MuMetal® Foil & Sheet
MuMetal® foil and magnetic shielding sheet for custom magnetic shielding, prototyping and precision fabricated shielding components. Available in a range of thicknesses from thin magnetic shielding foil to heavier-gauge sheet for wraps, formed parts, enclosures and specialist shielding applications.
Magnetic Shields USA supplies MuMetal® material in a range of forms to support both prototype and production shielding requirements. Depending on the application, material can be supplied as thin foil for flexible local shielding, or as sheet for fabricated covers, enclosures and more rigid shielding components.
Key Features
- Available as foil and sheet
- Suitable for local shields, wraps, covers, enclosures and fabricated shielding parts
- Can be supplied as raw material, cut pieces or custom fabricated components
- Technical guidance available on fabrication and annealing considerations
MuMetal® Sheet
MuMetal® sheet is used where a high-permeability magnetic shielding sheet is required for fabricated shields, enclosures, housings, cylinders, covers and other custom shielding components. Available in a range of thicknesses, MuMetal® sheet provides a practical route for both prototype and production shielding applications across scientific, industrial and OEM environments.
Recognised worldwide as a benchmark alloy for magnetic shielding, MuMETAL® is designed to provide high attenuation of low-intensity magnetic fields when correctly fabricated and annealed. It is widely used in applications where magnetic interference must be reduced and stable low-field conditions are required.
Manufactured to conform with ASTM A753 Alloy 4 and MIL-N-14411C Comp 1, MuMETAL® offers exceptional initial permeability, low coercivity, and high shielding efficiency when properly annealed.
Material Properties
- Nominal Composition: ~80% Nickel, ~15% Iron, ~5% Molybdenum
- Maximum Permeability (µmax): ≥ 300,000 (H ≈ 0.4 A/m)
- Coercive Force (Hc): < 0.03 Oe (2.4 A/m)
- Saturation Flux Density (Bs): ≈ 0.8 Tesla (8,000 Gauss)
- Electrical Resistivity: ≈ 45 µΩ·cm
- Density: 8.7 g/cm³
Typical Uses
MuMetal® sheet is commonly used in the manufacture of:
- magnetic shielding enclosures, covers and housings
- formed shields and cylindrical shielding components
- shielding for sensors, instrumentation and magnetometers
- electronic assemblies sensitive to static and low-frequency magnetic interference
- custom shielding parts and prototype shielding builds
MuMetal® Sheet Dimensional Range
- Thickness (Sheet): 0.014 – 0.080 in (0.36 – 2.00 mm)
- Width: 12 – 24 in (305 – 610 mm)
- Length: 15 – 120 in (381 – 3048 mm)
- Standard Gauges: 14, 20, 25, 30, 40, 50, 62 and 80 mil
- Custom sheet sizes and heavier-gauge formats available on request
Available Sheet Thicknesses
MuMetal® sheet is available in a range of thicknesses to support a wide variety of shielding and fabrication requirements, including heavier-gauge sheet where greater rigidity is required.
- Sheet: 0.014 – 0.080 in (0.36 – 2.00 mm)
Suitable for fabricated magnetic shields, formed covers, enclosures and general shielding components.
- Heavier-gauge sheet: 0.098 – 0.197 in (2.5 – 5.0 mm)
Used where additional rigidity is required, or where the shielding component forms part of a more robust fabricated structure.
Fabrication and Annealing
MuMetal® sheet can be supplied in a condition suitable for cutting and fabrication. Bending, welding, stamping, rolling and machining introduce mechanical stress that can significantly reduce permeability. Where maximum shielding performance is required, fabricated components should receive a full magnetic anneal in a controlled dry-hydrogen atmosphere after all forming and fabrication operations. The fabrication route and post-fabrication heat treatment should therefore be considered at the design stage.
Performance and Compliance
- Attenuation: Highly effective for static and low-frequency AC magnetic fields
- Suitable for applications requiring high permeability and low coercivity
- Conformance: ASTM A753 Alloy 4 / MIL-N-14411C Comp 1
- Can be supplied as raw material, cut blanks or as part of a fabricated shielding assembly, depending on project requirements
MuMetal® Foil
MuMetal® foil is used where a thin, flexible magnetic shielding foil is required for local shielding, wraps, liners, prototype builds and lightweight shielding assemblies. Supplied in the fully annealed condition, it provides excellent shielding performance in low-intensity magnetic fields while offering a practical solution where space is limited or a rigid fabricated shield is not required.
Manufactured in accordance with ASTM A753 Alloy 4 and MIL-N-14411C Comp 1, MuMETAL® Foil exhibits exceptional initial permeability (µ) and uniform magnetic response across thin-gauge forms.
It is widely used for compact low-field shielding applications, local shielding of sensitive assemblies and development work where a flexible shielding material is needed.
