Soft magnetic material
Materials that exert low magnetic force and are also highly permeable are known as soft magnetic materials. Despite the fact such materials become strongly magnetised when exposed to magnetic fields, the lack of magnetic force otherwise makes them particularly valuable for use in numerous industries.
Soft magnetic material parts have tended to be used for household appliances and computer-related office equipment or included in general industrial equipment included in a range of pneumatic equipment, the solenoid valves in motor vehicle fuel-injection devices, solenoid cores, injector cores, plungers and torque sensor cores as well as various sensors.
Amid frequent demand for high precision or complex shapes among soft magnetic parts, the current approach involves manufacturing using cutting and powder metallurgy methods but brings with it many issues. In response, Taisei KOGYO, or our µ-MIM® technology has spearheaded manufacturing research efforts as part of efforts to examine how MIM can be applied to magnetic parts (2008: METI, Strategic Foundational Technology Improvement Support Operation; adopted and commercialised full-scale in 2011).
By optimally exploiting the way MIM technology can facilitate miniaturisation, handle complex shapes and large batches and boost material yield. Moreover, our µ-MIM® technology can apply when manufacturing soft magnetic parts in a net shape high precision in the process.
Above all, this approach paves the way for machining without magnetic distortion, which can be problematic and eliminates the risk of deformation for shapes with thin-walled or shafts, to which they are often prone during magnetic annealing. Our manufacturing scope runs from ferritic stainless steel, Fe3Si and permalloys. Additionally compared to conventional cutting – depending on the shape and quantity involved – it may be possible to reduce the cost per product.
Features of magnetic materials used in µ-MIM® technology
- Complex design accommodated (exceptional design freedom)
- High dimensional accuracy
- High-volume output
Applicable materials and types
- SUS410L (ferritic stainless steel good corrosion resistance, high electrical resistance)
- Fe-Ni (permalloy, high permeability, high magnetic flux density, high resistance, low frequency, low coercivity)
- Fe-3%Si (high flux density, high frequency, low coercivity)
- Fe-Co (permendur, maximum saturation magnetic flux density)
Proper configuration of ferrite-forming elements such as Cr, Mo and Si means that even when ferrites are subject to heat treatment, there is no hardening like martensite and even at high temperatures, magnetism is also retained.
It contains more chromium than martensite type stainless steel and offers exceptional corrosion resistance.
The material features good weldability a smaller thermal expansion coefficient than austenite type stainless steel and excellent high-temperature corrosion resistance to sulphur-containing gases. The material is well applied for furnace parts and chemical equipment up to 800°C.
Permalloy: Created to boost initial permeability with an Ni-Fe alloy containing 35 to 80% nickel, with the term reflecting the combination of permeability and alloy. Its responsiveness to changes in minute magnetic fields explains its usefulness for numerous solenoid valve and magnetic head applications. There is also scope to alter the magnetic characteristics by adding copper, chromium, molybdenum, etc.
Iron-silicon materials: Adding Si to Fe means less Coersive force than pure Fe and minimal iron loss, due to the increased electrical resistance, resulting in an excellent soft magnetic material. However, the hard and brittle nature of the material hinders machinability.
Accordingly, from a powder base, leveraging MIM is expected to enable the production of the final shaped parts. Moreover, while retaining all the magnetic properties, it is under going the development of surface reforming, compounding techniques and examining trace additional elements to compensate for the poor strength and corrosion resistance.
Permendur is a soft magnetic material, featuring an alloy of iron and cobalt in a 1:1 ratio and its stand-out feature is the highest magnetic flux density. It is used in electromagnetic lenses, electron microscopes, the latest printer heads and linear pulse motors; all of which must be ultra-reliable. However, the material is prone to embrittlement or deformation during annealing, during conventional machining. MIM is often feasible to overcome issues such as complex-shaped or thin-walled parts with high accuracy mass production.
For examples of products and applications, click here!
- solenoid valves for fuel injection (injectors)
- magnetic heads
- electromagnetic relays
- various sensors in home appliances
- PC-related office equipment in industrial equipment etc.,
In the automotive industry, which is set to welcome major technological innovations such as self-driving vehicles and connected cars, as well as the electrification of power trains. The use of various soft magnetic materials, in areas ranging from control systems to sensor systems is increasing.
As control systems progress, spearheaded by the robot industry and AI, the future will see increasing the demand of soft magnetic components with high performance, miniaturisation, high precision, and complex shapes progressing in a wider range of applications.
We leverage μ-MIM® technology on an ongoing basis; developing new products to meet those needs. Please contact us for more details of other soft magnetic materials, new alloy systems and composites.