Testing Magnetic Materials

Do you need a magnetic material (magnetically hard) tested for its magnetic properties?

Magnetic Component Engineering can run a BH Curve (2nd Quadrant, or a full hysteresis loop) on magnetically hard materials (permanent magnet materials) for you using a  hysteresisgraph. Tests can usually be done within 72 hours from receipt of sample. The results are traceable to NBS (National Bureau of Standards).

Some important points about submitting samples for a magnetic analysis:

  1. The test is a destructive test. Even though the final sample is available and retained for traceability purposes, the original part is usually cut and ground to produce the test sample and therefore no longer useable as the original piece.
  2. The maximum intrinsic coercivity that can be tested is 27 kOe.
  3. Samples must have an orientation that is normal to a surface. Materials with a radial orientation cannot be tested at MCE.
  4. The minimum sample size required is 0.250 Diameter x 0.250 Long; or 0.250 cube.
  5. If your sample is less than 0.250 in the direction of orientation, you must submit multiple samples so that we can stack the samples up to build up the .250 dimension. However, parts cannot be stacked orthogonal to the orientation direction.  Note that some integrity of the data will be lost because of stacking, however, the data will still give a good indication of the type of material.

Coatings & Platings

Magnetic Component Engineering offers the following types of standard finishes on permanent magnets:

  1. Nickel Plating
  2. Phenolic Resin (PR1010)
  3. Phenolic for FDA Applications (PM1000)

Depending on the application and material being used, the selection of coating is important.

When using the magnet in a high vacuum environment, a metallic coating is recommended for Neodymium Iron Boron. Nickel is the most suitable. Alnico, Ceramic, and Samarium Cobalt magnets need not be plated for this application.

When using Neodymium Iron Boron magnets in non-vacuum or low vacuum applications (10-3 Torr and higher pressures), the phenolic resin coating is typically the preferred choice. Again, alnicos, ceramics and samarium cobalts need not be coated.

Samarium Cobalt generally is used without coating or plating because it typically does not show signs of oxidation during normal use. Occasionally, coating with PR1010, or an epoxy coating may be desired if cleanliness is very critical. Contact us with your requirements to determine how we can best help you.

Neodymium Iron Boron magnets are prone to oxidation and coating or plating is recommended.

Ceramic magnets cannot be plated since the material is non-conductive. Organic coatings such as phenolic resin are the best choice if coating is required.

Alnico magnets are not typically coated or plated.

Shapes such as blocks and discs and rings are easier to coat. Tubes (aspect ratios of internal diameter to axial length being 1:2 or greater) become more challenging since coating needs to be able to enter the internal diameter. Aspect ratios of 1:3 and higher, especially for diameters under 0.50” will leave areas with extremely thin coating thickness or uncoated areas in the diameter. If it is critical to coat the inside diameter, alternatives do exist and you are encouraged to contact us.

MCE uses proprietary methods of pre-processing the materials before plating or coating. Plating or coating magnets is quite different from coating metals, and the pre-processing is a very important part of the plating or coating treatment.

Contact MCE to discuss your application.

Magnetizing

Magnetic Component Engineering uses state of the art magnetizing equipment to ensure that your magnets are fully saturated. The high energy, high coercivity magnets available today require large amounts of energy to saturate the material. A partially saturated magnet will not work as designed in the application because the smaller magnetizers will only influence the weaker domains. However, it is the strong domains that offer the most resilience. To capture these strong domains, large magnetizing fields are essential.

Magnetizing specific configurations are achievable by making special magnetizing "fixtures" and "solenoids". Special magnetizing fixtures can be used to obtain radial magnetization patterns, multiple poles, bipolar fields and such.

If you require reversing the polarity of a magnet, we are equipped to handle the task. When reversing polarity, usually a higher amount of energy is required than that which was used for first magnetization, but MCE has the capability and equipment to effectively reverse a magnet's polarity.

Occasionally, magnets may need to be demagnetized for further processing, such as to dimensionally modify the magnet or have the magnet coated or plated. MCE is equipped to handle your demagnetizing needs as well.

Our magnetizers go as high as 84 kJ, and are pre-framed to be taken as high as 108 kJ if required. This can be delivered at 2000V. There is no job too big for us - contact us with your required specifications.

Marking and Identification

MCE can mark parts using laser engraving or standard engraving technology. Below are some use cases for marking parts and how we can help.

Marking Polarity of Magnets

We can mark the polarity on the surface of magnets using inks of contrasting color. The thickness of the ink on the surface will generally be under 20 microns. The marking could be done by simply putting a "N" or "S" or some other method such as your part number on the north side, or even printing your logo on the magnet.

In other cases, if you prefer, marking can be done with epoxy paint. Thickness using epoxy paint will generally run from 0.0005” to 0.001”. Standard colors are red, white, yellow, green, blue, and black.

Identifying the Magnets

In some cases it may be advantageous for you to have the magnet identified with your part number, your logo, or other information such as lot numbers, manufacturing date, or other such information that would be helpful for traceability. We have multiple technologies at our disposal to effectively mark magnets, contact your sales representative to determine which is the best for your job.

Availability

Marking of parts can be done on almost any magnet with any type of finish. The inks we use are "non-toxic". Font sizes can be as small or large as you wish. Standard ink colors are black and gold.

Contact us for further information.


Stabilization and Calibration

Stabilization is the deliberate treatment of a magnet by magnetic, thermal, physical, or other controlled external demagnetizing influences so as to preclude or minimize the future change in magnetic performance of a magnet in the field during use.

Calibration is the deliberate treatment of a magnet by magnetic, thermal, physical, or other means to reduce the level of magnetization to a precise, predetermined level, thereby achieving a tighter tolerance on the magnetic performance.

MCE is capable of both stabilizing and calibrating standalone magnets and those within assemblies. To learn more about the stabilization and calibration process, read our article on the topic here.


Testing & Certification

MCE offers a variety of tests and certifications to meet your project needs. Any of the below tests/certs can be performed on any portion of the order, whether it's one part per shipment or 100% inspection.

Below are some of the most common tests that we provide. If you'd like a specific certification or test that isn't listed (such as a salt spray test or pressure test) please contact us and we will work with you to design or source the test.

Certificate of Conformance

Also know in the industry as Certificate of Compliance, a “C of C” is a certification provided by MCE that states that the products being shipped to you comply with all the specifications submitted to us at the time of the order. It also states that we maintain quality files on hand that are open for inspection by authorized personnel. All orders that we process will be accompanied by this certification, even if you did not request this. This certification can be found on our packing slip that accompanies the product.

BH Curves

This is a “test report” where the test is magnetic in characteristics. This is a plot of the second quadrant hysteresis curve and shows how the magnet material will behave under different operating conditions. This type of test is only done on a sample from a material production lot. This information can be provided only if it has been agreed upon when the order was placed.

This is a destructive test - the sample will become unusable.

Flux Density and Total Flux Tests

These tests are conducted internally to ensure compliance. However, unless predetermined and agreements to standards have been established, MCE takes these readings only for reference purposes. Flux Density readings are taken using a gaussmeter, while the Total Flux readings are taken using a fluxmeter and a helmholtz coil or a search coil. The costs of these tests depend on the quantity of magnets that need to be tested, the documentation and subsequent analysis required.

These tests are non-destructive and magnets that have undergone these tests may be used in production.

First Article Inspection Report

This certification can be added to any order. MCE will inspect a number of parts per lot and record measurements for evaluation. These reports aim to show the accuracy of the lot without requiring 100% inspection. That being said, 100% inspection is also available. Contact us to discuss your inspection needs.

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