Blog

• How to Improve Cased Nanocrystalline Core Performance: The Game-Changing Impact of Varnish Curing Before Casing

  

  Jul 17, 2025

  As a professional OEM/ODM manufacturer and global exporter of nanocrystalline and amorphous magnetic cores, we’ve faced — and solved — one of the most frustrating problems in magnetic component manufacturing: performance degradation of cased nanocrystalline cores after copper winding. Despite our best efforts with process control and material optimization, the issue remained. Until we discovered one simple yet powerful step that changed everything: varnish curing of the core before casing. In this article, we’ll walk you through the core problem, why conventional fixes don’t work, and how pre-casing varnish curing is a proven solution to improve cased nanocrystalline core performance in real-world production.   The Problem: Performance Degradation After Winding in Cased Cores What Happens in Production Cased nanocrystalline cores — usually toroidal or rectangular cores sealed with plastic, epoxy, or metal shells — are widely used in: High-frequency transformers Common mode chokes EMI filters Inverters and power supplies Before being integrated into magnetic components, these cores are typically cased for mechanical strength, electrical insulation, and ease of handling. However, once copper winding is applied to these cased cores, we consistently observed a decline in performance, including: Lower initial permeability Higher core loss Reduced stability under temperature variation Poorer high-frequency behavior These issues directly affect the quality and efficiency of the final device.   Why Traditional Solutions Don’t Work 1. Process Optimization We tried: Adjusting winding tension Controlling ambient humidity and temperature Improving casing procedures Post-winding annealing None of these consistently prevented the performance drop in cased cores after winding. 2. Material Substitution We experimented with: Different casing materials Various adhesives and bonding resins Modified insulation layers Again, results were unstable. The degradation continued.   Root Cause: Internal Stress and Magnetic Structure Disruption Nanocrystalline ribbon is highly sensitive to mechanical stress and surface tension. During the winding process, pressure from the copper wire and friction from the casing interface can disturb the internal magnetic domains of the ribbon. In cased products, this stress is harder to relieve because the core is confined within a rigid structure. Once distorted, the magnetic domains no longer function optimally — permeability drops, core loss increases, and overall stability suffers.   The Real Solution: Varnish Curing Before Casing After multiple tests, we found a breakthrough: spraying insulating varnish on the bare nanocrystalline core and curing it before applying the casing and winding. This varnish — specifically, a solvent-free polymer-based varnish such as V852-3 — forms a thin, flexible, nanograde insulating layer on the surface of the core. Once cured, it acts as a buffer between the magnetic material and mechanical stress.   How Varnish Curing Works Step-by-Step Process Core Surface Cleaning: Dust, oil, and oxidation are removed. Varnish Spraying: The varnish is evenly sprayed over the entire surface. Curing: The core is baked at 80–120°C for 30–60 minutes, depending on size. Casing: The cured core is then inserted into the casing. Winding: Copper coils are applied as usual.   How It Improves Magnetic Performance Reduces Stress Sensitivity: The cured layer absorbs winding pressure and mechanical stress from the casing. Preserves Magnetic Domains: Magnetic alignment remains stable under force and heat. Improves Thermal Cycling Stability: Coating remains intact even after repeated temperature changes. Enhances Surface Uniformity: Coating smooths minor imperfections, improving magnetic consistency.   Real-World Results from Our Factory After adopting varnish curing in our production line, we observed the following: Test Parameter Without Varnish With Pre-Casing Varnish Initial Permeability (μi) Drops 15–25% after winding Stays within ±5% range Core Loss @20kHz, 0.1T Increases by 30% Reduced by 20–30% High-Frequency Stability Inconsistent Stable across samples Production Rejection Rate ~8–10% <2%   We also received positive feedback from export customers in Europe, South Korea, and the US, especially those working in automotive power supplies, photovoltaic inverters, and EV charging systems.   Why Varnish Curing Beats Other Solutions Method Effectiveness Comments Process tuning ★☆☆☆☆ Temporary benefit, not scalable Casing material change ★★☆☆☆ Costly and still stress-sensitive Annealing post-winding ★☆☆☆☆ Risky in cased products Varnish curing before casing ★★★★★ Simple, stable, and proven effective     Application Fields That Benefit Most High-frequency transformers (20kHz–100MHz) Common-mode chokes for EV charging EMI suppression for power electronics Photovoltaic inverters and wind converters UPS systems and power storage devices DC-DC converters in automotive and rail   We Are a Leading Manufacturer and Exporter With over 10 years of experience in nanocrystalline and amorphous magnetic core production, we provide: Customized OEM/ODM services Cased and uncased cores in toroidal, cut, and block shapes High-frequency, high-efficiency materials Mass production with stable quality control Global export logistics and multilingual support We do not manufacture varnish, but we successfully integrate varnish curing into our own core production lines to deliver the best performance for our customers.   ✅ Improve Your Magnetic Core Reliability Today If you're tired of post-winding performance issues in cased cores, consider switching to a better solution. Let us help you: 🧪 Request free samples 🛠 Get custom nanocrystalline core / amorphous core solutions 📦 Start stable OEM/ODM partnerships 🌍 Deliver globally with technical support 📞 Contact Us 🌐 Website: www.amorphousoem.com 📱 WhatsApp: +86 13686646827 📩 Email: julia@amorphousoem.com 🕘 Working Hours: Mon–Sat, 8:00–18:00 (China Time)   💬 Let’s Build a Better Core — From the Inside Out.

