At glance:
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Effective magnetic shielding requires careful material selection, geometry planning, and post-fabrication heat treatment.
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New England-based engineers and procurement teams can source custom-fabricated shields from a regional specialist with in-house engineering support.
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Matching shield design to frequency range and application environment is the most critical planning step.
Planning a magnetic shielding project means addressing several technical variables before a single part is fabricated. Getting those variables right from the outset reduces costly redesigns and ensures the finished shield performs as intended in its operating environment.
For over sixty years, The MuShield Company has been a worldwide industry leader in manufacturing custom magnetic shields, precision sheet metal fabrication, and hydroforming solutions. Organizations throughout New England seeking Magnetic Shielding in New England have access to a regional manufacturer capable of handling projects from initial consultation through final delivery. The sections below outline the primary considerations that should guide any shielding project.
Understanding Frequency Range and Material Selection
The first planning decision is determining the frequency of the interference you need to attenuate. This single variable drives material choice more than any other factor.
When the electromagnetic interference (EMI) includes low-frequency fields (30 to 300 Hz), magnetic shielding is essential to assure proper operation of the electronic equipment without failure. Standard conductive metals such as copper and aluminum are not effective at these frequencies.
Simple electrically conductive layers such as copper and aluminum are transparent to low-frequency magnetic fields that can cause noise in an electronic device. This low-frequency magnetic interference can be emitted from sources such as switches, motors, power supplies, and transformers and is typically a challenging EMI shielding problem.
For low-frequency applications, high-permeability alloys are the correct solution. According to the EMI shielding materials guide from Fotofab, alloys with high permeability and low core losses such as MuMetal are preferred candidates for attenuation at lower frequencies.
After working with high-permeability magnetic shielding alloys such as mumetal and HyMu 80 for decades, experienced fabricators have extensive knowledge of how this material will react to the different stresses introduced through cold working and welding. Sourcing materials from specialty mills at a specified temper, chemical composition, and grain size ensures the material will serve to shield the magnetic flux it is designed for.
Shield Geometry, Fabrication, and Heat Treatment
Once material is selected, geometry and fabrication method become the focus. The shape of a shield, the number of layers, and the presence of apertures all affect shielding effectiveness.
Key geometry and fabrication considerations include:
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Number of layers: Multi-layer shields can achieve higher attenuation than a single thicker layer of the same total mass.
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Apertures and seams: Even a 1 mm gap can significantly degrade shielding effectiveness at certain frequencies. Seam design and closure method must be specified early.
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Forming method: Hydroforming, stamping, and laser cutting each impose different mechanical stresses on high-permeability alloys.
Post-fabrication heat treatment is non-negotiable for high-permeability alloys. Cold-working during forming reduces magnetic permeability, and only a controlled annealing cycle restores it.
MuShield maintains vacuum and hydrogen furnaces on-site that are used for both in-process stress relief annealing and final heat treatment. The final heat treatment ensures maximum magnetic permeability on all magnetic shields.
Consolidating material supply, fabrication, and heat treatment under one roof eliminates vendor coordination risk and reduces lead time.
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Planning Stage |
Key Decision |
Common Pitfall |
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Material selection |
Frequency range and required attenuation |
Specifying a conductive metal for low-frequency fields |
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Geometry design |
Layer count, apertures, seam closure |
Leaving gaps that degrade shielding effectiveness |
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Fabrication method |
Hydroforming vs. stamping vs. machining |
Ignoring stress effects on permeability |
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Heat treatment |
Annealing atmosphere and temperature |
Skipping final anneal after cold-working |
Engineering Consultation and Prototyping
Before committing to production quantities, a structured engineering review reduces risk. Engineering staff can work with clients to solve magnetic shielding problems through FEA modeling, experimentation, and prototyping. From design concept to customer review through manufacturing, great attention to detail is made, ensuring the highest quality product.
Prototyping is particularly valuable when:
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The interference source geometry is irregular or difficult to model analytically.
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The application environment imposes vibration, temperature cycling, or mechanical shock.
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Regulatory or industry-specific performance thresholds must be documented before production.
Whether application engineers need to create a design from scratch that will best suit specific magnetic shielding needs, or existing design specifications are already in hand, qualified fabricators can provide service and help achieve the desired magnetic shielding solutions.
Frequently Asked Questions
What industries commonly require custom magnetic shielding in New England? The fabrication of custom magnetic shielding is used across the medical, defense, aerospace, biochemical, and aviation industries. Research institutions and electronics manufacturers in the region represent additional common end users.
Why does heat treatment matter for mumetal shields? Cold-working during forming lowers the magnetic permeability of high-permeability alloys. A controlled vacuum or hydrogen anneal restores permeability to specification and is required for the shield to perform as designed.
Can I supply my own design drawings? Yes. Fabricators with on-staff application engineers can work from customer-supplied drawings or develop a design from scratch based on the interference problem description and performance requirements.
What is the difference between mumetal and HyMu 80? Both are high-permeability nickel-iron alloys suited to low-frequency magnetic shielding. The primary differences lie in exact alloy composition and the specific permeability values achievable after annealing. A qualified engineer can recommend the appropriate grade based on field strength and attenuation targets.
For organizations planning a magnetic shielding project in New England, engaging a fabricator with in-house engineering, material supply, and heat treatment capabilities is the most reliable path to a first-time-right result. The MuShield Company, based in Londonderry, New Hampshire, offers consultation, custom fabrication, and full in-house processing for shielding applications across medical, defense, aerospace, and industrial sectors. Reaching out early in the design phase, before geometry is locked, provides the greatest opportunity to optimize both performance and cost.