Custom Magnets and Magnet Assemblies
About BUNTING Bunting is an industry leader in the design, manufacture,
With a team of engineers using world-class, computer-aided
and sales of cutting-edge magnetic equipment used in
design equipment, we can customise and develop products
applications such as magnetic separation, metal detection,
to fit any application or production line.
conveyor systems, custom manufactured magnets, and more. All of the products we sell are custom-designed by our
Bunting-DuBois has a unique role as it is the only North
engineering team. We work with customers to determine
American manufacturer of compression bonded, injection
their exact needs and develop a product that will perfectly
moulded, and hybrid magnets used in custom designed
suit the challenges of the industry they are working in and the
permanent magnet assemblies. These assemblies are used
materials they are handling, as well as being designed to fit
in the military, aerospace, automotive, and other industrial
within the existing layout of the customer’s facility.
commercial industries.
Since 1959, Bunting has been a family-owned, family-
Bunting-Elk Grove Village is home to the company’s Magnet
operated company. Headquartered in Newton, KS, Bunting
Materials division. Bunting-Elk Grove Village provides
currently has multiple manufacturing facilities within the
the largest online selection of permanent magnets and
United States as well as abroad in the United Kingdom. We are
magnetic equipment, with all in-stock items able to be
committed to upholding the values of innovation, dedication,
shipped within 24 hours of an order being placed on its
and hard work that Bunting was founded upon sixty years ago.
website, BuyMagnets.com.
As technology continues to advance across every industry,
Bunting-Berkhamsted provides total magnetic solutions—
Bunting remains committed to integrating new technology
from individual magnets and magnetic sub-assemblies to
into our products, creating solutions that address modern
magnetic separation, material handling, and metal detection
industry challenges, and continuing to expand our domestic
equipment to various industries throughout Europe and the
and international reach.
UK. Bunting-Berkhamsted also manages e-magnetsuk.com, where customers may purchase a wide variety of commonly
Bunting-Newton primarily focuses on magnetic equipment
used magnets.
for magnetic separation and metal detection applications. Newton, Kansas has served as the company’s headquarters since 1979. Here, we design and manufacture magnetic separation, metal detection and material handling equipment as well as a complete line of printing cylinders.
Bunting-Elk Grove Village
Bunting-Redditch provides a complete line of magnetic separation, recycling, and metal detection equipment to industries across the globe.
Bunting-Berkhamsted & Bunting-Redditch Bunting-China
Bunting-Newton
Bunting-DuBois
Bunting ® Magnetic Technology for All Industries
Separation, Detection, and Conveying Equipment for the Recycling Industries
The unique benefits of magnetic technology can be utilised across a wide range of applications, and Bunting is always looking to the future regarding new challenges that present themselves in the many industries we work with. Bunting engineers are constantly working to develop new technologies and improve upon our existing product lines. Bunting custom designs, manufactures, and distributes a broad selection of magnets and magnetic assemblies for automotive, medical, aerospace and defense, oil and gas, permanent magnet motors, consumer products, and sensors.
FOOD AND PHARMACEUTICALS PLASTICS RECYCLING AUTO SHREDDING AGGREGATE, MINING MINERALS CERAMICS TEXTILES METAL STAMPING & FABRICATING PRINTING, DECORATING AND CONVERTING CUSTOM MAGNETS AND MAGNETIC ASSEMBLIES STOCK MAGNETS & MAGNETIC TOOLS Across all the industries Bunting works with, our commitment to providing quality products and customer service remains consistent. Bunting enthusiastically offers custom designed applications for customers bringing unique challenges to the table, and we take pride in working individually with each customer in order to provide the best product possible.
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Contents Magnet Types..................................................................................................................... 5-6 Design Considerations................................................................................................. 7-9 Assembly Considerations...................................................................................... 10-11
Magnetisation Waveforms.............................................................................................. 12 Custom Magnets for Design Specific Applications............................................... 13 Magnet Materials................................................................................................................ 14 Magnet Assemblies........................................................................................................... 15 What Bunting Offers.................................................................................................... 16-18
Magnetising Equipment..............................................................................................19-22 Magnet Material Charts............................................................................................. 23-32
Technical Data of Sintered NdFb................................................................................... 33 Technical Data of Magnet Materials............................................................................. 34
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Permanent Magnets:
Alnico Magnets
Permanent magnets are essential to virtually
Alnico magnets are alloys comprised of
convenience. Being able to provide the optimum
highest operating temperature and temperature
every type of modern technology and
magnetic solution to the customer requires
in-depth knowledge of the full supply chain.
Bunting’s team of magnet experts and engineers is fully equipped with this knowledge. Bunting entered the magnetics industry in 1959 as a magnet distributor and rapidly grew to a
manufacturer of magnetic products, focused on custom design and customer-focused engineering. Today, Bunting is a leader in
manufacturing and designing a diverse range of innovative magnetic technologies across
aluminium, nickel, iron, and cobalt. They have the stability of any permanent magnetic material. They retain approximately 85% of room-temperature magnetisation at temperatures of up to 500°C.
They possess high residual induction as well as
relatively high energies. Alnico magnets naturally possess an excellent corrosion resistance. This
makes surface treatment unnecessary, although they may still be easily plated if desired. Alnico
magnets may be produced by either casting or sintering.
industry sectors. Listed below are the general
Neodymium Iron Boron Magnets
products.
Neodymium magnets are a type of rare earth
Ceramic
permanent magnets in the world. They are
Ceramic magnets, or ferrite magnets, are low
(B), and exhibit the highest maximum energy
permanent magnet types that are used in Bunting
cost, lightweight, moderate energy permanent magnets capable of withstanding operating
temperatures of up to 250°C. They are highly
corrosion resistant and work well in high volume applications. These qualities make them a
popular choice in manufacturing and consumer applications such as speaker magnets, DC
motors, reed switches, sweepers, MRIs, and
magnet and are the most common rare earth
composed of Neodymium (Nd), Iron (Fe) and Boron product of any permanent magnet material. However, these magnets are vulnerable to
corrosion if they are exposed to the elements. To
protect the magnet from corrosion, the magnet is usually coated with nickel. Other coating options are aluminium, zinc, tin, copper, epoxy, silver and gold.
automotive sensors. Ceramic magnets can be
• These high power magnets achieve maximum
intricate and accurate shapes, and can even be
• Can be made in blocks, rings, arcs, discs,
made in many shapes and sizes, can be ground to designed to be small enough to be used in micro applications.
performance while maintaining minimum size.
spheres, trapezoids, triangles, and many other shapes.
• Radially aligned magnets are available to replace arcs.
• Grain boundary diffusion is now available in commercial quantities.
• High-temperature neodymium magnets can
safely be used at operating temperatures up to 300° F (149° C). Special grades are also
available that can operate in excess of 392°F (200°C).
• Injection moulded magnets are available in both neodymium and ferrite varieties.
• Injection moulded ferrite magnets offer high durability and resistance to shock, as well as a low cost and extreme resistance to
corrosions and conditions such as low density.
Plastic Bonded Neodymium Magnets These magnets are-cost effective while offering high performance and tolerances in addition
to low electrical conductivity. It is possible to
multipole magnetise them as a complete ring,
• Available in high tolerance and complex shapes.
• No coating required, although black epoxy and Parylene coatings are available.
and they can be designed to achieve specific
Samarium Cobalt Magnets
suited for applications such as minimising
Samarium cobalt magnets are rare earth
moulded magnets are an excellent choice for
products and can operate in high temperature
flux density profiles. These are especially well cogging torque in motors. These injection higher volume applications. Compression
bonded magnets can also be easily machined,
making them suitable for low volume production in manufacturing magnets with multipole
magnetisation, skew angled poles, and various
other directions of magnetisations. Magnetising patterns are only limited by whether or not a
magnetising coil fixture can be produced to give the required magnetising pattern.