  Hot Tags : How to fix magnetic core performance drop Magnetic core winding stress solution Improve amorphous or nanocrystalline core properties Best practices for transformer core manufacturing OEM nanocrystalline core exporters with advanced curing improve cased nanocrystalline core performance

  Read More
• What is the diference between ferrite core and nanocrystaline core?

  

  Jul 15, 2025

  Magnetic cores are vital components in electronics, essential for efficient energy conversion in transformers, inductors, and chokes. The right core material significantly impacts a device's performance, efficiency, size, and cost. This article compares two key materials: traditional ferrite cores and advanced nanocrystalline cores. 1. What Are Ferrite and Nanocrystalline Cores? Understanding their basic structure is key to their properties. Ferrite Cores: The Established Workhorse Ferrite cores are dense ceramic structures made primarily from iron oxide (Fe2O3) mixed with other metal oxides like manganese, zinc, nickel, or magnesium. These mixtures are shaped and fired at high temperatures (around 1300°C). Their high electrical resistivity minimizes eddy current losses, making them ideal for low-frequency applications. Ferrites offer design flexibility and can be molded into various shapes, including U-cores low power allpications. MnZn ferrites are typically used below 5 MHz, while NiZn ferrites suit  0.01MHz up to 20MHz.   Nanocrystalline Cores: The High-Performance Innovator Nanocrystalline cores are advanced soft magnetic materials with exceptionally small grain sizes, typically 10 to 20 nanometers.Their metallic alloy composition is mainly iron (Fe) with additions of silicon (Si), boron (B), niobium (Nb), and copper (Cu).They are manufactured by rapidly solidifying molten metal into an amorphous ribbon, then precisely heat-treating it to induce nano-crystallization.This nanoscale structure results in remarkably low core loss, low magnetostriction, high saturation induction, and very high initial permeability，over 80Kμm at 10KHz and over 20Kμm at 100KHz.They also exhibit excellent thermal stability from -40 to 120 degree celsius. 2. Ferrite vs. Nanocrystalline: A Performance Showdown Nanocrystalline materials generally outperform ferrite cores in critical magnetic properties, though ferrite retains specific advantages. Advantage of Nanocrystalline Core Nanocrystalline cores offer significant performance benefits: Permeability: Nanocrystalline materials have significantly higher permeability, often ten times that of ferrite cores.This allows for smaller, more efficient components with fewer turns. Saturation Flux Density (Bs): Nanocrystalline cores boast a much higher saturation flux density (1.2 T to 1.32 T) compared to ferrite cores (around 0.3 T to 0.49 T for MnZn ferrite).This means they can handle stronger magnetic fields without saturating, enabling more powerful designs. Core Loss: A major advantage of nanocrystalline core is their significantly lower core losses across a wide frequency range. This leads to enhanced energy efficiency, less heat generation, and simpler thermal management. Frequency Response: Nanocrystalline cores offer a broadband frequency range and maintain properties at very high frequencies, such as 20MHz in transformers, due to vanishingly low magnetostriction. Thermal Stability: Nanocrystalline cores show superior thermal stability, with stable core loss from -40°C to 140°C and a high Curie temperature around 570°C. Ferrite core loss can vary more with temperature. Size & Weight: The superior magnetic properties of nanocrystalline cores enable smaller and lighter components, leading to higher power density (e.g., up to 12 W/cm³ compared to 6 W/cm³ for ferrite transformers).This is crucial for miniaturization. Where Ferrite Remains a Strong Choice & Considerations Despite nanocrystalline's superior performance, ferrite cores remain relevant: Cost-Effectiveness: Ferrite cores are generally more economical and easier to produce.While nanocrystalline cores offer higher performance, they typically have a higher upfront cost.   Specific Application Suitability: For simpler EMI noise scenarios with low energy or single frequencies, inexpensive ferrite cores are often sufficient and more cost-effective.   