What Is Controlled Atmosphere Brazing?

There’s brazing, and then there’s controlled atmosphere brazing (CAB). If you have assemblies produced at mid to high volume that need clean and strong joints, you may want to look into CAB. What is CAB, anyway? Read on to find out!

What Is Controlled Atmosphere Brazing?


When you need to join together two different metal components to form a part, CAB is a good method to use. It’s a technology that uses a molten filler material, such as a copper alloy or aluminum alloy, to bond two parts together. This material can be in paste, ring or sheet form. The filler material flows between tightly fitting joint surfaces due to capillary action. The interaction between the molten metal and the base materials forms a metallurgical bond as the filler material cools and solidifies. The controlled atmosphere furnace brazing weld is characterized by high strength and ductility. The bonding zone is equal to or stronger than the metals that have been bonded. It stands out for its tightness when it comes to containing fluids or gases.

The atmosphere in the brazing oven is controlled to prevent oxidation. Oxidation is a process where electrons move from the atoms that make up metal, to the oxygen atom found in the air. Rust, which occurs with iron, is the best-known example of oxidation. But oxidation slowly occurs to most metals. Oxidation rapidly increases as metal is heated. The problem with this is that oxidation makes it difficult for a molten filler to flow as it should to create a good brazed joint.

In CAB, oxygen is removed from the atmosphere of the brazing oven and replaced with a mixture of hydrogen and nitrogen that does not contain oxygen molecules. This allows for a clean, high quality joint to be created.

How Controlled Atmosphere Brazing Works

Parts move through a controlled atmosphere brazing furnace on a conveyer belt. The atmosphere inside the furnace consists of oxygen-free nitrogen or hydrogen. The general assembly line setup consists of the following stations:

  1. Cleaning and/or degreasing of components
  2. Pre-assembly by press fit or TIG welding
  3. Application of paste or ring
  4. Preheating (optional depending on oven type)
  5. Heating
  6. Brazing
  7. Cooling

Is Brazing An Ideal Method For My Parts?

Brazing is an ideal method of joining metal parts, where the joints need to strong and leak free. It’s faster and less expensive than welding, and it’s well suited to mid to high volume production. Brazing is quite effective for the following types of parts:

  • Small, complex parts
  • Large, oddly-shaped parts
  • Mass-produced parts
  • Parts that need to constantly withstand high temperatures (350 degrees or hotter)

When you consider the above criteria, you may realize that a lot of auto parts fall into this category. So chances are good that if your business produces auto parts, brazing may be an ideal solution for you.

This post lists some of the benefits of CAB.

The Advantages Of Controlled Atmosphere Brazing

CAB comes with several advantages over other methods.

  • Clean appearance: With CAB, the brazed joints will not need cleaning after the brazing process, because no flux is used
  • Low unit cost: A conveyor belt style oven results in a low brazing cost for each part
  • Consistent process: The CAB process is very consistent because no flux needs to be applied, and the duration of heating is easily controlled

Intran Offers High Quality Controlled Atmosphere Brazing Services

It’s always important to do your due diligence while looking for a contract manufacturer for the reasons listed here. It’s even more important when it comes to controlled atmosphere brazing.

You want to make sure that your manufacturer has adequate knowledge and experience. We specialize in brazing cold rolled steel and stainless steel. Because oven brazing often involves large quantities of parts, mistakes can be enormously expensive. Experience counts more than you think. Want to see how Intran completes brazing projects? Check out this video:

In Mexico, several manufacturers, including Intran, perform high-quality CAB for auto parts they manufacture. Intran is one of the very few plants that offer high-quality CAB as a stand-alone service. A lot of auto parts brands consider Intran as a top choice for controlled atmosphere brazing services. Here are a few reasons why:

  • Our continuous belt furnace brazing is cost-effective, highly efficient, and ideal for mass production.
  • Our brazing process complies with IATF certifications.
  • We comply with CQI-9. (CQI-9 establishes standards for heat-treating processes that suppliers to the automotive industry must meet.)

We’re adding another state-of-the-art furnace soon. This will increase our CAB capacity to over 2 million parts annually. We braze many automotive parts, but we also serve many other diverse industries. Contact us to learn more about Intran’s controlled atmosphere brazing services today!

July 17, 2020 Tagged: