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Diametric Neodymium Magnets
Radial & Diametrical Polarity
Diametrically Magnetized Neodymium Magnets
Engineered for rotational sensing and multi-axis mechanical assemblies, these sintered rare earth neodymium magnets (NdFeB) are magnetized across their diameter (side-to-side) rather than through their axial thickness. This orientation places the North and South poles on opposite curved edges, generating an alternating sinusoidal magnetic field ideal for rotary encoders, Hall-effect angle sensors, magnetic stirrers, and low-friction couplings.
Looking for standard face-magnetized round magnets? If your design requires poles on the flat circular ends for flush mounting or cabinet latches, explore our standard Neodymium Disc Magnets (thickness < diameter) or Neodymium Cylinder & Rod Magnets (length ≥ diameter).
Side-to-Side Orientation
Poles run across the diameter, creating a dynamic rotating field when spun on axis.
Rotary Sensing & Encoders
Optimized targets for Hall-effect ICs, angle sensors, tachometers, and flow meters.
Grades N35 to N52
High-flux sintered alloys providing tight air-gap coupling and signal stability.
Cylinder & Disc Profiles
Stocked in compact round and rod geometries with standard Ni-Cu-Ni corrosion plating.
Related Round Magnets: Diametric Magnets Cylinder Magnets (Axial) Disc Magnets (Axial) Countersunk Discs
Engineering Guide: Diametrically Magnetized Rare Earth Magnets
Unlike standard neodymium magnets which are magnetized along their central geometric axis (through the thickness or length), diametrically magnetized magnets are aligned across their diameter. In this configuration, the North pole is located on one curved side of the cylinder or disc, and the South pole is located on the opposing curved side.
Diametric vs. Axial Magnetization
| Specification | Diametrical Magnetization | Axial Magnetization (Standard) |
|---|---|---|
| Pole Location | Opposing curved side surfaces | Opposing flat end faces |
| Axial Rotation Effect | Produces alternating North/South field | Field remains stationary relative to rotation |
| Common Use Cases | Rotary encoders, Hall sensors, couplings, stirrers | Holding fixtures, latches, lifting, assemblies |
Key Engineering Applications
- Rotary Encoders & Shaft Sensors: Mounted to the end of a spinning motor shaft directly above or beside a Hall-effect IC to detect angular position, velocity, and RPM with zero mechanical contact.
- Magnetic Couplings: Enables torque transfer through non-magnetic containment barriers (such as sealed chemical pumps or hermetic enclosures) without dynamic seals.
- Magnetic Stir Bars & Drive Systems: Used in laboratory and industrial fluid mixers where an external rotating magnetic field drives internal stir bars through glass or plastic vessels.
- Flow Meters & Fluid Instrumentation: Installed in turbine paddle wheels to send clean digital magnetic pulses to external counting electronics as fluid passes.
Frequently Asked Questions
How can I determine the pole orientation of a diametric magnet?
Because the flat faces contain both North and South halves split across the center, viewing the magnet with magnetic viewing film reveals a distinct transition line dividing the face. You can also identify poles using a digital gaussmeter or by gently balancing the magnet on a smooth surface next to a known reference magnet.
Are diametric magnets suitable for holding or cabinet latches?
Generally no. When attached to flat steel, direct pull force is lower than an equivalent axially magnetized magnet because each flat face carries both polarities rather than a unified single pole. For holding applications, use axially magnetized disc magnets.
What are the operating temperature ratings?
Standard stock grades operate up to 80°C (176°F). For high-temperature sensor assemblies or close motor proximity, CMS Magnetics provides custom high-coercivity grades: M (100°C), H (120°C), and SH (150°C).
Can custom diametric cylinders or rings be manufactured?
Yes. We supply custom OEM runs with tailored aspect ratios, tight grinding tolerances (±0.05 mm), specialized coatings (epoxy, parylene), and multi-pole diametrical magnetization for high-resolution encoder designs.