Sintered NdFeB Magnets
Sintered NdFeB
Sintered NdFeB Magnet Come out from the early 1980s. Its main component is Nd2Fe14B with
high magnetic performance. Because of bad anticorrosion, the surface of magnet need handling with various coating for some especial applications from various clients, such as Zn ,Ni, Au ,Epoxy so on.
Characteristics：
1. It has higher magnetic performance. Its maximum energy density ----(BH)max is over 10 times as high as that of ferrite magnet.
2. it has good mechanical property, which is suitable for various processing, such as abrasive cutting, linear cutting and boring so on.
3. Its maximum working temperature can come up to 250 ℃,while it depends on the temperature more.
4. Because of bad anticorrosion, the surface of magnet need handling with various coating or electroplating for some especial applications.
Mechanical property of NdFeB Magnets：
Items
Reference Value
Auxilliary magnetic properties
Br Reversable temperature coefficient (α(Br))/(%/K)
-0.08～-0.12
Hcj Reversable temperature coefficient (α(Hcj)/%/K)
-0.42～-0.70
Curie temperature (Tc)/K
310～380
Recoil Permeability (μrec) [ - ]
1.05
Mechanical physical properties
Density/(g/cm3)
7.50～7.70
Vickers Hardness (Hv)
650
Electrical resistance /(μΩ•m)
1.4
Compressive strength /MPa
1050
Tensile strength /MPa
80
Bending strength /MPa
290
Thermal Conductivity /(W/(m•K) )
6～8
Young's modulus/GPa
160
Thermal expansion (perpendicular to orientation direction)/(10-6/K)
-1.5
Thermal expansion (parellel to orientation direction)//(10-6/K)
6.5
Introduction to Coating of NdFeB magnets：
Coatings
Thickness (µm)
Color
SST
PCT/HAST
Zn
5-15
Bright Blue
16-48
∕
NiCuNi
10-30
Bright Silver
≧24-72
≧24-72
Ni+Sn
10-30
Silver
≧36-72
≧48
Ni+Au
10-30
Gold
≧12
≧48
Ni+Ag
10-30
Silver
≧12
≧48
Epoxy
10-30
Black/Grey
≧48
≧48
NiCu+Epoxy
20-40
Black/Grey
≧72
≧96
Vacuum Aluminium plating
5-30
Silver
≧96
≧96
Passivate/Phosphate
1-3
Dark Grey
Temporary Protection
∕
Remarks： 1. For the same coating, magnets by barrel rolling plating will get better SST results than they're by rack plating.
2. SST condition: 5% sodium choloride solution, 35℃ temperature, continuously spraying for a certain period of time.
3. PCT condition: 2 atm, 95% relative humidity, 121℃, testing the bondability of plating. Zn, epoxy, phosphate platings do not under this test.
4. Testing methods for quality of coating: drop test, cut test, constant temperature and humidity test etc.
Tolerance Range：
方块形位公差控制标准
Block magnet
圆片形位公差控制标准
Block magnet
长度基本尺寸
Length Dimension(mm)
尺寸公差
Tolerance(mm)
垂直度
Perpendicularity
平行度
Parallelism（mm）
外径基本尺寸
Outer diameter(mm)
尺寸公差
Tolerance(mm)
圆度cylindricity
L≤10
±0.03
≤0.5°
0.03
D≤10
±0.03
0.03
10<L≤30
±0.05
≤0.5°
0.04
10<D≤30
±0.04
0.03
30<L≤50
±0.05
≤0.5°
0.05
30<D≤50
±0.05
0.05
L>50
±0.08
≤0.5°
0.08
D>50
±0.06
0.06
瓦型产品形位公差控制标准
Segment magnet
圆环产品形位公差控制标准
Ring magnet
名称
Name(mm)
基本尺寸Dimension(mm)
尺寸公差
Tolerance(mm)
内孔基本尺寸
Inner diameter(mm)
尺寸公差
Tolerance(mm)
同心度Coaxiality（mm）
壁厚
Wall thickness
T≤10
±0.04
D≤10
±0.04
0.06
10<T≤30
±0.05
10<D≤30
±0.05
0.08
30<T≤50
±0.06
30<D≤50
±0.06
0.1
长度 Length
L≤10
±0.04
50<D≤80
±0.08
0.12
10<L≤30
±0.05
D>80
±0.1
0.15
30<L≤50
±0.05
L>50
±0.08
宽度 Width
W<50
±0.05
W≥50
±0.08
Magnetic Property :
Prodution Process:
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