Induction Heating: Eliminate Cracking at Holes pt. 1

There are two factors that can cause the overheating: • An increase of power density (heat source) due to the redistribution of eddy current flow. • The lack of adjacent mass of metal there, meaning that there will be reduced heat transfer from the hot surface of the shaft toward the colder core due to the thermal conductivity (cold sink effect). Depending on shaft geometry, the impact of both factors may be different. If a longitudinal hole is located within one current penetration depth in hot steel from the shaft surface, then the first factor typically prevails and primarily is responsible for the overheating in that area.

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