Page 39 - Electrical Equipment Handbook _ Troubleshooting and Maintenance

INTRODUCTION TO MACHINERY PRINCIPLES

TABLE 2.3 Characteristics of Permanent Magnets

Residual flux Coercive Maximum energy Average
density force product, recoil
Type B , G H , Oe G Oe 10 6 permeability
r
c
1% Carbon steel 9,000 50 0.18
1
3 2% Chrome steel 9,500 65 0.29 35
36% Cobalt steel 9,300 230 0.94 10
Alnico I 7,000 440 1.4 6.8
Alnico IV 5,500 730 1.3 4.1
Alnico V 12,500 640 5.25 3.8
Alnico VI 10,500 790 3.8 4.9
Alnico VIII 7,800 1,650 5.0 —
Cunife 5,600 570 1.75 1.4
Cunico 3,400 710 0.85 3.0
Vicalloy 2 9,050 415 2.3 —
Platinum-cobalt 6,200 4,100 8.2 1.1
Barium ferrite-isotropic 2,200 1,825 1.0 1.15
Oriented type A 3,850 2,000 3.5 1.05
Oriented type B 3,300 3,000 2.6 1.06
Strontium ferrite
Oriented type A 4,000 2,220 3.7 1.05
Oriented type B 3,550 3,150 3.0 1.05
Rare earth—cobalt 8,600 8,000 18.0 1.05
NdFeB 11,200 8,500 30.0 1.05

FIGURE 2.8 Demagnetization curve of alnico V.
2.12
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