Is the N pole of the countersunk magnet located on the large hole surface?

During magnet application and selection, some customers inquire whether the large hole in countersunk magnets is the north pole during magnetization. Many rely on experience to determine polarity, but this understanding isn't entirely accurate. Below, Xiao Fu will explain this issue.

Countersunk magnets typically refer to magnets featuring a tapered or flared opening in the center, available in various shapes. The countersink facilitates screw insertion into the magnet's interior, enabling flush surface mounting. This structure serves solely as a mechanical mounting method and does not inherently determine the magnet's magnetization direction or pole distribution.

Is the side with the large hole always the N pole?

Not necessarily. After magnetization, the side with the large hole can be either the N pole or the S pole, depending entirely on the magnetization direction. Taking common axial magnetization as an example, simply adjusting the magnet's orientation when placed in a fixed magnetizing head can change the pole direction. A small number of customers may request specific poles for particular surfaces.

Illustration shows a circular countersunk ndfeb magnet

Why do many people assume the larger hole surface is the N pole?

This perception primarily stems from industry conventions and application preferences. In certain assembly scenarios, manufacturers may consistently designate the larger hole surface as the N pole for uniform identification or to facilitate magnetic attachment to iron components. Over time, this practice has solidified into a “default assumption.”

As explained above, you should now understand that magnetic poles are determined by magnetization method, not by countersink structure. You can discuss with magnet manufacturers which surface should be the N pole or S pole.

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