Bonded Magnets 2016: Current Status and Future Developments
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The global production of rare earth based bonded magnets is estimated to be $750 million in 2015. When the production of ferrite based bonded magnets is included the bonded magnet segment of permanent magnets is a very significant but often overlooked class of permanent magnet materials. In this presentation the main types of current materials and processing steps will be reviewed together with the latest developments in materials and novel manufacturing technologies e.g. additive manufacturing (3D printing). In addition the major applications and market drivers will be discussed.
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Bonded Magnets 2016: Current Status and Future Developments
- 1. Bonded Magnets 2016: Current Status and Future Developments Dr. John Ormerod Senior Technology Advisor Magnet Applications, Inc.
- 2. Presentation Outline •Introduction: who am I and who is MAI? •What are bonded magnets anyway? •Is there anything new in magnets (bonded or otherwise)? •What are the market and application drivers?
- 3. Introduction: John Ormerod • BSc, MSC and PhD in Metallurgy from the University of Manchester (1972 – 1978). • Magnetics career began with Philips (UK and Holland) - 1979 – 1990. • Developed and commercialized SmCo5, 2:17 and NdFeB magnets • Joined Arnold Engineering (US) responsible for soft and hard magnetic materials development and GM for permanent magnets ( 1990 – 2002). • 2002 - 2014 President of Res Manufacturing in Milwaukee. • Metal stamping and value added assemblies to the automotive market (Toyota, GM, Nissan) • Major supplier to Tesla Motors for Model S and future Model X • Recently provided expert testimony on issues of invalidity during the rare earth magnet ITC investigation and currently advising the Rare Earth Magnet Alliance on prior art relative to Hitachi Metals key patents. • Advisory Board member for Bunting Magnetics, Senior Technology Advisor for MAI and Technology Advisor for Niron Magnetics. • Founded business and technology consultancy for magnetics and metals related industries in 2015 – JOC LLC (www.jocllc.com).
- 4. Introduction: Magnet Applications, Inc. • Visit the website at: http://magnetapplications.com. • A Bunting Magnetics Company: https://buntingmagnetics.com/. • Largest North American manufacturer of compression bonded NdFeB and injection molded ferrite and NdFeB magnets. • Supply full range of engineered magnets and magnetic assemblies. • Located in DuBois, PA – Originally established in UK over 50 years ago – sister company located in Berkhamsted, UK. • Primary applications are BLDC motors and sensors in the automotive, medical and industrial markets.
- 5. Introduction: Magnet Applications, Inc. • Pre-production magnetic design services including 3D magnetic modeling. • Industry leading technical services to optimize the material for the application. • Investing in R & D for next generation of magnetic materials. • The backing of strong family ownership – in business for over 55 years. • ITAR / DFARS registered for Defense Industry. • ISO-9001 Certified Quality System with continuous improvement. • Very strong international supply chain for the complete range of permanent magnet materials.
- 6. Presentation Outline •Introduction: who am I and who is MAI? •What are bonded magnets anyway? •Is there anything new in magnets (Bonded or otherwise)? •What are the market and application drivers?
- 7. What Are Bonded Magnets Anyway? • Bonded magnets are composites of a permanent magnetic powder(s) embedded in a non- magnetic matrix. • The matrix is typically a thermoplastic, thermoset or elastomeric binder. • Common processing techniques are extrusion, injection molding, compression bonding, and calendering. • Exhibit excellent mechanical properties compared to fully dense rare earth and ferrite magnets. • End product has good finish and dimensional tolerances requiring no finishing operations. • Injection molded magnets can be formed into complex shapes and be insert or over molded directly onto other components to produce assemblies. • The non-magnetic binder lowers the density of the magnet and dilutes the contribution of the magnetic powder. • They generate less magnetic output per unit volume than fully dense magnets. • The two most common magnetic powders are isotropic NdFeB and hard ferrite.
