Brazing Furnace Configurations
Brazing furnaces are either gas fired or electrically heated. However now furnace uses electrical radiant heating elements to transfer heat to the workload. Multiple thermocouples and automatic temperature controllers are adjusted to maintain the uniformity in temperature distribution during brazing.

Furnaces for Brazing

Batch furnaces

Buying Tips You should be careful while purchasing the brazing furnaces. Firstly keep the application in mind and the type of base materials you intend to braze. The cooling system decide the pace of brazing hence it should be checked thoroughly. You should also check the insulation system of the furnace.

For brazing operations batch furnaces are also commonly used. The operation is used for small- to medium volume production, especially where many types of brazing operations are required. The brazing in batch furnace brazes in "batches," or one load at a time. Normally the batch atmosphere furnaces are of the box design and consist of box-type design which incorporates entry and exit doors, a heating chamber, and a water-jacketed cooling chamber.

Retort Furnaces
In a retort furnace hydrogen provides the active ingredient to clean the braze components, and eliminates the need to use flux. The enclosed hydrogen atmosphere is protected by an inner heat resistant alloy container. To accelerate the cooling rates, at the end of the cycle the nitrogen purge is used. However precaution must be taken with potentially explosive mixtures of hydrogen and air.

Vacuum Brazing Furnaces

Precautions Other than the normal for such equipment (electrical, thermal) there are no significant risks associated with vacuum brazing. Extraction should be examined to ensure venting into a safe area of volatile materials should be placed in the furnace. Proper precaution should be taken in case hydrogen atmosphere is used High vapor pressure elements like zinc, cadmium, lead, etc. should be avoided in vacuum brazing. To remove surface scale, grease and other contaminants all materials need to be cleaned prior to insertion in the furnace

In Vacuum Brazing furnaces loading may be either in batch or it may be semi-continuous. Vacuum furnaces may or may not use retorts that are evacuated and heated to brazing temperature. Vacuum furnaces are usually limited to smaller charges because of the inefficiencies relating to cooling the large mass of the vacuum retort. To speed up the cooling, sometimes an inert or purge gas is introduced into the retort to speed cooling. Some of the brazing furnace is of the coldwall type consisting of a water-cooled vacuum chamber with thermal insulation and heating elements located within the chamber where brazing takes place. Vacuum furnaces come in a variety of loading, material handling, and work zone configurations.

Base Metals
The characteristics of the base metals involved represent one of the most important parameters to judge whether the furnace brazing is the right joining technology. It is advisable to choose proper base metals for brazing. The metals commonly used for brazing are : Copper and copper alloys, Precious metals, low-carbon mild steels, high-carbon steels, alloy and tool steels, cast iron, nickel and nickel alloys, Cobalt and cobalt alloys, Stainless steels, Aluminum and aluminum alloys, Magnesium and magnesium alloys etc.

Applications
Following are the applications of brazing furnace:

• Electrical products.
• Electronic items
• Aeroengine components
• Nuclear and gas turbine
• Marine and other engineering applications
• Brazing of aluminum heat exchanger.