choosing transformer core materials

Choosing Transformer Core Materials

Transformers are integral components of electrical systems, facilitating the efficient transmission and distribution of electricity. Central to their design is the selection of appropriate lamination core materials, which significantly influence performance and energy efficiency. In this blog, we’ll explore the evolution of transformer core materials, from traditional silicon steel to advanced alloys like amorphous and nanocrystalline, highlighting their properties and impact on transformer efficiency.

Silicon Steel and Its Characteristics

Silicon steel, also known as electrical steel, lamination steel, or transformer steel, is a vital material in the construction of transformer magnetic cores due to its low core losses and high permeability.

Composed primarily of iron with a silicon content typically ranging from 3% to 6.5%, silicon steel exhibits properties that make it ideal for use in electrical machines applications.

material selection of motor lamination

The addition of silicon notably enhances the material’s magnetic properties, primarily in two aspects:

Reducing Hysteresis Loss

The silicon content in silicon steel decreases the area of the material’s hysteresis loop, thereby less energy loss in each magnetization cycle.

Mitigating Eddy Current Loss

Silicon increases the electrical resistivity of iron, aiding in minimizing losses due to eddy currents.

Transformer solid iron cores are made of laminating thin silicon steel sheets, further reducing eddy current losses as the laminations shorten the path for eddy currents within the core.

Amorphous and Nanocrystalline Alloys

In recent years, amorphous and nanocrystalline alloys have represented advancements in materials used in transformer cores, offering distinct advantages over traditional silicon steel.

Amorphous Alloys

Amorphous alloys are non-crystalline metallic materials with a disordered atomic structure. Typically composed of elements such as iron, nickel, and cobalt, they exhibit exceptionally low hysteresis losses and high resistivity.

The lack of grain boundaries in amorphous metals reduces magnetic domain movement, resulting in significantly reduced energy losses compared to silicon steel materials. They also are prone to low hysteresis loss because of the high response to magnetic fields.

However, their mechanical strength is relatively low, necessitating careful handling during manufacturing and assembly.

amorphous alloys materials

Nanocrystalline Alloys

Nanocrystalline alloys, on the other hand, possess a fine-grained crystalline structure with grain sizes typically on the order of nanometers. These alloys combine the high magnetic permeability of amorphous alloys with the mechanical strength of traditional metals.

They offer remarkably low hysteresis losses, excellent temperature stability, and improved mechanical properties compared to their amorphous counterparts.

Nanocrystalline alloys are particularly well-suited for high-frequency applications due to their reduced core losses and enhanced efficiency.

Both amorphous and nanocrystalline alloys represent significant advancements in motor iron core and transformer core technology, enabling the development of more efficient and compact electric motors, generators, and transformers capable of meeting the demands of modern electrical systems while reducing energy consumption and environmental impact.

Impact of Transformer Core Materials Selection on Losses and Efficiency

The choice of different materials directly affects the losses and efficiency of transformer cores:

Hysteresis Loss

The material’s hysteresis loss significantly impacts overall efficiency. Core materials with low hysteresis loss, such as amorphous and nanocrystalline alloys, can enhance transformer efficiency.

Eddy Current Loss

The material’s resistivity determines the magnitude of eddy current losses. High-resistivity materials like amorphous alloys contribute to reducing eddy current losses.

Frequency Effects

For high-frequency applications, the material’s loss characteristics are particularly crucial. Nanocrystalline alloys, owing to their excellent high-frequency performance, emerge as the ideal choice for high-frequency transformers.


The selection of transformer core materials plays a pivotal role in determining the efficiency and performance of electrical transformers.

While traditional silicon steel remains prevalent, the emergence of advanced alloys like amorphous and nanocrystalline presents exciting opportunities to improve efficiency, reduce losses, and meet the demands of modern electrical systems.

As technology continues to advance, the pursuit of innovative materials will undoubtedly drive further enhancements in transformer design and operation.

Lamnow – Transformer Lamination Core Manufacturer

Lamnow is a leading manufacturer specializing in transformer lamination cores in China, with over a decade of iron core design and manufacturing experience. 

Our laminated stacks find extensive applications in electric vehicle motors, pump motors, power tool motors, household appliance motors, industrial motors, renewable energy systems, and aerospace.

For amorphous core and silicon steel core transformers, we offer EI and UI  lamination core types, providing tailored solutions to meet diverse requirements.

With a commitment to quality and innovation, Lamnow continues to be a trusted partner for clients seeking efficient and reliable lamination core solutions worldwide.

lamnow transformer core laminations


What are the common types of transformer lamination cores?

The common types of transformer lamination cores include:

E-I Core: This is the most common type of transformer core. It consists of two E-shaped laminations and one I-shaped lamination sandwiched between them. The windings are then wound around the central leg of the core.

C-Core: In a C-core configuration, the laminations are shaped like the letter C. This type of core is often used in high-voltage transformers, as it provides a closed magnetic circuit and reduces magnetic flux leakage.

U-Core: U-core transformers have a U-shaped core, with windings wound around both legs of the U. This design is often used in applications where space is limited.

Toroidal Core: Toroidal cores are donut-shaped and provide a closed magnetic circuit. They offer advantages such as low magnetic flux leakage and reduced electromagnetic interference. Toroidal transformers are commonly used in audio equipment and power supplies.

Shell Type Core: Shell cores consist of two cylindrical sections with windings wound around them. They are used in applications where high voltage and high power are required.

Step-Lap Core: In a step-lap core, the laminations are stacked with alternating stepped ends, which helps to reduce magnetic losses and improve efficiency.

How are transformer lamination cores manufactured?

Cores are typically produced by stamping or laser cutting or wire cutting thin sheets of electrical steel to precise dimensions and then stacking and bonding them together to form the desired core shape.

What are the application areas of the transformer core?

The high-efficiency transformer cores find application in various electrical and electronic systems, including power distribution, voltage regulation, and signal processing. They are essential components in power transformers used in electrical grids for stepping up or down voltage levels.

Their versatility extends to renewable energy systems, such as wind turbines and solar inverters, where they facilitate the conversion and distribution of electrical power.

How do transformer lamination cores contribute to energy efficiency?

By reducing core losses and maximizing magnetic flux, transformer lamination cores play a critical role in improving the overall energy efficiency of electrical transformers, ultimately reducing energy consumption and costs.

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To learn more about our motor lamination manufacturing capabilities for your industry, contact our team today.