Sintered neodym magnet is manufactured by vacuum powder metallurgy process. The manufacturing process is as follows:
1. Raw Material
|Raw Material of Nd, Pr and Fe||Neodym Magnet Component Analysis|
There are two ways to melt the raw material and make into roughcast neodym material. One is Melting-Crushing. This process is simple, but the particle size of the magnetic powder is quite big. The other is Hydrogen Decrepitation, which can obtain the magnetic powder with smaller particle size.
2.1 Melting – Crushing
|High Vacuum Melting Furnace||Raw material are
melted into alloy
|Magnetic alloy initial form|
|Jaw Crusher||Alloy are crushed
form after crushed
2.2 Strip Casting – HD
The flakes of neodym cast alloys are prepared by using the strip casting technique. Then they are put into the HD machine, with vacuum and heat up to 700~800°C. The hydrogen enters the material in the spaces between the atoms and causes the material to expand. The differential expansion generates stress in the ingot and the alloy flakes break down into fine particle.
Rapid Solidification Strip Casting
|Vacuum Strip Casting Furnace||Neodym alloy flakes
are made by strip casting
|Magnetic alloy initial form|
|Hydrogen Decrepitation Furnace||Alloy flakes break down
into fine powders by HD
form change during HD
The high-pressure nitrogen flow in the jet mill blow the neodym particles with very high speed and make them collide with each other to be shattered. In order to guarantee the purity of the powder particles, and to prevent the detonation caused by the exposure to air, the entire milling process is under the high-purity inert gas protection.
|Jet Milling Furnace||Particle become fine powder
during jet milling flow
form after jet milling
The powders are pressed into shape in a magnetic field to obtain a preferred magnetization direction.
|Isostatic Press Machine||Powders are pressed into shapes||Isostatic press situation|
The material is sintered in the vacuum into roughcast under 1080 degree.
|Vacuum Sintering Furnace||Raw magnets are sintered
in vacuum furnace
|The initial magnet
cell form after sintered
The sintered neodym semi-finished products are made into proper shapes after mechanism process.
|Wire Cutting Machine||Raw magnets are
cut into proper shapes
|The magnet form
after machanism process
The Fe and Nd element in the neodym magnets are very easy to oxidative corrosion. So the coating is needed for protection. The common coating is Ni, Zn and Epoxy. You can find all information of our available surface treatments of sintered neodym magnets here.
|Electroplating Production Line||Magnets are electroplated
with special coatings
Key measurements include remnant flux density, coercivity, and maximum energy product. Only those magnets that pass the inspection are sent to subsequent processes including machining and assembly.
|Inspection Workshop||Worker use callipers or other
measure tools to inspect quality
The neodym magnet will be placed in the magnetizing coils with a high voltage pulse magnetic field until it is completely magnetized. You can find all information of our Methods of Magnetization in our resource center.
|Impulse Type Magnetizer||Magnets are magnetized
in high magnetic field
|Magnetic cell form
|Packing Machine||Magnets will be packed well
with thick plastic foam and carton box