TECHNICAL GUIDE
Everything project engineers and industrial buyers need to know to choose the right magnet.
In today’s industrial landscape, the drive toward electrification, advanced automation, and energy efficiency has fundamentally transformed the role of many engineering components. Among them, industrial permanent magnets are no longer regarded as simple off-the-shelf parts purchased solely based on unit price. They have become true technological enablers and drivers of strategic innovation.
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Every magnetic material integrated into a project directly affects thermal performance, overall efficiency, weight, dimensions, and, ultimately, the total lifecycle cost of the finished product.
An industrial permanent magnet is defined as a material capable of generating and maintaining a stable, constant magnetic field over time without requiring any external electrical power supply. This characteristic distinguishes permanent magnets from electromagnets, which require a continuous flow of electric current to generate and sustain their magnetic field.
While an electromagnet is inherently associated with energy consumption and heat generation due to the Joule effect in its coil, a permanent magnet provides a powerful yet passive magnetic flux by exploiting the alignment of electron spins within its crystalline structure.
The importance of these components has grown exponentially with the rise of electric mobility (e-mobility) and the need to reduce carbon emissions across all manufacturing sectors. From traction motors in electric vehicles to generators in offshore wind turbines, as well as precision industrial robotics and life-saving biomedical devices, permanent magnets are the “invisible engine” driving the energy transition.
For design engineers and industrial buyers, selecting the right magnetic solution has become a highly complex task. It is no longer simply a matter of choosing a geometry or a generic holding force. Engineers must understand how magnetic materials behave under demanding operating conditions, including extreme temperatures, corrosive chemical environments, strong opposing demagnetizing fields, and high-speed mechanical stresses.
This guide provides an in-depth analysis of material families, magnetic grades, manufacturing processes, and the selection criteria that drive permanent magnet engineering in modern industry.
Before examining the different material families, it is essential to define the physical parameters and magnetic properties that engineers use to evaluate and compare different types of industrial magnets. These properties are measured using dedicated instruments and plotted on the magnetic hysteresis curve (B-H curve), specifically in the second quadrant, known as the demagnetization quadrant.
Remanence (Br): Expressed in Tesla (T) or Gauss (G), remanence indicates the magnetic flux density that remains within the magnet after the external magnetizing field has been removed. In practical terms, it represents the magnet’s intrinsic strength in a closed magnetic circuit. The higher the remanence, the greater the magnetic flux the magnet can deliver to the circuit.
Coercivity (Hc): Expressed in Ampere per meter (A/m) or Oersted (Oe), coercivity measures the magnet’s resistance to demagnetization. It is divided into:
Maximum Energy Product (BHmax): Expressed in kilojoules per cubic meter (kJ/m³) or MegaGauss-Oersted (MGOe), this is the point on the hysteresis curve where the product of magnetic induction (B) and magnetic field strength (H) reaches its maximum value. This parameter represents the magnet’s energy density: the higher the BHmax value, the smaller the volume of material required to generate a given magnetic flux. It is the primary benchmark for evaluating material efficiency in miniaturized designs.
Curie Temperature (Tc): The critical temperature at which a material completely loses its permanent magnetic properties and becomes paramagnetic. Above this temperature, thermal agitation irreversibly disrupts the alignment of atomic spins.
Maximum Operating Temperature (Tmax): The highest temperature at which the magnet can operate continuously without experiencing irreversible magnetic flux losses (which can only be restored by remagnetizing the component). This value depends not only on the material itself but also on the magnet’s geometry and the magnetic circuit in which it operates.
Material selection represents the true turning point in any industrial project. Each of the four main magnet families possesses unique characteristics that make it ideal for certain operating environments while making it completely unsuitable for others.
Neodymium-Iron-Boron magnets (NdFeB), introduced to the market in the 1980s, represent the pinnacle of rare earth-based magnets. Their introduction revolutionized industrial design, making it possible to miniaturize components that previously required massive dimensions.
