Science, Research and Education from Magnetic Shield Corporation
Science and Research
Whether you are an independent research scientist, inventor or student performing research at a university, national laboratory or design firm, we are here to help. As a technology leader since 1941, Magnetic Shield Corporation has seen it all. Maintaining very low magnetic fields in a cryogenic or vacuum environment is critical for laboratory evaluation and experimentation. Based on decades of field proven experience, our most popular item used in research is our MuMETAL® Zero Gauss Chambers. These scientifically engineered chambers provide a laboratory work space of extremely low magnetic field. We stock several chamber sizes, and can produce custom sizes and configurations for you. Although theoretical calculations exist, "hands-on" evaluation is necessary. This is why Magnetic Shield Corporation suggests using one of our hands-on Lab Kits to test, measure and evaluate the affects of low-frequency fields within your physical environment. We can also help with wall shielding, rooms and enclosures to create a low-field lab. Our engineers are available to perform site surveys under a consulting contract agreement, reporting our recommendations of how to mitigate EMI/EMF disturbances.
Why work with Magnetic Shield Corporation? Because our shielding alloys are field proven in the research community, and, with our decades of hands-on experience, you can be certain you are not wasting valuable time or funding. For additional help, network with Universities on Facebook, or contact our Engineering Department with any specific questions.
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Technical Resources and Tools
Whether you want to learn shielding theory, shielding calculations, or the differences between our shielding alloys, we can help. We are all affected by, and becoming acutely aware, of the affects electromagnetic interference has on safety and compliance. Each day we receive unique inquiries from students, inventors, scientists, engineers and buying professionals - many with limited knowledge of how magnetic shielding materials can be used to avoid unwanted interference.
Generally, the Technical Resources and Tools listed above will give you the answers. However, feel free to email us if you have any specific application questions: firstname.lastname@example.org.
Product Literature and Specifications
Measuring Magnetic Fields
How do you "see" magnetic fields? By using a Gauss Meter, the electromagnetic source field strength is measured in "Gauss", and output into numeric values. An example of measuring gauss before and after shielding an electrical panel with our MuMETAL® alloy can be seen on YouTube. We offer a cost effective, handheld, single-axis AC magnetic field meter, to provide quick & reliable measurements of electromagnetic field (EMF) radiation generated by external sources like power lines, electrical wiring, audio/visual equipment, motors and other devices. No probe is required - just hold the Gaussmeter in the affected area. Then measure the same after shielding with MuMETAL®, Co-NETIC® or NETIC® shielding alloys. This educational "hands-on" evaluation is possible with purchase of our Gaussmeter, or Internet Special combination of Evaluation Kit and Meter (saving you 10% when you purchase the Evaluation Kit and Meter). For detailed specifications and to order, go to: Evaluation Kits.
How do you calculate shielding requirements? At the bottom of this page are our Slide Rule Calculator, Online Calculator, and B-H Curve. These valuable tools can help you compare our shielding alloys, different thicknesses, and shielding efficiencies, and select the size of shielding required to reduce (attenuate) unwanted fields. But first, we want to familiarize you with our specialty alloys and explain their differences.
Shielding efficiency is a result of material composition, specific gravity, thickness, grain structure within the alloy, and hardness. Depending on strength of the unwanted field (HO) and the amount of field Attenuation you need, one of our three alloys may be selected.
Our most popular shielding alloy - so popular the name has been used generically in worldwide markets. Buyers beware: MuMETAL® is a registered brand of Magnetic Shield Corporation, and we do not support other companies that sell shielding materials they claim are mumetal. MuMETAL® is not a generic name - it is a proprietary brand that we certify to exacting quality standards and material specifications. MuMETAL® offers maximum permeability i (Mu) and is used primarily in low intensity fields where high attenuation, high initial permeability and high shielding efficiency are desired. Available as stress annealed (partially annealed for ease of machinability), sheet stock is used for fabricated shields such as enclosures, cylinders, cans, channels or 3D boxes. Typically, atmospherically controlled annealing is required after stamping, machining, bending, rolling or welding to provide maximum shielding performance. MuMETAL® is available in many forms, but most shields are fabricated from our MuMETAL® Sheet and Foil. We stock sheet in gauges from .014" to .062" thickness [0,36mm to 1,57mm] and foil in gauges from .002" to .010" thickness [0,05mm to 0,25mm].