High Permeability Challenge: The extremely high permeability of nanocrystalline cores can sometimes lead to saturation issues in specific toroidal core designs, where a ferrite material with low permeability might be more effective.   Table 1: Ferrite vs. Nanocrystalline Core Comparison Property Ferrite Core Nanocrystalline Core Composition Ceramic (Iron Oxide + Mn/Zn/Ni/Mg oxides) Metallic Alloy (Fe, Si, B, Nb, Cu) Typical Grain Size Micrometers Nanometer range (10-20 nm) Permeability (µ) Lower (e.g., 5000+ for MnZn) Very High (e.g., 20,000 – 200,000µ) Saturation Flux Density (Bs) Lower (e.g., 0.3-0.49 T) Higher (e.g., 1.2-1.25 T) Core Loss (relative) Higher Very Low (e.g., 1000x reduction vs SiFe) Frequency Range Up to 20KHz (MnZn <5MHz) Broadband (up to 20MHz for Thermal Stability Less stable (loss varies with temperature) Excellent (stable -40°C to 140°C, high Curie ~570°C) Typical Cost (relative) Lower Higher Size Implication Larger components Smaller/Lighter components In a military-grade three-phase switching power supply project, the customer originally used four high-performance ferrite magnetic cores (φ130 × φ70 × 50 mm). These were successfully replaced by a single conventional nanocrystalline core (φ130 × φ90 × 30 mm). The change not only reduced the number of components but also enhanced overall system performance and thermal reliability. Key highlights of this case include: - Structural optimization: 4× Ferrite cores → 1× Nanocrystalline core - Size & Weight: Despite larger individual size, only one nanocrystalline core was needed - Performance: Improved efficiency and temperature control at 100 A operating current - Design Margin: The system maintained performance redundancy, enhancing long-term reliability   3. Applications: Where Each Core Excels The distinct properties of ferrite core and nanocrystalline core make them suitable for different applications. Ferrite Core Applications Ferrite cores are widely used due to their reliability and cost-effectiveness: General low-Frequency Applications: low-frequency transformers, wideband transformers, adjustable inductors. Power Applications: Power transformers , converter/inverter transformers, voltage converters, output chokes, and Switched-Mode Power Supplies (SMPS). Noise and Interference Suppression: Noise filters and EMI line filters, especially for simpler EMI scenarios. Sensing and Control: Measuring and instrumentation transformers, electric fencing, motor speed control, loading sensing, earth leakage sensing, and LED drivers.   Nanocrystalline Core Applications Nanocrystalline cores are used in cutting-edge, high-performance applications where efficiency and miniaturization are critical: Advanced Power Electronics: High-performance power transformers, inductors, and chokes for compact, lightweight designs, ideal for high current output inverters. Electric Vehicles (EVs): Crucial in EV chargers, motor drives, and battery management systems, minimizing energy losses for faster charging and extended range. Renewable Energy Systems: Improved performance at high frequencies for efficient power conversion. Current and Magnetic Sensors: High sensitivity and accuracy due to excellent magnetic properties. Complex EMI Suppression: Excel in EMI suppression and common mode chokes for high-energy or multi-frequency noise due to high impedance and wide effective frequency band. Telecommunications: Contribute to faster data transfer and more compact, reliable equipment by minimizing signal distortion and handling high power densities. Other High-Performance Fields: UPS systems , medical imaging (MRI) , and aerospace.   4. Powering Innovation with the Right Core Choosing the optimal magnetic core is a strategic decision impacting design success and competitiveness. Dongguan JH Amorphous is committed to tailored solutions, from standard offerings to custom configurations. Our engineering support is available at every stage to ensure optimal results. Partner with us to achieve your design goals and ensure the reliability of your electronic systems. Contact our experts today to discuss your project requirements and explore our range of high-quality magnetic core solutions.  

