Manufacture of Soft Magnetic Composites (SMC) for High-Efficiency BLDC Brushless DC motors

Manufacture of Soft Magnetic Composites (SMC) for High-Efficiency BLDC Brushless DC motors

Manufacturer of Soft-Magnetic-Composites (SMC) for High-Efficiency BLDC-Brushless DC motor
Manufacture of Soft Magnetic Composites (SMC) for BLDC Motors
Manufacturer of Soft-Magnetic Composites (SMC) for BLDC Motor
Manufacture of Soft Magnetic Composites (SMC) for Brushless DC Motors
Manufacturer of Soft-Magnetic Composites (SMC) for Brushless DC Motor
Manufacture of Soft Magnetic Composites (SMC) for BLDC Motors in India
Manufacturer of Soft-Magnetic Composites (SMC) for BLDC Motor in India
Manufacture of Soft Magnetic Composites (SMC) for Brushless DC Motors in India
Manufacturer of Soft-Magnetic Composites (SMC) for Brushless DC Motor in India
Manufacture of Soft Magnetic Composite (SMCs) for BLDC Motors
Manufacturer of Soft-Magnetic Composite (SMCs) for BLDC Motor
Manufacture of Soft Magnetic Composite (SMCs) for Brushless DC Motors
Manufacturer of Soft-Magnetic Composite (SMCs) for Brushless DC Motor
Manufacture of Soft Magnetic Composite (SMCs) for BLDC Motors in India
Manufacturer of Soft-Magnetic Composite (SMCs) for BLDC Motor in India
Manufacture of Soft Magnetic Composite (SMCs) for Brushless DC Motors in India
Manufacturer of Soft-Magnetic Composite (SMCs) for Brushless DC Motor in India

Lightweight thermoplastic coated soft magnetic composites (SMC) and application for high-efficiency brushless DC motors

1: What is a BLDC motor?

Ans: A BLDC motor, or Brushless DC motor, is an electric motor that operates using a permanent magnet rotor and a stator
with electronically controlled commutation. It doesn’t have brushes and commutator like a traditional DC motor, resulting in
improved efficiency, reliability, and durability.

Q2: What are the main advantages of BLDC motors?

Ans: BLDC motors offer several advantages over traditional DC motors and even some AC motors:

High efficiency: BLDC motors are known for their excellent efficiency, which leads to reduced energy consumption and
longer battery life in applications such as electric vehicles.
Longer lifespan: Since BLDC motors lack brushes, there is no brush wear, leading to longer operational lifespans and
reduced maintenance requirements.
High torque-to-weight ratio: BLDC motors can deliver high torque output relative to their size and weight, making them
suitable for applications where space is limited.
Precise control: BLDC motors provide precise speed and torque control, making them ideal for applications that require
accurate positioning or variable speed operation.
Reduced electromagnetic interference: The absence of brushes reduces electrical noise and electromagnetic interference
generated during motor operation.
Q3: What are the common applications of BLDC motors?

Ans: BLDC motors find applications in various industries and devices, including:

Electric vehicles (EVs) and hybrid vehicles (HV): BLDC motors are widely used in EVs and HVs to drive the wheels,
providing efficient and reliable propulsion.
HVAC systems: BLDC motors are used in fans, blowers, and compressors for heating, ventilation, and air conditioning
systems, improving energy efficiency.
Industrial automation: BLDC motors power robotic systems, CNC machines, and various automated equipment due to
their precise control and high torque.
Consumer electronics: BLDC motors are found in appliances like refrigerators, washing machines, and power tools for
improved efficiency and quieter operation.
Aerospace and defense: BLDC motors are utilized in aerospace applications such as actuators, pumps, and cooling
systems, offering high reliability and performance.
Q4: How are BLDC motors manufactured?

Ans: The manufacturing process for BLDC motors typically involves several steps:

Stator manufacturing: The stator, which includes the windings, laminated cores, and other components, is manufactured
using techniques like stacking, winding, and varnishing.
Rotor manufacturing: The rotor is usually made of permanent magnets attached to a shaft or rotor core. Magnet insertion
and assembly are crucial steps.
Assembly: The stator and rotor are combined, and other components like bearings, housings, and enclosures are added
to complete the motor assembly.
Testing: Each motor undergoes rigorous testing for performance, electrical characteristics, and quality assurance.
Finalization: After passing the tests, the motors are labeled, packaged, and prepared for shipment.
Q5: Are there any quality standards or certifications for BLDC motors?

