Trends in bonded magnets, ferrite Bonded magnet, NdfeB bonded Magnet and its application on Automotive system, Industrial sensors

1. TRENDS OF BONDED NdFeB MAGNETS &
ITS APPLICATIONS
by
N.D.Senthil Ram

2. Magnetics 2N.D.Senthil Ram
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What are Bonded Magnets
Magnet made from a mixture of Magnetic Material
embedded with a polymeric binder / plastic / rubber
material
Bonded Magnet processes
Compression Moulding
Injection Moulding
Extrusion
Calendaring
CharacteristicsBondedMagnets

3. Magnetics 3N.D.Senthil Ram
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Compression Moulding
Stages of Compression Moulding
Process
Mixture
Compact
Cure
Coat/Inspect
Magnetic Material Binder
Magnetize
Blend
Compression Moulding Production
process – Assembly diagram

4. Magnetics 4N.D.Senthil Ram
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Comparison of Manufacturing Processes
Process
Injection
Extrusion
Compaction
Sintering
Calendering
(Rubber)
High
Low
Cost
Low
Excellent
Tolerance
Process Versus
Energy Product
Compression
Ferrite
AlNiCo
NdFeB
SmCo
Process
Calendaring
Extrusion
Injection
Sintering
Energy Product
0.5 1.0 2.0 4.0 6.0 8.0 10.0 15.0 20.0 25.0 30.0 40.0
Cost & Tolerance
with process

5. Magnetics 5N.D.Senthil Ram
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Characteristics
Grades of NdFeB Magnetic Materials
Magnetic Characteristics
Thermal Characteristics
Permograph Characterization
FEMM Characterization
Characteristics

6. Magnetics 6N.D.Senthil Ram
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Grades of NdFeB
In addition to MMPA and IEC
grade designations, we now
have Chinese NdFeB grades
as denoted by:
A number representing
the energy product in
MGOe
A suffix indicating the Hci
(or jHc - intrinsic
coercivity)
Since almost all NdFeB is
now supplied from China
and the designations are
descriptive and easy to use,
it makes sense to apply
them
CharacteristicsCharacteristics
No suffix - 80ºC maximum
M -100º H - 120º SH -150º
UH - 180º EH - 200º

7. Magnetics 7N.D.Senthil Ram
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NdFeB Thermal Behavior
Reversible Temperature Coefficients,
%/ºC
TCBr ≅ -0.07 ~ -0.13 %/ºC
TCHcJ ≅ +0.4 ~ +0.5 %/ºC
Characteristics
T = desired temperature (ºC)
Br (T) = Br adjusted for temperature T
BrRT = Br specification for room temperature (23ºC)
Hci (T) = Hci adjusted for temperature T
HciRT = Hci specification for room temperature(23ºC)
Tcx = reversible temperature coefficient for either Br or Hci
(%/ºC)

8. Magnetics 8N.D.Senthil Ram
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Advantage
Higher loading than injection molded, but lower than
fully dense
Creates a compromise in energy product
Limited to simple geometries: rectangles, cylinders,
arcs
Tight geometric tolerancing except in pressed
thickness
Brittle - requires careful handling
Isotropic powder allows complex magnetizing
patterns
ProcessProcess

9. Magnetics 9N.D.Senthil Ram
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FEMM
Finite Element Method on Magnetics
2D solver for all magnetostatics problems
2D solver in 3D mode
Successive Approximation Method
FEMM magnet Characteristics
Distribution of Magnetic Flux Density of magnet
Magnet Flux Density Distribution Spectrum
Air Gap Flux
Normal Flux Density at Pole point
FEMMFEMM

10. Magnetics 10N.D.Senthil Ram
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Multipole Magnets
Magnets having 2 or more pole pairs
Multi-Magnetic Profiles
Axial Bi-polar
Diametrical Bi-polar
Radial Bi-polar
Radial Uni-polar
Radially Out Multi-polar
Radially In Multi-polar
FEMM Characteristics
Flux Penetration depth
Flux Flow & Direction
Magnetic Field Developed in the magnet
& Fixture
Total Magnetic Energy
FEMM
N
S
N
SN
S
N
S

11. Magnetics 11N.D.Senthil Ram
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Multipole Magnets Results
Magnetic flux density measurement
11mm diametrically magnetized
FEMM result
Peak value 0.1400 Tesla per pole
Measured result
Peak value 0.1385 Tesla per pole
FEMM
FEMM Result
Measured Result

12. Magnetics 12N.D.Senthil Ram
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Applications
Computer peripherals
Audio-Visual Equipments
Military Equipments
Aerospace
Communications
Power Generation
Electrical/electronic goods
Medical
Security industries
Applications

13. Magnetics 13N.D.Senthil Ram
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Sensors
Automotive applications
Speed Sensor Magnet
Drive-by-wire
Brake-by-wire
Steer-by-wire
Throttle position sensor
Active suspension control
Steering wheel angle
Headlight range adjustment
Current measurement
Battery management
Liquid level sensor
Power steering
Applications
Image Courtesy: www.micronas.com

14. Magnetics 14N.D.Senthil Ram
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Sensors
Industrial applications
Commutation of BLDC
motors
Cooling fans
Rpm measurement
Wheel speed sensors
Revolution counting
Final position switch
Contactless switch
Liquid level
Liquid flow
Pressure switch
Rotary switch
Applications
Image Courtesy: www.micronas.com

15. Magnetics 15N.D.Senthil Ram
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Motors
Stepper Motor
BLDC Motor
Starter Motor
Synchronous Motor
Applications

16. Magnetics 16N.D.Senthil Ram
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Permanent Magnet Economics
Most Cost-efficient Magnets
FEMMMarket
Normalizedcost(US$/Watt)
Ferrite
Rubber
Sintered
Ferrite
Alnico
SmCo
5
NdFeB
Sintered
Ferrite
Ferrite
Rubber
NdFeB NdFeB
Power (Watts)
TotalCostofmagnet(US$)
Weight of magnet (g)
Processing cost
Material cost

17. Magnetics 17N.D.Senthil Ram
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Consumption
Application of Bonded
NdFeB Magnets 3,200
MT in 2002
Largest Market is
Computer Peripherals
1,450 MT in 2002
Computer Peripherals
50%
Office Automation
12%Consumer Electronics
11%Automotive
10%
Misc. Motors
5%
Air Conditioning
3%
Small Appliance
3%
Communication
2%
Misc.
4%
Market
FDD Spindle
(Laptop)
4.8%
FDD Stepper
(Pick-Up
Carriage)
7.7 %
ODD Spindle
36.1%
ODD Stepper
(Pick-Up
Carriage)
13.2%
HDD Spindle
38.2%

18. Magnetics 18N.D.Senthil Ram
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Market
TV Set Boxes (DVD-R).
DVD-R
DVR - HDD combined with DVD-R
120 million units/year by 2008.
Computer Game Consoles.
70 million units/year by 2008.
Continued growth in PC sales.
Rapid Growth in non-PC HDD market.
Expected to be larger than PC market
by 2008.
164 million units in 2003.
Estimated 300 million by 2008 (12%
growth).
Growth in PC market will use large
quantities of bonded NdFeB.
Market
36
46
58
70
93
119
34 34 41 49 59 70
0
25
50
75
100
125
150
175
200
2003 2004 2005 2006 2007 2008
MillionsofUnits
Games TV Set Boxes
105
120
139 133 139
164
187
210
235
260
295
0
50
100
150
200
250
300
350
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Actual Forecast
MillionsofUnits

19. Magnetics 19N.D.Senthil Ram
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Q&A

20. Magnetics 20N.D.Senthil Ram
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