Date
18 August 2026
Category
Author
Conal McLaughlin
Magnetisation direction defines where the north and south poles appear on a permanent magnet. It determines how the magnetic field leaves the component, which surface becomes the working face and how the magnet interacts with a sensor, steel target, rotor, coupling or adjoining magnet.
Two magnets made from the same material, grade and dimensions can behave very differently if they are magnetised in different directions. A disc magnetised through its thickness concentrates its usable field on the two flat faces. The same disc magnetised across its diameter places the poles on opposite sides of its curved surface.
For this reason, magnetisation direction should be treated as part of the magnet specification—not as a detail to decide after the geometry has been fixed.
Key takeaway: Magnetisation direction determines where the usable field appears. Material, grade and dimensions alone do not fully define how a magnet will perform within an application.
These simplified diagrams show the usual pole positions. North and south may be reversed, so the required polarity and working surface should always be confirmed on the component drawing.
The poles appear on the two opposing flat or end faces, creating a clear working pole face.
The two main pole regions sit on opposite sides of the curved surface rather than on the end faces.
The field runs between the inner and outer curved surfaces. The inward or outward polarity can be reversed.
Alternating north and south poles are arranged on a face, around a circumference or along a strip.
A permanent magnet develops a preferred magnetic axis when it is magnetised. The direction of this axis relative to the part geometry determines the position of the poles and the shape of the external field.
The term can become ambiguous when words such as length, height and thickness are used without a drawing. On a cylindrical magnet, axial usually means along the centreline. On a thin disc or block, the same direction may be described as through-thickness. A drawing with a direction arrow and an identified pole face is much clearer than terminology alone.
Magnetic orientation is established during manufacture for anisotropic materials. The particles or grains are aligned along a preferred—or easy—axis before the part receives its final magnetising pulse. To achieve the expected material properties, the finished magnet normally needs to be magnetised along this orientation direction.
Isotropic materials do not have the same strongly preferred direction and can offer greater freedom in the final pole pattern, although their magnetic output is normally lower than that of an equivalent anisotropic material. This distinction is important when considering unusual radial or multipole patterns.
Axial magnetisation runs along the main axis of a magnet. On a disc, cylinder or ring, the north and south poles are positioned on the two opposing flat faces. For a block, it is often described as magnetisation through the thickness, although the relevant dimension should still be identified on the drawing.
This is one of the most common permanent-magnet configurations because it produces a clear working pole face and can be straightforward to manufacture and inspect.
| Example drawing note: Axially magnetised through the 5 mm thickness. North pole on datum face A. |
A diametrically magnetised cylinder or ring has its magnetic axis across the diameter. One side of the curved surface behaves as the north-pole region while the opposite side behaves as the south-pole region. The end faces are not the main opposing pole faces.
This arrangement is useful when the field needs to change as the magnet rotates. A sensor positioned beside a diametrically magnetised cylinder can detect north and south during each revolution, making the configuration suitable for certain position, speed or switching functions.
| Example drawing note: Diametrically magnetised across the outside diameter. North-pole centreline aligned with angular datum B. |
Radial magnetisation follows the radius of a ring or curved segment. In a simple radially magnetised ring, one cylindrical surface can form one pole and the opposing inner or outer surface forms the other. The polarity can face inward or outward depending on the requirement.
For an arc segment, the magnetic axis follows the local radius between the inner and outer curved surfaces. Several radially magnetised arc segments can therefore be arranged around a rotor or stator to create an alternating pole pattern.
A one-piece radially oriented ring is more specialised than a conventional axially or diametrically magnetised component. Feasibility depends on material, grade, dimensions, wall thickness, production route, pole requirement and expected quantity. Dedicated orientation or magnetising tooling may be required.
| Example drawing note: Radially magnetised through the ring wall, with north pole on the outside diameter and south pole on the inside diameter. |
The terms are sometimes used interchangeably, particularly for ring magnets, but they describe different field directions.
The magnetic axis crosses the ring or cylinder from one side to the opposite side.
The magnetic axis follows the local radius between the inner and outer surfaces.
If the distinction matters to the application, include a sectional drawing or pole diagram. A written description alone can be misinterpreted.