• Bonded NdFeB magnets can be compression
or injection moulded to net shape. These high
tolerances can be achieved without the need for further machining.
magnets that offer high maximum energy
environments. They are extremely strong and
typically allow for smaller size magnet profiles. Though not as strong as neodymium magnets, samarium cobalt magnets present three
significant advantages. They work over a wider temperature range, have superior temperature
coefficients, and also have a greater resistance to corrosion. Special coatings are available for specific marine and automotive applications.
Samarium cobalt magnets are known for their
excellent temperature stability—maximum use
temperatures are between 250 and 550°F; Curie temperatures range from 700 to 800°F.
10000 F 9000 F 8000 F 7000 F 6000 F 5000 F 4000 F 3000 F 2000 F 1000 F
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Neodymium Iron Boron Magnets 392º F (200º C)
Plastic Bonded Neodymium Magnets 302º F (150º C)
Samarium Cobalt Magnets 572º F (300º C)
Ceramic Magnets 482º F (250º C)
Alnico Magnets 1,022º F (550º C)
Design Considerations
to many days and we pride ourselves on the cost effectiveness of this service. THE BH CURVE:
Basic problems of permanent magnet design revolve around estimating the distribution of magnetic flux in a magnetic circuit, which may include permanent magnets, air gaps, high permeability conduction elements, and electrical currents. Exact solutions of magnetic fields require complex analysis ofB many factors, although approximate solutions are possible based on certain simplifying assumptions. Obtaining an optimum magnet design often involves experience H and tradeoffs. FINITE ELEMENT ANALYSIS: Hysteresis Loop Magnetic Design has become a critical feature of Bunting’s growth and we seek to work with our customers to realise their ideas. Finite Element
Analysis (FEA) modeling programs are used to analyse magnetic problems in order to arrive at more exact solutions, which can then be tested and fine-tuned against a prototype of the magnetic structure. Using FEA models, flux densities, torques, and forces may be calculated. Results can be output in various forms, including plots of vector magnetic potentials, flux density maps, and flux path plots. Bunting uses a suite of 2D and 3D transient FEA modeling packages backed up with in-house design software and a team with many years of experience in magnetics as well as general engineering. This allows us to undertake a wide range of design programs across many industries including automotive, defense, medical, and more, and across many applications, including sensors and Brushless DC (BLDC) motors. The length of design contract ranges from a few hours
The basis of magnet design is the BH curve, or hysteresis loop, which B characterises each magnet material. This curve describes the cycling of a magnet load line at BHmax in a closed circuit as it H is brought to saturation, demagnetised, saturated in the opposite direction, and then H demagnetised again under Hc Hysteresis Loop the influence of an external magnetic field. The second quadrant of the BH curve, commonly referred to as the B “demagnetisation Br BHmax curve,” describes load line at BHmax the conditions under which permanent magnets are used BH H in practice. A Hc permanent magnet will have a unique, The Demagnetisation Curve static operating point if air-gap dimensions are fixed and if any adjacent fields are held constant. Otherwise, the operating point will move about the demagnetisation curve, the manner of which must be accounted for in the design of the device. The three most important characteristics of the BH curve are the points at which it intersects the BH axes (at Br—the residual induction—and Hc—the coercive force—respectively), and the point at which the products of BH are at a maximum (BH max— the maximum energy product). Br represents the maximum flux the magnet is able to produce under closed circuit conditions. In actual useful operation, permanent magnets can only approach this point. Hc represents the point at which the magnet becomes demagnetised under influence of an externally applied magnetic field. BH max represents the point at which the product of BH and the energy density of the magnetic field into the air gap surrounding the magnet are at a maximum. The higher this product, the smaller need be the volume of the magnet. Designs should also account for the variation of the BH curve with temperature. Measurement of BH curves requires specialised equipment. The most common type is DC Hysteresis graphs (Permeameter) where the magnet is driven around its BH loop in a DC electromagnet with sensing coils to measure the BH of the magnet. Bunting has a temperature controlled permeameter which can generate BH curves at temperatures from ambient up to 150 C. We use this data to qualify our materials and to supply accurate material data for our design software.
Br
B
The Demag
Design Considerations PERMANENT MAGNET STABILITY:
Irreversible but recoverable losses:
The ability of a permanent magnet to support an external magnetic field results from small magnetic domains “locked” into position by crystal anisotropy within the magnet material. Once established by initial magnetisation, these positions are held until acted upon by forces exceeding those which lock the domains. The energy required to disturb the magnetic field produced by a magnet varies for each type of material. Permanent magnets can be produced with extremely high coercive forces (Hc) which will maintain domain alignment in the presence of high external magnetic fields. Stability can be described as the repeated magnetic performance of a material under specific conditions over the life of the magnet.
These losses are defined as partial demagnetisation of the magnet from exposure to high or low temperatures. These losses are only recoverable by remagnetisation, and are not recovered when the temperature returns to its original value. These losses occur when the operating point of the magnet falls below the knee of the demagnetisation curve at expected elevated temperatures. This will prevent performance variations at elevated temperatures.
Factors affecting magnet stability include: time, temperature, reluctance changes, adverse fields, radiation, shock, stress, and vibration.
Irreversible and unrecoverable losses: Metallurgical changes occur in magnets exposed to very high temperatures and are not recoverable by remagnetisation. The table below shows examples of critical temperatures for the various materials where: • Curie point is the Curie Temperature at which the elementary magnetic moments are randomised and the material is demagnetised.
TIME: The effect of time on modern permanent magnets is minimal. Studies have shown that permanent magnets will see changes immediately after magnetisation. These changes, known as “magnetic creep,” occur as less stable domains and are affected by fluctuations in thermal or magnetic energy, even in a thermally stable environment. This varies as the number of unstable domains decreases. Rare Earth magnets are not as likely to experience this effect because of their extremely high coercitivities. Long term time versus flux studies have shown that a newly magnetised magnet will lose a minor percent of its flux as a function of age. Over 100,000 hours, these losses are in the range of essentially zero for Samarium Cobalt materials to less than 3% for Alnico 5 materials at low permeance coefficients. TEMPERATURE:
• Max operating temperature is the maximum practical operating temperature in air, for general classes of major materials. Different grades of each material exhibit values differing from the values shown below. Critical Temperatures for Various Materials °C
Material
Max Operating Temp. Curie Point
Material
NdFeB
150
310
NdFeB
SmCo
300
750
SmCo
NdFeB Bonded
150
N/A
NdFeB Bonded
Alnico
540
860
Alnico
Ceramic
300
460
Ceramic
Flexible NdFeB **
100
N/A
Flexible NdFeB
Temperature effects fall into three categories: **Due to the bonding agents used, flexible magnets may not operate at temperatures above 100 C • Reversible losses • Irreversible but recoverable losses • Irreversible and unrecoverable losses Partially demagnetising a magnet by exposure to elevated temperatures in a controlled manner stabilises the magnet with respect to temperature. The slight reduction in flux Reversible losses: density improves a magnet’s stability because domains with low commitment to orientation are the first to lose their These are losses that are recovered when the magnet orientations. A magnet thus stabilised will exhibit constant returns to its original temperature. Reversible losses flux when exposed to equivalent or lesser temperatures. cannot be eliminated by magnet stabilisation. Reversible losses are described by the Reversible Temperature Coefficients (Tc). Tc is expressed as % per degree C. These figures vary for specific grades of each material as a whole. It is because the temperature coefficients of Br and Hc are significantly different that the demagnetised curve develops a “knee” at elevated temperatures.
