Understanding Magnetization Direction: Axial, Diametrical, Radial and Multi-Pole
Introduction
When industrial buyers request custom magnets, they often describe what the magnet needs to do: hold, push, pull, sense or separate. But the final magnet design depends on one critical decision that many first-time buyers overlook: magnetization direction.
Magnetization direction determines where the North and South poles are located on the magnet. This affects not only the magnetic force but also how the magnet can be assembled, how it performs in the final product, and how much it will cost to produce.
For custom magnet projects, choosing the wrong magnetization direction can mean re-engineering the product or scrapping the order. This is why magnetization direction should be confirmed early-ideally before the first prototype.
What Does Magnetization Direction Mean?
During magnet manufacturing, the sintered NdFeB is exposed to a strong magnetic field. This process aligns the magnetic domains inside the material and creates the North and South poles.
The direction of that magnetic field during manufacturing determines where the poles end up:
- Axial magnetization: The poles are at the two flat ends (top and bottom of a disc or cylinder).
- Diametrical magnetization: The poles are on opposite sides of the magnet (like left and right halves of a disc).
- Radial magnetization: The poles are arranged from center to outer edge (like a wheel or ring).
- Multi-pole magnetization: Multiple pole pairs are created on the same magnet surface (north-south-north-south pattern).
Axial Magnetization: The Most Common Choice
Axial magnetization is the most straightforward and economical. The magnetic field during manufacturing is applied along the axis (height) of the magnet. The result is one North pole at the top and one South pole at the bottom.
Typical use cases:
- Simple disc or block magnets held by hand
- Motor rotors with stacked magnet layers
- Magnetic holders and pot magnets
- Sensor magnets in simple on-off applications
- Magnetic couplings
Advantages:
- Lowest manufacturing cost
- Easiest tooling
- Standard lead times
- Familiar to most suppliers
Limitations:
- The magnet can only pull or push along its height
- Not suitable when magnetic force is needed along a different direction
- If the assembly space is very flat, an axial magnet may be too tall
Diametrical Magnetization: When Side-to-Side Force Is Needed
Diametrical magnetization creates poles on opposite flat sides of a disc. This is useful when the magnet needs to attract or repel another magnet sideways, or when the magnet needs to be mounted in a thin slot.
Typical use cases:
- Magnetic brakes and clutches
- Thin magnetic encoders and angle sensors
- Sliding or rotating assemblies where side force matters
- Safety switches that detect position change
Advantages:
- Pulls or pushes sideways, not just vertically
- Useful in flat or compact designs
- Good for sliding or rotating sensor applications
Limitations:
- More expensive than axial magnetization
- Requires custom tooling
- Longer lead time
- Magnetic field pattern is different-not all applications can use it
Radial Magnetization: For Rotating Applications and Ring Magnets
Radial magnetization creates poles arranged radially-from the center outward toward the outer edge. Imagine a ring magnet with alternating North and South on the inner radius and outer radius, or the poles distributed around a ring like a compass.
Typical use cases:
- Permanent magnet motors with rotor rings
- Large generators and wind turbine magnets
- Magnetic bearings and couplings
- Encoder rings with multiple position sensing
- Rotary dampers and magnetic brakes
Advantages:
- Concentrates magnetic field in a specific rotational plane
- Enables compact motor designs
- Useful for high-speed rotating applications
Limitations:
- Significantly more expensive than axial or diametrical
- Requires specialized magnetization equipment
- Long lead times
- Not all magnet shapes can be radially magnetized (rings and cylinders mainly)
Multi-Pole Magnetization: Many Poles on One Surface
Multi-pole magnetization creates multiple pole pairs on the same magnet surface-such as North-South-North-South around a ring, or a checkerboard pattern on a disc.
Typical use cases:
- High-resolution encoders and angle sensors
- Stepper motor rotors
- Magnetic linear encoders
- Position detection systems requiring multiple sensor points
- Specialized industrial automation
Advantages:
- Enables high-resolution sensing
- Compact design with multi-point detection
- Useful for precision position feedback
Limitations:
- Most expensive magnetization option
- Requires advanced equipment
- Long lead time
- Demands high precision in magnet dimensions and placement
How to Choose the Right Magnetization Direction
Before choosing, answer these questions:
1. How should the magnet attach or work?
If it pushes downward, axial may work. If it attracts sideways, diametrical is better. If it rotates, radial may be needed.
2. What is the available space?
If space is very flat, diametrical or thin axial designs may be better. If the magnet can be tall, axial is simpler.
3. What is the production volume?
For small quantities, axial is fast and cheap. For large volumes, radial or multi-pole magnetization cost becomes proportionally lower.
4. What is the required magnetic force and field pattern?
Simple holding needs simple magnetization. High-precision sensor applications need multi-pole.
5. What is the budget and lead time?
Axial is fastest and cheapest. Anything else costs more and takes longer.
Magnetization Direction Affects Tolerance and Assembly
Custom magnet suppliers can achieve different tolerances depending on the magnetization direction:
- Axial: Tolerances can be very tight (±0.05 mm typical for sintered NdFeB)
- Diametrical: Tolerances are still good but may be slightly looser
- Radial: Tolerances require careful process control, especially for ring magnets
- Multi-pole: Requires the tightest process control; tolerance verification with a Gaussmeter is common
When requesting a quote, always specify the required tolerance and confirm whether your supplier can achieve it with your chosen magnetization direction.
How HIMAGNET Supports Custom Magnetization
HIMAGNET manufactures custom neodymium magnets with axial, diametrical, radial and multi-pole magnetization options. Our team works with your drawing or application description to recommend the right magnetization direction before production.
For motor, sensor, encoder and automation projects, we can support custom magnetization combined with custom size, grade, coating and tolerance to match your assembly requirements.
Not sure which magnetization direction is right for your custom magnet? Share your application details, available space, required magnetic force and volume with HIMAGNET. Our team will recommend the best magnetization direction and provide a quote.
