Heating Devices Used for forging

The stocks that needed heating for optimizing product requirement or specifications are heated to correct the forging temperature in a smith's hearth or in a furnace located near forging operations. Gas, oil or electric- resistance furnaces or induction heating classified as open or closed hearths can be used. Gas and oil are economical, easily controlled, and mostly used as fuels. The formation of scale, due to the heating process, specially on steel creates problems in forging. A non-oxiding atmosphere should, therefore, be maintained for surface protection. New styles of gas-fired furnaces have been developed to reduce scaling to minimum. Electric heating is most modern answer to scaling, and it also heats the stock more uniformly. In some cases, coal and anthracite, charcoal containing no Sulphur and practically no ash are the chief solid fuels used in forging furnaces. However, fuels must have a calorific value of at least 1400 to 1500 large calories (5600 to 6000J). Petroleum sometimes serves as an excellent fuel.

Forge furnaces are built so as to ensure a temperature up to 1350*C in the working chambers. They should be sufficiently large to allow proper combustion of fuel, and to obtain uniform heating of the workpiece. Each heating furnace consists of the following parts : firebox, working chamber, chimney, flues, recuperator or re-generator , and various auxiliary arrangements. Several types of furnaces are used for heating the workpiece .

The various heating devices used for forging are :

1. Box or Batch type furnace.

2. Rotary -Hearth Furnace.

3. Continuous or Conveyor Furnaces.

4. Induction Furnaces.

5. Resistance Furnace

6. Open fire and stock furnace.

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