Steel can be joined by using a technique called brazing. A high temperature is needed for this and so a brazing hearth is normally used. Brazing gives a permanent joint that is ideal for most metalworking projects in schools and colleges. In industry this technique is used on products such as bicycle frames where there is a need for a certain amount of flexibility in the joint.
In simply terms, two steel parts are joined by heating them to ‘red’ heat and then applying a brazing rod to the joint. The brazing rods melts at a lower temperature than the steel and so it melts to form a molten liquid. This liquid brazing rod then flows along the joint between the two steel parts. The equipment needed is shown below.

THE EQUIPMENT

The brazing Hearth contains a compressor which pressurises air and gas so that it is forced out the nozzle of a gas-air torch. As it comes out the nozzle it can be ignited so that it burns fiercely. If the torch is used correctly it can heat up metals to a high temperature. This is exactly the type of equipment that is needed for a brazing joint between two pieces of steel.
Above the brazing hearth is an extractor. This extracts any fumes that collect during the heating process.
The hearth normally has fire bricks arranged on its surface. These reflect heat back into the heating area so that high temperatures can be reached.
A small rotating table is sometimes used to position the metals to be heated.

QUESTIONS:
1. Draw a simple diagram of a brazing hearth and label the important parts.
2. Draw a detailed diagram of the torch and explain how it works.

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