General Introduction

Neodymium magnet (NdFeB), the most widely used type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron and boron. Two kinds of Neodymium, Sintered NdFeB and Bonded NdFeB, are commercial according to their different manufacturing process.

Features

NdFeB is the strongest type of permanent magnet commercially available.
Higher remanence (the strength of the magnetic field), coercivity (resistance to being demagnetized), and energy product (density of magnetic energy) than other type magnets, however often lower curie temperature.

Typical Grades

Sintered NdFeB: N33 - 52 (M,H,SH,UH,EH,AH)
Bonded NdFeB: BNM 5 - 12

Property

Some important properties used to compare permanent magnets are:

• Remanence (Br), measure the strength of the magnetic field;
• Coercivity (Hcb / Hcj), the material's resistance to becoming demagnetized;
• Energy product (BHmax), the density of magnetic energy, which relates to the magnetic flux output per unit volume. Higher values indicate stronger magnets;
• Curie temperature (Tc), the temperature at which the material loses its magnetism.

You could check the Property Table in the below linkage for reference:

• Sintered NdFeB: Property Table
• Bonded NdFeB: Property Table

Shape

Neodymium magnets could be made into various shapes:

Disk/Cylinder, Bar/Block, Ring, Arc, Countersunk, etc.

Custom design is available to us for client`s specific needs

Coating

NdFeB tends to be vulnerable to corrosion, which could cause serious deterioration, including crumbling of a magnet into a powder of small magnetic particles, or spalling of a surface layer. Coating prevents these magnets from oxidation.

Widely used coatings are NiCuNi, Ni, Zn, Epoxy, as well as some special coatings, for example, Copper, Gold, Silver, and etc.

Application

Neodymium magnets have replaced Alnico and Ferrite magnets in many of the myriad applications in modern technology where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets for a given application. Some examples are:

• Permanent Magnet Motor/Generator
• Magnetic Separator/ Filter
• Magnetic Lifter
• Magnetic Pot/Hook
• Magnetic Bearings and Couplings
• Magnetic Sensors
• Magnetic Resonance Imaging (MRI)
• Bench-top NMR spectrometers
• Loudspeakers and headphones

Production

Sintered NdFeB:

Raw Materials → Melting → Pulverizing → Aligning & Pressing → Sintering → Annealing → Machining → Surface Treating → Magnetizing → Inspecting → Packing & Delivery

Bonded NdFeB:

Rapidly quenched NdFeB Powder → Particle size adjustment → Kneading with other material → Molding → Secondary Process, Surface Treating, Grinding → Inspecting → Packing & Delivery