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International Rare Earth Standards
The International Organization for Standardization (ISO) recently established a Technical Committee tasked with writing standards within the field of rare earth elements. The scope of the Technical Committee covers basic definitions, industry terminology, testing, analysis, rare earth products, element recycling, environmental stewardship, and material traceability. Standards spanning the global rare earth supply chain will be of critical importance to large consumers like the U.S. To ensure that U.S. market needs and perspectives are adequately represented, an advisory group of U.S.-based rare earth stakeholders, from a variety of sectors, have engaged in the process of helping write these new standards. The presentation will expand on this effort, as well as the opportunities that exist for additional stakeholder engagement.
Brian Zupancic, Senior Project Manager, CSA Group
Permanent Magnets Material Options: Why $/kg and (BH)max are Misleading Metrics
It has become accepted practice in the permanent magnet industry that $/kg and (BH)max are the primary metrics determining the optimum material choice for an application. However, there are many situations were both metrics are misleading and may lead to a less than optimal material selection. These shortcomings will be illustrated using case studies and alternative metrics will be discussed An update on the permanent magnet market and application drivers together with the history and latest status of the Hitachi Metals patent litigation will also be presented.
Dr. John Ormerod, Senior Technology Advisor, Magnet Applications, Inc.
New Permanent Magnet Materials from the Critical Materials Institute
Strong permanent magnets are an important component of many energy technologies, such as electric and hybrid electric vehicles. Despite this, finding permanent magnets to surpass or supplement the Nd2Fe14B magnet discovered in 1984 remains a challenge. This presentation will discuss several recent discoveries by the US DOE-funded Critical Materials Institute including: the rare-earth-free potential Alnico-beating “gap magnets” Fe5PB2 and Fe5SiB2; the potential high-performance magnet LaCeCo16Ti; and a less costly high performance magnet alloys based on the Nd2Fe14B material. The presentation will close with a description of future research directions and an outlook for the future of permanent magnets.
Dr. David Parker, Staff Scientist, Oak Ridge National Laboratory
AC Magnetic Field Measurements with the Senis Magnetic Field Mappers
The Senis Magnetic Field Mappers, or Field Scanners, were initially developed for high position resolution mapping of the three field components Bx, By, Bz in a 3D volume around a permanent magnet assembly. The Mapper hardware, signal processing and display software can also be applied for ac field measurement. Maps of the AC magnetic field in and around a power supply can show the fringe magnetic field from the transformer and inductor magnetic components as a function of position. Changes in the field amplitude and harmonic content can be used to estimate inductive coupling into nearby sensitive circuits and evaluate different component ratings or shielding strategies. Three-component Field Probes with field ranges to +/-3T and as thin as 0.25 mm can be used in the stator-rotor gap of an operating motor to make field maps at selected axial and polar positions as a function of speed and torque loading to compare with the motor design model. The harmonic content can help determine and reduce vibration and acoustic noise sources.
Dr. Zhen Xu, Development Engineer, GMW
Permanent Magnet Specifications: What About all Those Non-Magnetic Properties?
Standard practice for specifying permanent magnets involves naming the magnet family and relevant magnetic properties such as Remanence, Intrinsic Coercivity and Energy Product. Sometimes the weight or density of a part is identified but not as a controlled parameter. Every permanent magnet supplier and distributor lists the relevant magnet parameters on their website with the non-magnetic parameters off to the side, or banished to another page. Normally these specifications are considered uncontrolled or reference values. Occasionally a designer references these parameters on a drawing, implying they should be controlled. This can lead to back & forth discussions about what can and cannot be provided. The MMPA, ASTM and IEC standards all leave decisions on these issues to the customer and supplier. This presentation will discuss the non-magnetic properties such as Tensile or Yield Strength, Hardness and others. The origin of some of the values will be discussed, the limitations on the measurements and why they shouldn’t be used as controlling parameters on drawings or specifications.
Michael Devine, Senior Applications Engineer, Adams Magnetic Products
Injection Molded Magnets: Methods to Improve Their Accuracy for Positional Sensor Applications
The positional accuracy of magnetic sensor systems with injection molded magnets depends on different parameters. Those are the appropriate choice of the magnet for a given type of sensor, the magnets geometry together with its inherent distribution of polarization, an adequate design of magnetizing facilities as well as the management of the injection molding process. In this presentation the different sorts of injection molded magnets for the most common magnetic position sensors will be explained as well as the basic physical principles of their interaction. By different examples there will be shown how to improve external field components of the magnets, so that lower positional errors result at the sensor output. Those improvements can be reached often by relatively simple shape enhancements. In other cases a meticulous design of the magnetizing facilities is needed to provide sensor signals with low deviations from an ideal behavior. Beside experimental results, related design methods on FEM basis will be explained for the magnetization process of the magnet as well as for the analysis of the magnet-sensor interaction itself. Finally the impact of process parameters of injection molding will be presented, by general experimental studies as well as with data from series products.