Design Considerations RELUCTANCE CHANGES: Reluctance changes occur when a magnet is subjected to permeance changes such as changes in air gap dimensions during operation. These changes will change the reluctance of the circuit, and may cause the magnet’s operating point to fall below the knee of the curve, causing partial and/or irreversible losses. The extent of these losses depends on the material properties and the extent of the permeance change. Stabilisation may be achieved by pre-exposure of the magnet to the expected reluctance changes. ADVERSE FIELDS: External magnetic fields in repulsion modes will produce a demagnetising effect on permanent magnets. Rare Earth magnets with coercive forces exceeding 15KOe are difficult to affect in this manner. However, Alnico, which has a lower coercive force, will encounter magnetic losses in the presence of any magnetic repelling force, including similar magnets. Applications involving ceramic magnets with coercive forces of 4KOe should be carefully evaluated in order to assess the effect of external magnetic fields. SHOCK, STRESS, AND VIBRATION: Below destructive limits, these effects are very minor on modern magnet materials. However, rigid magnet materials are brittle in nature and can be easily damaged or chipped by improper handling. Samarium Cobalt in particular is a fragile material and special handling precautions must be taken to avoid damage. When Ceramic and Samarium Cobalt magnets are exposed to high temperature gradients, thermal shock can cause fractures within the material. High temperature gradients should be avoided for this reason. PHYSICAL CHARACTERISTICS AND MACHINING OF MAGNETS: Sintered Samarium Cobalt and Ceramic magnets exhibit small cracks within the material that occur as a result of the sintering process. Provided that cracks do not extend more than halfway through a section, they do not normally affect the operation of the magnet. This is also true for small chips that may occur during machining and handling of these magnets, especially on sharp edges. Magnets may be tumbled to break the edges. This is done to avoid “feathering” of sharp edges due to the brittle nature of materials. Tumbling can achieve edge breaks of 0.003” to 0.0100”. Although sintered NdFeB is relatively tough compared to Samarium Cobalt and Ceramic, it is still brittle and care must be taken in handling. Bonded NdFeB is not as brittle as the sintered materials, but it is softer and must be handled with care as well. Because of these inherent material characteristics, it is not advisable to use any permanent magnet material as a structural component of an assembly.
Rare Earth, Alnico, and Ceramic magnets are machined by grinding, which may considerably affect the magnet cost. Maintaining simple geometries and wide tolerances is therefore desirable from an economic point of view. Rectangular or round sections are preferable to complex shapes. Square holes (even with large radii) and very small holes are difficult to machine and should be avoided. Magnets may be ground to virtually any specific tolerance. However, to reduce cost, tolerances of less than 0.001” should be avoided if possible. Cast Alnico materials exhibit porosity as a natural consequence of the casting process. This may become a problem with small shapes which are machined out of larger casting, but can account for a large portion of the smaller fabricated magnets. This may cause a problem where uniformity or low variation is critical and it may be advisable either to use a sintered Alnico or another material. In spite of its slightly lower magnetic properties, sintered Alnico may yield a higher or more uniform net density, resulting in equal or higher magnetic output. In applications where the cosmetic qualities of the magnet are of a concern, special attention should be placed on selecting the appropriate material, since cracks, chips, pores, and voids are common in rigid magnet materials. COATINGS: Samarium Cobalt, Alnico, and Ceramic materials are corrosion resistant and do not require to be coated against corrosion. Alnico is easily plated for cosmetic qualities and Ceramics may be coated to seal the surface which will otherwise be covered by a thin film of ferrite powder. NdFeB magnets, both sintered and bonded, are susceptible to corrosion and consideration should be given to the operating environment to determine if coating is necessary. Plating and/or coatings may be used for NdFeB magnets, however, the material must be properly prepared. Aluminium Chromate or Cadmium Chromate vacuum deposition (PVD) is a successful process that can provide a coating thickness as low as 0.0003”. Parylene, various epoxies, and other organic coatings are relatively inexpensive and are also successful as NdFeB coatings. A further option for critical applications is to apply two types of protective coatings or to encase the magnet in a stainless steel or other housing to reduce the chances of corrosion. The effectiveness of coatings on customer’s parts can be tested in Bunting’s Temperature and Humidity Controlled Environmental Chamber.organic coatings are
relatively inexpensive and are also successful as NdFeB coatings. A further option for critical applications is to apply two types of protective coatings or to encase the magnet in a stainless steel or other housing to reduce the chances of corrosion.
The effectiveness of coatings on customer’s parts can be tested in Bunting’s Temperature and Humidity Controlled Environmental Chamber. 9
Assembly Considerations Affixing magnets to housings:
Magnetisation:
Magnets can be successfully affixed to housings using adhesives. Cyanoacrylate adhesives which are rated to temperatures up to 180 C with fast cure times avoid the need for fixtures to hold the magnets in place while the bond cures. Adhesives with higher temperature ratings are also available, but these require oven curing and fixturing of the magnets to hold them in a vacuum. Potential outgassing of the adhesives should be considered.
Permanent magnet materials are composed of small regions or “domains” each of which exhibit a net magnetic moment. An un-magnetised magnet will possess domains which are randomly oriented with respect to each other, providing a net magnetic moment of zero. Thus, a magnet when de-magnetised is only de-magnetised from the observer’s point of view. Magnetisation is achieved by exposing the magnet to a very high magnetic field, the strength of which depends on the type of magnet material. The magnetic field aligns the domains to give a net, externally observable field.
Mechanical fastening: When arrays of magnets must be assembled, especially when the magnets must be placed in repelling positions, it is very important to consider safety issues. Modern magnet materials such as neodymium are extremely powerful, and when in repulsion they can behave as projectiles if adhesives were to break down. It is recommended that in these situations mechanical fastening be included in the design in addition to adhesives. Potential methods of mechanical retention include encasement, pinning, or strapping the magnets in place with non-magnetic metal components.
Magnetisation
Saturation (All magnetic domains aligned)
Partially magnetised condition
Unmagnetised condition
Potting: Magnet assemblies may be potted to fill gaps or to cover entire arrays of magnets. Potting compounds cure to hard and durable finishes and are available to resist a variety of challenging environments, such as elevated temperatures, water flow, etc. When cured, the potting compounds may be machined to provide accurate finished parts. Welding: Assemblies which are required to be hermetically sealed can be welded using either laser welding (which is not affected by the presence of magnetic fields) or TIG welding (using appropriate shunting elements to reduce the effect of magnetic fields on the weld arc). Special care should be taken when welding magnetic assemblies so that the heat dissipation of the weld does not affect the magnets.
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It is important when magnetising a magnet to always magnetise the magnet to saturation, even if it will subsequently be de-magnetised for calibration or stabilisation purposes. Saturating the magnet and then de-magnetising it in a controlled manner ensures that the domains with the least commitment to orientation will be the first to lose their orientation, thereby leading to a more stable magnet. Not achieving saturation, on the other hand, leads to orientation of only the most weakly committed domains, resulting in a less stable magnet.
