Neodymium Ring Magnet – 20mm OD x 10mm ID x 8mm H

The Neodymium Ring Magnet – 20mm OD x 10mm ID x 8mm H is a compact rare earth permanent magnet measuring 20mm outside diameter (OD) x 10mm inside diameter (ID) x 8mm high. Manufactured from Neodymium Iron Boron (NdFeB), this annular magnet combines a practical central through-hole with the high magnetic performance relative to size associated with neodymium magnetic material.

The 10mm central opening allows the magnet to be incorporated around suitably sized shafts, rods, tubes, pins, locating features and other components where appropriate mechanical clearance is provided. With an 8mm height and 20mm outside diameter, the magnet has a substantial ring-shaped profile suitable for engineering, manufacturing, product assemblies, sensors, fixtures, positioning systems, research, prototypes and custom OEM applications.

Also known as a neodymium ring magnet, rare earth ring magnet, NdFeB ring magnet, annular magnet, donut magnet or ring-shaped rare earth magnet, this magnetic component provides permanent magnetic operation without electricity, batteries or charging.

Key Features

• Outside diameter (OD): 20mm
• Inside diameter (ID): 10mm
• Height: 8mm
• Shape: Ring / annular
• Magnetic material: Neodymium Iron Boron (NdFeB)
• Magnet type: Rare earth permanent magnet
• Central opening: 10mm straight through-hole
• Compact ring-shaped geometry
• High magnetic performance relative to size
• Suitable for engineering and manufacturing
• Useful for product assemblies
• Suitable for positioning and alignment
• Useful for sensors and instrumentation
• Suitable for fixtures and mechanical assemblies
• Useful for research and laboratory applications
• Suitable for prototypes and custom OEM products
• Permanent magnetic operation
• No electricity, batteries or charging required

Common Applications

• Engineering
• Manufacturing
• Product assemblies
• Mechanical assemblies
• Component positioning
• Alignment systems
• Fixtures and jigs
• Sensors and instrumentation
• Position detection
• Proximity sensing
• Magnetic switching
• Machinery
• Equipment housings
• Research and development
• Laboratory equipment
• Prototype devices
• Custom OEM products

20mm OD x 10mm ID x 8mm High Ring Magnet

This neodymium ring magnet measures:

• 20mm outside diameter
• 10mm inside diameter
• 8mm height

The central opening is half the magnet's outside diameter, creating an annular magnetic body with a compact overall footprint.

The ring geometry can be useful where another mechanical component needs to pass through or occupy the centre of the magnetic assembly.

Potential applications include:

• Circular housings
• Mechanical assemblies
• Sensor systems
• Positioning devices
• Magnetic alignment
• Fixtures
• Prototype mechanisms
• Custom products

The stated dimensions describe the physical geometry of the magnet and should not be interpreted as a pull-force or load rating.

What Is a Neodymium Ring Magnet?

A neodymium ring magnet is an NdFeB permanent magnet featuring a central through-hole.

Unlike a solid disc or cylinder magnet, the annular shape leaves the centre open, which can provide additional options for mechanical integration.

Depending on the complete design, ring magnets can be incorporated into:

• Shafts and rod assemblies
• Positioning systems
• Sensors
• Magnetic couplings
• Fixtures
• Equipment components
• Experimental magnetic systems
• Custom OEM products

The ring shape itself does not establish the magnet's magnetisation direction or pole configuration.

Neodymium Iron Boron Rare Earth Material

Neodymium Iron Boron is a high-performance rare earth permanent magnetic material commonly selected where strong magnetic properties are required from compact dimensions.

NdFeB magnets are widely used in applications involving:

• Magnetic attraction
• Positioning
• Alignment
• Sensing
• Switching
• Product integration
• Magnetic assemblies

The specific neodymium grade has not been supplied for this magnet and should not be assumed.

10mm Central Through-Hole

The magnet features a 10mm inside diameter, forming a straight central opening through the 8mm height.

Depending on the finished design, this opening may provide space for:

• Shafts
• Rods
• Tubes
• Pins
• Locating features
• Housings
• Other mechanical components

However, the stated 10mm inside diameter should not automatically be interpreted as compatibility with a 10mm shaft, bolt, tube or other component.

Mechanical fit depends on the actual dimensions, dimensional tolerances and required clearance of both components.

Because neodymium is brittle, the magnet should not be force-fitted around an oversized or excessively tight component.

Product and Mechanical Assemblies

Ring magnets can be particularly useful where the magnet must integrate with another circular mechanical component.

