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(Q) What are the precautions for converting from ferrite magnets to rare earth magnets?
(A) Converting to rare earth magnets, which have 10 times or more the energy product of ferrite magnets makes it easy to make devices more compact and light weight. However, it is necessary to pay attention to whether or not the same type of cost reduction can also be expected. In making your judgment, please think carefully about the performance improvement, cost performance, power consumption reduction, and the other elements of the effect of the conversion on the product as a whole.
  Also, the electrical conductivity of rare earth magnets is extremely large compared to ferrite magnets and in environments where motors or the like generate alternating magnetic fields, heat generated due to eddy currents must also be taken into account. Moreover, because rare earth magnets demonstrate a completely different coefficient of thermal expansion from ferrite magnets, the selection of the right adhesive to match the usage conditions is also extraordinarily critical.
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(Q) What are the precautions for converting from SmCo magnets to NdFeB magnets?
(A) Compared to SmCo magnets, neodymium family magnets have inferior corrosion and heat resistance. Therefore, neodymium magnets must be treated with anti-corrosion coating, such as plating or paint. Moreover, when using magnets at high temperatures, the neodymium magnet with the coercive force appropriate to the usage temperature must be selected.
  Also, where hydrogen gas or corrosive gas is present, it is necessary to pay attention to the fact that neodymium family magnets react more easily with such gases than SmCo magnets do. They are also inferior to SmCo magnets in their ability to withstand different kinds of radiation.
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(Q) Are there methods for holding down costs?
(A) Methods that can be mentioned for reducing costs are optimum design of the magnetic circuits and optimization of the usage temperature environment. First, optimum design of the magnetic circuit. If the magnetic circuit yoke shape and magnet layout are optimized, the magnet weight can be reduced. Next, the temperature environment. The coercive force iHc, which is an index of the ability of a neodymium family magnet to withstand heat, can be improved by adding dysprosium or other rare earth element. Thus, high heat resistant grades are expensive because they include a large amount of the rare earth element dysprosium. If steps are taken to minimize the impact from the outside environment and to keep the magnet temperature from rising, the danger of thermal demagnetization is reduced, so it becomes possible to switch to a grade with less dysprosium. Also, if the magnet shape is simplified, processing costs can be reduced, so costs can be reduced further.
  Shin-Etsu provides engineering support for magnetic field design, magnetic material selection, etc. as customers desire. For details, please consult with our marketing staff.
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(Q) Are there problems with the supply of rare earth raw materials?
(A) Resource problems are not that severe for neodymium, which is the main rare earth element in rare earth magnets. As mentioned in the section "Basics of rare earth magnets", neodymium is present in the earth's crust in amounts similar to those of cobalt and copper and is not that rare an element. Furthermore, it is also known that sizeable reserves of neodymium-producing deposits are present in various places around the world. It is thought that if the demand for neodymium increases, it will be extracted and produced from those mines to meet the market demand. On the other hand, conditions are somewhat different for dysprosium, which is the main element added to neodymium magnets. The amount of dysprosium in the Earth's crust is about 1/5 that of neodymium. Since less dysprosium is used than neodymium, this should not be that much of a problem. However, the problem is the quality of dysprosium deposits. There are few useable deposits from which dysprosium can be taken economically. Looked at in terms of resources, dysprosium-bearing deposits are present in various places around the world. However, these either have low content or environmental problems or are note economically viable. Currently, almost all economically extractable dysprosium deposits are in China. This is because the Chinese government turned its gaze on neodymium magnets early on and has a history as a nation state of developing rare earth resources.
  Well then, is there a problem with supplies of dysprosium being dependent on China? This is a difficult problem. It is difficult to give a simple and direct answer. However, this is what we think at this time. In the past, various resource crises have been proclaimed. However, almost none of these actually reached crisis levels. This is because when the need for a specific resource is recognized, new development moves forward, deposits are discovered and mining technology is improved. When it comes to commerce, businesses develop implementing these measures. Actually, not so much effort has been put into looking for dysprosium deposits until now. Detailed resource exploration like that undertaken within China has not yet been carried out that much worldwide. Recent resource exploration research has reported the possibility of new dysprosium deposits. Dysprosium mines are being developed in Southeast Asia, Australia, Canada, etc. Certainly, one can see dysprosium resource development lagging behind the development of neodymium deposits. There is a possibility that time differences will appear between the demand and supply of dysprosium. However, we think that ultimately dysprosium resource development will move forward and that it will be possible to secure the dysprosium required for magnets.
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(Q) Roughly what is the minimum practical size?