In general, permanent magnets are supplied with a simple 2 pole magnetisation pattern: a North pole on one face and a South pole on the opposite face. However, by appropriate configuration of the magnetising coils it is possible to construct a fixture that will magnetise a magnet with many pole-pairs, and for some materials, pole patterns on a single surface of the magnet. This is called multi-pole magnetisation. Magnetising Patterns
Diametrical
Radial Through Arc Segment
Prototype Magnetising Fixtures/Tooling: For development projects, prototype fixtures can be built quickly after design. These allow for a small quantity of magnets to be magnetised and built into a prototype build program. Prototypes usually do not have built in cooling or interlock features and can only be guaranteed for small volumes. Pre-assembly and post-assembly magnetisation:
Radial
Straight Through Arc Segment
Parallel to Length
Parallel to Thickness
Multiple Poles
Anisotropic magnets, typically sintered magnets such as sintered NdFeB or ceramic magnets, have a preferred direction of magnetisation which gives them higher magnetic properties than isotropic magnets of the same material. These magnet materials must be magnetised parallel to the preferred direction to achieve these optimum magnetic properties. Consequently, these materials are not generally suitable for multipole magnetisation and such assemblies have to be constructed from individual pre-magnetised segments. However, isotropic magnets have no preferred direction and can therefore be magnetised in any direction, making them ideally suitable for multi-pole magnetisation in a single operation. This is one of the key advantages of Bremag ® bonded magnets. Bremag ® is a trademark of Bunting bonded materials. Magnetising Fixtures/Tooling:
For customers who wish to bring the magnetisation process in house, Bunting can supply turnkey magnetising systems for integration into a production line. This can range from magnetising fixtures to run on customers’ own magnetising equipment or full systems which include both the capacitor discharge magnetising unit and fixtures. Bunting manufactures its own capacitor discharge units, which are all PLC controlled and therefore can be integrated into the customer’s own production lines. The units employ all the same interlock and safety features for production including magnetisation fixture temperature control. Through appropriate consultation with customers, Bunting will manage the process to ensure the magnetising system meets the production requirements in the most efficient way. From a production point of view, the most desirable approach is to build a multi-pole magnet assembly with un-magnetised magnets and then magnetise the assembled device as the final step in the manufacturing process. This avoids all the production issues associated with handling and locating very strong magnets. This process is called post assembly magnetisation. Multi-pole magnetising fixtures can be built to post-assembly magnetise customers own assemblies or those assembled by Bunting. It is not always possible to achieve 100% saturation throughout the magnet volume, but the effect of this can be simulated by Bunting using our specialised FEA software. This software allows customers to assess if the practical and cost advantages of post assembly outweigh the disadvantages of a slight drop in performance.
Magnetisation is a key step in the manufacture of any permanent magnet component and it is usually the last stage in the manufacturing process. While simple 2 pole magnets can be magnetised in one of our standard solenoid magnetising coils, multi-pole magnets need their own custom made fixtures. Bunting designs and manufactures all its own magnetising fixtures either for use in house or to be used on customers’ own equipment. Due to the high energies required to generate the magnetising fields, particularly for rare-earth magnets, production magnetising fixtures are designed with water cooling and safety interlocks to protect the operators. These features also ensure the fixtures can never be operated with the wrong settings and result in only partially magnetised components. Production fixtures are built for the life of a project. 11
Magnetisation Waveforms The software utilised by Bunting can take full account of the true magnet properties achieved during magnetisation and predict the surface or air-gap flux density waveforms of multi-pole magnets with the actual magnetising fixture that will be used in production. This technique is not restricted to isotropic magnets and can also be applied to permanent magnet assemblies. This is an invaluable capability when it comes to moving from development to production phases within a project. In addition, it allows us to design magnets with specialised flux density wave forms to meet specific customer requirements, whether it is for encoders, general switching magnets, or rotor magnets for permanent magnet motors. On radially magnetised parts or assemblies it is possible to skew the poles to help reduce cogging torque and for isotropic magnet ring magnets, square waves, trapezoidal, or sinusoidal waveforms can all be achieved, sometimes to within a few percent total harmonic distortion. Increasingly, there is a demand for very complex multi-pole, multi-track systems that require a very careful choice of materials to ensure requirements are met. HALBACH MAGNETISATION: Halbach arrays or cylinders are a particular type of permanent magnet assembly which produces a field on one face of the assembly while canceling out the field on the other side. In the case of a cylinder, the field will be concentrated into the centre of the cylinder with zero field on the outside. In other words, it is completely self-shielding. A true Halbach can only be achieved with a sinusodially varying field distribution within the assembly. Close approximations to Halbach arrays can be achieved with arrays of magnet blocks but single isotropic ring magnets which can be multipole magnetised with continuously varying fields are ideal for this technology. Through careful design of the magnetising fixture, close approximations to Halbach arrays can also be achieved without having to use complex multiple segment magnet assemblies which are both difficult to assemble and expensive.
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Custom Magnets for Design Specific Applications Bunting provides complete engineering, design, and consulting services. Our expert engineering team complements your design and manufacturing team to develop a permanent magnet or a complete magnetic assembly specific to your need and application. Custom blended neodymium powders mixed with resin: The most significant feature of our bonded magnet processes is our ability to precisely target the magnetic performance and utilise net-shaping techniques, allowing us to achieve even the most complicated shapes. We offer a number of different performance levels and can create a precise blend to give you the most effective solution and achieve the level of performance that is needed for your specific application. Pressure bonded at press tonnages from 4 to 200: Based on techniques used in ceramics, powder metal, and harmaceuticals, compression moulded magnets require the lowest level of non-magnetic binder, thus producing the highest magnetic performance in bonded magnets. The use of compression moulding is typically used in rare earth alloy products such as Neodymium Iron Boron. The most common shapes produced by this method are 2-D rings, but discs, blocks, and segments can also be produced by this method. The binders used in compression moulding are typically epoxy resins, which have good dimensional stability and resistance to chemicals. Some are able to withstand temperatures in excess of 250 °C. We have a wide range of compression bonding capabilities, ranging from 4 tons up to 200 tons to give you the exact product for your needs. Injection moulded to meet customer requirements: Bunting uses injection moulding to create intricately shaped magnets that boast highly
desirable properties. Injection moulding is an ideal process for applications that require high levels of precision, highly complex shapes, and insert or over-moulding. By utilising injection moulding, many identical components can be created in a short amount of time, making injection moulding appealing for high volume production. Full inspection and certification capabilities: Bunting is ISO 9001:2015 certified, ITAR registered and DFARS compliant. Bunting’s world-class manufacturing facility includes an option for glove box clean air assembly and an end of line pass/fail test to ensure spotless products that promise to uphold your brand and reputation. Our magnet materials and assemblies meet your quality and precision standards while maintaining a competitive price. Rapid prototyping to speed up design timelines: When working with our engineers, you are involved with the design process from start to finish. We have an on-site prototype manufacturing facility and our engineers are backed by our world-class manufacturing team, delivering you a product in two weeks or less. We provide as much application engineering as needed, and allow you to receive more than one prototype at a time if you are configuring multiple parts together. Our rapid prototyping capabilities allow you to receive real results in real time. One-stop shop for magnetic assemblies and subassemblies: Bunting is a one-stop shop specialising in magnetic assemblies. With our extensive knowledge of CNC machining, magnet fabrication, and final assembly capabilities, we can meet any magnetic assembly need no matter the complexity. We utilise the latest and leanest technologies applied to assembly processes such as bonding, fastening, and potting. Assemblies can be welded, sleeved, or encapsulated. Our final processes (post assembly) include final grind, balancing, and field mapping, allowing Bunting to deliver a quality driven and precise magnet assembly no matter the complexity.
