What Is a Pot Magnet? Comprehensive Explanation of Pot Magnets

When asking “What is a pot magnet?”, the answer is actually straightforward: a pot magnet is a magnetic assembly in which a magnet is encased inside a protective metal shell. The magnet can be a simple disc or equipped with additional mounting accessories such as hooks or threaded stems to support a wide range of applications. Below is a complete explanation covering how pot magnets work, where they are used, and the various types available.

Ideal for Everyday Clamping Applications

A pot magnet is typically built around a magnet embedded in a metal housing. This exterior shell is usually made of plated mild steel, though ferritic stainless steel is also commonly used for better corrosion resistance.

When placed in direct contact with a ferrous surface, the design enables the pot magnet to produce a strong, concentrated holding force. Compared with standard magnets, pot magnets generally demonstrate significantly stronger clamping force because the internal magnetic circuit is engineered to minimize air gaps and direct magnetic energy efficiently.

How a Pot Magnet Is Constructed

A standard pot magnet exposes only one magnetic surface, focusing the magnetic field into a tight, powerful clamping area. This exposed magnetic face is usually protected by a keeper plate during storage or handling to maintain performance and prevent accidental attraction.

During the design process, engineers aim to maximize the pull force for a given size by eliminating unnecessary air gaps in the magnetic path. The steel cup functions as part of the magnetic circuit, channeling the magnetic field toward the working surface.

If the visible face is the North pole, the steel ring around the magnet effectively behaves as a South pole. This short distance between the poles increases magnetic efficiency, creating a powerful clamping effect.

Mounting Options and Attachment Styles

Pot magnets are valued for their versatility in installation. The ferromagnetic cup can be manufactured with numerous attachment designs, including:

• Male threaded studs
• Female threaded holes
• Countersunk holes for screws
• Counterbore holes for bolts
• Blind holes for adhesive bonding
• Precision-ground outer diameters for press-fit assembly

Unlike standalone magnets, which are brittle and prone to cracking under the force required for threading, pot magnets allow secure mounting because the housing absorbs the mechanical stress.

Enhanced Protection and Durability

The metal cup provides substantial protection for the magnet, making pot magnets highly durable in demanding clamping applications. The design typically positions the magnet slightly recessed inside the housing so that impact forces hit the steel rather than the magnet, greatly reducing the risk of damage.

The casing also shields the magnet from environmental exposure, improving resistance to corrosion and extending service life. Press-fitting becomes possible thanks to the protective metal body, something not feasible with a bare magnet.

Understanding Pot Magnet Clamping Forces

Pot magnets are rated by clamping force, which represents the maximum pull force achievable when the magnet is in direct contact with a thick, high-quality mild steel surface. These forces are usually expressed in kilograms or newtons.

However, several factors can reduce real-world performance:

• Thin steel surfaces
• Poor-quality or contaminated ferrous materials
• Curved, coated, painted, or uneven surfaces
• Mesh structures with gaps

In such cases, users may need to increase the thickness of the steel, use multiple pot magnets, or select a design with a shallower magnetic field for better results.

Pot magnets also offer superior resistance to sliding compared with typical magnets. A standard magnet may slide at around 20% of its pull force, while a pot magnet often resists sliding until about 33% of its pull strength is reached. Rubber- or polyurethane-coated versions offer even higher friction, sometimes surpassing their own vertical pull force.

One important limitation is that pot magnets perform best in full contact with the metal surface. They are not suitable for clamping through large air gaps, and they are not optimized for pot-magnet-to-pot-magnet attraction unless specially manufactured with opposite polarities.

Materials Used in Pot Magnets

Several magnet materials can be incorporated into pot magnet designs:

• Ferrite (ceramic)
• Alnico
• Neodymium (NdFeB)
• Samarium Cobalt (SmCo)

Each material offers different performance characteristics. Neodymium provides the strongest magnetic output for its size, while ferrite is a more economical option with lower magnetic strength. Samarium Cobalt offers excellent temperature stability, and Alnico supports very high operating temperatures depending on the construction.

Temperature Resistance

Pot magnets come in a wide range of pull-force capacities, generally from under 1 kg up to well over 130 kg. Most standard pot magnets using neodymium work safely up to about 80°C, while rubber-coated versions are usually limited to around 60°C.

For higher temperatures, pot magnets may require:

• High-temperature magnet grades
• Adhesives with elevated heat tolerance
• Special construction to accommodate different expansion rates

Some Alnico versions can operate at temperatures exceeding 200°C, and specialized designs can even work at 450–550°C for high-heat environments such as welding stations.

Available Variants and Options

Pot magnets are available in multiple styles, each engineered for specific applications:

• Hook variants for vertical lifting
• Eyebolt types for suspension
• Countersunk styles for screw mounting
• Through-hole versions for bolts
• Threaded male and female designs
• Blind-hole designs for press-fitting
• Shallow or deep configurations depending on required flux depth
• Bi-pole versions using half-moon steel poles with no exposed magnet

Because pot magnets are widely used across industrial, commercial, and consumer applications, customized designs can be manufactured to meet unique size, performance, or mounting requirements.