Multipole magnetisation creates several alternating north and south poles on a specified surface. The poles may be distributed around a circumference, across a flat face or along the length of a strip. Multipole is therefore a pole pattern rather than one single geometric direction.
Examples include an axially multipole ring with alternating poles on one flat face, or a ring with alternating poles arranged around its outside diameter. The number of poles, pole pitch, working surface and angular position all influence the resulting magnetic waveform.
Multipole patterns normally require a purpose-built magnetising fixture. As the number of poles increases, the available pole pitch becomes smaller and the material, geometry and measuring distance become increasingly important. The achievable surface field and waveform should be reviewed against the real sensor or motor requirement rather than specified as pole count alone.
| Example drawing note: Eight poles, alternating N-S around the outside diameter. Equal 45-degree pole pitch. Pole transition and starting-pole position referenced to datum feature C. |
Magnetisation direction does not change the basic alloy grade, but it changes where the field is available and how effectively the magnet works within the magnetic circuit.
For an initial estimate of face pull, use the GUK Magnetic Pull Force Calculator. Results assume idealised conditions and should not be treated as a substitute for testing in the final configuration.
High magnetic performance and normally anisotropic. Conventional axial or diametric directions are common; specialised radial or multipole patterns may require dedicated tooling, a different production route or a segmented assembly.
High output · orientation-sensitiveAvailable in isotropic and anisotropic forms. Rings and arc segments are widely used, but achievable direction and output depend on how the material was oriented during pressing.
Isotropic and anisotropic optionsCan offer greater geometric and pole-pattern flexibility, including multipole rings. Magnetic output is normally lower than comparable sintered rare-earth material.
Greater pattern flexibility · lower outputDirection, geometry and magnetic-circuit conditions require care because AlNiCo has relatively low coercivity. The intended operating point and risk of demagnetisation should be considered.
Magnetic circuit requires particular careThese are general manufacturing considerations, not universal capability limits. Final feasibility depends on the complete specification and supplier process.
The most useful magnetisation specification links the pole direction to the geometry and intended working surface. Where possible, include a drawing with a clear direction arrow, pole labels and a physical datum.
The correct magnetisation direction is not automatically the pattern that produces the highest field at one surface. It is the pattern that places the required field in the correct location while remaining practical to manufacture, assemble and inspect.
A magnet can sometimes be demagnetised and magnetised again, but changing the axis is not simply a matter of applying a new field. For anisotropic magnets, the preferred orientation was established during manufacture. Remagnetising across a different axis may produce weak, inconsistent or unusable performance.
Before considering remagnetisation, confirm the material, original orientation, geometry, coating, required new pole pattern and whether the part can safely withstand the necessary magnetising field. In many cases, supplying a new magnet manufactured for the correct direction is the more reliable option.
GUK Magnetics supplies neodymium, samarium cobalt, ferrite and AlNiCo magnets to customer drawings and specifications. Magnetisation direction and pole orientation can be specified to suit application, sensing and installation requirements, subject to material, geometry, tooling and quantity.
Our role is to review the requirement, advise on manufacturability and identify suitable magnet or assembly options. GUK Magnetics does not design the customer’s complete product or magnetic system. Final application performance should be validated in the intended configuration.
To receive an accurate review and quotation, the most useful information to provide is:
Send your drawing, pole diagram, material requirement, working air gap and anticipated quantities. We can review manufacturability and advise on practical magnet or assembly supply options.
Discuss Your RequirementsAxial or through-thickness magnetisation is one of the most common patterns for discs, cylinders, rings and blocks. The correct direction still depends on which surface must provide the working field.
It affects where the usable field and pole faces are located. A pull-force value measured on the main pole face should not be assumed to apply to a side surface or a different field direction.
Diametric magnetisation crosses a cylinder or ring from one side to the opposite side. Radial magnetisation follows the radius, commonly between an inner and outer curved surface or through a radial arc segment.
Yes. Multipole rings can have alternating north and south poles on a flat face or around a circumference. Feasibility depends on material, geometry, pole pitch, magnetising fixture and required magnetic performance.
Yes, but it must be compatible with the material orientation, shape and manufacturing route. Special patterns may require dedicated tooling or a segmented assembly.
Use a direction arrow, label the required north and south pole faces and reference the pattern to a physical datum. Multipole drawings should also define pole count, pitch, working surface and angular position.
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