Ans: Yes, several standards and certifications are relevant to BLDC motor manufacturing, including ISO 9001 for quality
management systems, ISO 14001 for environmental management, and IEC 60034 for rotating electrical machines. Additionally,
industry-specific certifications and compliance requirements may apply depending on the application or market.

Axial Flux Motors using Soft Magnetic Composite
Soft Magnetic Composite (SMC) is a magnetic core made by iron powder in a three-dimensional shape by compaction process.
SMCs are used in many applications such as automotive area because of the features that are superior in flexibility of core shape
and better high frequency characteristic in the practical use than an electrical steel used in conventional radial flux motor. When
using SMC as a magnetic core for electric motor, it is necessary to generally place insulation parts to secure the insulation-resistant
between a magnetic core and copper winding. Our unique insulation coating on SMC enables to wind copper winding on SMC
directly and reduce of parts cost and the assembly cost. Furthermore, this technology contributes to reduce the size of motor.
SMC (FMCM series) shows a superior soft magnetic properties in wide frequency range, from low to high frequencies.

The introduction of new materials and manufacturing technologies has significantly improved soft magnetic composites
(SMCs) applications, with unique 3D shapes, reduced weight, and lower energy losses, material waste, and manufacturing costs.
However, coating materials and existing iron powder insulation techniques limit the applicability of SMCs. This study used an
organic polyether ether ketone (PEEK) coating to insulate iron particles using a more effective technique. The prepared SMCs
comprised several volume concentrations of iron and PEEK, which were evaluated based on their magnetic, electric,
and physical properties. Their magnetic properties were studied at various temperature ranges, considering the operating
temperature limits for different applications. A mass magnetization saturation value of 236.2 emu/g was achieved at
348.15 K for a 6.2 g/sample. Furthermore, lighter and energy-efficient brushless direct current (BLDC) motors featuring
SMC cores were manufactured and compared with a laminated core-based motor. The developed SMC motors (93 %)
were approximately 9.90 % more efficient than the laminated core-based motors (83.1 %), while the core losses of SMC
core (<1 %) were approximately 5.50 % less than those of the laminated core (6.50 %).

The world’s electricity consumption reached a new high of 25,300 TWh in 2021, and this continuously growing demand is
correlated with difficulties in supplying clean and affordable energy [1], [2]{IEA, 2020 #240;EIA, 2022 #13}. Therefore,
the research and development of advanced and efficient engineering materials have important environmental and economic
significance. Soft magnetic materials (SMM) are important for energy production (generators), transmission (transformers),
and consumption (sensors, electric motors, and other actuators). The term SMM refers to both laminates of coated iron/electric
steel sheets and powder-based soft magnetic composite (SMC) materials [3]. SMCs can be understood as bulk multiphase
systems, in which one or more insulating phases coat an SMM, which is mainly powdered iron.

SMCs have excellent 3D design capability, isotropic ferromagnetic behavior, high efficiency at higher frequencies, and lower
eddy current losses compared with laminated electric steel sheets [4], [5], [6]. The insulating layers are either organic or inorganic,
but diamagnetic insulations are preferred because of their non-interfering magnetic properties. Inorganic materials generally exhibit
better thermal stability than most organic coatings, although depending on the application, both types of coatings have been widely
used [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. The insulating layer is usually developed by mixing the iron powder in a solvent
solution of dielectric material (organic and inorganic) [17], [18], [19]; these solvent-based coating methods require solvent preparation,
mixing with magnetic powder, and drying. Inorganic coating techniques are preferred because of their borrowed and well-established
powder metallurgy techniques. In the case of organic materials, such as thermoplastics, it is difficult to coat them uniformly on iron
particles because of their high viscosity, lack of appropriate solvents, and manufacturing methods. However, achieving a high SMC
density-reducing resistivity remains a challenge [20], [21]. Organic coatings are advantageous for reducing the compaction pressure
and temperature requirements for curing. Of these, thermosetting polymers are not preferred because of their limited thermal stability.

