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How different steel shell shapes affect the magnetic field distribution of pot magnets?

How different steel shell shapes affect the magnetic field distribution of pot magnets?

Aug 28, 2025

     Compared to a bare magnet of the same size, a pot magnet with steel shell can increase its effective pulling force by two to five times. However, many people don't realize that the shell shape is crucial to magnetic field distribution. Different shell geometries affect not only the strength of the attractive force but also the distribution of the magnetic field across the contact surface.

 

 

Basic Principles of Pot Magnets

     Pot magnets typically consist of three main components:

  • The powerful rare earth magnet itself—typically neodymium magnets, ferrite, or alnico.
  • The shell—a protective casing that also serves as part of the magnetic circuit.
  • A spacer or adhesive layer—typically nylon—is used to ensure structural integrity.

     The shell acts like a magnetic conductor. Instead of allowing magnetic flux to escape in all directions, it guides the flux along a specific path, concentrating it on the open pole surface. This design improves efficiency and protects the magnet from breakage or corrosion.

 

 

Comparison of Different Shell Shapes

1. Round Shell Housing Pot magnets

  • Magnetic Field Distribution: Symmetrical and concentrated toward the center.
  • Advantages: Provides strong vertical pulling force and stable holding power.
  • Applications: Retail display hooks, ceiling suspension systems, magnetic tool racks.
  • Visualization: Magnetic lines of force flow evenly downward, creating a circular attractive force.

 

Round Pot Magnets without Hole

 

2. Shallow-Walled or Flat-Walled Housing Pot Magnets

  • Magnetic Field Distribution: The magnetic field is more dispersed, with less central concentration.
  • Advantage: Provides a balance between pulling force and coverage area.
  • Applications: Securing nameplates, lightweight signage, or aligning metal panels.
  • Visualization: Magnetic lines of force spread outward, resulting in a wider distribution but weaker strength.

 

Disc Pot Magnets with Countersunk Hole

 

3. Square or Rectangular Housing Pot Magnets

  • Magnetic Force Distribution: Magnetic lines of force tend to be concentrated at edges and corners.
  • Advantage: Better suited for applications requiring alignment.
  • Applications: Magnetic mounting systems, modular fixtures, and custom engineered solutions.
  • Visualization: Corners provide greater pull force and facilitate gripping of flat edges.

 

Nickel Coated Block Channel Magnets

 

Why Housing Shape Matters

     The design of the steel housing affects magnetic circuit efficiency. A deeper housing increases pull force but limits the working distance. A shallower housing extends the magnetic field over a larger area but reduces maximum holding force. Engineers often need to balance pull force, reach, and application environment when selecting the appropriate pot magnet design.

 

     Pot magnets may appear simple, but their performance depends heavily on the geometry of the housing. From round housings that maximize vertical force to flat, square housings that optimize reach and alignment, each design has its own unique applications. By understanding these magnetic circuit principles, neodymium pot magnets suppliers and engineers can provide better choices for industrial, commercial, and domestic applications.

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