Thomas Schliesch, Head of R&D, Baermann GmbH
Site Specific Magnetic Anisotropy in Rare Earth and Transition Metal Based Permanent Magnetic Materials
The very first criteria for the permanent magnetic material design is crystal structure which allows magnetic moments to align along the anisotropic crystal axis. Hexagonal and tetragonal structures do fall within this category. The involved crystal sites play a key role in determining the magnetic moments and uniaxial magnetic anisotropy. Here we present how advanced density functional calculations incorporating electron correlation and spin orbit coupling are capable to predict and optimize magnetic anisotropy contributed by the rare-earth sites due to the crystal-field split and spin-orbit coupled 4f-states followed by the small but non-negligible magnetic anisotropy contributed by 3d-states. We focus on the site substituted SmCo5 and it’s derivatives to show how theory helps to design and tailor intrinsic properties of permanent magnetic materials.
Durga Paudyal, Ph.D., Associate Scientist, Ames Laboratory
Magnetic Materials Fabricated by Cold Spray Additive Manufacturing
This presentation discusses the cost effective fabrication of soft and hard magnetic materials using cold spray additive manufacturing. This technique allows for 3D build-up of complex shapes permitting fabrication of high complexity motor designs for enhanced performance. Combination of sprayed soft and hard magnetic materials opens up synergetic design possibilities for additional performance gain and cost savings. Measured hard magnetic properties (coercivity and remanence), soft magnetic properties (permeability and losses) and mechanical properties (adhesion and cohesion) will be presented. Use of the materials for the realization of motor prototypes will be discussed.
Jean-Michel Lamarre, Research Officers, National Research Council of Canada
Expanded Temperature Capability for Permanent Magnet Testing and a New Single Sheet Tester for Electrical Steels
The testing of demagnetization curves of permanent magnets at elevated temperatures in hysteresigraphs is fairly routine, but testing below room temperature is not. A new system of thermoelectrically cooled electromagnet pole tips for testing magnets down to approximately -40°C is described along with examples of measurements that have been made with the equipment. For magnetically soft materials, there is a new single sheet tester for measuring the magnetic properties and anisotropy of sheet steel. It is exceptionally user-friendly and complies with specific ASTM and IEC test methods.
Reinhold M.W. Strnat, President, Magnet-Physics, Inc.
Rare Earth Permanent Magnets for Rotary Machines
Rare earth permanent magnets, such as neodymium iron boron and samarium cobalt, are commonly used in permanent magnet motors and generators. The magnetic circuit design, magnet grade selections, magnetic specifications, magnetic testing, magnet brittleness and handling, assembly techniques, in situ magnetization of rotors, containment band, rotor testing, and some possible failure mode of magnet rotors will be the focus of this talk. We will also discuss some of the misconceptions about magnet assemblies for rotary machines.
Jinfang Liu, President & COO, Electron Energy Corp.
Magnetization Vector Rotation in the Presence of Various Shielding Materials
A Vibrating Sample Magnetometer (VSM) has been used to characterize vibrating sample magnetization-vector rotation in the presence of Cartesian and Cylindrical shielding configurations. Shielding material permeability, susceptibility, conductivity, thickness and initial magnetization parameters are related to shielded magnetization-vector rotation. The test methods are ultimately expected to discern shielding penetration port effectiveness, shielding effectiveness, magnetization-vector rotation, and to be highly correlated with complicated modeling of shields utilizing permeability, susceptibility and conductivity as design parameters.
Ronald Lukins, Senior R&D Engineer, Measurement Analysis Corp.
Additive Printing of Permanent Magnets
This presentation is focused on the additive manufacturing techniques to print magnets with complex size and shape. Big Area Additively Manufactured (BAAM) NdFeB bonded magnets with performance comparable to, or better than, magnets of the same composition made using traditional injection molding. The density of the printed magnet is 5.2 g/cm3. The room temperature magnetic properties are: intrinsic coercivity Hci= 8.9 kOe (708.2 kA/m), remanence Br = 5.8 kG (0.58 Tesla), and energy product (BH)max= 7.3 MGOe (58.1 kJ/m3). Additive manufacturing can now be applied for a wide range of magnetic materials and assemblies. We will review all the additive printing techniques that are suitable for fabricating bonded magnets. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.