(A) In general, sintered magnets are produced through grinding machining processes for finishing the magnets into the final product shape. For NdFeB magnets, machining deteriorates the surface particles. If the magnet is large, the deterioration due to machining is small enough to ignore, but the smaller the magnet body, the larger the proportion of the volume taken up by the layer that deteriorates due to machining and there is a negative impact on the magnetic characteristics. For example, if the magnet dimensions are 1 mm x 1 mm x 1 mm, the machining deterioration is about 3%. In addition, since the magnetization can invert easily in the deterioration layer area, the amount of flux reduction becomes double or more than volume proportion. Furthermore, for ultra-small magnets, for example 0.5 mm x 0.5 mm x 0.3 mm, the flux value falls 30% below the catalog value. However, the coercive force of the machining deterioration layer can be restored somewhat with heat treatment and chemical treatment.
  SmCo magnets do not have the machining deterioration of NdFeB magnets. However, since the material itself is brittle, during machining or assembly to make an ultra-small magnet, cracking and splintering occur easily.
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(Q) A magnet was thermally demagnetized. If we remagnetize the magnet, is there any problem?
(A) The characteristics after remagnetization depend on what level of temperature environment the thermal demagnetization occurs in. For example, for demagnetization in a high-temperature environment exceeding 300°C, there is a danger of the magnet material degenerating, so remagnetization may not necessarily secure magnets with the same characteristics. On the other hand, even thermal demagnetization below 300°C has the possibility of coating deterioration for surface treated products. In particular, if nickel plated products are heated to over 100°C, the surface deterioration is striking.
  Also, magnets and magnetic circuits glued in place have a large possibility of the adhesive itself degenerating, so there is a danger of remagnetization damaging them.
For magnets free from the above issues, remagnetizations is basically possible, but since the external magnetic field required for magnetization depends on the magnet shape and material, please consult our marketing staff concerning details.
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(Q) Are there restrictions on shape? (Is it possible to handle complex shapes?)
(A) Even for large magnets about 100 mm along one edge, it is possible to produce the magnet as a single magnet. Also, for long magnets that are only large in one dimension, it is sometimes possible to produce magnets a little larger than 100 mm. When it is difficult to produce a magnet as a single piece, we offer ways to produce the product in pieces and glue it together.
  At the other end of the spectrum, for small magnets, since they are produced by cutting them out form large blocks of the material, production is possible down to sizes of about 1 mm square. However, the surface layer of neodymium family magnets lose their function as magnets and for small magnets the impact on the overall magnet characteristics is large, so when using small magnets, we suggest that adequate study is necessary.
  For complex shapes, generally whetstones are used for carving out the required shape. If the magnet shape has a concave section or sharply projecting section and production, sometimes production with a whetstone is difficult. For details, please consult with our marketing staff.
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(Q) Do rare earth magnets comply with the EU-RoHS directive?
(A) The EU-RoHS covers a total of six types of materials, four heavy metals plus two bromine-based flame retardants. For magnets, nickel plating is a subject of these regulations. Shin-Etsu sees countermeasures to environmental problems as the most critical issue and has no problem whatsoever with supplying compliant products.
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(Q) In selecting surface treatment for neodymium magnets, are there restrictions on shape and size?
(A) Shin-Etsu has a number of types of surface treatment, but there are cases in which shape and size make it impossible to apply them. There are cases in which the shape and size do permit application of surface treatment, but make it extremely expensive. It is necessary to select the surface treatment comprehensive understanding the magnet shape and size, the level of corrosion resistance it must have, cost, etc. For details, please consult with our marketing staff.
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(Q) Roughly what is the film thickness for surface treatment?
(A) The standard film thickness for nickel plating, inorganic paints, and epoxy is about 10-30 µm. The standard film thickness for RX coating and aqua coating is about 1 µm. However, depending on the particular surface treatment type, there are cases in which it is possible to set the film thickness thicker or thinner to match the customer's corrosion-resistance specifications.
  Also, there are cases in which the type of surface treatment and magnet shape make the film thickness uniformity poor, so it is necessary to be careful about this. For details, please consult with our marketing staff.
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(Q) Are there restrictions on the size of radial rings?
(A) Shin-Etsu's radial magnet production method makes it comparatively easy to produce even long, small-diameter shapes that are difficult to produce with normal radial ring magnets. For details, clicking on "About characteristic map shapes" will bring up material on the shapes of radial ring magnets that can be produced.
  However, extremely small-diameter products and extremely thick-wall products can make it difficult to achieve the desired characteristics, so it is necessary to be careful about this. For details, please consult with our marketing staff.
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(Q) Roughly what are the minimum pole width and the neutral width for multi-pole magnetization?
(A) General multi-pole magnetization is carried out by pulse magnetization using a magnetization yoke on which the magnetization coil has been wound to match the magnetization pattern. Therefore, the minimum pole width for multi-pole magnetization depends on how finely the magnetization yoke can be made. However, because generating the specific magnetization magnet field requires taking into account the winding diameter and number of windings, there is also a limit on how fine the magnetization yoke can be made. In particular, if the yoke is thicker than 2-3 mm in the magnetization direction, it becomes difficult to generate the magnetic field required for full magnetization, so the restrictions become tighter.