  Hot Tags : Low loss core material for high current inverters Nanocrystalline core for EV charging station Custom magnetic cores for industrial power supply High efficiency transformer core material for SMPS Replace ferrite core with nanocrystalline Nanocrystalline core supplier

  Read More
• Tips of how to choose Fe-based Amorphous or Nanocrystalline Magnetic Cores

  

  Jul 07, 2025

    By Senior Applications Engineer, Dongguan JH Amorphous Co., Ltd. Visit: www.amorphousoem.com   Magnetic cores are critical in suppressing EMI, increasing efficiency, and managing energy conversion in power electronics. At Dongguan JH Amorphous, we manufacture both Fe-based Amorphous and Fe-based Nanocrystalline cores. While they appear similar in structure, their magnetic properties, temperature behavior, and application targets differ significantly.   This article provides a side-by-side technical overview to help engineers select the most suitable core material based on design priorities like saturation flux, operating temperature, resistivity, and mechanical strength.   Relationship between Amorphous and Nanocrystalline Alloy   Amorphous Metals have a unique non-crystalline structure and possess excellent physical and magnetic properties that combine strength and hardness with flexibility and toughness.    The key to amorphous proprietary manufacturing process is the rapid-solidification of molten alloy at a rate of approximately one million degrees Celsius per second, forming a disordered atomic structure without long-range crystalline order.   Nanocrystalline cores are developed from amorphous materials by applying controlled annealing, which causes the formation of nanometer-sized grains (10–30 nm) within the amorphous matrix.   Nanocrystalline materials originate from amorphous materials and are formed through heat treatment.   Difference   Part 1: Fe-Based Amorphous Cores   Key Characteristics   Property Fe-Based Amorphous Saturation Flux Density (Bs) 1.56 T Electrical Resistivity 130 μΩ·cm Crystallization Temperature 508 °C Curie Temperature 400 °C Vicker’s Hardness 860 Hv Density 7.18 g/cm³ Initial Permeability(μi) 5,000 Coercivity Hc (A/m) 2.4 Working Temperature -20 ~ 150°C   Advantages   High Saturation Flux: Ideal for applications that need high peak flux without early saturation.   Good Electrical Resistivity: Reduces eddy current loss in mid-frequency range.   Cost-effective: Generally more economical than nanocrystalline alloys.   Stable for ≤100 kHz Applications: Excellent for low-frequency and mid-frequency common-mode chokes and transformers.   Common Applications:   AC line filters (50/60 Hz)   Output chokes in inverters   Power Factor Correction (PFC) input filters   General EMI suppression in household appliances   Example Case: A 10 A common-mode filter in a household inverter passed EMC Class B after replacing ferrite with a JH amorphous toroid (35×20×10 mm). Losses reduced by 20% with minimal temperature rise.   