Magnet Materials Bunting engineers are ready to assist you with the important task of magnet material selection. The design considerations include temperature, vibration, cost, energy product, oxidisation, electrical conductivity amongst other specific considerations in your circuit. The following is a brief description of magnet materials and we suggest you contact our sales engineers for further assistance. NEODYMIUM IRON BORON (NdFeB) falls within the Rare Earth category of magnets. Neodymium offers the highest Br and Hci values and exhibits the strongest magnet materials commercially available (currently up to 52 MGoe). Neodymium magnets are susceptible to oxidisation due to the high concentration of iron particles. Dependent on the Permeance Coefficient, Neodymium magnets can be designed into environments up to 200 deg C. SAMARIUM COBALT (SmCo) magnets fall into the Rare Earth category and are also considered extremely strong (currently up to 32 MGOe). Samarium magnets are less susceptible to oxidisation, however they are more brittle than Neodymium. Samarium magnets are typically designed into high temperature environments (up to 300 deg C). Samarium magnets are typically more expensive than neodymium. BONDED NEODYMIUM is a resin bonded magnet that is increasingly popular as a mid level rare earth in cost and relative performance. The magnet has a high concentration of resin which is used to bond the particles during the compression or injection mould process. The magnets exhibit up to 11 MGOe mag-
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net strength and can be used with or without a coating. Typical applications are utilised in encoders or BLDC motor applications that require multiple poles in a single piece magnet ring. The material structure is isotropic and thus can be magnetised in a wide variety of patterns. Temperature limitations are up to 150 deg C. A significant and popular aspect is that the material can be manufactured dysprosium free making the material very attractive from a cost basis. The material also exhibits low electrical conductivity making it suitable for applications to reduce eddy current losses. Bunting is the premier magnet manufacturing facility left in North America for the manufacture of bonded materials. CERAMIC MAGNETS (also commonly referred to as Ferrite magnets) are produced from Barium or Strontium ferrite powders. Ceramic magnets are an excellent choice for low cost and low Br requirements up to 4.2 MGOe. They offer excellent resistance to corrosion, are great electrical insulators and can operate in environments up to 300° C. ALNICO MAGNETS (the oldest manufactured material in the industry) derived from iron are made of aluminium, nickel and cobalt. Referred to as Alnico. These magnets are in production due to their ability to handle temperatures up to 540° C. Alnico magnets can be produced up to 5.5 MGOe, however can be easily demagnetised due to its low HCi values and should be considered carefully in your application. Alnico magnets are good electrical conductors and are resistant to oxidisation. FLEXIBLE MAGNETS are produced from a slurry compound of magnet powders and a resin binder that is typically calendared to develop into a flexible rubberised material. Flexible magnets exhibit the lowest magnetic properties (up to 1.4 MGOe) but can be magnetised multiple pole to develop strong magnetic fields. The material can be cut, slit, scored, stamped and coiled for unique applications. Relative cost is low compared to the other magnet materials.
Magnetic Assemblies Bunting is a one-stop shop specialising in magnetic sub-assemblies. With our machining, magnet fabrication, and final assembly capabilities, we have the ability to provide finished assemblies to meet your customised needs. Our final processes (post assembly) include final grind, balancing, and field mapping allowing Bunting to deliver a quality driven and precision magnet assembly. Bunting has a “design for manufacturability” engineering team ready to discuss your product. We can reduce cost drivers and develop a repeatable manufacturing process to deliver a quality product.
downhole applications. We offer a wide variety of material grades which have a high strength-to-weight ratio and will not lose attractive force over time, unless otherwise damaged. AUTOMOTIVE:
MOTORS/GENERATORS:
Our injection mould, insert mould, and overmould capabilities allow us to produce magnetic sub-assemblies in high volume to automotive production and quality standards. Our ISO 9001 certification is critical to the success of our automotive customers. Bunting can offer full level 3 PAPP documentation for all of your requirements. Some of our most common assemblies include hub, rotor, and back-plate machining and assembly including potting, final grind, and balancing for Internal Permanent Magnet (IPM), Surface Permanent Magnet (SPM), and linear motor designs. We are the premier supplier of bonded magnets into the Brushless DC Motor (BLDC) market.
MEDICAL:
OIL AND GAS:
Our clean assembly area includes component assembly with an option for glove box clean air assembly and an end-of-line pass/fail test. Bunting offers a wide selection of materials that meet your quality and precision standards while maintaining a competitive price.
We are industry experts in high temperature samarium magnet assemblies typically including stainless steel encapsulation and welding for pressure and vibration
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What Bunting Offers
Aerospace and Defense:
Bunting’s magnetic capabilities in consumer products are vast. These products are diverse and complex, demanding Bunting’s engineering expertise to find the optimum solution and utilising our production process to manufacture it. For over 50 years, we have developed unique solutions for thousands of customer products. Our unique capabilities, such as our injection moulding capability, allow us to produce highly unique magnets with special features that are unable to be produced by other manufacturing methods. Bunting has served many different consumer industries in the past, and our magnetic assemblies are essential to making the modern lifestyle we all live possible. Magnets are present in your cell phone, your tablet, your computer, and other electronic devices such as speakers and cameras. Anti-theft devices at department stores utilise magnets in sensors to deter shoplifting. In the home, magnets can be found in every room as they are used in appliances such as home security systems, washing machines, refrigerators, vacuum cleaners, and blenders.
Bunting is a trusted name in aviation, military, and defense applications. Bunting is ITAR registered and DFARS compliant, making us approved to support military and defense projects. Our products have withstood the high standards of many defense related customers and programs. We have supplied magnets and magnetic assemblies on several missile programs as well as magnets and magnetic assemblies used in flight control decks for both commercial and fighter aircraft. We are equipped to meet the most stringent quality and security demands. Our design process for military and civilian aerospace projects puts your needs first and designs a product to meet them perfectly. We consider critical design issues such as dimensional, magnetic flux, thermal, environmental, and more. We seek to design products that don’t simply “do” a job, but optimise the way that job is done. Our designs go above and beyond in order to reduce cost, reduce weight and size, and increase efficiency. We are committed to durable, lasting products that perform to the highest standard, no matter how harsh the conditions they are operating in may be.
Consumer products:
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Magnetic Sensors: Bunting offers first-hand, unmatched sensor/magnet design and industry experience in numerous industries and applications. Magnetic sensors (sensors activated by a magnetic field) are vital devices in many applications and industry segments. Their primary function is to interact with a magnetic field and convert mechanical motion or position to an electrical signal. These sensors operate with no need for contact, no physical wear or tear, and are able to work through sealed barriers with high reliability. Within a sensor, the role of the permanent magnet is to provide a magnetic field in an air gap. This field can be constant and extremely precise, or vary in magnitude and direction. When determining the ideal magnet for your application, our engineers help you select the best magnet first in terms of cost-efficiency, grade, and optimised geometry. Our engineering team then goes on to analyse your environmental factors including temperature and humidity; mechanical requirements such as vibration, air gap, tolerances, and electrical conductivity; and your magnetic field strength, orientation, and number of poles required by your sensing IC. In order to meet the challenging requirements of modern sensor applications, Bunting can provide a full range of materials covering numerous product geometries, grades, and processing operations while achieving superior product quality.