Structure and Performance Characteristics
The atomic configuration of the alloy gives the material an extremely high magnetocrystalline anisotropy, resulting in exceptionally high coercivity and remanence values. In the most advanced commercial sintered grades, the maximum energy product (BH)max can easily exceed 50 MGOe. This means that, with equivalent performance, a neodymium magnet can be up to ten times smaller than a comparable ferrite magnet.
Magnetic Grade Classification and Thermal Resistance
Neodymium magnetic grades follow an internationally standardized coding system that allows engineers and buyers to immediately identify the mechanical and thermal performance of the component. The nomenclature typically consists of an initial letter (usually “N” for Neodymium), followed by a two-digit number and one or two final letters.
Taking the N42SH grade as an example, the designer immediately knows they are dealing with a magnet featuring medium-high energy density (42 MGOe) capable of operating reliably inside an electric motor running at 150°C.
HRE-Free Sintered Innovation
In recent years, raw material sourcing has taken on crucial geopolitical and economic importance. In traditional metallurgy, increasing the thermal resistance of neodymium magnets (required, for example, to move from an H grade to a UH grade) involved the extensive addition of Heavy Rare Earth Elements (HREs), particularly Dysprosium (Dy) and Terbium (Tb), directly incorporated into the molten alloy. These elements, however, are rare, extremely expensive, and, starting from 2025, subject to strict government export licensing requirements.
To address these constraints, the current technological frontier has decisively moved toward HRE-Free Sintered NdFeB magnets (or magnets with a very low content of heavy rare earth elements). This approach not only optimizes magnetic performance while maintaining the same volume but also drastically reduces the use of critical materials, ensuring manufacturers and buyers a much more stable, sustainable supply chain that is less exposed to geopolitical disruptions.
Intrinsic Limitations and Surface Treatments
The main weakness of neodymium is its high sensitivity to oxidation and corrosion. The significant iron content in the alloy exposes the material to rapid degradation when exposed to moisture or saline environments. If oxygen penetrates the structure, the magnet deteriorates, causing an irreversible loss of its magnetic properties. To overcome this limitation, a protective surface coating is mandatory.
Consult and download the technical datasheet for NdFeB grades.
When operating temperatures exceed the physical limits of neodymium, or when magnetic field precision cannot tolerate thermal drift, Samarium-Cobalt (SmCo) becomes the mandatory choice for project engineering.
Composition and Subfamilies
Also belonging to the rare earth magnet family, Samarium-Cobalt is mainly available in two chemical formulations:
Unique Advantages: Thermal Coefficient and Environmental Resistance
The true strength of Samarium-Cobalt lies in its extremely low temperature coefficient of remanence (αBr), which is approximately -0.03%/°C. This means that as temperature changes, the intensity of the generated magnetic field remains extremely stable, preventing signal drift in sensors or sudden torque losses in motors.
SmCo magnets maintain stable and reliable performance up to temperatures of 300°C – 350°C, conditions in which a neodymium magnet would immediately demagnetize. Furthermore, unlike NdFeB, Samarium-Cobalt has excellent intrinsic resistance to oxidation and chemical corrosion, eliminating the need for expensive surface galvanic coatings in most applications.
Mechanical Limitations and Economic Considerations
The material’s limitations lie in its exceptional mechanical brittleness. SmCo is a hard and fragile crystalline material, highly prone to chipping or breaking when exposed to impacts, severe vibrations, or tensile stress. As a result, it requires extreme care during handling and automated assembly processes, imposing simpler and more linear geometric design tolerances.
From an economic perspective, cobalt and samarium are high-cost raw materials subject to significant volatility in global financial markets. The cost of an SmCo magnet is considerably higher than that of a neodymium magnet of the same size, which is why its use is strictly limited to application niches where thermal reliability is a non-negotiable technical requirement: aerospace actuators, high-temperature turbines, sensors for heavy chemical industries, and military instrumentation.
Consult and download the technical datasheet for SmCo grades.
Hard ferrites, also known as ceramic magnets, historically and quantitatively represent the backbone of global industrial magnet production. Developed in the 1950s, they continue to maintain a dominant market share thanks to their unmatched cost-effectiveness and environmental stability.
