A reference for engineers
How advanced multipole magnets work.
An advanced multipole magnet is one piece of magnet material carrying many small poles arranged in a deliberate pattern across one face. The pattern is what does the work: it decides whether two faces align to a single position, latch hard on contact, push back like a spring, or click into steps as they slide.
This site explains the technology. The magnets themselves, and the custom patterns, are invented and manufactured by Polymagnet, the product line of Correlated Magnetics Research. Multipole Mag is part of the WholeMagnetics family.
The idea
One magnet, many poles
An ordinary permanent magnet is a dipole. It has one north pole and one south pole, and its field reaches out broadly from both ends. Put two near each other and they do one of two things: pull together or push apart, depending on which way you turn them. That is the whole repertoire.
A multipole magnet, also called a coded or programmable magnet, is cut from the same kind of material but magnetized differently. Instead of a single north and south, its face carries a grid of many small poled regions, some north, some south, laid out in a chosen pattern. Because the field now comes from that pattern rather than from one big pole pair, the designer controls how two faces behave when they meet, not just whether they stick.
Nothing about the material changes. The same disc can be programmed to align, to latch, or to repel, purely by how its poles are arranged.
The pole pattern and maxels
The pattern is the program
Each small poled region on the face is called a maxel, the magnetic equivalent of a pixel. On its own a maxel is just a tiny north or south spot. Arranged by the hundred, they become a layout the designer controls.
A maxel has a polarity, a position, and a size. Group them one way and the face reads as a checkerboard; group them another way and it reads as stripes, rings, or a spiral. That map of polarities is the design input. It behaves like a program written in magnetism: change the arrangement and you change what the magnet does, without touching the alloy, the thickness, or the overall shape.
Two things follow from this that an ordinary magnet cannot offer. First, behavior becomes a design choice rather than a property of the material. Second, a magnet can be made to respond strongly only to a matching partner, because the full designed effect appears when a face meets the complementary pattern it was drawn against.
What the pattern is for
Behaviors built into the geometry
A few distinct behaviors come straight out of how the poles are placed. Each one is a function first: what the magnet should do when two faces come together.
One correct orientation
Give the pattern no rotational symmetry and it only lines up with its partner in a single position. As the faces approach, they rotate and shift until the poles match, then settle. The part seats itself the right way around instead of sticking anywhere it lands.
Strong hold on contact
Pack many north-to-south transitions close together and the attractive force between two matched faces concentrates right at the contact surface. The result is a firm hold when the faces touch, with a clearly defined grip rather than a vague pull.
Push that grows with closeness
Lay the poles so like meets like and the faces repel. Because the repulsion rises steeply as the gap narrows, the pair behaves like a spring or a cushion with no contact and no coil, resisting more the harder it is pressed.
Steps as they move
A repeating pole layout creates a run of stable positions. Slide or rotate one face against the other and it clicks from one aligned position to the next, giving indexed stops, the magnetic version of a detent, with nothing mechanical to wear.
Firm one way, easy the other
Because force depends on the poles staying matched, a pattern can hold hard against a straight pull yet let go with a small twist or slide that breaks the match. Strong when you want it, easy to part when you turn it.
A common comparison
Multipole magnet vs a Halbach array
Both deliberately arrange the direction of magnetization rather than leaving one plain north and south. They are built for opposite goals, which is why they look and behave differently.
Halbach array: steer the far field
A Halbach array rotates the magnetization step by step so the fields add up on one side and cancel on the other. The intent is a stronger, one-sided field that still reaches out to a working distance. That is useful where a magnet has to act across a gap, such as in motors or on a guideway.
Coded multipole: shape the near behavior
A coded multipole magnet arranges a two-dimensional pattern of poles across the face to control what happens at or near contact: alignment, latching, spring, detent. It accepts a short reach in exchange for precise behavior where the parts meet. The field is engineered for the handshake, not the distance.
Put simply, a Halbach array concentrates and directs the field so it carries further on one face. A coded multipole magnet spends the same freedom on programming behavior at the surface. One optimizes reach; the other optimizes what the contact does.
Read this before you design with them
The honest limits
Coding the poles buys control over behavior. It does not repeal physics, and it adds a few constraints worth planning around.
- Short reach. Because neighboring north and south regions sit close together, their fields largely cancel a short way off the face. The field pulls in tight. That makes these magnets strong on contact and weak at a distance, and the finer the pattern, the faster the field fades as the gap opens. Design for engagement, not for action across a wide air gap.
- They want a matching partner. The full designed effect appears when a face meets the complementary pattern it was drawn for. Against plain steel or an unmatched magnet, you get a weaker, more ordinary response, not the programmed behavior.
- Material sets the ceiling. A coded magnet is still made from a permanent-magnet material, so it inherits that material's strength and its maximum safe operating temperature. Run it too hot and it loses strength or demagnetizes, and the pattern cannot restore what the heat took. Material choice and grade decide those limits, not the coding.
Technical FAQ
Questions engineers ask first
What actually makes a multipole magnet different from a normal one?
A normal magnet is a dipole: one north pole, one south pole, one broad field. A multipole magnet carries many small poled regions arranged in a pattern across its face. That pattern, not the material, determines how it behaves against another face, so the same piece can be made to align, latch, or repel.
What is a maxel?
A maxel is a single small magnetized region on the face, a magnetic pixel. Each has a polarity, a position, and a size. The arrangement of maxels across the face is the pattern that defines the magnet's behavior.
Why are coded magnets strong on contact but weak at a distance?
Adjacent north and south regions sit close together, so their fields cancel each other out a short way from the surface. Most of the field is concentrated near the face. The closer the pole spacing, the shorter the reach, which is the trade for precise behavior at contact.
How is a behavior like alignment or latching programmed in?
Through the geometry of the pattern. An asymmetric layout gives a single correct orientation, so the faces align. Densely packed pole transitions concentrate force at the surface, so the faces latch. Like-facing-like produces repulsion, a spring. The designer chooses the behavior by choosing the arrangement.
Is a multipole magnet the same as a Halbach array?
No. Both arrange magnetization on purpose, but a Halbach array steers the field to be stronger on one side at a working distance, while a coded multipole magnet shapes behavior at or near contact and accepts a short reach. Different goals, different results.
Does the other side need a matching pattern?
For the full designed behavior, yes. A coded face is drawn to work against its complementary partner. Put it against plain steel or a mismatched magnet and you get a reduced, more ordinary pull rather than the programmed effect.
What limits the temperature a coded magnet can take?
The permanent-magnet material it is made from, not the coding. Each material and grade has a maximum safe operating temperature; above it the magnet loses strength or demagnetizes. Choose the material for the thermal environment the way you would for any magnet.
Where do the actual parts come from?
From Polymagnet, the product line of Correlated Magnetics Research, which invented and manufactures coded magnets and produces custom patterns. This site is a reference to the technology; Polymagnet is the source for the magnets themselves.
The maker and the source
The parts and the patterns come from Polymagnet
Advanced multipole magnets were invented by Correlated Magnetics Research and are sold under the Polymagnet name. They design the pole patterns, magnetize the parts, and build custom codes for specific jobs. When you are ready to move from understanding the technology to specifying or buying a part, go to the source.
Visit Polymagnet