- 8. Bonded vs. Sintered Bonded • Excellent geometric tolerances with minimal or no secondary operations • Good mechanical properties • Complex shapes • Insert/overmolding of sub assemblies • Higher electrical resistivity • Multipole magnetization • Tailored flux output for given size/shape magnet Sintered • Highest flux output • Higher operating temperature
- 12. Compression Bonding HYDRAULIC OR MECHANICAL RAM DIE PUNCH PRESS FRAME Encapsulated powder
- 13. Compression Bonding or Injection Molding? Injection Molding • Complex forms with good geometrical tolerances • Multi-cavity tooling • Over and insert molding But • Expensive tooling • Lower magnetics (66% volume loading of magnetic powder) • NdFeB and ferrite Compression Bonding • Thin walled large L/D ratio rings • Simple low cost tooling • Higher magnetics (75% volume loading of magnetic powder) But • Simple geometries • Value added operations during pressing very difficult • NdFeB only
- 14. Presentation Outline •Introduction: who am I and who is MAI? •What are bonded magnets anyway? •Is there anything new in magnets (bonded or otherwise)? •What are the market and application drivers?
- 15. Is There Anything New in Magnets (Bonded or Otherwise)? • In the summer of 2011, the price of rare earth elements was skyrocketing, blasted upward by uncertainties around sourcing. • What goes up must come down, and the rare-earth market has done so with a vengeance. • In 2010, the Chinese government cut the export quota by 40%. • Customers began doubling and tripling orders, and speculators moved in. • A widespread misconception in industry holds that the bubble formed because the Chinese government curtailed supply. • The cut in export quotas was the precipitating event but it was the response of customers and the supply chain that caused the problem, not an absolute limitation in the supply. Source: K. Lewotosky, MCMA 11/23/2015
- 16. • However, it did trigger a Global response to spend mainly other people’s money (ARPA-E, DARPA-E, EU-REFREEPM) on the search for a RE-free or reduced RE content magnet. • So what’s new-ish (but not yet commercialized): Ce-TM Mn-Bi Nanocomposite exchange spring Optimized AlNiCo Fe-N Co-Fe-C nanoparticles Nanocrystalline Mn-Al Fe-Ni Hf-Co etc., etc. Is There Anything New in Magnets (Bonded or Otherwise)?
- 17. Recent Development - Mn-Bi
- 18. Commercially Important Recent Developments • Next Generation La-Co doped hard ferrite magnets e.g. HML, TDK • Dy diffusion processing - Reduced Dy content high operating temperature NdFeB magnets
- 19. What’s New in Bonded Magnets? • Rare Earth-Free Fe16N2 based magnets. • Application of 3D Printing/Additive Manufacturing to Bonded Magnets and Assemblies. • Higher Energy Product Compression Bonded Isotropic NdFeB magnets.
- 20. 23 Some History on Fe16N2; The Slater-Pauling Curve
- 21. 0 10 20 30 40 1.5 2.0 2.5 3.0 3.5 4.0 N at. % magneticmomentperFe(µB) Fe Fe16N2 Fe4N ε-Fe3N ζ-Fe2N Strange departure from the regular SP curve was claimed back in 1970 that Fe16N2 possesses a giant Ms, corresponding to an average magnetic moment of 2.9~3.5 µB/Fe according to different reports. Some History of Fe16N2 24
- 22. 40 Years Later No Fe16N2 Magnet – Why? • Difficult to synthesize pure Fe16N2 by conventional methods e.g. solubility of N in liquid Fe very low (0.045 versus 5.5 wt % for C). • Alloy cannot be formed by conventional processing methods e.g. melting and casting. • Contradictory results over the years probably due to inconsistent sample preparation and measurement techniques. • Fe16N2 decomposes above 300 C. • Cannot be formed by powder metallurgical processing. • Lots of magnetization available but need coercivity for a useful PM compound; theoretical magnetocrystalline anisotropy H is 16 kOe but will need help from other mechanisms e.g. shape, strain.
- 23. 26 • Strained wire method used to enhance magnetic property; strain-assisted annealing. Bulk Fe16N2 Magnet Reported by UMN Team and Niron Magnetics Formed Source: Niron Magnetics
- 24. Niron Magnetics – Good News/Bad News Good News • The company is producing bulk iron nitride magnets today for further research and development. • First principles calculations demonstrate a theoretical BHmax of 135 MGOe and Hc of 16 KOe. • Raw materials are cheap and abundant. • Isotropic bonded magnet BHmax > 30 MGOe feasible. Bad News • Iron nitride by itself is inherently heat sensitive. • It decomposes before it sinters – iron nitride magnets will all be bonded in some fashion. • Coercivity needs to be improved. • They will need the same corrosion protection as raw iron. • Niron hasn’t announced a commercial product yet
- 25. What’s New in Bonded Magnets? • Rare Earth-Free Fe16N2 based magnets. • Application of 3D Printing/Additive Manufacturing to Bonded Magnets and Assemblies. • Higher Energy Product Compression Bonded Isotropic NdFeB magnets.
