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Applications Guide of Permanent Magnet in Industry

What is the use of permanent magnet except for compass?
Modern permanent magnet has plenty of uses. And the permanent magnet used on compass is the traditional type. You would be surprised by the uses of magnets around us. For example, every time you use your IPHONE, magnets are being utilized in permanent magnet vibration motor, speaker and sensor to perform certain operations. Then our IPHONE have vibrant state, quality sound and different intelligent functions.

Types of Permanent Magnet Uses:

Based on how magnetic force is applied, there are four basic methods to categorize permanent magnets’ uses

Category 1: The attraction and/or repelling force of magnet. Permanent magnets used on Daily life mainly belong to this category. And it is the simplest use of magnets. This category includes:

Magnetic Clasps
Magnetic Name Badge
Magnetic Hook
Pot Magnet
Lifting Magnet
Magnetic Filter
Cow Magnet
Magnetic Packing
Magnetic Toy
Magnetic Acrylic Frame
Magnetic Charge Cable
Magnetic Screen Door Curtain
Magnet System with Rubber Coated
Magnetic separator
Magnetic holding device
Magnetic torque drive
Magnetic bearing device

Category 2: Using magnetic field to convert electric force into mechanical force. This mainly belongs to industrial use. This category includes:

Electric motors
Meters, Relays
Actuators, linear, and rotational

Category 3: Using magnetic field to convert mechanical force into electric force. This category mainly belongs to industrial use which includes:

Generators and alternators
Eddy current brakes

Category 4: Using magnetic field to affect ion beams. Of course it is industrial use. This category includes:

Magnetic focused cathode-ray tubes
Ion Pumps
Klystrons Traveling Wave Tubes
Cathode-ray tubes

Based on Types of Permanent Magnet, there are five type permanent magnets and its application


Magnet Material




Sintered Neodymium Magnets

Very high Hc and Hci
High energy for size
Strong magnetic force
More economical than Samarium Cobalt
Good in room temperature situations
Relatively high price
easily oxidized
temperature coefficient of .13%/ degree centigrade

Microphone assemblies
Magnetic separators
Computer rigid disc drives
Linear actuators
Hammerbank printers
DC Motors
Automotive starters
Servo Motors


Bonded Neodymium Magnets

Compared with sintered ndfeb, Strong Mechanical
multi-poles magnetization direction
make to a variety of shapes
good size accuracy

power tools
auto micromotor
office automation
communication tools
house electric appliance


AlNiCo Magnets

Low Hc
Higher Br and Bh(max) than ceramic magnet
Strong Mechanical
Very temperature stable
Good corrosion resistance
Cast AlNiCo can cast to a variety of shapes
with minimum reversible temperature coefficient,
can work above 600 degrees Celsius.
Can change magnetization direction
Sintered AlNiCo has better tolerance raw material
to make mini size product

electron tubes
traveling wave tubes
holding magnets
watt-hour meters (bearings and dampeners)
clutches & bearings
coin acceptors
bell ringers
guitar pickups
cow magnets
automotive sensors
process control instruments


Samarium Cobalt Magnets

Expensive material
High Hc and Hci
High Bhmax
Strong magnetic force
Very good temperature stability

Computer rigid disc drives
Traveling wave tubes
D.C. Motors
growing automotive applications
linear actuators


Ferrite Magnets

low magnetic force
compared to Alnico, higher Hc and Hci
can only make simple shapes
fragile material
Cheap material
require expensive tooling for every size
temperature sensitive (0.2%°C.)

