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Alternative Sources of Heat

As you evaluate induction heating for your manufacturing process, it is important to understand advantages and disadvantages of alternative heating methods. All other industrial heating methods utilize one or more of three basic heat transfer methods:

  • Conductive heating is the direct flow of heat through a material resulting from physical contact. The smoother the surface, the better the heat transfer.

  • Convection heating systems rely on heat transfer between a surface and adjacent fluid (gas, air, liquid) and by the flow of fluid from one place to another induced by temperature.

  • Radiation heating (electromagnetic radiation) does not require any transfer medium; thermal energy is transferred through matter or space by electromagnetic waves - ultraviolet, infrared, microwave, or radio frequency. So microwave ovens and infrared heaters are examples of radiant heating.

Alternative Industrial Heating Methods

Flame Heating
flame heating
Flame heating involves the use of gas flame to heat the part (workpiece) without melting the part or removing material. Heating torches and flame heaters are widely used for brazing, soldering, hardening, hot forming, pre-heating for welding, and many other applications.

Flame heating, an example of conductive heating, offers the advantages of relative economy and speed for one-off applications. However fumes and heat produce an unpleasant working environment, and there is the potential for burns. Other disadvantages include lack of accuracy and repeatability. Even in the hands of a skilled operator, it is difficult with flame heating to achieve consistency when working through a series of parts.

Resistance Heating
Resistance heating relies on a current being passed through a resistive material such as graphite, molybdenum, tantalum, etc. The electrical current is connected directly to the heating element. Heat from the element is then radiated towards the part to be heated. Resistance heat is used to melt metals, glass and plastics before forming; for welding, brazing, and selective surface heat treatments.

Resistance heating is very localized and works quickly. However it tends to have very poor temperature control with significant differences arising across the heating zone. Additionally, due to the fact that one piece must be done at a time, it can only be considered for low volume applications.

Traditional Ovens and Furnaces
Ovens and furnaces are employed most often to heat batches of parts. Ovens generally operate up to 1400°F; furnaces generally heat at higher temperatures. Ovens and furnaces employe convection and radiation – either individually or in combination – to achieve the desired heating results.

Ovens are often used for applications such as pre-heating and annealing, whereas furnaces are used for higher temperature processes such as brazing, heat treating, and sintering.

Ovens and furnaces require a substantial investment in valuable floor space and must be continuously operated to avoid long startup delays. Continuous operation requires relatively high operating costs. While generally effective at whole part heating, they cannot be used to heat sections of a part. Loss of heat into the factory environment is another factor to consider.

Lean, Green Induction Heating
For most industrial applications, induction heating technology offers significant advantages: speed, accuracy, repeatability, cost-effectiveness, and an operator-friendly working environment. Learn more about the advantages of induction heating.

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