Potential applications include:

• Equipment components
• Mechanical assemblies
• Positioning systems
• Alignment mechanisms
• Sensor assemblies
• Fixtures
• Prototype products
• Custom housings
• OEM equipment

The finished assembly should support the magnet appropriately and avoid placing excessive mechanical stress on the brittle NdFeB material.

Sensors and Instrumentation

Neodymium ring magnets may be incorporated into sensing systems where their magnetic field configuration is compatible with the selected sensor.

Potential uses include:

• Position detection
• Proximity sensing
• Magnetic switching
• Hall-effect sensing
• Reed switch activation
• Instrumentation
• Equipment monitoring

Sensor performance depends on factors including:

• Magnetisation direction
• Pole orientation
• Distance between magnet and sensor
• Sensor sensitivity
• Installation geometry

The magnetisation configuration has not been supplied, so it should be confirmed before designing a sensor system around this magnet.

Magnetisation Direction

Neodymium ring magnets can be manufactured with different magnetisation configurations.

A ring magnet may potentially be:

• Axially magnetised through its 8mm height
• Diametrically magnetised across its diameter
• Radially magnetised
• Multipole magnetised
• Manufactured with another application-specific pole configuration

The magnetisation direction and pole configuration have not been supplied and should not be assumed from the ring geometry.

Confirm this specification where magnetic field direction is important.

Magnetic Coupling Applications

Ring magnets can also be incorporated into magnetic coupling systems where the geometry and pole configuration are appropriate.

Potential uses may include:

• Contactless coupling concepts
• Rotating mechanisms
• Positioning systems
• Magnetic alignment
• Prototype mechanical systems

The suitability of this magnet for a specific coupling depends strongly on its magnetisation configuration, magnetic grade, spacing and the design of the complete magnetic circuit.

No coupling force or torque should be assumed from the dimensions alone.

Magnetic Performance

Practical magnetic performance depends on factors including:

• Neodymium grade
• Magnetisation direction
• Pole configuration
• Magnetic circuit design
• Target steel composition
• Target steel thickness
• Available contact area
• Air gaps
• Surface condition
• Installation geometry
• Load direction
• Mechanical leverage

No specific pull force or magnetic flux density in Gauss has been supplied.

These values should not be inferred from the 20mm OD x 10mm ID x 8mm H dimensions alone.

Pull Force vs Safe Working Load

Where a magnet has a published pull-force figure, this is generally measured under defined test conditions.

It should not automatically be treated as the amount of weight the magnet can safely support in a practical installation.

Real-world holding may be reduced by:

• Thin target steel
• Paint
• Powder coating
• Dirt
• Rust
• Air gaps
• Uneven contact
• Side loading
• Vibration
• Mechanical leverage

No pull-force value has been supplied for this product.

The magnet's dimensions do not represent a safe working load.

Direct Pull vs Shear Force

Where the magnet is used against ferromagnetic steel, magnetic holding will vary according to the direction of the applied load.

Direct pull occurs when the magnet is separated perpendicular to the target.

Shear loading occurs when the magnet is encouraged to slide parallel to the target.

Shear holding is influenced by:

• Surface friction
• Surface condition
• Installation orientation
• Contact area
• Air gaps
• Mechanical leverage

Test the finished assembly under realistic conditions where magnetic holding is important.

Air Gaps and Magnetic Attraction

Even relatively small gaps between a neodymium magnet and its magnetic target can reduce attraction.

Air gaps may be created by:

• Paint
• Powder coating
• Adhesive
• Plastic
• Protective films
• Dirt
• Rust
• Product housings
• Mechanical clearance

For maximum practical attraction, unnecessary separation should generally be minimised.

Target Steel Thickness

The properties of the target steel also influence magnetic holding.

Important factors include:

• Steel composition
• Steel thickness
• Target dimensions
• Surface condition
• Contact geometry
• Magnetic saturation

Thin steel may not provide the same magnetic response as a suitable thicker ferromagnetic target.

For performance-critical applications, test the magnet against the actual target material.

Bonding a Neodymium Ring Magnet

This ring magnet may be adhesively bonded into an appropriately designed housing or recess.

Before bonding:

• Confirm the required magnetisation direction
• Confirm polarity where multiple magnets are used
• Clean the magnet and mating surface
• Remove grease, dust and contamination
• Select an adhesive compatible with the actual magnet surface
• Provide appropriate mechanical clearance
• Avoid force-fitting
• Allow the adhesive to cure according to its instructions

The specific coating or plating has not been supplied, so adhesive compatibility with the actual surface finish should be confirmed.