- 26. Additive Manufacturing – MAI and ORNL Joint R and D Project • MAI and ORNL were recently awarded a Cooperative Research and Development award to study the application of additive manufacturing to bonded magnets and systems.
- 27. Types of AM/3D printing Source:ORNL
- 28. ASTM International: Technical Committee F42 on Additive Manufacturing Vat Photo- polymerization Material Jetting Material Extrusion Sheet Lamination Powder Bed Fusion Directed Energy Deposition Binder Jetting Types of Additive Manufacturing Source:ORNL
- 29. -40 -20 0 20 40 -200 -150 -100 -50 0 50 100 150 200 per gram of composite per gram of MQP assuming 60 wt % M(emu/g) H (kOe) i HC = 9 kOe Binderjet MQP-resin Initial MQP Magnets Produced by Binder Jetting Source: ORNL
- 30. BAAM system at ORNL Fabricated rotors Post Magnetic field alignment (9 Tesla) Magnetization behavior of the bonded magnet The process: 36 Large Scale Polymer Deposition of Bonded Magnets Source: ORNL
- 31. Large Scale Additive Manufacturing What’s next? Permanent magnet based motors!!! 3D printed all electric Shelby Cobra car Source: ORNL
- 32. What’s New in Bonded Magnets? • Rare Earth-Free Fe16N2 based magnets. • Application of 3D Printing/Additive Manufacturing to Bonded Magnets and Assemblies. • Higher Energy Product Compression Bonded Isotropic NdFeB magnets.
- 33. BHmax Improvement in Compression Bonded Magnets The BHmax of a compression bonded isotropic NdFeB magnet is influenced by the following two factors: 1. Volume fraction of magnetic phase in the magnet – typically measured by the density of the magnet. • We are investigating increasing the pressing pressure which requires special press construction, lubricants and tooling materials – current production pressing pressures are 7tonnes/cm2 for 5.9 g/cm3 and 10MGOe; estimated that > 20 tonnes/cm2 required for 6.3 g/cm3 and > 11 MGOe. • Optimize the particle encapsulation chemistry and process. • Tailored multimodal PSD’s for maximum packing density. • Particle shape control. 2. Magnetic powder Br/BHmax • Increase isotropic Br of powders while maintaining sufficient Hci to have “linear” B-H demagnetization characteristic at the application temperature.
- 34. 20% BHmax Improvement - True 11 MGOe Standard production minimum magnetics at 5.9 g/cm3: Br = 6800 G Hci = 9.1 kOe HcB = 5.4 kOe BHmax = 9.2 MGOe High density minimum magnetics at 6.3 g/cm3: Br = 7400 G Hci = 9.1 kOe HcB = 6.0 kOe BHmax = 11.1 MGOe
- 35. Presentation Outline •Introduction: who am I and who is MAI? •What are bonded magnets anyway? •Is there anything new in magnets (bonded or otherwise)? •What are the market and application drivers?
- 36. Magnet Type Tons x 1,000 % by Weight Million USD % by Value ASP - $/Kg Sintered NdFeB 70 10.9% $10,500 54.8 % $150 Bonded NdFeB 9 1.4 750 3.9 90 Sintered /Bonded Ferrite 565 87.6 6,780 35.4 12 Samarium Cobalt 4 0.6 700 3.7 175 Alnico 6 0.9 420 2.2 70 TOTAL 645 100.0% $19,150 100.0% - Global Production Of Permanent Magnets In 2014
- 37. PM Markets and Devices/Applications Devices • Electromechanical machines and devices e.g. motors, generators, actuators • Acoustic transducers e.g. speakers, earphones, ringers • Mechanical force and torque devices e.g. holding, lifting, clutches • Microwave and ion beam control e.g. TWT’s, particle accelerators • Conversion of external stimuli to electrical signal e.g. sensors • DC field generation e.g. MRI Markets and Industries • Automotive and transportation • Industrial and commercial • Consumer products • Military and aerospace • Medical
- 38. Sensors/Encoders Hall Effect Encoder for end of shaft applications. Hall Effect through-shaft encoder. Low cost, speed or position sensors typically seen in automotive applications e.g. Cam position, crank position, engine speed, ABS.
