As an industry leader in the design and manufacturing of tape wound soft magnetic cores, at MK Magnetics, Inc. we are in a unique position to identify industry trends and changing customer needs. Early on in our history, we recognized a deficiency within the industry for custom manufactured tape wound soft magnetic cores. Although our lines of standard products are extensive, the increasing shift towards custom designs was an area of that required a solution. To accomplish this, MK Magnetics assembled a team of highly experienced tape wound core veterans with the goal of augmenting standard cores with highly customizable products. Superior Engineering and Customer Service Support are an inherent part of this process which allows MK Magnetics to manufacture cores that provide maximum performance. From innovative engineering to cutting edge materials such as nanocrystalline, various amorphous materials, 3% grain-oriented and 6.5% non-oriented silicon steel, 50% and 80% nickel materials, Supermendur, and many other highly specialized materials.

Another key advantage of this service is the flexibility of MK Magnetics manufacturing capabilities. Within our facility, we can build cores weighing from .002 up to 4,000 lbs. +, and in dimensions up to 7.5’ in height by 4’ in width, depending on overall geometry. They can be configured as C, E, and pie type D-cores, cased and uncased toroid, bars, and a variety of custom shapes. We also have the flexibility and expertise to develop custom processes to accommodate virtually any core design with no restriction on volume. This is comprehensive offering and is backed up by a robust quality program and a full range of in-house testing capabilities, providing compliance with various industrial standards. MK can typically begin delivering in 3-5 weeks with expedited deliveries available.

For more information, please see the table below or contact us directly.

What Are Tape Wound, Soft Magnetic Cores?

Tape wound cores are key components in transformers, amplifiers, filters, and other complex electronic circuitry assemblies. Due to their reliability, they are commonly used in critical applications, such as those found in the aerospace, communications, military, e-vehicles, Smart Grid, mining, and nuclear industries. 

Generally made from thin strips of soft magnetic materials, cores are available in various shapes, weights, and material thicknesses to suit different frequency, flux densities, and other requirements. The MK Magnetics team will work with you to meet your specifications by combining innovative engineering with access to cutting-edge materials typically used in the manufacture of tape wound cores. These materials may include:

  • Nanocrystalline materials: These polycrystalline materials are made from crystallites that are a few nanometers in size (typically less than 100 nm). Cores made from them generally offer high permeability and saturation and very low power loss. 
  • Amorphous metals: Amorphous metals have a disordered atomic microstructure. It is non-crystalline and glass-like. Cores made from them have excellent magnetic properties, including high permeability, high saturation magnetic flux density, and low power loss. 
  • 3% grain-oriented and 6.5% non-oriented silicon steel: Silicon steels are available in two forms: grain-oriented and non-oriented. Grain-oriented silicon steels have magnetic properties developed in the rolling direction, while non-oriented silicon steels have magnetic properties that are similar in all directions. High saturation magnetic flux density and low cost combine to make this a good choice in many applications. 
  • 50% and 80% nickel alloys: These alloys offer some of the best soft magnetic properties, making them well-suited for use in amplifiers, inductors, transformers, and other magnetics-based devices. 
  • Supermendur®: This cobalt-iron material has high flux density and low core loss, making it suitable for use in chokes and transformers when size and mass are important, such as in the aerospace industry. 
  • & many other highly specialized materials!

Tape Wound, Magnetic Cores at MK Magnetics

Another key advantage of working with us is our flexible manufacturing capabilities. We can build cores that are between 0.002 to 4,000 lbs. in weight and up to 7.5 ft. (height) by 4 ft. (width) in size, depending on overall geometry. They can be configured as C-, E-, D-cores, pie-type, cased and uncased toroid, bars, and a variety of custom shapes. We also have the freedom and expertise to develop custom processes to accommodate virtually any core design with no restriction on volume. This is a comprehensive offering and is backed up by a robust quality program and a full range of in-house testing capabilities, ensuring compliance with various industrial standards. Our team can typically begin delivering in three to five weeks. Expedited deliveries are available.

We can design and manufacture a broad selection of standard and custom soft magnetic core products. 

Magnetic cores are components made from magnetic materials that are designed to contain and control magnetic fields in electrical, electromechanical, and magnetic devices. We make the following types of cores: tape wound cores, cut C-cores (single-phase), cut E-cores (three-phase), toroids, multiple cut cores, epoxy-coated cores, and Optifficient cores. 

Toroids are magnetic cores with a toroidal shape (i.e., a circular ring). This unique shape allows for shorter coils, lower resistive or windings losses, and better overall efficiency in electrical and electronic circuitry assemblies. We offer them in cased, uncased, gapped, and other variations. 

In addition to supplying magnetic core components, we also manufacture stacked and custom assemblies.