  Also, the neutral width is generally incorporated as part of the specifications based on the results of observation with a magnet viewer. However, even if this inspection method is taking hold, it can not be said that there has been adequate verification of the relationship between the area observed with the magnet view and areas of actual incomplete magnetization.
  Therefore, Shin-Etsu measured the neutral width using the more precise Gauss meter rather than using a magnet viewer. Shin-Etsu suggests a neutral zone width of 0.8 mm as the standard neutral width when the magnet is no more than 3 mm thick in the direction of magnetization.
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(Q) What are the precautions for disposing of magnets?
(A) When a magnet is disposed of, it is first necessary to thermally demagnetize it. If a magnet is disposed of still magnetized, there is a danger of the attractive force of the magnet causing injury and accident. Neodymium magnets need to be thermally demagnetized by heating them to at least 300°C. Because neodymium magnets Nd2Fe14B contain nearly 70% iron, after demagnetization, they are generally disposed of mixed in with scrap iron.
  However, with the rapid increase in demand for magnets in recent years, in the future it will become necessary to deal with magnets assuming recycling. At the current point in time, the technology for recycling waste matter generated in the magnet manufacturing process has been established, but recycling of general products is in the process of being developed and the form for processing has not yet been established. For the sake of preserving precious resources as well, this is a topic that industries can be expected to come together to tackle.
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(Q) What are the primary applications for rare earth magnets?
(A) The primary application, for rare earth magnets, is the voice coil motors that are a part of computer hard disk drives. Other applications include various industrial motors, sensors, consumer electronics, office equipment, musical instruments, and cellular phones. Recently, rare earth magnets have been used in products that help protect the environment and save energy such as electric vehicle motors, wind powered generators, and air conditioner compressors. We are enthusiastic about further developments and invite you to look on our website under each Magnet Applications for further details.
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(Q) I would like to order rare earth magnets, please advise standardized sizes and prices.
(A) Shin-Etsu Rare Earth Magnets are made-to-order so we do not have standardized sizes and prices. We design and manufacture based on customer specifications, each with differing material and dimensional requirements. However since we might have produced an identical magnet in the past, please feel free to contact an authorized Shin-Etsu sales representative.
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(Q) I would like to order the most powerful magnet available...
(A) Shin-Etsu Chemical's rare earth magnet lineup includes those with the highest performance and grades available in the world. Please feel free to contact an authorized Shin-Etsu sales representative. However, since specifications such as dimensions, temperature, coercivity (HcJ) and remnance (Br) differ, we will recommend a product after reconfirmation of design specifications with final determination to be made after sample verification.
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(Q) I've heard that as a rule, Neodymium magnets are susceptible to heat. Are there any Neodymium grades that can be utilized at 150-200 degrees C?
(A) Shin-Etsu has developed and is mass-producing Neodymium magnets with advanced properties for high temperatures, and with high levels of coercivity. However, actual maximum temperature varies according to the magnetic circuit of the magnet. Through computer analysis, we will optimize and recommend the ideal solution.
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(Q) We would like to utilize rare earth magnets in a motor we designed. Would Shin-Etsu be able to advise us as to the ideal shape, dimensions and grade?
(A) Shin-Etsu utilizes its know-how, obtained from many years of experience, to support development of magnetic circuits. Based on customer specifications, we will run a computer analysis and derive material type, grade and dimensions. We can also design the ideal magnetic circuitry for your application. Please refer to the Magnetic Circuit Design section on this website for further information.
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(Q) We have used an adhesive to glue the rare earth magnet to another part. Please tell me the ideal adhesive to be used in such an application.
(A) We have experience with various acrylic and epoxy based adhesives. We can recommend the ideal adhesive by taking into consideration the actual use conditions.
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(Q) Can Shin-Etsu ship magnets glued onto another object?
(A) Shin-Etsu has a track record of assembling many products including small magnetic parts such as VCM assemblies and motor rotors as well as larger products such as magnetic separators, sputterers and undulators. From magnetic circuit design to magnetic assembly, we combine our experience and engineering know-how to respond to your parts production requirements.
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(Q) Is it possible to drop ship rare earth magnets to offshore factories?
(A) Shin-Etsu, through its global network, can offer delivery, support and technical services to most locations in the world. For further information, please contact an authorized Shin-Etsu sales representative.
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(Q) We would like to export rare earth magnets by airfreight. Can magnetized magnets be shipped by airfreight?
(A) Yes, magnetized magnets can be shipped by airfreight. If you advise us at the time of purchase that the magnets will be exported by airfreight, we will pack the magnets in a package that meets airfreight safety specifications, utilizing methods to counter flux leakage. For further information, please contact an authorized Shin-Etsu representative.
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(Q) What are the safety concerns when handling rare earth magnets?
(A) Please refer to the warnings on this website and in the Shin-Etsu Rare Earth Magnet catalogue where they will be specified in detail.
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