The Vacuum Brazing Furnace: A Silent Champion of Leak-proof Metal Joints

Step into a manufacturing facility working on aerospace products, heat exchangers, or other high-precision assemblies, and it is likely that you will encounter a vacuum brazing furnace operating somewhere in a corner. Even though such equipment does not attract much attention compared to CNC machines and robotic arm assemblies, it is usually a silent champion of the most critical joints of the assembly. In our experience of Bionics Scientific as a company that has been collaborating with manufacturers that use this equipment, there is one thing that became evident to us: choosing a wrong vacuum brazing furnace leads to spending more money on reworks than virtually any other piece of malfunctioning equipment.

Vacuum Brazing Compared to Conventional Joining Technologies

Vacuum brazing is a technology that combines vacuum conditions, lack of oxygen, and melting of a filler alloy. Inside a vacuum chamber, the filler alloy melts and joins the components using capillary forces. Being performed in vacuum rather than in air, the process is free from oxidation, fluxing, and needs cleaning after brazing. These facts make vacuum brazing a preferred method for assembly in those cases where stainless steel, titanium or other nickel-based superalloys have to be used, and a joint has to be absolutely leak-proof and clean.

Why Vacuum Level and Temperature Control Are Crucial

The main value of a vacuum brazing furnace is its ability to control two parameters: vacuum level and temperature control. Ineffective vacuum pumps provide access to trace amounts of oxygen to the vacuum chamber, making brazed joint weaker or even porous. An uneven distribution of heat within the chamber produces thermal stresses that result in deformation of thin-walled heat exchangers. This is why buyers of quality equipment care about pumping speed, chamber uniformity, and programmable heating and cooling rates.

Industrial Applications of Vacuum Brazing Furnaces

The technologies utilized in the vacuum brazing furnaces seem to get applied much more frequently than one might suppose at first glance. They allow aerospace manufacturers to make joints of turbine blades and the fuel system components, for which failure is simply out of the question. Vacuum brazing is utilized by the automotive industry to manufacture high-quality heat exchangers and radiators. The medical devices industry uses another technology related to vacuum brazing called diffusion bonding that allows for joining the components of surgical instruments without any biocompatible contaminations. Lastly, vacuum brazing allows for manufacturing hermetically sealed packages that are resistant to thermal cycling in the electronics industry.

Choosing the Right Vacuum Brazing Furnace for Your Business

First of all, it is important to choose the proper size of the chamber according to your current needs and not the predicted production volume. Besides that, you need to think about the cooling system of the furnace since its quality impacts the final metallurgical properties of the joint, and a metal joining furnace with a poorly-controlled cooling system can produce residual stresses. At Bionics Scientific, we understand the importance of our vacuum furnace engineering both in terms of maintaining the vacuum integrity and the cooling system that is capable of preserving the metallurgical properties of the joint.

Vacuum Brazing Furnace Maintenance Practices

Changing the vacuum pump oil, checking seals and hot zone insulations is something that needs to be done regularly as otherwise, your furnace will develop a small leak and will quietly reduce the quality of the joint without giving any warning signals.

Conclusion

Vacuum brazing furnace may lack the glamorous appearance of other equipment pieces, but without it, many assembly processes become impossible.