In POT magnet, we all know the influence of magnet grade to pull force, that is the higher of grade (To be precise, the higher of Br), the stronger of pull force.

In this article, we will discuss the influence of steel cup material to pull force.

First of all, let us explain how POT magnet works very briefly.

The steel is produced to be a cup shape, then cover the magnet around except the suction face. It conducts the magnetism of the other magnet side to the suction face, then magnetism is confined to one face only, where it is concentrated to give the maximum holding force possible for the size of the magnet.

So the magnetic conductivity of the material can affect the pull force. Because that determines how much magnetism of other magnet side is conducted to the suction face. 

Second, we would like to introduce three commonly used steel materials in POT magnet. 

1.Carbon steel. Like Q235,45# in China. This kind of steel is easy to rust, we always need to coat Zinc or Nickel on it. And it can conducts magnetism easily.

2.Magnetic stainless steel. Like 410, 460 in China. This material does not rust easily, and can also conduct magnetism, but not that easily.

3.Nonmagnetic stainless steel. Like 304, 316 in China. This material will not rust in conventional conditions, but can’t conducts magnetism.

The magnetic conductivity of these 3 materials is: Carbon steel is better than magnetic stainless steel, and the nonmagnetic stainless steel has NONE.

So if we use the carbon steel, the pull force of POT magnet is stronger. And if we use the 304 stainless steel, this only plays a protective role, and has no help to increase the pull force.

In addition, In carbon steel, the lower the carbon content, the better the magnetic conductivity. Such as use Q235 (Low carbon steel), the pull force is stronger than use 45#( Medium carbon steel).

Hope this article can help you to design the POT magnet, and choose the correct material for magnet cup.