- 39. Summary • What is the best magnet material and process? • It depends; on the weight/space limitations, application operating conditions, operating parameters of the magnetic circuit, annual quantities, device assembly mechanization etc. • Despite having lower flux output bonded magnets can offer advantages for many applications. • No new significant materials over the last 30 years but there are several promising developments in bonded magnets on the horizon. THANK YOU FOR YOUR ATTENTION – ANY QUESTIONS
Editor's Notes
- Good afternoon. My name is John Ormerod and I am Senior Technology Advisor to Magnet Applications Inc. In my presentation I will attempt to give a review of bonded magnet technologies and describe the latest developments.
- I will be covering the following items: Brief introduction of myself and MAI What are bonded magnets Latest developments Finish with a few words about the BM markets and applications
- A few words about myself: Graduated in the UK in metallurgy Began magnetics career with Philips developing RE magnets Joined Arnold Engineering in 1990 and ran their PM buisnesses 2002 left the industry and ran a manufacturing business became a major supplier to Tesla Motors Expert witness for the ITC and RE Magnet Alliance challenging the validity of the HML NdFeB patents Senior Technology Advisor for MAI Founded JOC LLC
- A few words about MAI
- Bonded magnets come in many shapes and sizes. This manufacturing approach may be used to make all types of magnets by using plastic processing technologies. Because of the many types of binders, a wide range of mechanical properties can be achieved: strong, flexible, impact resistant, etc. The end products are usually used as-is because the finish and dimensional tolerances are generally acceptable. Tooling cost may be a draw back for injection molded marts, although extrusion and compression molded dies are usually reasonable. However, injection molds may range from $10,000 to $100,000 or more.
- Advantages and disadvantages of bonded and fully dense (sintered) magnets
- There are four fundamental manufacturing processes: Compression bonding using thermoset epoxies; Extrusion and Calendaring which use thermo-elastomers; and Injection molding which uses thermo-plastic materials. This chart summarizes the type of product manufactured by these processes and the type of magnetic powder commonly used.
- Highly loaded Thermoplastic compound is fed into the injection mold screw. The compound is transported and mixed down a heated barrel by the auger screw which injects the softened, highly filled thermoplastic compound into a mold where the compound solidifies. The mold is held closed by the force of a hydraulic system. The mold may contain magnetic circuit(s) using either permanent magnets or an electromagnetic system to provide an orienting field The process can produce very precise and complex-featured components. It is highly capable with the ability to generate complex orientation patterns. Magnetization (during processing) and insert or overmold capabilities for assemblies are all possible
- The raw material used in the extrusion process is typically a compound of a thermoelastomer and ferrite powder. The screw works against the barrel to push the compound through a heated die at high pressure. The resulting strip of material is collected, either on a spool, cut sheet is stacked, or strip is cut into pieces of specific length. The cross-section profile of the strip must remain the same along the length of the extrusion. Continuous extrusion of a highly loaded elastomeric or thermoplastic compound is used to produce continuous profiles of strip or sheet in a very efficient process. A strip extrusion process is shown.
- Calendering is the rolling process for making continuous magnet sheets. It is used for flexible, rubber-based magnets. The granulated compound is fed in the top and through a series of heated rolls. By applying pressure on the rolls and pulling the strip as it exits the rollers, a continuous roll (jumbo) of several hundred feet can be formed. Mechanical orientation occurs with ferrite due to the applied pressure and plate-like shape of the crystals. The ferrite powder is oriented mechanically during the calendering to produce oriented magnetic properties. The continuous strip of magnet sheet is rolled on drums and can be 60 cm or more wide. The rolling process allows good thickness control, and sheets between 0.7 mm to 10 mm can be made this way. Product may be slit to a desired width and either cut to length or punched into a specific geometry. The photo on the right shows the output from a fully automated calender system. The calendering process utilizes highly loaded elastomeric compound to produce wide sheet. The ferrite powder is oriented mechanically during the calendering to produce anisotropic orientation.
