Magnetization Process

The Gauss

 is the unit of magnetic induction, B, in the cgs electromagnetic system. One gauss 

is equal to one maxwell per square centimeter. 

 

A Gaussmeter

 is an instrument that measures the instantaneous value of magnetic induction, 

B. Its principle of operation is usually based on one of the following: the Hall-effect, nuclear 

magnetic resonance (NMR), or the rotating coil principle. 

 

The Gilbert

 is the unit of magnetomotive force, F, in the cgs electromagnetic system. 

 

A Hysteresis loop

 is a closed curve obtained for a material by plotting (usually to rectangular 

coordinates) corresponding values of magnetic induction, B, for ordinates and magnetizing force, 

H, for abscissa when the material is passing through a complete cycle between definite limits of 

either magnetizing force, H, or magnetic induction, B. 

 

Irreversible losses

 are defined as partial demagnetization of the magnet, caused by 

exposure to high or low temperatures external fields or other factors. These losses are 

recoverable by remagnetization. Magnets can be stabilized against irreversible losses by partial 

demagnetization induced by temperature cycles or by external magnetic fields 

 

A keeper

 is a piece (or pieces) of soft iron that is placed on or between the pole faces of a 

permanent magnet to decrease the reluctance of the air gap and thereby reduce the flux leakage 

from the magnet. It also makes the magnet less susceptible to demagnetizing influences. 

 

Leakage flux

 is flux, 

φ

, whose path is outside the useful or intended magnetic circuit; 

measured in maxwells. 

 

The major hysteresis loop

 of a material is the closed loop obtained when the material is 

cycled between positive and negative saturation. 

 

The Maxwell

 is the unit of magnetic flux in the cgs electromagnetic system. One maxwell is 

one line of magnetic flux. 

 

The neutral section

 of a permanent magnet is defined by a plane passing through the 

magnet perpendicular to its central flux line at the point of maximum flux. 

 

The Oersted

 is the unit of magnetic field strength, H, in the cgs electromagnetic system. One 

oersted equals a magnetomotive force of one gilbert per centimeter of flux path. 

 

An open circuit

 condition exists when a magnetized magnet is by itself with no external flux 

path of high permeability material. 

 

The operating line

 for a given permanent magnet circuit is a straight line passing through the 

origin of the demagnetization curve with a slope of negative Bd/Hd. (Also known as permeance 

coefficient line.) 

 

The operating point

 of a permanent magnet is that point on a demagnetization curve 

defined by the coordinates (BdHd) or that point within the demagnetization curve defined by the 

coordinates (BmHm). 

 

An oriented (anisotropic) material

 is one that has better magnetic properties in a given 

direction. 

 

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A permeameter

 is an instrument that can measure, and often record, the magnetic 

characteristics of a specimen. 

 

Reversible temperature coefficients

 are changes in flux which occur with temperature 

change. These are spontaneously regained when the temperature is returned to its original point. 

 

Magnetic saturation

 of a material exists when an increase in magnetizing force, H, does not 

cause an increase in the intrinsic magnetic induction, B, of the material. 

 

A search coil

 is a coiled conductor, usually of known area and number of turns, that is used 

with a fluxmeter to measure the change of flux linkage with the coil. 

 

The temperature coefficient

 is a factor which describes the reversible change in a 

magnetic property with a change in temperature. The magnetic property spontaneously returns 

when the temperature is cycled to its original point. It usually is expressed as the percentage 

change per unit of temperature. 

 

An unoriented (isotropic)

 material

 has equal magnetic properties in all directions. 

 

 

 

 

 

 

 

Conversions 

 

Designation CGS 

SI 

Conversion 

H 

Oersted (Oe) 

A/m 

1A/m = 12.57 x 10

3 

 Oe 

B 

Gauss (G) 

Tesla (T) 

1 T = 10,000 G 

φ 

Maxwell (M) 

Weber (Wb) 

1 Wb = 10

8

 M 

F 

Gilbert 

Amp-turn 

1 A-t = 1.256 Gilbert 

BH MGOe 

Joule/m

3

 1 

J/m

3

 = .1257 x 10

6

 GOe 

10

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Hysteresis and Demagnetization Curves 

 

 

 

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Magnetic Products for American Industry 

  

15.0         12.5            10.0             7.5               5.0              2.5          

H kOe

 

 

  

 

10.0

 

 

 

9.00 

 

 

8.00 

 

 

 

 

7.00 

 

 

6.00 

 

 

5.00 

 

 

 

 

4.00 

 

 

3.00 

 

 

2.00 

 

 

 

 

 

 

1.00 

 

 

B kG

 

150 C 

125 C 

75 C 

25 C 

- 40 

Residual Induction Br 

G 

6,400 

6,800 

Coercive Force Hc 

Oe 

5,320 

5,720 

Intrinsic Coercive Force Hci 

Oe 

 

9,420 

Max. Energy Product (BH)max 

MGOe 

10.3 

? 

Material Density 

g/cm

3

 

4.5 

Max. Operating Temperature  

C 

150 

Temperature Coefficient for B  

-%/C 

0.03 

Temperature Coefficient for H 

-%/C 

0.30 

Required Magnetizing Force 

Oe 

Material Composition 

SmCo powder w/ various resins 

25,000 

Typical   Minimum 

Injection Molded Samar-

ium Cobalt magnets are 

made with SmCo powder 

compounded with a binder  

material which is then 

molded into highly complex 

shapes or co-injected with 

other materials to form 

complete assemblies. Very 

low magnetic degradation 

at elevated temperatures.  

  

Phone: 

219-548-3799   

Fax: 

219-548-7071   

email: 

[e-mail] 

www

.Allianceor

g.com 

For more information please call or email Alliance technical support at: 

-1.0

-2.0

-5.0

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