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Standard & Custom Tape Wound Soft Magnetic Core Capabilities

Rapid Prototyping
Custom Cores
Custom Processes
Multiple Cut Cores
Engineering Support
Design Support
Rapid Quoting
Test Lab
70,000 sq. ft. Campus
Stocking Programs

  • JIT
Custom & Standard Core Configurations
Tape Wound Cores / Cut Cores

  • C-Cores
  • E-Cores
  • Uncased Toroids including: Epoxy Coated, Cut in Half, Gapped, etc.
  • Cased Toroids including: Machined Nylon, Injection Molded, Aluminum, etc.
  • Pie Type 3-phase Cores, D-Cores
  • Bars
  • Other Custom Shapes
  • Other Special Configurations Available
Tape Cores
Tape Wound Cores
C-Cores (Single Phase)
E-Cores (3-Phase)
Cased Toroid
Gapped Toroid
Stacked Assemblies
Custom Cores
Custom Assemblies
Multiple Cut Cores
Epoxy Coated Cores
Optifficient Cores
Small to Very Large
Weights from .002 to 4,000 lbs.
Sizes up to 7.5′ tall and 3′ wide
Single piece production to 1M+
  • Nanocrystalline
    • Prime DFARS Compliant, Finemet FT3, Vitroperm800
    • Metglas® Inc. Finemet® FT-3W 5.6” wide,  DFARS Compliant US Manufactured
    • DFARS (Defense Acquisition Regulations System)
  • Amorphous Materials
    • Metglas® 2605SA1 Material
    • Industry Standard Series
    • Optifficient Core Series: Ultra-Low Loss Amorphous Cores
  • 2714 Cobalt-Based Amorphous
  • 3% Grain-Oriented Silicon Steel Materials (GOS)
    • High Flux (17.6 KG)
    • Standard Flux (15.0 KG)
  • 80% Nickel Materials
    • Supermalloy
    • Permalloy
    • Square Permalloy
  • 50% Nickel Materials
    • Square Loop
    • Round Loop 4750
  • Supermendur®, Cobalt-Iron High Flux Materials
  • 6.5% Non-Oriented Silicon Steel Materials
  • Other Specialized Materials

Metglas Finemet FT3-W is a registered trademark of Metglas Inc.
Finemet FT3 is a registered trademark of Hitachi Metals.
Metglas 2605SA1 is a registered trademark of Metglas Inc.

Common Mode Chokes
Pulse Transformers
Motor Stators and Back Iron
Energy Harvesting
Full Magnetics Test Laboratory
Core Loss
3 Phase Testing
CCFR (Constant Current Flux Reset)
BH Loop
Magnetizing Current
Pulse Testing
Magnetic Amplifier Core Matching
Production Volume
Prototyping to Production
Low Volume
High Volume
*No minimum Order
MK can typically begin delivering in 3-5 weeks with expedited deliveries available.
Markets Served
Medical Devices
Medical Imaging
Energy Storage
Smart Grid
Industrial Controls
Oil and Mineral Exploration
Directional Drilling
Railroads and Locomotive
Magnetic Levitation
Particle Accelerators
Fusion Power
UPS (Uninterruptible Power Supplies)
Space Vehicle
Microwave Transmitter
Hybrid Electric Vehicles

  • Automotive
  • Buses
  • Ship
  • Aircraft
Industry Standards
ANSI (compliant)
ASTM (compliant)
ISO 9001:2015
Mil-Spec (compliant)
EIA Standard RS-217

Industries Served

Our magnetic cores are suitable for use in a wide range of electrical and electronic applications. Some of the industries we cater to with our products include:


Our tape wound, soft magnetic cores are ideal for energy storage and harvesting applications due to their high efficiency, low-loss operation. 

For one energy storage industry customer, we produced a custom optifficient, ultra-low loss amorphous core that met their core loss requirements, budgetary constraints, and tight timeline. This line of core products can deliver up to and exceeding 30% lower loss than standard amorphous cores offered by our competitors (depending on frequency and flux density).

For smart grid operations, we can supply energy harvesting cores. These inductively powered coupling devices facilitate energy-efficient and cost-effective energy collection and transfer in low line current conditions. We can also build cores from silicon steel if cost is a concern or high-nickel and nanocrystalline materials if high-performance is critical. 


Many medical devices and systems rely on magnetic components. High reliability and efficiency are critical factors in medical equipment. Our magnetic cores find application in medical imaging systems and other medical devices. 


Magnetics play a vital role in a variety of aerospace systems. Typical applications include communication systems, control systems, navigation systems, power supply systems, power distribution systems, filters, and more. 


The military industry relies on magnetic components that are robust, highly reliable and efficient. MK Magnetics works closely with Magnetic Design engineers to provide the right core for the right application. We observe all International Traffic in Arms Regulations, ITAR, when making military products.

MK Magnetics: Your Expert and Partner for Magnetic Core Needs

For magnetic cores you can trust in your most critical applications, MK Magnetics has you covered! Our team has what it takes to deliver the right solution for your needs, whether you’re in the aerospace, energy, medical, military, or another industry. For more information about our capabilities, see the table below or contact us directly. To discuss your product requirements with one of our experts, request a quote