Variety of certifications and compliance for critical applications Bunting is ISO 9001:2015 certified, ITAR registered and DFARS compliant. Bunting ensures that we have restricted the use of certain hazardous substances (RoHS), namely lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers. Our stock magnets meet or exceed US Magnet Materials Association Standards for physical quality and magnetic properties. All permanent magnet products are RoHS compliant
Torque, Force, and Flux requirements: Basic problems of permanent magnet design revolve around estimating the distribution of magnetic flux in a magnetic circuit, which may include permanent magnets, air gaps, high permeability conduction elements, and electrical currents. Exact solutions of magnetic fields require complex analysis of many factors, although approximate solutions are possible based on certain simplifying assumptions. Obtaining an optimum magnet design often involves experience and tradeoffs. 2D and 3D modeling:
ITAR-Registered
9001:2015 R E G I S T E R E D
Design Engineering Services to assist as needed:
Bunting’s experience, accumulated through decades of providing customers with unique magnetic designs, provides us with valuable insight into the changing needs and rigorous demands of our customers. As a result, our engineers are equipped with extensive knowledge to provide you with the optimum solution for your application. Our team of engineers has extensive experience in many types of magnetic designs and is able to assist in the design and execution of Finite Element Analysis models. Our design services include: --Complete engineering, design, magnetic evaluation, and consulting services --Magnetic field mapping --Holding force calculations --Insert and over-moulding designs --World-class design and instrumentation equipment --And more
Magnetic Design has become a critical feature of Bunting’s growth and we seek to work with our customers to realise their ideas. Finite Element Analysis (FEA) modeling programs are used to analyse magnetic problems in order to arrive at more exact solutions, which can then be tested and fine-tuned against a prototype of the magnetic structure. Using FEA models, flux densities, torques, and forces may be calculated. Results can be output in various forms, including plots of vector magnetic potentials, flux density maps, and flux path plots. Bunting uses a suite of 2D and 3D transient FEA modeling packages backed up with specialised design software and a team with many years of experience in magnetics as well as general engineering. This allows us to undertake a wide range of design programs across many industries including automotive, defense, medical, and more, and across many applications, including sensors and Brushless DC (BLDC) motors. The amount of design time ranges from a few hours to many days and we pride ourselves on the cost effectiveness of this service. Diametric, Radial, Parallel, Arc, and multi-pole magnetisation experience: The software utilised by Bunting can take full account of the true magnet properties achieved during magnetisation and predict the surface or air-gap flux density waveforms of multi-pole magnets with the actual magnetising fixture that will be used in production. This technique is not restricted to isotropic magnets and can also be applied to permanent magnet assemblies. This is an invaluable capability when it comes to moving from development to production phases within a project. 17
In addition, it allows us to design magnets with specialised flux density wave forms to meet specific customer requirements, whether it is for encoders, general switching magnets, or rotor magnets for permanent magnet motors. On radially magnetised parts or assemblies it is possible to skew the poles to help reduce cogging torque and for isotropic ring magnets, square waves, trapezoidal, or sinusoidal waveforms can all be achieved, sometimes to within a few percent total harmonic distortion. Increasingly, there is a demand for very complex multi-pole, multi-track systems that require a very careful choice of materials to ensure requirements are met. Turn-key production line magnetisation system design and development: Bunting offers customers turnkey solutions for magnetic assemblies, each designed and built around our core magnets. With all of our projects – from a two-piece assembly to
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a complex product that demands precision design – Bunting strives to meet your exact requirements and complete projects that will reduce cost drivers and develop a repeatable manufacturing process. Plus, we can work with you on your lean manufacturing replenishment program (JIT, Kanban, Dock-to-Stock, etc.) to ensure your parts are always available when you need them. Bunting can design the assembly, source the magnetic material, integrate the manufacture of the magnet and assembly, coat it, glue it, magnetise it, package it and ship it, all on time and within budget. Our interdisciplinary capabilities make Bunting the ideal choice for the design, engineering, prototyping and manufacturing of magnetic assemblies.
Magnetising Equipment Bunting’s magnetising equipment is excellent for use in both laboratory and industrial environments. We offer industrial magnetisers, bench top and laboratory magnetisers, magnet setters, and custom built magnetising systems designed to suit your exact needs.
Industrial Magnetisers Bunting’s standard range of industrial magnetisers were originally designed to meet the higher energy demands of some of the more complex industrial applications. They have a modular construction which allows these magnetisers to be supplied with a wide range of energy levels with different voltage and capacitance configurations depending on the application, as well as with multiple magnetising fixture outputs. They are PLC controlled and can be interfaced with customers’ own production systems. These magnetisers are suitable for most industrial applications: from simple 2 pole fixtures to high energy multi-pole magnetisation such as flywheels, permanent magnet rotors, or traction motors. Key Benefits: • Rugged industrial design. • Modular construction for a wide range of energy levels. • Voltage and capacitance can be optimised for slow or fast pulse waveforms. • PLC controlled with remote LAN access for maintenance or production control. • Multiple fixture outputs for more flexible operation. Specifications: • Power Supply: 3 Phase, 400V, 20A • Standard Output Voltages: 800V, 3000V, or 5000V • Discharge Energy: up to 100kJ • Maximum Peak Current: ~35kA • Charge Rate: 6kJ/s • Standard PLC Controller Siemens s7-1200 Typical Applications: • Large NdFeB/SmCo blocks • Loudspeaker magnet assemblies • Permanent magnet rotors • Traction motor assemblies • Flywheel rotors • Magnetic bearings 19
Bench Top and Laboratory Magnetisers Bunting’s BLMC series is ideally suited for laboratories or other small-scale production environments. These magnetisers have a workbench area on top of the unit where the fixtures are placed for operation and either hard wired in for permanent installations or connected by quick release plugs in the case of environments where many different fixtures may be used. They can be fitted with a standard push button control panel or with an HMI interface if preferred. Standard safety interlocks are included to prevent fixtures from being operated when over temperature. For situations where multiple magnetising fixtures may be used, additional safety interlocks are recommended. The process of setting individual fixture parameters can be automated such that all the operating parameters are stored in the fixture control plug, which once connected to the magnetiser automatically sets the machine ready for production. This prevents fixtures from ever being operated at too high a voltage or when over temperature, which in turn prevents damage to the magnetising fixture. These magnetisers are ideal for magnetising small multipole magnets up to diameters of approximately 50mm, as well as being well suited for fine pitch magnetisation as well as more general 2 pole magnetisation of most permanent magnet materials, including rare earth materials. Key Benefits: • Ideal for laboratory/small scale production. • Desktop/workstation design. • Quick release fixture outputs for highly flexible operation. • Extensive safety interlocks protect you and your equipment. • Optional automated fixture setting feature • PLC controlled with remote LAN access for maintenance or production control. Specifications: • Power Supply: 110Vac/230Vac. • Standard Output Voltages: 3000V. • Discharge Energy: 1 – 4kJ. • Maximum Peak Current: ~20kA. • Charge Rate: 500J/s. • Standard PLC Controller Siemens s7-1200. Typical Applications: • Small NdFeB/SmCo magnets. • Ferrite and AlNiCo magnets. • Multipole rings or rotors up to ~50mm. • Encoder/sensor magnetisation. 20
Magnet Setters Bunting offers a range of magnet setters for use in magnetising and setting permanent magnets. These machines utilise capacitor discharge technology to generate either a pulsed magnetising or demagnetising field inside the fixture bore. In the “Mag” mode, the machine will deliver the full charge to the magnetising fixture. In the “Demag” mode, the polarity of the magnetising field is automatically reversed, with the level of demagnetisation controlled by the dial on the control panel. Used in conjunction with a suitable magnet measurement system, these magnet setters can be used to calibrate a magnet to a specific working point. Features: • Voltage range 0-1000V. • Energy 100-200J. • Mag/Demag operating modes. • For production or laboratory use. • Optional dual fixture outputs. • Optional automatic calibration. Available Options with Standard Machine:: • Digital display of voltage set point. • Two fixture outputs. • Automatic calibration. Magnetising Systems: Bunting offers custom built magnetising systems, including automation. Examples include: • Multipole Surface Mounted Halbach Rotors— Post Assembly. • IPM Machine Rotors + Skewing. • Passive Magnetic Bearings—Internal and External. • Bespoke Magnetic Field Generation, including magnetic modelling.
