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MUMETAL® offers important electromagnetic field shielding characteristics, including very high magnetic permeability - its ability to absorb magnetic energy. The unique properties of this family of alloys results in the highest possible attenuation, making these shielding alloys the materials of choice for reducing low-frequency electromagnetic interference (EMI).

MUMETAL® is an industry reference material and proprietary brand of Magnetic Shield Corporation, with different characteristics than proprietary alloys. MUMETAL® meets MILSPEC 14411C, composition 1. When the specification or the application calls for a magnetically soft or high permeability material, MUMETAL® can frequently be successfully applied.

To obtain optimum magnetic properties, annealing MUMETAL® alloy following fabrication is essential. This should be done in a furnace that allows for careful control of the annealing temperature and cooling rate. Optimum properties are reached in a pure hydrogen atmosphere.

MUMETAL® has a positive coefficient of permeability with respect to temperature. This is a quick way of saying that the permeability increases as temperature increases. This occurs until operating temperature nears the Curie temperature (850ºF.), defined as the temperature where permeability goes to 1 and the alloy becomes magnetically transparent. At operating temperatures above the Curie temperature, the shield will not provide any attenuation of the magnetic field. Roll off of permeability begins as operating temperature nears (within 25ºF) the Curie temperature listed, so a safety factor for allowable operating temperature should be used.

MUMETAL® magnetic shielding material is available in 30 inch by 120 inch sheet form, in seven thicknesses. Sheets can be sheared from 120 inch sheets into shorter lengths for ease of shipping. MUMETAL® is made in the U.S.A. and stocked in our distribution facility near O'Hare airport in Chicago.

MUMETAL® magnetic shielding prevents magnetic fields from reaching areas where they would cause magnetic interference. Magnetic shielding is used around either the source of interference, to prevent electromagnetic radiation from leaving a device; or more typically, around a sensitive device, to prevent the electro magnetic interference (EMI) from disrupting normal operations.

Material MUMETAL®

Specifications

ASTM A-753, Alloy 4; MIL N-14411C Composition 1

Characteristics

An alloy with exceptionally high magnetic permeability, very low coercive force, very low core losses, and low remnance by magnetic field annealing. The alloy finds application in magnetic shielding where fields much less than the Earth's magnetic field are required. Final annealing is necessary to develop magnetic shielding performance. Typical Annealed Properties

0.2% Yield Strength

49 ksi (338 MPa)

Density

0.316 lb/in

₃ (8.25 g/cm3)

Tensile Strength

99 ksi (682 MPa)

Electrical Resistivity

47 microhm cm

Elongation

32% in 2" (51 mm)

Grain Size

ASTM 7 or finer
(Mill annealed)

Hardness

15T 85 Availabilities

Sheet Form

Width: 30" (762 mm)
Thickness:
0.014" (0,36mm)
0.020" (0,51mm)
0.025" (0,64mm)
0.030" (0,76mm)
0.040" (1,02mm)
0.050" (1,27mm)
0.062" (1,57mm)
Length: 120" (3048mm)

Typical Chemistry (Wt.%)

C

0.015

Mn

0.50

P

0.005 max

S

0.001 max

Si

0.30

Cr

0.02 max

Ni

80.20

Mo

4.85

Al

0.01 max

Co

0.02 max

Fe

Balance Special Properties
Magnetic Properties*

DC μ @ 40 gauss

80,000

DC μ @ 100 gauss

105,000

DC μ maximum

350,000

DC Hc

0.005 Oe

DC Br (gauss)

4000

AC 60Hz μ @ 40 gauss

65,000

*0.014" (0.36 mm) test sample thickness
after test lab anneal.

Data are typical and should not be construed as maximum or minimum values for specification or for final design. Data on any particular piece of material may vary from those shown herein.

MUMETAL® may be ordered online at www.mumetals.com, www.magnetic-shield.com or by calling our office at 1-877-290-5558 and asking for the MUMETAL® quote desk.