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| Multi-turn Coils: In multi-turn coils, as the heated length increases, the number of turns generally should increase in proportion. The multi-turn coil is generally utilized for large-diameter, single-shot heating, in which the quench medium can be sprayed between the coil turns. When the length of the coil exceeds four to eight times its diameter, uniform heating at high power densities becomes difficult. In these instances, multi-turn coils that scan the length of the workpiece are often preferable. Multi-turn coils generally improve the efficiency, and therefore the scanning rate, when a power source of a given rating is used. |
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