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Magnetising Fixtures Bunting offers a wide variety of magnetising fixtures in varying sizes and strengths to best suit your application. Our fixtures are designed to best utilise the availability of your magnetiser depending on the material you are working with. We are also able to provide complex multipole/ Halbach field distributions in order to create a specific magnet for your application. Available Fixtures
Single Axial Solenoids Fixture
Single Axial Solenoids Fixture: Generate a 2 pole field along the length of the coil and are suitable for magnetising all 2 pole magnet materials. External Radial Multipole Fixtures: Designed to produce a multipole radial field on the external diameter of a ring magnet or magnet assembly such as a permanent magnet rotor. Internal Radial Multipole Fixtures: Designed to produce a multipole radial field on the internal diameter of a ring magnet or magnet assembly such as the rotor of an exterior rotor permanent magnet machine, permanent magnet stators, or flywheels.
External Radial Multipole Fixture
Axial Field Multipole Fixture: Designed to produce a multipole axial field on the face of a ring, disc, or block magnet. Homopolar/Radial Fixture: Designed to produce a single radial pole on the inner and outer diameters of a ring magnet.
Internal Radial Multipole Fixture
Multi Pole Circumferential Fixture: Specifically designed for applications such as encoders and sensors with specific requirements, such as pole pitches less than 3mm or multiple sensor tracks on a single component. Prototype Magnetising Fixture: To avoid the cost of a production magnetising system, Bunting can build prototype fixtures which will be magnetically the same as a production unit, but may be manufactured from less hard wearing materials and will be without all the cooling and normal fixture interlocks. These fixtures are ideal for research and product development. Low volume sample runs and fast turnaround times are available.
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Multi Pole Circumferential Fixture
Prototype Magnetising Fixture
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0
Material: Samarium Cobalt S28H SAMARIUM COBALT S28H
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Pc = B/H 1.0
0.6
0.5
0.3
1.5
3.0
6.0
20°C
150°C
200°C 250°C 300°C 350°C
0.1
k0e
18
kA/m
1400
16
14
1200
12
10
1000
800
8 600
Demagnetising Field, H
6
4 400
Polarisation, J
Pc = B/H
2
0
200
0
T
kG
1.2
12
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
0
0
Flux Density, B
Material: Samarium Cobalt S28 SAMARIUM COBALT S28
Polarisation, J
Demagnetisation Curves
Flux Density, B
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29
MAGNET APPLICATIONS ®
Pc = B/H 3.0
6.0
0.5 20°C
0.3
100°C
150°C 200°C 250°C 300°C 350°C
0.1
k0e
CERAMIC 5
18
16
14
12
10
8
1400 1200 1000 800 600 kA/m Demagnetisation Curves Demagnetising Field, H Material: Ceramic 5
6
4 400
2 200
2.5
1.2
1.2
12
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
®
0
12 Industrial Drive DuBois, PA 15801 Toll Free: 800-437-8890 Ph: 814-375-9145 Fax: 814-375-9146 eMail: Sales@MagnetUS.com www.MagnetApplications.com
T
5.0
kG
0.5
5
0.4
4
0.3
3
0.4
0.2
2
0.2
0.1
1
0.0
0
0.8
20°C 80°C
0.6
120°C
k0e 5 kA/m 30
kG
0 0 MAGNET 0 APPLICATIONS
Pc = B/H 1.0
T
4 350
3 300
250
2 200
150
Demagnetising Field, H
1 100
0 50
0
Flux Density, B
1.5
Polarisation, J
1.0
0.6
Polarisation, J
Material: Samarium Cobalt S30 SAMARIUM COBALT S30
Flux Density, B
12 Industrial Drive DuBois, PA 15801 Toll Free: 800-437-8890 Ph: 814-375-9145 Fax: 814-375-9146 eMail: Sales@MagnetUS.com www.MagnetApplications.com
Demagnetisation Curves
MAGNET APPLICATIONS ®
12 Industrial Drive DuBois, PA 15801 Toll Free: 800-437-8890 Ph: 814-375-9145 Fax: 814-375-9146 eMail: Sales@MagnetUS.com www.MagnetApplications.com
Pc = B/H 2.5
1.2
T
5.0
kG
0.5
5
0.4
4
0.3
3
0.4
0.2
2
0.2
0.1
1
0.8
20°C 80°C
120°C
0.6
k0e 5
3
2
1
350 300 250 200 150 kA/m Demagnetisation Curves Demagnetising Field, H Material: Alnico 5 & 6
100
®
50
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0
Pc = B/H 16
20
40
160
12 Alnico 6
ico
5
8
Aln
ALNICO 5-6
4
M0.0 AGNET0 A0PPLICATIONS
4
0e 1000 900 kA/m
70
800
700 60
600
500
50
40
400 30
Demagnetising Field, H
300
200 20
100 10
0
T
kG
1.6
16
1.4
14
1.2
12
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
0
0
Flux Density, B
1.0
Flux Density, B
Material: Ceramic 8
Polarisation, J
CERAMIC 8
Polarisation, J
Demagnetisation Curves
0
31
MAGNET APPLICATIONS ®
ALNICO 8-9
Material: Alnico 8 & 9
Pc = B/H 8
10
20
80
6
Alnico 9 E
o 8-H Alnic
4
2
H
o8 nic
Al
-B
8 co lni
A
0e 2000 1800 1600 1400 1200 1000 800 kA/m
32
140
120
100
80
60
Demagnetising Field, H
600
400 40
200 20
0 0
T
kG
1.6
16
1.4
14
1.2
12
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
0
0
Polarisation, J
Demagnetisation Curves
Flux Density, B
12 Industrial Drive DuBois, PA 15801 Toll Free: 800-437-8890 Ph: 814-375-9145 Fax: 814-375-9146 eMail: Sales@MagnetUS.com www.MagnetApplications.com
TECHNICAL DATA OF SINTERED NDFEB Grade Br mT(kGs) Hcb kA/m(kOe) Hcj kA/m(kOe) N33 1130-1170(11.3-11.7) ≥836(≥10.5) ≥955 (≥12) N35 1170-1220(11.7-12.2) ≥868(≥10.9) ≥955(≥12) N38 1220-1250(12.2-12.5) ≥899(≥11.3) ≥955(≥12) N40 1250-1280(12.5-12.8) ≥907(≥11.4) ≥955(≥12) N42 1280-1320(12.8-13.2) ≥915(≥11.5) ≥955(≥12) N45 1320-1380(13.2-13.8) ≥923(≥11.6) ≥955(≥12) N48 1380-1420(13.8-14.2) ≥923(≥11.6) ≥955(≥12) N50 1400-1450(14.0-14.5) 796(10.0) 876(11) N52 1430-1480(14.3-14.8) 796(10.0) 876(11) 30M 1080-1130(10.8-11.3) 796(10.0) 1114(14) 33M 1130-1170(11.3-11.7) 836(10.5) 1114(14) 35M 1170-1220(11.7-12.2) 866(10.9) 1114(14) 38M 1220-1250(12.2-12.5) 899(11.3) 1114(14) 40M 1250-1280(12.5-12.8) 923(11.6) 1114(14) 42M 1280-1320(12.8-13.2) 955(12.0) 1114(14) 45M 1320-1380(13.2-13.8) 995(12.5) 1114(14) 48M 1360-1430(13.6-14.3) 1027(12.9) 1114(14) 50M 1400-1450(14.0-14.5) 1033(13.0) 1114(14) 30H 1080-1130(10.8-11.3) 796(10.0) 1353(17) 33H 1130-1170(11.3-11.7) 836(10.5) 1353(17) 35H 1170-1220(11.7-12.2) 868(10.9) 1353(17) 38H 1220-1250(12.2-12.5) 899(11.3) 1353(17) 40H 1250-1280(12.5-12.8) 923(11.6) 1353(17) 42H 1280-1320(12.8-13.2) 955(12.0) 1353(17) 45H 1320-1380(13.2-13.8) 955(12.0) 1353(17) 48H 1370-1430(13.7-14.3) 995(12.5) 1353(17) 30SH 1080-1130(10.8-11.3) 804(10.1) 1592(20) 33SH 1130-1170(11.3-11.7) 844(10.6) 1592(20) 35SH 1170-1220(11.7-12.2) 876(11.0) 1592(20) 38SH 1220-1250(12.2-12.5) 907(11.4) 1592(20) 40SH 1240-1280(12.5-12.8) 939(11.8) 1592(20) 42SH 1280-1320(12.8-13.2) 987(12.4) 1592(20) 45SH 1320-1380(13.2-13.8) 1003(12.6) 1592(20) 28UH 1020-1080(10.2-10.8) 765(9.6) 1990(25) 30UH 1080-1130(10.8-11.3) 812(10.2) 1990(25) 33UH 1130-1170(11.3-11.7) 852(10.7) 1990(25) 35UH 1180-1220(11.8-12.2) 860(10.8) 1990(25) 38UH 1220-1250(12.2-12.5) 899(11.3) 1990(25) 40UH 1240-1280(12.5-12.8) 899(11.3) 1990(25) 28EH 1040-1090(10.4-10.9) 780(9.8) 2388(30) 30EH 1080-1130(10.8-11.3) 812(10.2) 2388(30) 33EH 1130-1170(11.3-11.7) 836(10.5) 2388(30) 35EH 1170-1220(11.7-12.2) 876(11.0) 2388(30) 38EH 1220-1250(12.2-12.5) 899(11.3) 2388(30) * Other material grades and custom grades are available upon request.