Avoid Force-Fitting Through the 10mm Hole

Neodymium Iron Boron is hard and brittle.

Do not force an oversized shaft, tube, bolt, pin or other component through the 10mm central opening.

Excessive mechanical pressure may cause the ring magnet to:

• Chip
• Crack
• Split
• Fracture

Provide appropriate clearance based on the actual dimensions and tolerances of the magnet and mating component.

Do Not Machine Neodymium Magnets

Finished neodymium magnets should not be modified using conventional workshop processes.

Avoid:

• Drilling
• Cutting
• Grinding
• Crushing
• Machining
• Enlarging the central hole

If a different hole size or magnet geometry is required, select a magnet manufactured to the required dimensions.

Compatible Target Materials

Neodymium magnets attract suitable ferromagnetic materials, including:

• Mild steel
• Iron
• Magnetic steel
• Compatible ferromagnetic components

They will not effectively attract inherently non-magnetic materials such as:

• Aluminium
• Copper
• Brass
• Plastic
• Timber
• Glass

Many stainless steel grades can also be weakly magnetic or non-magnetic and should be tested before relying on magnetic attachment.

Neodymium vs Ferrite Ring Magnets

Neodymium and ferrite ring magnets provide different performance characteristics.

Neodymium ring magnets generally provide:

• Higher magnetic performance relative to size
• Strong magnetic properties from compact dimensions
• Advantages in space-restricted assemblies
• Suitability for compact sensors and engineered products

Ferrite ring magnets generally provide:

• Lower cost
• Good natural corrosion resistance
• Good resistance to demagnetisation
• Suitability where larger magnetic dimensions are acceptable

Neodymium is commonly selected where higher magnetic performance within a compact ring-shaped component is an important design requirement.

Permanent Magnetic Operation

This neodymium ring magnet is a permanent magnet.

It requires:

• No electricity
• No batteries
• No charging
• No external power supply

Its magnetic field remains continuously active during normal use.

Technical Specifications

• Product Type: Neodymium Ring Magnet
• Alternative Names: Rare Earth Ring Magnet, NdFeB Ring Magnet, Neodymium Annular Magnet, Donut Magnet, Ring-Shaped Rare Earth Magnet
• Outside Diameter (OD): 20mm
• Inside Diameter (ID): 10mm
• Height: 8mm
• Central Opening: Straight through-hole
• Shape: Ring / Annular
• Magnetic Material: Neodymium Iron Boron (NdFeB)
• Magnet Type: Rare Earth Permanent Magnet
• Magnetic Operation: Permanent
• Power Required: None
• Compatible Targets: Suitable ferromagnetic iron and steel
• Primary Functions: Magnetic attraction, positioning, alignment, sensing and product integration
• Typical Applications: Engineering, manufacturing, product assemblies, sensors, fixtures, machinery, research, prototypes and OEM products

Safety and Handling

Neodymium magnets can attract other magnets and ferromagnetic objects suddenly and with considerable force.

Handle carefully to reduce the risk of:

• Pinched fingers
• Trapped skin
• Magnet collisions
• Chipping
• Cracking
• Fragmentation

Neodymium is brittle despite its strong magnetic properties. Eye protection may be appropriate where fragmentation is possible.

Keep powerful permanent magnets an appropriate distance from:

• Pacemakers
• Implanted medical devices
• Magnetic storage media
• Magnetic cards
• Sensitive electronic equipment

Keep magnets securely away from children.

Please Note

This product is a Neodymium Ring Magnet measuring 20mm outside diameter (OD) x 10mm inside diameter (ID) x 8mm high, manufactured from Neodymium Iron Boron (NdFeB) rare earth magnetic material.

The 10mm inside diameter describes the physical size of the central through-hole and should not automatically be interpreted as compatibility with a 10mm shaft, tube, bolt or other component. Appropriate mechanical clearance and dimensional tolerances should be considered.

No specific neodymium grade, pull force, Gauss rating, coating or plating, magnetisation direction, pole configuration, dimensional tolerance or maximum operating temperature has been supplied and these specifications should not be assumed.

Actual magnetic performance depends on the neodymium grade, magnetisation configuration, magnetic circuit, target material, target steel thickness, available contact area, air gaps, surface condition and installation geometry.

Neodymium is a hard and brittle magnetic material. Avoid impact, force-fitting, drilling, cutting, grinding or machining.

The stated dimensions describe the physical geometry of the magnet and do not represent its pull force, holding capacity or safe working load.

This magnet is not certified lifting equipment and should not be used for overhead or safety-critical lifting.