Heating Methods of Brazing

- Jan 24, 2019-

There are many heating methods that can be used to complete the brazing operation. The most important factor in selecting the heating method is to achieve efficient heat transfer throughout the joint and to do so within the heat capacity of each of the base metals used. The geometry of the brazed joint is also a key factor to consider, as is the required productivity and yield.

The easiest way to categorize brazing methods is to group them by heating method. Here are some of the most common:
* Torch brazing
* Furnace brazing
* Induction brazing
* Dip brazing
* Resistance brazing
* Infrared brazing
* Blanket brazing
* Electron beam and laser brazing
* Braze welding

These heating methods are classified through localised and diffuse heating techniques and offer advantages based on their different applications.

Brazing may require exposure to harmful chemical fumes. The National Institute for Occupational Safety and Health recommends that these smoke exposures be controlled below the allowable exposure limits.

Advantages and disadvantages
Brazing has many advantages over other metal joining techniques, such as welding. Since brazing does not melt the base metal of the joint, tolerances can be tightly controlled and clean joints can be produced without secondary finishing. In addition, different metals and non-metals (ie metallized ceramics) can be brazed. Generally, brazing also produces less thermal deformation than welding due to uniform heating of the braze. Complex and multi-part components can be brazed cost-effectively. Welded joints must sometimes be ground, which is an expensive secondary operation that is not required because it produces a clean joint.
Another advantage is that the brazing can be coated or clad for protective purposes. Finally, brazing is easily adapted to mass production and it is easy to automate because the individual process parameters are less sensitive to variation.
One of the major drawbacks of the lack of joint strength compared to welded joints due to the use of softer filler metals. The strength of the brazed joint may be less than the strength of the base metal but greater than the strength of the filler. Another disadvantage is that the brazed joint can be damaged at high operating temperatures. Brazing joints in industrial environments require a high degree of base metal cleanliness. Some brazing applications require the use of sufficient flux to control cleanliness. The bond color is typically different from the color of the base metal, creating aesthetic disadvantages.