Chemical Nature and Technical Profile
Ferrites are non-conductive ceramic compounds obtained through the sintering of metal oxides. Since they are essentially oxides, ferrites are chemically inert. They do not rust, do not corrode, and show excellent resistance to acids, solvents, lubricants, and seawater. They do not require any type of protective surface coating, reducing post-treatment costs to zero and eliminating the risks associated with protective film detachment.
The magnetic profile is characterized by a relatively modest energy density, with a (BH)max value ranging between 1 and 4 MGOe. Remanence is also limited, requiring significantly larger structural surfaces and volumes to generate the same useful force delivered by a rare earth magnet. However, ferrites possess excellent intrinsic coercivity and exhibit a unique behavior: their resistance to demagnetization increases as temperature rises (up to approximately 200°C), the exact opposite of what occurs in metallic magnets such as neodymium.
Isotropy vs. Anisotropy in Ferrites
During the ferrite selection process, buyers and designers must clearly distinguish between two fundamental manufacturing variants:
Applications and Size Limitations
Ferrites are widely used in all sectors where cost is the primary driver and where space or total system weight do not represent critical design constraints. They are ideal components for fractional horsepower electric motors in household appliances, commercial audio speakers, magnetic lifting and fastening systems, and industrial magnetic separators used in food processing and recycling screening lines, where the absence of corrosion risks ensures maximum hygiene and durability.
The main limitation is their inability to be used in highly miniaturized projects or applications requiring extremely lightweight solutions, such as mobile robotics or high-power-density automotive systems.
Consult and download the technical datasheet for Ferrite grades.
AlNiCo alloys (Aluminum-Nickel-Cobalt, with the addition of Iron and Copper) represent the transition technology between the first steel magnets and the modern rare earth era. Although it is a mature technology, AlNiCo still retains unique physical properties that make it irreplaceable in specific engineering applications.
Magnetic Characteristics and Linear Behavior
AlNiCo is characterized by exceptionally high remanence values (Br), often comparable to those of neodymium. However, its coercivity (Hc) is extremely low. This means that the magnet can project a very intense magnetic flux within a closed circuit, but it is extremely vulnerable to opposing external magnetic fields, which can demagnetize it very easily.
To prevent self-demagnetization (caused by the magnet’s own poles), AlNiCo components must be designed with highly elongated geometries, such as long cylinders, bars, or the classic and iconic horseshoe shape. This geometry allows the magnetic poles to remain sufficiently separated, reducing the internal demagnetizing field.
A unique technical advantage of AlNiCo is its exceptional linearity and stability of behavior as temperature varies. It has the lowest temperature coefficient among all industrial magnetic materials (down to -0.01%/°C). Furthermore, it offers the highest maximum operating temperature, being able to operate reliably in industrial environments up to 500°C – 550°C, conditions that would destroy any other type of permanent magnet.
Production Methods and Niche Applications
AlNiCo magnets can be manufactured through two different production processes:
Industrial applications of AlNiCo are concentrated in high-precision scientific measurement instruments, aerospace sensors, traveling wave tubes, aircraft engine ignition systems, and professional audio speakers, where magnetic flux purity and linearity are more important requirements than compact size.
Consult and download the technical datasheet for AlNiCo grades.
Beyond the chemical nature of the material, the method used to physically form and consolidate the magnet has a decisive impact on its microstructure, final geometric properties, and industrial production cost. The two main reference technologies on the global market are sintering (powder metallurgy) and bonding (plastic-bonded technology).
Sintering is a powder metallurgy process that starts from a molten alloy, reduced into an extremely fine powder, pressed into a mold under a strong orienting magnetic field, and subsequently heat-treated in a furnace at temperatures close to the material’s melting point.
Advantages: allows each material family to achieve the highest possible energy product, ensuring superior magnetic performance.
Limitations: requires mechanical finishing operations to achieve tight tolerances and requires surface coatings to protect against corrosion, especially in the case of Neodymium.
Bonded magnets, or plastic-bonded magnets, are produced by mixing magnetic powder with a polymer binder (PA6, PA12, PPS) and forming the component through injection molding or compression molding.