- A uniaxial pressing process is used to manufacture compression bonded magnets. The binder is usually a thermosetting epoxy. Key is the chemistry of the binder and the particle encapsulation process. The magnetic material is normally neodymium-iron-boron. It is rather straightforward to manufacture samples of simple geometry but thin walled rings with large L:D ratios can be produced. Compression bonded magnets have higher loading than molding, 75 versus 66 volume percent, resulting in higher BHmax.
- Advantages and disadvantages of compression bonding and injection molding
- Alphabet soup of magnet R and D programs leading to the renaissance in basic magnetic material research…..while no new breakthrough material have been commercialized these programs have produced a new generation of engineers and scientists with a fundamental knowledge of magentics
- I do want to mention two significant developments that came out of industry
- What’s new in bonded magnets; Here are the three developments I want to discuss this afternoon
- In the 1930’s Slater and Pauling discovered that the magnetic moment of transition metals and their binary alloys can be approximated by the number of valence electrons per atom. Shown here as the theoretical prediction compared to experimental measurement.
- Fe16N2 has been known as a potential PM material since the early 1970’s. It has interested Physicists because the saturation magnetization is much higher than theory predicts (Slater-Pauling curve dependence on number of outer shell electrons).
- However, it has been difficult to synthesize and reproduce the results until a group at the UMN in 2012 fabricated thin films of Fe16N2 and confirmed Ms > 3.0 T or 30 kG i.e. double that of Nd2Fe14B
- In 2014 Niron Magnetics (based at the UMN) announced a bulk magnet based on Fe16N2 detailed in their 2014 patent application.
- So we have the Holy Grail of PM materials……RE free and based on Fe and N2. However, there is good and bad news……
- Next area of development is the application Additive manufacturing or 3D printing to bonded magnets and assemblies. MAI and ORNL have been awarded a research grant by the DOE to study the fabrication of net shaped NdFeB magnets utilizing 3D printing/additive manufacturing technologies.
- Many types of additive manufacturing technologies – these are the ones available at ORNL
- http://www.utwente.nl/ctw/opm/research/design_engineering/rm/RM%20processes/ http://www.3dsystems.com/quickparts/prototyping-pre-production/process-comparison
- I’m going to introduce you to the 10 principles of additive manufacturing. These principles were coined by Hod Lipson from Cornell. The first principle of Additive Manufacturing is that complexity is free. It doesn’t matter if I’m building a solid block or a very complex shape such as what you see here. The machine doesn’t care. All it sees at one time is a 2 dimensional cross section of each layer. So, usually, if you can design it, we can build it. So our manufacturing process has actually outpaced our design capability, which is a huge opportunity for design software developers. If they can help us design things that use material efficiently, that will be a huge game changer as far as really using Additive manufacturing to it’s fullest capacity.
- Some initial samples produced using ExOne binderjet process
- Also produced larger structure using a large scale polymer deposition process
- A major challenge is to develop a highly loaded ink that can ink jet printed.
- This is not lab scale processing equipment but industrial scale fabrication. The real breakthrough in utilizing additive manufacturing will be combing hard magnetics, soft magnetic, electrical and structural components to manufacture assemblies and ultimately complete motors.
- Typical properties of a compression bonded isotropic NdFeB bonded magnet
- One goal we have is to improves the BHmax of a compression bonded isotropic NdFeB magnet. Good news is there are only two ways to increase the Br and therefore BHmax….bad news is there are only two ways to improve the Br and BHmax.
- One goal we have is to improves the BHmax of a compression bonded isotropic NdFeB magnet. Good news is there are only two ways to increase the Br and therefore BHmax….bad news is there are only two ways to improve the Br and BHmax.
- Production dominated by hard ferrite in terms of weight but NdFeB is over half the value in dollars. Bonded NdFeB at $750 million is a distant third but still a significant contributor to the PM market
- Segmentaion of market by device function and end industry group. One device segment that uses bonded magnets is sensors that finds application across all industries