Permalloy: A Versatile Magnetic Alloy for Wide-Ranging Applications
Permalloy, an alloy primarily composed of nickel and iron, possesses high permeability and low coercivity, making it an indispensable material in various industries including magnetic shielding, electronic components, transformer cores, and magnetic sensors.
This article explains the characteristics, applications, and machinability of permalloy in detail.
What is Permalloy?
Permalloy is an alloy primarily composed of nickel and iron. Its unique physical and chemical properties are determined by the ratio of these components. The two types of permalloys we frequently receive machining requests for at Koyo High Precision are classified as:
- • PB Permalloy (Ni 45% – Fe 55%)
- • PC Permalloy (Ni 77% – Fe 14% – Cu 5% – Mo 4%)
Characteristics of Permalloy
High Permeability
Permalloy is an alloy that is highly valued across many industrial fields due to its unique magnetic properties.
In particular, its high magnetic permeability attracts significant attention.
Magnetic permeability is an indicator of how easily a material can be magnetized. In the case of permalloy, it responds sensitively even to very small changes in external magnetic fields.
This characteristic means that permalloy excels at detecting and responding to subtle magnetic field fluctuations, which in turn helps ensure precise and reliable operation of electronic devices.
Low Coercivity
Permalloy has low coercivity, meaning that magnetization is quickly released once the external magnetic field is removed.
Low coercivity indicates that very little residual magnetism remains after the magnetic field disappears, which is a significant advantage.
This property is particularly valuable in magnetic memory devices and sensors, where reusability and reset capability are required.
Magnetic Shielding Performance
Permalloy’s magnetic shielding performance is highly effective due to its combination of high permeability and low coercivity.
Magnetic shielding materials are used to protect equipment from unwanted magnetic fields or magnetic noise, and permalloy is extremely well-suited for this role.
Its high permeability absorbs external magnetic fields effectively, while its low coercivity helps it avoid retaining them.
As a result, it acts as a protective barrier against magnetic noise, helping maintain equipment performance.
Magnetic Flux Concentration
Permalloy has the ability to concentrate magnetic flux, meaning it can produce a much stronger magnetic output than the magnetic field applied to it, essentially amplifying the magnetic effect.
Because of this property, permalloy is widely used as a core material in magnetic sensors and power converters. In sensors, it enables the precise detection of even small changes in magnetic fields, while in transformers and inductors, it helps achieve efficient conversion of magnetic energy. Permalloy’s strong flux concentration capability makes it ideal for both applications.
Property Enhancement through Heat Treatment
Permalloy’s properties can be further enhanced through heat treatment. Magnetic annealing at temperatures above 1000°C significantly increases permeability, resulting in improved performance for specific applications.
This treatment optimizes the microstructure of the material, enhancing its magnetic characteristics and enabling high-performance components.
Applications of Permalloy
Permalloy is a magnetic material that takes advantage of its high magnetic permeability and low coercivity, playing an important role across a wide range of applications.
It is widely used in magnetic shielding, electronic components, transformer and transformer cores, magnetic sensors, and inductors, where stable and precise magnetic performance is required.
Magnetic Shielding
In magnetic shielding, permalloy plays a crucial role in protecting precision equipment from magnetic noise and external fields.
For example, medical devices and communication equipment that are sensitive to minor magnetic influences can lose accuracy and reliability without permalloy shielding.
Permalloy effectively blocks unwanted magnetic fields, ensuring that equipment operates under ideal conditions.
Electronic Components
Permalloy has a wide range of applications in electronic components.
In electron microscopes, it is used for magnetic shielding to prevent interference when observing microscopic samples.
In acoustic and measurement equipment, permalloy shielding cases help reduce noise and improve signal clarity.
Additionally, in inverter motor control devices, permalloy helps minimize magnetic interference, enhancing the precision and efficiency of the equipment.
Transformer and Inductor Cores
When used as cores for transformers and inductors, permalloy enables efficient power conversion due to its high permeability and magnetic flux concentration.
High permeability allows magnetic field changes to be transmitted quickly through the core, while magnetic flux concentration efficiently converts input energy to output energy.
These features allow transformers and inductors to remain high-performing while being miniaturized, improving the stability and cost-effectiveness of power supplies.
Magnetic Sensors
In magnetic sensors, permalloy enables accurate detection of small magnetic field changes, providing high sensitivity and precision in applications such as geomagnetic measurement, vehicle position and speed sensing, and digital compasses.
By using permalloy, sensors can respond quickly to subtle environmental changes and deliver reliable measurement results.
Machinability of Permalloy
While permalloy offers good machinability among nickel-based alloys, certain characteristics make it challenging to process.
This is due to its specific viscosity, low thermal conductivity, and tendency to harden during machining.
Furthermore, permalloy tends to form strong bonds with tools during processing, and when the processed area heats up, chips or the material itself can easily adhere to the tools. Therefore, when using conventional tools, early tool wear, breakage, and decreased processing precision are likely to occur.
During processing, not only is adjusting the speed important, but also cooling the work area is critical. Proper cooling depends on selecting and supplying the right cutting oil, which plays several key roles beyond cooling—such as reducing tool wear and helping with chip evacuation.
Therefore, high-precision machining of permalloy requires specialized knowledge and techniques, including the selection of appropriate tools and the setting of optimal cutting conditions.
Trust Koyo High Precision for Machining Materials
The difficulty of machining permalloy originates from its unique physical properties.
It has high viscosity, low thermal conductivity, and a strong tendency to harden during processing. As a result, conventional machining methods can easily lead to problems such as tool wear or breakage and reduced machining accuracy.
Koyo High Precision has extensive experience and proven expertise in the precision machining of special alloys, enabling high accuracy machining even for difficult materials such as permalloy.
Our technical capabilities cover every aspect required for permalloy machining, including proper tool selection, optimization of cutting conditions, and effective cooling of the machining area.
If you are considering permalloy machining, Koyo High Precision is a reliable partner you can trust.
