Rare earth magnets questions:
[Q] What are rare earth magnets?
[A] The term Rare Earth Magnets is used to refer to a group of magnetic materials whose alloys consist of one or more of the Rare Earth elements on the periodic table. These materials are characterized by exceptionally strong magnetic properties.
[Q] What are alnico magnets?
[A] Alnico magnets are aluminum-nickel-cobalt magnets.
[Q] What are ceramic magnets?
[A] Ceramic magnets are made from strontium and iron oxide powders. They are generally harder, more brittle and lighter than metal alloy magnets. Ceramic magnets have a high electrical resistance.
[Q] What are magnetic assemblies?
[A] Magnetic assemblies are up to 32 times stronger than regular magnets and are typically made with ceramic magnets. We can make magnetic assemblies in custom sizes, designs, and coatings.
[Q] What are permanent magnets made of?
[A] Today’s permanent magnets are made of alloys. Alloy materials include
Neodymium-Iron-Boron (Neo magnets or “super magnets”, a member of the rare earth category)
Samarium-Cobalt (a member of the rare earth category)
Strontium-Iron (Ferrite or Ceramic)
Rare earth magnets questions [Q] How are magnets made?
[A] Magnets are made using the following manufacturing methods:
Pressing and sintering
[Q] How is magnetic strength measured?
[A] A number of devices measure the strength of magnets. Here are a few common devices.
Permeameters measure the magnetic characteristics of a specimen.
Gaussmeters measure the strength of a magnet in units called Gauss units.
Magnetometers measure in Gauss or arbitrary units for comparing magnets.
Pull Testers measure the strength of a magnet’s pulling power in pounds, kilograms, or other force units.
[Q] What kind of magnets are the strongest?
[A] Rare earth magnets are the strongest.
[Q] What are neodymium magnets? Are they the same as “rare earth”?
[A] Neodymium magnets are a member of the rare earth magnet family. Neodymium magnets are the strongest of the rare earth magnets and are the strongest permanent magnets.
Rare earth magnets questions [Q] What are neodymium magnets made from and how are they made?
[A] Neodymium magnets are actually composed of neodymium, iron and boron (they are also referred to as NIB or NdFeB magnets). The powdered mixture is pressed under great pressure into molds. The material is then sintered (heated under a vacuum), cooled, and then ground or sliced into the desired shape. Coatings are then applied if required. Finally, the blank magnets are magnetized by exposing them to a very powerful magnetic field in excess of 30 KOe.
[Q] What does the “N rating”, or grade, of the neodymium magnets mean?
[A] The grade, or “N rating” of the magnet refers to the Maximum Energy Product of the material that the magnet is made from. It refers to the maximum strength that the material can be magnetized to. The grade of neodymium magnets is generally measured in units millions of Gauss Oersted (MGOe). A magnet of grade N42 has a Maximum Energy Product of 42 MGOe. Generally speaking, the higher the grade, the stronger the magnet.
[Q] Can I cut, drill, or machine neodymium magnets?
[A] The Neodymium Iron Boron material is very hard and brittle, so machining is difficult at best. The hardness of the material is RC46 on the Rockwell “C” scale, which is harder than commercially available drills and tooling, so these tools will heat up and become damaged if used on NdFeB material. Diamond tooling, EDM (Electrostatic Discharge Machines), and abrasives are the preferred methods for shaping neodymium magnet material. Machining of neodymium magnets should only be done by experienced machinists familiar with the risk and safety issues involved. The heat generated during machining can demagnetize the magnet and could cause it to catch fire posing a safety risk. The dry powder produced while machining is also very flammable and great care must be taken to avoid combustion of this material.
Rare earth magnets questions [Q] Can I solder or weld to neodymium magnets?
[A] You definitely cannot solder or weld to neodymium magnets. The heat will demagnetize the magnet and could cause it to catch fire posing a safety risk.
[Q] Do I have to worry about temperature with neodymium magnets?
[A] Yes. Neodymium Iron Boron magnets are sensitive to heat. If a magnet heated above its maximum operating temperature (176°F (80°C) for standard N grades) the magnet will permanently lose a fraction of its magnetic strength. If they are heated above their Curie temperature (590°F (310°C) for standard N grades), they will lose all of their magnetic properties. Different grades of neodymium different maximum operating and Curie temperatures. See our Neodymium Magnet Specifications Page for more details. We do stock a range of high temperature magnets, which you can see here.
[Q] What is the gauss rating of your magnets?
[A] This depends on the context it is used. Most magnetic therapy people like to present the largest number possible, so they often use the Residual Flux Density (Brmax) of the material, which really doesn’t specify much about the actual magnet. This value is essentially the magnetic field density inside the magnet material. Since you will never be inside the magnet, or using the field inside the magnet, this value doesn’t really have any practical value. The surface field of a magnet is a much more accurate specification for a magnet. The surface field is exactly what it sounds like. It is the magnetic field density at the surface of the magnet as measured by a Gaussmeter. This value is tested and specified for each of our stock magnets.
Rare earth magnets questions[Q] Do neodymium magnets require a keeper?
[A] No, neodymium magnets do not require a keeper for storage like Alnico magnets.
[Q] Will my neodymium magnets lose strength over time?
[A] Very little. Neodymium magnets are the strongest and most permanent magnets known to man. If they are not overheated or physically damaged, neodymium magnets will lose less than 1% of their strength over 10 years – not enough for you to notice unless you have very sensitive measuring equipment. They won’t even lose their strength if they are held in repelling or attracting positions with other magnets over long periods of time.
[Q] Will neodymium magnets lose strength if they are held in repelling or attracting positions for a long time?
[A] In most applications, the answer is simply “no”. If the magnets will be exposed to higher temperatures while in repelling applications, the answer is “possibly”. The exact answer is a bit too complicated for a FAQ answer, and requires specifics about the application.
Rare earth magnets questions[Q] Are your Neodymium Rare Earth Magnets RoHS compliant?
[A] Yes, our magnets are fully RoHS compliant, meeting the European Parliament Directive entitled “Restrictions on the use Of Hazardous Substances” (RoHS). This Directive prohibits the use of the following elements in electrical/electronic equipment sold after 7/1/2006: cadmium (Cd), lead (Pb), mercury (Hg), hexavalent chromium (Cr(VI)), polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs). Download an official RoHS Compliance Statement from K&J Magnetics here. Or, you can find individual PDF files for each specific magnet on the product detail pages, under the “Downloads” tab.
[Q] Can I make a magnet that I already have any stronger?
[A] Once a magnet is fully magnetized, it cannot be made any stronger – it is “saturated”. In that sense, magnets are like buckets of water: once they are full, they can’t get any “fuller”.
[Q] What is the difference between the maximum operating temperature and the Curie temperature of the magnets?
[A] The maximum operating temperature is the maximum temperature the magnet may be continuously subjected to with no significant loss of magnetic strength. This is 176ºF (80ºC) for standard grades of neodymium magnets. The Curie Temperature is the temperature at which the magnet will become completely demagnetized. This is 590ºF (310ºC) for standard grades of neodymium magnets. Higher temperature grades have higher maximum operating temperatures and higher Curie Temperatures. At temperatures between these two points, a magnet will permanently lose a portion of its magnetic strength. The loss will be greater the closer to the Curie Temperature it is heated.
[Q] How strong of a magnetic field is necessary to magnetize a neodymium magnet?
[A] As a general rule of thumb, a peak field of between 2 and 2.5 times the intrinsic coercivity is required to fully saturate a magnet. For standard neodymium magnets, the field required is minimum of 24 KOe, but 30 KOe is usually the minimum used.
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