DC permanent magnet motors
garden tractors
outboard motors
Magnetic Resonate Imaging (MRI)
DC brushless motors with controllers
dental equipment

Based on functions, there are 7 Categories as list below which posted by Karl J. Strnat in his paper:

1. Electro-Mechanical Machines and Devices

a) Electric Motors
Types-DC (commutator and brush less), synchronous,induction start/synchronous run, hysteresis; rotary andlinear; continuous, servo, torque, or stepping operation
Geometries — permanent magnet stator (conventionaland iron less armatures), permanent magnet rotor; inneror outer rotor; radial or axial field (disc) motors.

b) Generators
Types — Magnetos, ignition or other pulse generators,tachometers, auxiliary exciters, alternators, multiphase synchronous machines, homopolar DC machines.
Geometries-permanent magnet rotor; radial or axialfield; stator winding with or without iron

c) Electro-Mechanical Actuators
Linear — Force motors for valves, etc.; printer hammer mechanisms; computer disc-drive head actuators (VCM); laser focusing and tracking(optic/magneto-optic recording: audio CDs, video, data); recorder pen positioners. Rotary-Disc drive VCMs; aircraft controlsurface actuators; materials handling robots.

d) Measuring Instruments
Moving-coil (d’Arsonval and long scale geometries) and moving-magnet meters for many functions

e) Electric Current Control
Circuit breakers, reed switches, miniature biased relays, thermostats, automotive ignition, eddy, Current motor overspeed switch, arc blow-out magnets

2. Acoustic Transducers

a) Sound Generators:
Loudspeakers, earphones, telephone receivers, ringers, buzzers, ultrasonic generators

b) Sound Receivers:
Dynamic microphones, ultrasound pickups

c) Other Audio Frequency Transducers
Phonograph pickups

3. Mechanical Force and Torque Applications

a) Contact Holding and Lifting
Machine-tool chucks, grippers, load-lifting magnets (electrically switchable), tool holders, door catches, refrigerator seals, advertising signs, toys, and many more.

b) Traction Devices
Conveyers, separators for ores and other materials, fieldgradient water purifiers, photocopier rollers.

c) Couplings and Brakes
Synchronous torque couplings, linear followers, eddy current and hysteresis couplers and brakes, rotary-tolinear motion converter.

d) Magnetic Bearings and Suspensions
Passive-watt-hour meters, ultra-centrifuges, record player tone-arm support, textile spinning turbines. Partly active servoed systems-gyros, satellite momentum and energy wheels, laser beam scanner, turbo-molecular pumps, electro-magnetic tracked vehicle levitation.

e) Electro-Balances
Modern weighing devices from analytical balances to supermarket scales and truck weigh stations

4. Microwave/MM-Wave Devices, Electron Ion Beam Control

a) Power Tubes
Magnetrons (radar, kitchen ovens); PPM focusing for TWTs and klystrons; crossed-field amplifiers, gyrotrons, etc

b) Waveguide Devices
Biasing ferrite or YIG elements in resonance filters, switches, and isolators

c) Particle Accelerators, Synchrotron Radiation Sources, free Electron Lasers
Lenses, deflecting magnets, wigglers, undulators

d) Mass Spectrometers
Deflecting magnets

e) Cathode Ray Tubes
Ion trap, focusing, pin-cushion correction

5. Sensors, Electric Signal Transducers

a) Transducers Using Permanent Magnetss
Inductive, Hall effect, magnetoresistive, temperature sensitive elements

b) Quantities Measured
Position, velocity, acceleration, fluid and heat flow, pressure, vibration, temperature, etc

c) Use Areas
Automotive, industrial, aerospace, computer peripherals (keyboards, read/write head sensors), office equipment

6. Medical Electronics and Bioengineering

a) NMR Imaging Devices:
DC field source for MRI tomographs

b) Mechanical Prostheses
Eyelid muscle assist, dental prostheses, stoma seals, valves, heart-assist pumps, artificial limbs

c) Surgical Clamps
For incisions and severed blood vessels

d) Diagnostic Aids
Catheters; sensors/transducers

e) Miniature Hearing Aids
External devices and implants

7. Miscellaneous Applications

a) Magnetic Locks
Key and cylinder with encoded magnets

b) Magnetic Jewelry
Necklaces, clasps, earrings

c) Electronic Choke
Steady bias field for core

d) Magnetic Bubble Memory
Bias field for bubble element

e) Vacuum Technology
Ton getter pumps, vacuum gauges.

Contact information
China Magnets Source Material Limited
Tower B, Qiongzhu Building,
Huawang Rd,Longhua District,
Tel: +86 755 28174720
Fax: +86 755 28174720