Conventional coating methods typically produce SMC chunks rather than powders; therefore, it is difficult to process during molding.
They have a high overall coating process time and produce a non-uniform coating of iron particles owing to the insufficient solubility
of thermoplastic polymers in solvents. Moreover, the volume fraction of iron particles decreases with increasing coating time regardless
of the particle size [22], [23], [24], [25], [26]. To develop an insulating layer, a solvent-free coating method was introduced in this study,
in which ultra-fine, dry, powdered polymer was coated over iron particles in a mixer and compacted to the required shape using a hot press.
Polyether ether ketone (PEEK) was used as insulating material. It has excellent thermal stability, good adhesion, high flexibility, and is
non-toxic and recyclable. The use of powdered-based organic coatings helps to minimize air gaps comparing to inorganic coatings.
The curing process of the polymer enhances the coating’s effectiveness and improves the contact area between the coating material
and iron particles, thereby enhancing mechanical stability.

An investigation of the electric and magnetic properties based on various SMC densities and temperatures was performed using a
vibrating sample magnetometer (VSM) to ensure the feasibility of the developed SMC. Furthermore, prototype BLDC motors featuring
the developed SMC core material were fabricated and compared with a laminated core motor. It is acknowledged that SMC offers
weight reduction and lower core losses in motors, which can be proven correct when accurately applied to transformers, generators
and other electromagnetic applications. However, it is essential to consider the design aspects of applications. An excellent example
of SMC implementation is its application in BLDC motors used in Electric Vehicles (EVs). Despite being their lower mechanical properties,
as a static part of BLDC motors, and possessing vibration-damping properties, they can overcome their limitations. Moreover, SMC-based
applications exhibit high performance at high frequencies.

An illustration of the soft magnetic composite is shown in Fig. 1.

The metal particles investigated in this study were water-atomized iron powders designed for soft magnetic applications.
They can be compacted to a density of up to 7.4 g/
(without insulation). The iron powder (ATOMET 1001HP, Rio Tinto Iron & Titanium (Suzhou) Co., Ltd, China) for size < 45 (14.1 %),
45–150 (66.4 %), and 150–250 (19.5 %) microns were used to achieve high SMC density. PEEK (450G, Victrex, United Kingdom)
ground to an ultra-fine powder using a ball milling machine was used as

Electromagnetic properties
Fig. 5a shows the mass magnetization (emu/g) values of the four soft magnetic composite samples with densities of 4.2, 4.97, 5.72, and 6.2 g/
at temperatures ranging from 298.15 K to 373.15 K for a magnetic field strength of 5000 Oe. For the 4.2, and 4.97 g/
samples, the mass magnetization values exhibited a slight reduction of approximately 1 emu/g until 323.15 K, and the values reduced
more sharply (by 10–12 emu/g) for the next increment to 348.15 K. Further magnetization loss occurred

The primary objective of this study was to develop a novel soft magnetic composite to minimize energy losses in the core, reduce weight,
and improve the SMC manufacturing process. The following conclusions were drawn based on the results.
1) SMCs were fabricated using an advanced coating method for iron particles and hot-pressing at 350 °C for 1 h. The complete coating time
was<1 min, which is significantly lower than that of conventional coating methods.

2) The particles were separated from each other

Soft Magnetic Composites
Soft magnetic composite (SMC) materials are made from bonded iron powders. The iron powder is coated with an insulating layer
and pressed into a solid material using a die before final heat treatment to cure the bond. It is not a powder metallurgy process where
sintering is used. SMC materials are rather new and have a number of advantages. The material is isotropic, enabling the design of
magnetic circuits that have three-dimensional flux paths, and since there is an insulating layer between the iron powder particles,
losses due to eddy currents are minimized.The material can be used at frequencies up to 100 kHz, and the cross-over point for
core loss for it and 3% silicon steel (0.5 mm thick) is about 400 Hz, where at 1.5 T the loss for both materials is about 90 W kg−1.
The main advantage of the material may be in low-cost manufacture, as parts can be made to net shape, using highly-automated
mass production methods. The main disadvantage of the material is its high core loss at 50 Hz when compared with silicon–iron
electrical steels. Nonetheless, a number of prototype transverse flux and claw-pole electrical machines have been made using
SMCs (Jack 1998).