Part 2: Fe-Based Nanocrystalline Cores   A nanocrystalline alloy of a standard iron-boron-silicon alloy, with addition of smaller amounts of copper and niobium, called NANOPERM (Fe–Zr–Nb–Cu–B) alloys.    It is available under names like e.g. Nanoperm(Fe73.5 Cu1 Nb3 Si15.5 B7) registered by Magnetec, Vitroperm registered by VAC, Hitperm and Finemet registered by Hitachi Metals, Ltd., and Metglas is a registered by Metglas®, Inc.     Property Fe-Based Nanocrystalline Saturation Flux Density (Bs) 1.2 T Electrical Resistivity 115 μΩ·cm Crystallization Temperature 510 °C Curie Temperature 570 °C (↑ very high) Vicker’s Hardness 960 Hv Density 7.2 g/cm³ Initial Permeability(μi) 80,000 Coercivity Hc (A/m) 1.2 Working Temperature -40 ~ 140°C   Advantages Extremely High Initial Permeability (µi): Up to 80,00~12,000, significantly better than amorphous or ferrite.   Lower Core Loss: Particularly effective in 20 kHz–1 MHz range.   High Thermal Stability: Suitable for continuous operation at elevated temperatures (up to 140 °C).   Ideal for EMI Suppression: Excellent for fast-switching SiC/GaN circuits where broadband noise filtering is critical.   Common Applications High-frequency EMI chokes (20 kHz–5 MHz)   EV on-board charger filters   Solar inverter output stages   SMPS and server power supplies   Differential-mode and common-mode chokes in automotive/rail/aerospace/marine   Example Case: In a 20 kW EV charger filter, the replacement of ferrite with a nanocrystalline JH-60×35×15 core resulted in a 30% loss reduction, 8 dB EMI improvement, and a 25 °C lower core temperature under full load.   Material Selection Guide   Application Type Recommended Core Notes Low-frequency EMI Filter (≤100 kHz) Fe-based Amorphous Cost-effective, stable, suitable for Class B filters High-frequency EMI Filter (100 kHz+) Fe-based Nanocrystalline Superior suppression for fast-switching applications Harsh Thermal Environments Nanocrystalline Higher Curie temperature and thermal endurance High Saturation Flux Requirements Amorphous Bs = 1.56 T for larger flux window     When choosing between amorphous and nanocrystalline magnetic cores, it's essential to match your design frequency, thermal limits, and EMI suppression goals with the right material.   Use amorphous when budget, space, and low-frequency performance are key.   Choose nanocrystalline when performance, high-frequency stability, and thermal resilience are critical.   At Dongguan JH Amorphous, we offer full OEM customization, quick sample delivery, and application engineering support.   Learn more: www.amorphousoem.com  

  Hot Tags : Key Differences in Magnetic Properties Between Amorphous and Nanocrystalline Cores Thermal and Structural Advantages of Nanocrystalline Alloys in Power Electronics Nanocrystalline Magnetic Cores Nanocrystalline Cores for High-frequency EMI Suppression Amorphous Cores in Low-frequency Power Applications Fe-based Amorphous Core

  Read More
• How Do Nanocrystalline Cores Improve Efficiency in EV Charging and Power Electronics?