(BH) max KJ/m3 (MGOe)
Max. Working Temp (Tw)
247-263(31-33) 263-287(33-36) 287-310(36-39) 302-326(38-41) 318-342(40-43) 342-366(43-46 366-390(46-49) 382-406-(48-51) 398-422(50-53) 223-247(28-31) 247-263(31-33) 263-287(33-36) 287-310(36-39) 302-326(38-41) 318-342(40-43) 342-366(43-46) 366-390(46-49 382-406(48-51) 223-247(28-31) 247-271(31-34) 263-287(33-36) 287-310(36-39) 302-326(38-41) 318-342(40-43) 342-368(43-46) 366-390(46-49) 223-247(28-31) 247-271(31-34) 263-287(33-36) 287-310(36-39) 302-326(38-41) 318-342(40-43) 342-366(43-46) 207-231(26-29) 223-247(28-31) 247-271(31-34) 263-287(33-36) 287-310(36-39) 302-326(38-41) 207-231(26-29) 223-247(28-31) 247-271(31-34) 263-287(33-36) 2877-310(36-39)
80°C 80°C 80°C 80°C 80°C 80°C 80 60 60 100 100 100 100 100 100 100 100 100 120 120 120 120 120 120 120 120 150 150 150 150 150 150 150 180 180 180 180 180 180 200 200 200 200 200 33
TECHNICAL DATA OF MAGNET MATERIALS Grade
34
G
Br
mT
Oe
Hc
kA/m
Oe
Hci
kA/m
BHmax MGOe kA/m
Max Oper Temp (C)
SmCo, Sintered 32 28 26H 26 20 18
11500 10900 10600 10600 9200 8800
1150 1090 1060 1060 920 880
8000 9000 9200 8500 8600 8400
636 716 732 676 684 668
10000 12000 18000 12000 18000 18000
796 955 1432 955 1432 1432
32 28 26 26 20 18
254 223 207 207 159 143
300 300 300 300 280 280
NdFeB, Bonded B11N B10N B8N B6N
7200 6800 6000 5500
720 680 600 550
5500 5800 5000 4700
440 461 398 374
9000 9100 9100 9100
716 724 724 724
11 10 8 6
85 80 64 48
130 150 150 150
NdFeB, Injection 45/60 P2 38/60 P1 30/60 P1
5500 5000 4500
550 500 450
4700 4000 3900
374 318 310
9000 9000 9000
716 716 716
6 5 4
48 40 32
150 150 150
Alnico, Cast 5-7 8
13500 8200
1350 820
740 1650
59 131
740 1700
59 135
7.5 5.3
60 42
525 550
Alnico, Sintered 8 5
7400 10900
740 1090
1500 620
119 49
1600 630
127 50
4 3.9
32 31
550 525
Ferrite, Sintered 8 5 1
3900 3800 2200
390 380 220
3200 2400 1900
255 191 151
3250 2500 3250
259 199 259
3.5 3.4 1.1
28 27 8
250 250 250
Ferrite, Injection 16/21 P1 14/21 P1 12/22 P1 3/17 P1
2870 2780 2600 1300
287 278 260 130
2250 2250 2200 1080
179 179 175 86
2600 2700 2830 2170
207 215 225 173
2 1.8 1.5 0.4
16 14 12 3
150 150 150 150
Pure success: What the Bunting name means to you and your business. Bunting is proud to provide innovative, custom-designed solutions of bonded magnets, and magnetic assemblies. Our magnets and assemblies are durable, dependable, and driven by the needs of our customers and the modern challenges they face. Bunting has been a family –owned, family-led company since 1959. Sixty years later, we have made massive strides in developing new technology to meet the unique needs of the 21st century, while remaining committed to delivering the highest quality products accompanied by excellent customer service. We invite you to experience our customer service and products for yourself. Contact your Bunting representative today for more information or to obtain a specific quote. For more information about products shown in this catalog please contact these two Bunting locations. Bunting-Berkhamsted Northbridge Road Berkhamsted, Hertfordshire, HP4 1EH | UK +44 (0) 1442 875081 Email: Sales.Berkhamsted@BuntingMagnetics.com www.BuntingEurope.com
Bunting-DuBois 12 Industrial Drive DuBois, PA 15801 800.437.8890 | 814.375.9145 FAX: 814.375.9146 Email: Sales.Dubois@BuntingMagnetics.com www.MagnetApplications.com
Manufacturing & Distribution Locations: Bunting - Newton
Bunting - Berkhamsted
500 S. Spencer Road | P.O. BOX 468
Northbridge Road,
Newton, KS 67114 | USA
Berkhamsted, Hertfordshire, HP4 1EH | UK
Sales.Newton@BuntingMagnetics.com
Sales.Berkhamsted@BuntingMagnetics.com
800.835.2526 or 316.284.2020
+44 (0)1442 875081
Bunting - Elk Grove Village
Bunting - Redditch
1150 Howard Street
Burnt Meadow Road, North Moons Moat,
Elk Grove Village, IL 60007 | USA
Redditch, Worcestershire, B98 9PA | UK
Sales.ElkGroveVillage@BuntingMagnetics.com
Sales.Redditch@BuntingMagnetics.com
800.232.4359 or 847.593.2060
+44 (0) 1527 -65858
Bunting - DuBois
Bunting - China
12 Industrial Drive
Nordic Industrial Park Co., Ltd.
DuBois, PA 15801 | USA
A3 Building, 89 Jinchuann Road
Sales.Dubois@BuntingMagnetics.com
Zhenhal, Ningbo 315221 | China
1-800-437-8890 or 1-814-375-9145
+86 (574) 86305971
B U N TING M AG NE TI C S.CO M 36
©2020 BUNTING
Custom Magnets and Magnet Assemblies 01/29/20 rev1