Soft magnetic composites
SMCs are insulation-coated magnetic particles that are often consolidated using high pressure to form a desired geometrical shape.
They have been considered potential candidates since early 1990 [71]. The SMC refers to amorphous soft magnets, consolidated
amorphous ribbon, and powder-based magnets and magnetic wires [122]. To date, SMCs are the main ingredients that allow fabrication
of near-net shaped electrical cores in conventional manufacturing methods [123]. The isotropic distribution of magnetic particles in
soft magnetic electrical cores produces ripple-free mechanical torque. The insulation coating increases the electrical resistance of the laminates,
which is responsible for reducing losses from eddy currents; however, it greatly reduces the magnetization and mechanical strength of the
electrical parts. In addition to insulation, the compressed particles enclose air gaps, which greatly increases the resistivity.
The SMCs should be produced either from iron or high-magnetic materials such as Fe3P, Fe–Si, and Fe–Co alloys [46]. A benefit of AM with
SMCs will be the achievement of more complex geometries than possible conventionally. FINEMET [68] is a Fe–Si rich SMC alloy
(with a body-centered cubic Fe structure) that can be synthesized in fine-grained nanocrystalline forms with the addition of Cu, Nb, and B,
yielding excellent soft magnetic properties. It can have moderate magnetization, extremely high permeability (40,000 to 100,000), and
significantly high electrical resistivity. The use of AM has been reported for FINEMET [39,67,72,120,124,125]. It is also reported to be
additively manufactured through SPS and LENS, with the latter producing soft magnets with coercivities of 1,194 to 3,024 A per meter.

Soft Magnetic Composite: The Basics
Once insulated, the powder is pre-mixed with compaction lubrication to smooth the way for compaction and ejection from the die.
The lube gets removed during heat treating afterward.

Soft magnetic composites offer possibilities that simply didn’t exist before. With the right SMC material your technology can:

Run faster
Consume far less energy
Become more compact & dense
Achieve high permeability
Use higher frequencies
Experience lower core/eddy loss
Definition: Soft magnetic composites are ferromagnetic powder particles ideally coated with a uniform layer of electrical insulating film.
SMC materials vary depending upon the final application.

Keep in mind that magnetic performance is a function of:

Alloy system used
Density of final part (saturation induction and permeability are influenced by density)
Sintering temperature
Carbon and nitrogen content after sintering
Soft magnetic composites are compacted just like any other powder metal part. Heated die compaction is often used to promote higher density.
As noted earlier: Higher density = higher permeability = higher induction.

Why SMCs Matter in Electric Motor Design
Powder metal magnetic materials can be classified as either sintered (for DC, or direct current applications) or soft magnetic composite
types (for AC, or alternating current, applications).

The beauty of soft magnetic composites over sintered materials is that they’re designed with competitive magnetic properties, but with
higher electrical resistivity. That resistivity is a big part of what makes SMCs appealing to those who are building low-loss parts,
especially at high frequency.

Advantages of SMC materials reside in the shape-making capability of the powder. Shapes typically created through powder metal
are easily achieved with soft magnetic powders. This enables 3-D flux carrying capabilities and round corners — that’s right, complex,
3-D geometries can be done with efficiency.

You can even combine SMC with laminations or sintered parts. There are some electric motor applications out there for which only the
tip is made from soft magnetic composite. Innovative designs are possible by combining the best parts of each part-making process.

What else does SMC allow for?

Fewer necessary components
Easy manufacturing of components
Tight tolerances
Smooth surfaces
Savings on system level
Compact winding
Compact geometry
Flux concentration
Short flux path
High iron fill factor

The Heat Factor
As we discussed, SMC components use the shape-making skills of powdered metal, but the components aren’t sintered.

As such, they won’t have metallurgical bonds between powder particles. You’re instead relying on the strength of the interlocking particles
plus the strength the insulating layer provides.
Heat treating your soft magnetics can have an effect on magnetic performance. The point of heat treatment is twofold:

Improve the soft magnetic properties (Relax the stresses)
Improve mechanical properties
Heat treatment or curing is not sintering — remember, no metallurgical bonds are formed. The higher the temperature, though, the better
the strength of your SMC. Your components vendor should know the optimum temperature for resistivity and strength.

The Heat Factor
As we discussed, SMC components use the shape-making skills of powdered metal, but the components aren’t sintered.