Ready to use from stock, Co-NETIC® AA Perfection Annealed alloy is used for flat shields such as covers, doors, walls and simple two-dimensional shapes. Considered far superior to other alloys because of our Perfection Annealing process, it is used where maximum attenuation is desired. Co-NETIC® is fully annealed to exacting specifications in a quality controlled environment which builds grain structure, an important mechanical property for ultimate shielding performance. Co-NETIC® AA Perfection Annealed alloy is available in foil & sheet stock gauges from .002" to .062" thickness [0,05mm to 1,57mm].
Often applied in fields of high intensity (strong fields), NETIC® provides high magnetic saturation characteristics. It has the ability to absorb stronger electro-magnetic fields without saturating. In complex fields, NETIC® is commonly used in combination (in layers) with Co-NETIC® or MuMETAL®, with the NETIC® layer placed closest to the source of interference. Used for either fabricated or flat shields, it may be re-annealed for better performance. For electronics applications requiring corrosion resistance, electro-tin plated stock is available. NETIC® Sheet and Foil are available in stock gauges from .004" to .095" thickness [0,10mm to 2,41mm].
After fabricating a magnetic shield, final annealing is generally required to increase grain structure, which improves shielding efficiency. Final anneal is a critical process step and extra care must be taken to avoid dropping or denting as shock may weaken an annealed shield's grain structure. When Magnetic Shield Corporation provides MuMETAL® magnetic shields, they are Perfection Annealed (fully annealed in a controlled hydrogen atmosphere) to Magnetic Shield Corporation's exacting standards. Optimum magnetic properties are obtained by annealing at a temperature of 1950-2050°F [about 1120°C], and cooling at a consistent rate which is critical to maintaining grain structure and part dimensions. To insure your shield is annealed properly, we can measure attenuation (a shield's ability to absorb magnetic energy) in our ISO 9001:2008 certified Quality Control Lab using one of our Helmholtz Coils. Fully annealed MuMETAL® offers attenuation properties that are considered the best available for most applications worldwide.
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Formulas may be used to determine which materials and thicknesses will provide the most effective shielding. The source (interfering) field known as HO is measured in Gauss. Knowing HO, and estimating the approximate size of your shield, shield thickness can be determined. Certain characteristics of shielding alloys are theoretically constant such as permeability ì (Mu), saturation induction, and flux density (B).
Usually, theory provides no finite answer to technical professionals. Validation is required. That is why Magnetic Shield Corporation has developed practical methods of evaluating performance. Evaluation begins with our Co-NETIC® Slide-Rule Calculator to determine alloy thickness required to attenuate unwanted fields. However, the slide-rule is based on mathematics derived for specific cylindrical shaped shields; therefore it is necessary to further evaluate using our "hands-on" developmental Lab Kits to provide real evidence of success.
Online Calculator - Shield Size Vs. Source Field Strength
How do you determine field reduction (attenuation) ratios of different thicknesses of shielding alloy? The first thing to do is estimate the physical size (diameter in inches) of a cylinder required to separate the area you need to protect from the source. Then, measure the source field strength (HO) in Gauss, and enter the data below.
To determining possible attenuation ratios (A), we have developed an automated, online calculator. Simply input the estimated shield size (diameter in inches) and measured source field strength (gauss value); then click on the calculate button. The online calculator will return possible attenuation ratio values for various shielding alloy thicknesses. Now you can see the thickness of material required, and its effectiveness (attenuation ratio).
Over several decades, Magnetic Shield Corporation has performed hundreds of laboratory tests and calculated thousands of shielding equations - all in an effort to continually validate the theoretical application of magnetic interference control in both AC and DC applications, and to aid engineers in shield design. Theory behind the B-H curve is well documented, and it remains an effective reference tool. By use of the B-H curve, our shielding alloys MuMETAL®, Co-NETIC® and NETIC® have been developed and refined to offer the most effective shielding characteristics for a variety of applications and markets. The B-H curve (below) depicts our materials' capabilities to attenuate and absorb a wide range of magnetic fields.
Radio Frequency (RF) Shielding
Our alloys provide interference control of H-fields, DC or AC to 100 kiloHertz, and differ fundamentally from RF shielding. Shielding for E-fields at radio frequencies (RF) above 100 kiloHertz involves use of high conductivity materials such as Copper, Aluminum or certain conductive coatings. Because MuMETAL®, Co-NETIC® and NETIC® alloys are also conductive, they can shield high frequency (RF) fields, even though they are formulated specifically for low frequency magnetic fields. When both high frequency and low frequency fields are present, our alloys may be most effective if grounded and designed with proper RF shielding practices.
When it comes to magnetic shielding, remember: "Theory is one thing, practicality is another, evaluation is everything."
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