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Material selection of Armature Sheet

Material selection of Armature Sheet
The core of the armature is used to form the magnetic flux path and supports the armature windings. Generally stacked from silicon steel sheet.

The magnetic field polarity of the core has been changing because the armature turns. The rapid changes in the polarity will generate eddy current in the core making the current into excessive heat and consumption. The eddy current loss is inversely proportional to the resistance of the ferromagnetic material, which is proportional to the square of the thickness of the core steel sheet.

There is not only the eddy current loss in the core, but also the hysteresis. And the hysteresis loss is related to the hysteresis loop area of the ferromagnetic material. The smaller the hysteresis loop is, the smaller the hysteresis loss.

Silicon steel sheet is adding a small amount of silicon to the steel thus the resistivity is bigger and the hysteresis loop is narrower, so using the silicon steel plate to make the core can have a smaller eddy current loss and a hysteresis loss.

But in order to reduce the cost of armature production, the manufacturers in domestic will use cold-rolled plate or even scrap steel plate to produce the core of armature. So the quality of the armature won’t be hard to imagine.

Tips by Junmiao Wang & Michele Leng