Advantages: complex geometries without the need for machining, tight dimensional tolerances achieved directly in the mold, reduced weight, and the possibility of advanced multipolar magnetization, including straight and asymmetric Halbach configurations.
Limitations: lower magnetic performance compared to sintered magnets.
The Overmolding Process
A major industrial advantage of injection-molded bonded magnets is the possibility of directly overmolding the magnet onto supporting metal components, such as steel motor shafts, bushings, or pre-existing plastic inserts. The molten magnetic polymer is injected directly around the shaft positioned inside the mold.
This process creates a perfect and extremely strong mechanical and chemical bond, eliminating subsequent manual or automated stages of gluing, assembly, quality control, and dynamic balancing of rotors. The result is a drastic reduction in Time-to-Market and in the total Bill of Materials (BOM) cost.
Industrial permanent magnets are extensively present in virtually every high-tech manufacturing sector. Their versatility comes from the combination of high energy density, long-term reliability, and the ability to operate without external power supply. These three factors make them indispensable in all applications where efficiency, miniaturization, and operational lifespan are critical design parameters.
Automotive and e-mobility: today represents the main driver of permanent magnet demand growth, particularly for sintered NdFeB. Permanent Magnet Synchronous Motors (PMSM) used in electric vehicles offer the highest available power density on the market, with efficiencies exceeding 95%. Even in conventional vehicles, permanent magnets are used in dozens of components: starter motors, electric pumps, ABS systems, EPS systems, position sensors, and climate control systems. The transition toward full electrification is accelerating this demand, making the selection of reliable manufacturing partners with advanced technical capabilities increasingly strategic.
Renewable energy: next-generation wind turbines, especially offshore direct-drive generators, use large quantities of neodymium magnets to ensure maximum energy conversion with the minimum number of moving mechanical components. Small hydroelectric generators, energy recovery systems, and mechanical energy storage systems also benefit from the efficiency of permanent magnets. In the context of decarbonization, these components are key enablers of new clean energy technologies.
Industrial automation and sensors: in automation systems, permanent magnets are the core components of servo motors, encoders, linear actuators, proportional valves, and position sensors.
Medical devices and precision industries: magnetic resonance imaging machines, dialysis pumps, robotic surgical instruments, and laboratory equipment use permanent magnets engineered with extremely tight magnetic tolerances.
The difference between a generic supplier and an industrial partner lies in the ability to support customers throughout the entire project lifecycle. In industrial permanent magnets, this means covering three complementary areas.
Magnetic Behavior Simulation
Through simulation software such as Comsol Multiphysics, it is possible to predict magnet behavior in its real operating environment, taking into account temperature effects, external disturbance fields, interaction with surrounding ferromagnetic materials, and mechanical stresses. This phase, carried out before physical prototyping, allows project optimization. The CIBAS engineering team performs these simulations as an integral part of its technical consulting service.
Quality and Certifications
ISO 9001 and IATF 16949 certifications ensure compliance with documented quality control procedures, complete traceability of each production batch, and risk management for critical processes. Having production units equipped with the same geometric, environmental, and magnetic measurement instruments ensures consistent performance across different business units and reduces batch-to-batch variability.
Supply Chain Management
The rare earth market is subject to strong price fluctuations and periodic geopolitical tensions. Relying on a partner that constantly monitors raw material market trends allows procurement planning well in advance. It is possible to explore price trends further through the dedicated pages on our website.
Industrial permanent magnets are much more than catalog components: they are engineered elements where the quality of technical consulting and the integration between engineering and production make the difference between a successful project and one requiring costly redesigns.
CIBAS Group has been supporting industrial customers worldwide for over 100 years, combining dedicated R&D in Milan, Comsol Multiphysics simulations, two proprietary production sites for sintered and bonded magnets, and a strategic vision for rare earth supply chains. For every application, there is an optimal magnetic solution: the starting point is a technical discussion with the right team.
To explore the design possibilities of industrial permanent magnets and evaluate the most suitable solution for your application, you can contact the CIBAS Group team for a dedicated consultation.