As such, they won’t have metallurgical bonds between powder particles. You’re instead relying on the strength of the interlocking particles
plus the strength the insulating layer provides.
Heat treating your soft magnetics can have an effect on magnetic performance. The point of heat treatment is twofold:

Improve the soft magnetic properties (Relax the stresses)
Improve mechanical properties
Heat treatment or curing is not sintering — remember, no metallurgical bonds are formed. The higher the temperature, though,
the better the strength of your SMC. Your components vendor should know the optimum temperature for resistivity and strength.

Soft Magnetic Composites (SMC) is a breakthrough technology with massive potential to shape the future of electrified applications.
SMC have unique features that allow for a non-magnetic material to become magnetic in application use. Adding an electric current to
a carefully designed component made with SMC, an electro-magnetic field is created. SMCs are used in the powder metal process
as a lower cost replacement to stacked laminations in BLDC E-Motors. The motor designer can utilize this technology to design a
smaller thus lower cost alternatives to traditional laminated technology. With mounting pressures for higher efficiencies, smaller components,
and sustainable materials; SMC components lead the way.

Soft Magnetic Composites are created by coating each individual particle of iron with an insulation material. By providing an insulation
prior to compacting the part, the result is a component with high-resistivity and very little eddy current losses. Coupling the material
capabilities with the design freedom of conventional powder metallurgy, components can be designed to guide the magnetic flux
taking advantage of 3D vertical architecture such as axial, transverse, and radial flux motors operating at 400Hz to 2000 Hz.

What Are The Advantages of these Soft Magnetic Composite Materials?
When an application is designed with SMC the advantages quickly compound. Most notably, design complexity and freedom that is
achieved through using the powder metallurgy process with an SMC material. As PM is a naturally green technology, there is the
reduction in overall manufacturing costs and time. Complex geometries that direct magnetic flux allow for application designers to
reduce the size, weight, and waste of the end product.

Utilizing PM SMC eliminates the need for the expensive lamination process and limited material availability of NOES steel, while
providing superior magnetic flux properties compared to the 2D competitor. With less processing and a smaller component design,
integration not only becomes possible but more so becomes the next logical step. For example; an electric motor that was previously
purchased separately and attached to an application, could now be designed as an integrated motor with modular assembly directly
into the final product.

Components are made in tooling with a single pressing followed by a low temperature thermal operation and are ready for assembly
immediately following. SMC components have 3D flux paths allowing the motor designer to take advantage of extended back irons
and tooth tips facilitating optimal utilization of copper and magnet materials reducing flux leakage and tooth tip saturation effects.

The 3D geometry can also facilitate pre-wound copper facilitating modular assembly. The PM process is ideal for Axial Flux and
Radial Flux Stator manufacture.

Another advantage of SMC materials is the very high electrical resistivity, making it a beneficial material for axial flux motors where
magnetic fringing flux can create significant eddy current losses in laminations.

Soft Magnetic materials are at the center of the efficient running of next-gen electric motors and Drives. SMCs can deliver the following results:

Enhanced assembly capabilities.
Reduction in the size and weight of components.
Increased performance levels from high saturation of magnetic flux density.
Cost-efficient design and production methods requiring less material and less secondary operations.
Lower core and eddy current losses

Industry Applications For SMCs
New developments in powder metallurgy make SMC materials interesting for electrified applications when combined with cutting edge
designs and new production techniques. This is particularly beneficial to the automotive industry that’s currently at an inflection point in
finding cost-efficient traction motors. Soft Magnetic Materials (SMCs) will allow the transition to electric vehicles to happen at a faster rate.
Not only does it reduce the need for fossil fuels, but it also eliminates the use of Rare Earth Magnets and Rare Earth Materials used in traditional motors.

The SMC technology also has useful applications in industrial markets. Some of the uses in Industrial applications include solar power,
off-board power generation, motors, and drives. SMCs are also advantageous in other automotive applications, including traction motors,
E-pumps, direct current conductors, and compressors.

Soft magnetic composite materials make it possible to design innovative, compact, and powerful electric motors that match your specific
application. Some examples of these applications are:

Traction motors
Axial Flux motors
Radial Flux motors
Linear Motors
Solenoids and Actuators
Valve Controls

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