Dr. M. Parans Paranthaman, Corporate Fellow and Group Leader, Oak Ridge National Laboratory
A Comparison of Permanent Magnet Axial Flux Motors to Permanent Magnet Radial Flux Motors in Commercial Drone Applications
Commercial applications for battery powered autonomous vehicles used in air, land and sea environments will grow exponentially in the next few years. The drone application is the most popular of these applications in the present time. Currently most of the present applications use a special low weight design of the radial flux permanent magnet outer rotation motor. These applications need the low weight to allow a higher payload and a very low resistance to allow longer flight times. The Axial Flux motor can also be made in this type of design of a motor with a short height and a large OD and ID to minimize weight and resistance. This case study will compare the low weight Axial Flux design with both the inner rotation and outer rotation radial flux motor. The motor case study will be for a 3.5-inch diameter and 1.25 inch length motor. The input and output conditions will be the same and the weight and resistance of the three magnetic circuits will be compared. This case study will also compare the cost and reliability of the three motor types.
Lowell Christensen, Consultant Permanent Magnet Motor Design, Lowell Christensen LLC
Building Your Magnetic Field Mapper with LEGO
We will present a prototype of a modular, easily reconfigurable system for mapping magnetic fields. The basic module is a LEGO®-compatible “brick,” based on a recently introduced 3-axis digital “magnetometer on a chip.” Multiple bricks are assembled with LEGO, providing a flexible, inexpensive and accurate mechanical framework. A USB “super-hub” provides communication as well as synchronization of the acquisition. A user-friendly program allows the user to enter the coordinates of the bricks, launch the acquisition and display the resulting field map.
Philip Keller, Marketing & Product Management, Metrolab Technology SA
Wide Temperature Range Hall Effect Sensors with Minimal Planar Hall Effect
Recent development efforts have resulted in a new sensor technology for accurately measuring magnetic fields. These sensors rely on the Hall effect in a 2DEG structure, resulting in advantages such as an enormous operating temperature range, a massive reduction in planar Hall effect and excellent sensitivity. These sensors open up new measurement opportunities that may previously have been out of reach, such as high-stress cryogenic environments or high temperature industrial applications.
Daniel Hoy, Application Engineer, Lake Shore Cryotronics
Big Magnets are a Big Problem No More
More and more applications enlist magnets and the according magnet sensors for position, fixation or tracking purposes. For optimal system functionality, both parts have to meet very specific standards. While the magnet sensors may be calibrated all in the same manner, the characterization of the respective magnets is more complex. Depending on the application, we will find mostly dipole permanent magnets, but the geometries ranging from small tablets to vast cuboids or big, thin rings of various materials. In order to characterize these magnets, there is a range of measurement systems from very small sizes to medium-sized magnets based on the far-field theorem for dipole magnetic fields. The larger the geometry on permanent magnets becomes the harder these measurements can be enabled, as the magnetic response becomes increasingly smaller. The recent technology development allows the characterization of magnets up to 50 Am² based on a completely new sensor set-up using multiple orders of the magnetic field for the determination of the magnetic moment of big magnets. Equipped with Hall sensors surrounding the measurement area, it guarantees the same accuracy as the m-axis systems for smaller magnets with a system the same overall size.
Matthias Schmidt, Research Associate, MATESY GmbH
Nanostructured Rare Earth Ferrites Fabricated by Solution Combustion Synthesis
The rare earth ferrites exhibit a high electrical resistivity as well as an excessive value of magnetic permeability and low power losses that describes a growing interest for electronic applications at higher frequencies. Extensive studies specified the projections of such materials for constructing magnetic field sensors, microwave, recording and reading devices. In this report, the development of nanostructured particles of rare earth ferrites by Solution Combustion Synthesis (SCS) is described. The method uses exothermic reaction to produce a thermal front that moves through the sample converting components to the desired rare earth ferrite nanoparticles. The yttrium, lanthanum, cerium, samarium and iron nitrates were used as metal precursors and glycine as a fuel. The glycine is completely combusted during the thermal decomposition of the nitrates and generates a temperature front that propagates through the sample. Thermodynamic analysis of the systems predicted a maximum adiabatic temperature in the range of 2200-2800 K with generation of carbon dioxide, nitrogen and water vapor. The substantial gas generation during the reaction helps to produce the synthesized powders friable and loosely agglomerated. Increasing the glycine content increased the reaction temperature during the SCS and consequently the particle size.
Dr. Karen Martirosyan, Professor in Physics, University of Texas Rio Grande Valley
Theoretical and Practical Comparison of Open-Loop and Closed-Loop Hysteresis Measurement Systems for Permanent Magnets
It is established that measuring the BH curve of permanent magnets with open-loop and closed-loop measurement system yields the same results for the key parameters of a hysteresis trace: Br; HcB, HcJ and BHmax. Beyond these four key parameters, there exists small differences between the two measurement systems. This presentation will focus on these differences from the theoretical point as well as highlight some practical cases.
From the theoretical point, it is recognized that small differences can be observed near the knee point. Our efforts show that this can be accounted for using simple numerical techniques. But the proof is in the pudding, and in our continuous efforts to demonstrate that both systems yield the same results together with our customers and partners, we have gathered numerous data of which we will present some cases.
Dr. Luc Van Bockstal, Technical Director, Metis Instruments n.v