  

  Jun 13, 2025

  With the popularity of electric vehicles, the demand for high-efficiency power electronic components in the electric vehicle industry continues to grow. As an important supporting facility for electric vehicles, the performance and stability of charging piles are increasingly concerned. In the internal structure of charging piles, nanocrystalline magnetic cores are an indispensable component, which plays a vital role in improving the efficiency and safety of charging piles.   Nanocrystalline magnetic core is a material composed of ultrafine particles, with a grain size usually ranging from tens to hundreds of nanometers. The core component is iron oxide containing iron elements, and the surface is covered with a non-ferromagnetic film layer. This structure achieves better electromagnetic properties by changing the magnetic properties of traditional magnetic cores.     Unique advantages of nanocrystalline cores Compared with traditional silicon steel sheets or ferrite materials, nanocrystalline cores have the following significant features: Extremely high magnetic permeability (up to 100,000 µ) Extremely low loss at high frequencies Excellent thermal stability Smaller size but higher energy density These characteristics allow engineers to design smaller and more efficient magnetic devices, especially for scenarios such as on-board chargers and DC-DC converters.   In the process of fast charging of electric vehicles (EVs), power converters (such as high-frequency transformers, filters, and inductors) are core components, and their efficiency directly affects the charging speed and energy utilization. Traditional silicon steel or ferrite core materials are prone to hysteresis loss and eddy current loss when operating at high frequency and high power, while nanocrystalline cores have obvious advantages in this scenario due to their extremely high magnetic permeability (usually more than 10 times that of ferrite) and low loss characteristics.   In addition, nanocrystalline materials also have good resistance to DC bias magnetism, which effectively improves the stability of transformers and inductors during high-frequency repeated charging and discharging, reduces EMI interference, and improves the overall reliability and life of the charging system.   For example,a large European charging pile manufacturer replaced ferrite materials with nanocrystalline toroidal cores in a 22 kW fast charging module, and the overall energy efficiency of the system increased from 94.5% to 97.2%. The use of nanocrystalline toroidal cores reduces the overall size and cost; the heat sink is reduced to save space; the heat is reduced and the safety performance is improved.   Taking a charging station that works 10 hours a day as an example, the annual power saving can reach 200 kWh, with obvious long-term benefits.   The energy-saving advantages of nanocrystalline cores in electric vehicle charging piles fully demonstrate their great potential in improving energy efficiency. However, their applications go far beyond charging equipment. In a wider range of power electronic systems, especially in scenarios with high requirements for high-frequency operation, miniaturized structure and thermal stability, nanocrystalline cores are being increasingly adopted and showing excellent performance.   Nanocrystalline cores in inverters and power electronics In high-power inverters such as electric buses or industrial motor drives, custom nanocrystalline cores can effectively suppress EMI (electromagnetic interference) and withstand high-frequency ripple currents. With a saturation flux density of up to 1.2T, they still provide strong performance in a compact design.   For example, a 100 kW electric bus inverter system, after replacing the raw materials from amorphous cores with nanocrystalline magnetic components, the overall weight of the system was reduced by 8%, the thermal stability was improved by 15%, and the component life was significantly extended.   Due to its excellent high-frequency performance and low energy consumption characteristics, nanocrystalline core materials are now widely used in: Electric vehicle on-board chargers Photovoltaic inverters Transformers for smart grids High-frequency switching power supplies Compared with traditional amorphous cores, nanocrystalline materials have lower coercivity and higher saturation flux density, making them the first choice for the new generation of power electronic systems.   As electric vehicles and new energy power systems continue to develop, nanocrystalline cores play an increasingly critical role in improving efficiency, optimizing thermal management, and achieving high-frequency compact designs. If you are developing power components or EV charging systems, please learn about our customized nanocrystalline cores, high-frequency magnetic materials, and soft magnetic material component solutions.   As a full-service, one-stop amorphous core manufacturer, we provide comprehensive servces including  winding, annealing, coating,  and custom assembly. Contact us now! 

  Hot Tags : amorphous core for ev charger nanocrystalline magnetic cores for ev nanocrystalline cores for high-frequency transformers nanocrystalline core for filters low loss at high frequencies material nanocrystalline core for inductors

  Read More