Manufacturing of Neo and SmCo Magnets
Raw Materials: NdFeB, SmCo
Induction Melting
Milling
Pressing in field
Temper Treatment in Ar at 1,100 C
EDM, Grinding, Slicing
Temper Treatment at 600 C
Coating or Plating
Magnetizing
Sintering at 1,000 C
NdFeB
SmCo
Finished Parts
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Manufacturing of AlNiCo Magnets
Raw Materials: Al, Ni, Co, Fe
Induction Melting
Casting
Shake-Out
Finished Parts
Shell Molding
Zone Melting
Rou
Solution Treatment 1,200 C
Magnetic Field Treatment
at 800 C
Temper Treatment at 600 C
Finish Grinding
gh Grinding
Magnetizing
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Manufacturing of Ferrites (Ceramic)
Anisotropic Wet Pressed
Calcining
Crushing and Milling
Finished Parts
Pelletizing
Pulverizing to fine powder
Pressing in Magnetic Field
Sintering in multi-stage
Kilns for up to 60hrs
Grinding
Ultra Sonic Cleaning
Magnetizing
Air Drying to soft slurry
Weighing and mixing
with water
Raw Materials: FeO3, SrCo3
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NdFeB Coatings
Properties
Organic: E-Coat
Metallic: Nickel Plating
Application Type
Immersion
Electrodeposition
Epoxy/Urethane
Water Based
Immersion
Barrel
Electroplate
Electroless
Pretreat Process
Alkaline Clean
Acid Etch/Passivate
Alkaline Clean
Electroclean
Acid Etch/Activate
Thickness
15-25
µ
(0.6-1.0 mil)
10-50
µ
(0.4-2.0 mil)
Uniformity
(Flatness/Edges)
Excellent
20% Edge Loss
Good
50% Edge Gain
Durability
Good
Pencil 2H-4H
Excellent
300-1000 V
100
Temp and Humidity
at 85
°
C and 85% RH
250 Hours
Over 1200 Hours
Things to consider when specifying coatings:
•
Platings can be electroless Zn, Ni, Ni-Cu-Ni, Cu-Ni
•
Must have 100% corrosion protection
•
Protect against oxidation at high temperatures
•
Encapsulate all magnetic particles
•
Chip and crack resistance
•
Determine functional properties: bonding of magnet, dielectric, oils
•
Coatings will have different appearance. Epoxy coat can be many colors
Property of Alliance LLC.
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Adverse Effects on Magnetic Performance
Permanent magnets in external magnetic fields work because of the small magnetic
domains which are in "locked" positions and direction. When this formation is formed by
the initial magnetization, the positions are held until the magnet is exposed to external
forces of larger magnitude than the forces which locked the domain positions and
direction. The force needed to affect these domains within the magnetic material vary
depending on the material. Permanent magnets can be produced with extremely strong
inner forces (Hci), which hold the domains in place within the magnet even after
exposure of strong external magnetic fields. Magnetic Stability can be explained as the
magnet's ability to preserve its magnetic characteristics after repeated exposure of
external magnetic fields. Factors that affect a magnet’s stability are time, temperature,
change in reluctance, external magnetic fields, radiation, and vibration.
Time
The effect of time on modern permanent magnets is minimal. Magnets will see changes
immediately after magnetization. These changes, known as "magnetic creep",
occur as
less stable domains are affected by fluctuations in thermal or magnetic energy, even in a
thermally stable environment. This variation is reduced as the number of unstable
domains decreases. Rare Earth magnets are less likely to experience this effect
because of their high coercivity. Studies have shown that a newly magnetized magnet
will lose only a minor percent of its flux as a function of age.
100
99
98
97
96
95
94
93
%Br
1
100
1,000
10,000
Hours at 100ºC
Temperature
Temperature effects fall into three categories:
• Reversible losses
• Irreversible losses
• Metallurgical changes
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