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Products » Magnetics Cores » Tape-wound cores produced by Magnetics »

Tape-wound cores produced by Magnetics

Magnetics Tape Wound cores are often key components of complicated electronic circuitry found in high reliability applications including military, aerospace, communications, down hole drilling, and nuclear reactors. Tape wound cores and Bobbin cores are made from thin strips of high permeability nickel-iron alloys such as Square Orthonol®, Square Permalloy 80, Round Permalloy, Supermalloy, and 48 Alloy, or grain oriented silicon iron known as Magnesil®. Specific applications for tape wound cores include magnetic amplifiers (MagAmps), converter and inverter transformers, current transformers, and static magnetic devices.

Such materials are specially selected and processed with a purpose to satisfy precise requirements for concrete magnetic circuit and are produced to ensure compliance with tight tolerances with testing in accordance with standard IEEE and to other common-used industrial techniques.

Strip Wound cores

Types of produced cores:

  • Magnetics’s ring cores based on a tape - Tape Wound Cores
  • Magnetics’s ring cores based on a thin rape - Bobbin Cores

"Square" Orthonol

Material Code — "A"

Square Orthonol, a grain-oriented 50% nickel-iron alloy, is manufactured to meet exacting circuit requirements for very high squareness and high core gain, and is usually used in saturable reactors, high gain magnetic amplifiers, bistable switching devices, and power inverter-converter applications. Other applications such as time delays, flux counters and transductors demanding extremely square hysteresis loops require selection of Square Orthonol.

"Square" Permalloy 80

Material Code — "D"

Square Permalloy 80 Square Permalloy 80, a non-oriented 80% nickel-iron alloy, is manufactured to meet the high squareness, and high core gain requirements of magnetic preamplifiers and modulators. It is especially useful in converters and inverters where high voltage at low power levels are required, but where circuit losses must be kept to a minimum. Square Permalloy 80 has a saturation flux density approximately 1/2 that of the Orthonol’s, but has coercive force values 1/5 to 1/7 that of the 50% oriented nickel-iron alloys. Core gain for Square Permalloy 80 is higher by approximately 1.7 times the core gain of Orthonol.


Material Code — "F"

Supermalloy Supermalloy is a specially processed 80% nickel-iron alloy. It is manufactured to develop the ultimate in high initial permeability and low losses. Initial permeability ranges from 40,000 to 100,000 while the coercive force is about 1/3 that of Square Permalloy 80. Supermalloy is very useful in ultra-sensitive transformers, especially pulse transformers, and ultra-sensitive magnetic amplifiers where low loss is mandatory.


Material Code — "K"

TMagnesil Magnesil, a grain-oriented 3% silicon-iron alloy, is processed and annealed to develop high squareness and low core loss. It is usually used in high quality toroidal power transformers, current transformers and high power saturable reactors and magnetic amplifiers. It exhibits high saturation flux density with high squareness but has comparatively high coercive force and core loss. With its high Curie temperature, it is quite useful in magnetic devices which are to be exposed to temperatures between 200°C (392°F) and 500°C (932°F). At higher temperatures, uncased cores should only be used due to case temperature limitations.

48 Alloy

Material Code — "H"

48 Alloy, a 50% nickel-iron alloy, has a round B-H loop and exhibits lower saturation flux density, squareness, coercive force, and core gain than the Orthonol types. It is useful in devices requiring lower coercive force such as special transformers, saturable reactors, and proportioning magnetic amplifiers. AC core losses are typically lower than with Orthonol.

"Round" Permalloy 80

Material Code — "R"

Round Permalloy 80, a non-oriented 80% nickel-iron alloy, is processed to develop high initial permeability and low coercive force. It has lower squareness and core gain than the square type, as these characteristics are sacrificed to produce the high initial permeability and low coercive force properties. Round Permalloy 80 is especially useful in designing highly sensitive input and inter-stage transformers where signals are extremely low and DC currents are not present. It is also useful in current transformers where losses must be kept to a minimum and high accuracy is a necessity. The initial permeability of this material is between 20,000 and 50,000 with coercive force values about 70% that of Square Permalloy 80.


Material Code — "S"

This material being a high-degree cleaning alloy with 50% of iron and 50% of cobalt, is produced in small quantities on special orders. It is processed and annealed by special techniques to obtain a high degree of hysteresis loop’s squareness and a high saturation magnetic flux density.. Supermendur is successfully used id devices requiring a maximum possible miniaturization and an operation in environment with high temperature. This material may be used in the same applications as Magnesil but a higher magnetic flux density (approximately 21000 gauss) of this material permits to reduce a size and a weight of core. This material has a highest value of Curie temperature among all available alloys having a square-form hysteresis loop and therefore it is especially suitable for operation at high temperatures.

Typical Features of Magnetic Alloys

Feature Si-Fe (K)
Alloys, 3%
Ni-Fe (A, H)
Alloys, 50%
Ni-Fe (R, D, F)
Alloys, 80%
Co-Fe (S)
Alloys, 50%
% of iron 97 50 17 49
% of nickel   50 79  
% of cobalt       44
% of silicon 3       5
% of molybdene     4  
% of other materials       2
Density (g/sm³) 7,65 8,2 8,7 8,2
Melting Temperature 1475 1425 1425 1480
Curie Temperature (°C) 750 500 460 940
Specific Heat Emission (cal/g-sm³) 0,12 0,12 0,118 0,118
Specific Resistance (uOhm-sm) 50 45 57 26
CTE (X10-6/°C) 12 5,8 12,9 9,9
Rockwell Hardness B-84 B-90 B-95 B-98

Magnetics Materials – Comparison of Characteristics

Code Material Type Magnetic Flux Density Br/Bm Coercitive Force
CCFR at a frequency of 400 Hz**
    kiloGauss Tesla   Oersted A/M
A "Square" Orthonol 14,2 - 15,8 1,42 - 1,58 0,88 and more 0,15 - 0,25 11,9 - 19,9
D "Square" Permalloy 80 6,6 - 8,2 0,66 - 0,82 0,80 and more 0,022 - 0,044 1,75 - 3,50
F Supermalloy 6,5 - 8,2 0,65 - 0,82 0,40 - 0,70 0,004 - 0,015 0,32 - 1,19
H 48 Alloy 11,5 - 14,0 1,15 - 1,40 0,80 - 0,92 0,08 - 0,15 6,4 - 12,0
K Magnesil 15,0 - 18,0 1,5 - 1,8 0,85 and more 0,45 - 0,65 35,8 - 51,7
R "Round" Permalloy 80 6,6 - 8,2 0,66 - 0,82 0,45 - 0,75 0,008 - 0,026 0,64 - 2,07
S Supermendur 19,0 - 22,0 1,9 - 2,2 0,90 and more 0,50 - 0,70 39,8 - 55,7
09.10 19 

LEPCOS invites you to attend the Stand C23 at ChipEXPO 2019 exhibition, which will be held from 16 to 18 October 2019 in Moscow in the Expocentre, in the pavilion "Forum".


26.06 19 
According to the results of 2018 Lepcos has received "best ferrites seller 2018" seal of excellence from TDK company.

18.04 19 
Dear colleagues! We would like to draw your attention to the fact that, since December 2018, the package content of electrolytic capacitors has been changed.


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