Disc, ring, block or arc?

Start with the geometry. Then look at how the magnet will work in the complete assembly.

The shape is a starting point.

Discs, rings, blocks and arcs describe geometry. They do not, on their own, tell you a magnet’s field direction, useful holding force or temperature capability.

Four forms to explore

• Disc magnets have a circular face. Define the diameter, thickness and magnetisation direction.
• Ring magnets add a central opening. Specify both diameters, thickness and the required magnetic orientation.
• Block magnets use rectangular geometry. Identify the three dimensions and magnetisation axis on a drawing.
• Arc magnets follow a curve. Define the radii, angle, length and pole orientation together.

A hole does not mean a radial field.

Ring and arc shapes can be magnetised in different ways. Always specify the required arrangement and confirm what the manufacturer can produce.

Holding assemblies are a separate question.

A pot magnet combines a magnet with a housing. The contact surface, air gap and load direction affect the result. A published pull-off value must be understood with its test conditions.

Further reading: Dura: magnetisation options and Bunting: pot magnet information.

This guide is an introduction. Final selection and acceptance criteria need to be agreed for your application.