MuMetal® Foil Dimensions
| Property | Imperial | Metric |
| Thickness Range | 0.002 – 0.012 in | 0.051 – 0.305 mm |
| Standard Widths | 8 in, 12 in | 203 mm, 305 mm |
| Minimum Slit Width | 0.25 in | 6.35 mm |
| Width Tolerance (Uncoated) | ±0.010 in | ±0.25 mm |
| Width Tolerance (With Adhesive) | ±0.015 in | ±0.38 mm |
| Operating Temperature (Adhesive) | 32°F – 140°F | 0°C – 60°C |
Available Foil Thicknesses
MuMETAL® Foil is available in stock gauges from 0.002 in (0.051 mm) to 0.012 in (0.305 mm).
Most commonly specified gauges:
- 0.002 in (0.051 mm)
- 0.008 in (0.203 mm)
- 0.012 in (0.305 mm)
Width Options: 8.00 in (203 mm) and 12.00 in (305 mm)
Width Tolerance: ±0.010 in (0.25 mm) standard, ±0.015 in (0.38 mm) with adhesive backing
Minimum Slit Width: 0.25 in (6.35 mm)
Material Properties
- Nominal Composition: ~80% Nickel, ~15% Iron, ~5% Molybdenum
- Maximum Permeability (µmax): ≥ 300,000 (H ≈ 0.4 A/m)
- Saturation Flux Density (Bs): ≈ 0.8 Tesla (8,000 Gauss)
- Coercive Force (Hc): < 0.03 Oe (2.4 A/m)
- Resistivity: ≈ 45 µΩ·cm
- Density: 8.7 g/cm³
- Anneal Type: Full magnetic anneal for optimum shielding properties
Typical Uses
MuMetal® foil is commonly used for:
- local low-field magnetic shielding
- sensor calibration and instrumentation applications
- shielding of sensitive electronic assemblies
- prototype shielding and experimental low-field setups
- lining or wrapping of compact shielding components where a thin flexible material is required
Adhesive-Backed MuMetal® Foil
All MuMETAL® Foil gauges are available with or without pressure-sensitive adhesive backing (PSA) applied to one side for simplified installation.
- Adhesive Type: Acrylic-based, release liner-backed
- Operating Temperature Range: 32°F to 140°F (0°C to 60°C)
- Suitable for temporary shielding, local shielding additions and applications where bonding is preferred over mechanical fixing
Fabrication and Handling
MuMETAL® Foil is supplied in the fully annealed condition to deliver maximum permeability and optimum shielding performance.
It retains its magnetic properties without additional heat treatment unless subjected to severe forming, welding, or mechanical stress, in which case a full magnetic anneal is recommended to restore peak performance.
- MuMetal® foil can be supplied uncoated or adhesive-backed
- Can be slit to custom widths
- Can be cut to custom lengths or pieces
- Can be supplied as part of a wider shielding assembly where required
Performance and Compliance
- Magnetic Attenuation: Exceptional performance in static and low-frequency magnetic fields
- Adhesive temperature range: 32°F to 140°F (0°C to 60°C). This limitation applies to the adhesive backing, not to the MuMetal® alloy itself.
- Material Standards: Conforms to ASTM A753 Alloy 4 / MIL-N-14411C Comp 1
- Surface Condition: Smooth rolled finish, suitable for lamination or bonding
The magnetic properties shown are typical of fully annealed MuMetal® and are provided for engineering reference only. Actual values depend on material thickness, fabrication process and annealing parameters.
Frequently Asked Questions
What is the difference between MuMetal® foil and sheet?
The main difference is thickness, rigidity and how the material is typically used. MuMetal® foil is a thin, flexible material used for wraps, liners, local shielding and prototype work where space is limited. MuMetal® sheet is more rigid and is commonly used for fabricated covers, enclosures, cylinders and custom shielding parts, including heavier-gauge sheet where additional rigidity is required.
What is MuMetal® foil and sheet used for?
MuMetal® foil and sheet are used as magnetic shielding materials for low-intensity magnetic fields in scientific, industrial and OEM applications. Typical uses include local magnetic shielding, fabricated enclosures, sensor and instrumentation shielding, prototype shielding builds, cryogenic shielding components and specialist shielding parts for low-field systems.
Can Magnetic Shields USA supply cut pieces, custom sizes or fabricated MuMetal parts?
Yes. Magnetic Shields USA can supply MuMetal® foil and sheet in a range of standard and custom formats, including cut pieces, slit foil, custom blanks and fabricated shielding parts.
If you have a specific application, we can advise on the most suitable material format, thickness and fabrication route.
Does MuMetal® need to be annealed after cutting or forming?
It depends on how the material is processed and the level of shielding performance required. MuMetal® sheet should generally be fully magnetic annealed after fabrication if it has been bent, welded, stamped, rolled or otherwise mechanically stressed. MuMetal® foil is supplied fully annealed and may not require re-annealing for simple cutting or installation, but severe forming or welding can still reduce performance and may require a full magnetic anneal.
Talk to Us About Your Application
If you need MuMetal® foil, sheet or fabricated shielding parts, get in touch with your application details and any available drawings or dimensions.
To help us advise quickly, it is useful to include:
- required material form (foil or sheet) if known
- thickness or size requirements
- application / shielding objective
- whether the part will be cut, formed or fabricated
- any annealing or performance requirements