copper for controlled atmosphere brazing. Our brazing process is used on parts made from carbon steel, cast iron, stainless steel, and nickel alloys. These cover industries as varied as automotive, agricultural, marine, and power sports.

7. How Can I Be Sure CAB Will Give Consistent Results?

Achieving consistent results with CAB requires precise control of the brazing process, including temperature monitoring and gas composition. At Intran, our processes comply with CQ1-29 guidelines, which set the benchmark for heat-treating practices in the automotive supply chain.

Ensuring Consistency And Reliability With CAB

• Precise Temperature Control: We use ovens with advanced temperature control systems, which ensure uniform heating throughout the process.
• Gas Quality and Flow: Our process involves monitoring and maintaining the gas supply, which is essential for maintaining the correct atmospheric conditions.
• Furnace Maintenance: Routine maintenance of the brazing oven avoids contamination and ensures peak performance.
• Quality Assurance: We implement rigorous testing and inspection procedures. This is needed to verify the quality of each batch and the integrity of the braze joints. We use electronically controlled dispensers for perfect results.

Intran adheres to stringent IATF certifications, which is the only way to ensure that our oven brazing processes meet strict international standards.

8. Where Should I Get Controlled Atmosphere Oven Brazing Products Manufactured?

Choosing the right manufacturer for CAB products is the most important first step to ensure high-quality results. Look for a facility that:

• Specializes in CAB: Look for a manufacturer with expertise in Controlled Atmosphere Brazing. They will have the right equipment, gas handling capabilities, and technical knowledge.
• Offers Customization: Depending on your project, you may need tailored solutions. Intran can customize the brazing process to fit your specific materials and product requirements. Our brazing furnace can hold parts up to 5 feet in length with a height of 6 inches and a width of 12 inches.
• Adheres to Industry Standards: Ensure the facility complies with IATF 16949:2016 and ISO 9001:2015 industry standards.
• Has a Track Record of Success: Intran has over 50 years of experience in the automotive manufacturing industry. We have a solid reputation for delivering high-quality brazed components.

Ask The Right Questions:

• What cleaning and quality procedures are used? – Intran’s processes include ultrasonic cleaning, leak testing, and final inspection of every unit.
• Are there dedicated staff to address issues or unforeseen problems? – Intran has experienced staff who are ready to assist with any issues.
• How much experience does the manufacturer have with CAB? – Intran has over 50 years of automotive manufacturing experience.

Controlled Atmosphere Oven Brazing can deliver consistent, high-quality results. Just make sure you choose the right partner for your CAB requirements. Intran has over 55 years of experience in the automotive manufacturing business and has produced OE parts for American Motors, Chrysler Corporation, Nissan, and Volkswagen. Take a look at our wide range of manufacturing capabilities here. If you’d like more information on Controlled Atmosphere Brazing (CAB) or any of our processes or products, contact us here.