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Electric Discharge Machine for Soft Ferrite

About soft ferrite:
Application of soft ferrite began in the end of 19th century. It features high permeability, high resistivity, low wear and tear, and stable property. It’s easy to produce and to be made into molds to form magnet cores with a low cost. All these make it widely used in communication equipment, transducers, audio equipment, power supply and magnet heads.
With the increasing demand and development of electronic information in China, it asks the soft ferrite to be more compatible for a wider range of application.

Main contents of magnetic materials are Fe, Co, and Ni. These magnetic elements can be divided by ingredients, magnetic property, and structures.

The electric discharge machine can be used to process various kinds of soft ferrite, including:
(1)alloys like stalloy, Permalloy, non-crystal and nanocrystal alloy
(2)powder cores like magnetic powder core, including iron powder core, sendust core, high flux powder core,
Permalloy powder core (MPP)
(3)ferrite, a special kind of powder core, including Mn-Zn ferrite and Ni-Zn ferrite

Requirement of material and roughness for soft ferrite molds
Upper and lower die holder: 45#
Upper and lower die pad: Cr12MoV (Cr12), hardness: HRC52°
Master mold: YG15 carbide (2 million times molding), no internal or external crack
Upper and lower mold: Cr12MoV die steel, coating layer: CrAlTiN, hardness: HRC58-60°(HRC55-58° for bigger size), no internal or external crack
Cores: YG15 carbide (2 million times molding), no internal or external crack, die case: 45# (coating hard Cr12 on surface), abrasion depth for 2 million times molding: ≤2mm, upper connecting sheet, press board, screw and nut: 45#
Surface roughness of upper and lower mold and core rod, work station and die case chamber: ≤Ra 0.2μm

Relationship between soft ferrite and electric discharging:
----To make carbide molds as the material for soft ferrite
Rapid development of soft ferrite challenges the life and precision of its molds. Carbide is wear resistant and heat resistant with a short thermal movement. So it’s more suitable for the material of molds. Compared with steel dies, carbide dies can be used for millions of times, which greatly saves the cost. Moreover, its physical and thermal structure make carbide dies hard to be processed by ordinary machines. So it has to be processed by electric discharge machines, introducing a contactless technology for higher hardness, higher strength and higher tenacity.

Difficulties in the process of carbide by electric discharge machines:
1.To process carbide is usually difficult and inefficient.
2.It requires a high roughness and power supply of the machine tools.
3.The higher melting point, boiling point, heat capacity and vaporization heat the metal has, the less electrode can be charged, and the more difficult to be processed.
For example, in the electric charging, cobalt is melted and vaporized earlier than tungsten carbide. Particles of tungsten carbide will be thrown into the gaps and cause unstable charging, which costs more time and lowers the final quality.

Our solution:
High quality power supply
Strong blasting power and specially designed circuit ensure an intensive current suitable for carbide process.
Equal-impulse controlling system
Same energy of every impulse ensures the consistence in the material surface, whose roughness can reach Ra0.25mm for carbide dies and Ra0.1mm for die steel.
MONITRON spark inspecting system
It controls every sparks in the charging to make sure there’s no ablation in the surface.
Single impulse control system
It makes the electrode wear ratio as low as 0.1%. Thus the products will have a clear edges and corners.
Unlimited resistor in the power supply
It doesn’t heat the cabinet, costs less energy and gives the machine tool a longer life.
Our electric discharge machine for soft ferrite can be used in various electrodes like red copper-steel, black lead- steel and red copper-diamond.

Comparison of machining efficiency
Size of female chamber: 4.55+0.01+0.005 mm
Depth: 2.43±0.02mm
Roughness of chamber (with side wall): Ra0.4μm

Comparing with another company:

JCSJM N Company
Material of Electrode Red Copper Red Copper
Material of Workpiece Carbide YG20C Carbide YG20C
Machining Depth 9.47mm 9.47mm
Machining Tool GW-735P(64A) XX-430(50A)
Rough Machining Electrode Used: 1
Time Cost: 7h45min
Electrode Used: 3
Time Cost: 30h
Half Precision Machining Electrode Used: 1
Time Cost: 5h30min
Translation Time: 45min
Electrode Used: 3
Time Cost: 14h
Translation Time: 2h45min
Precision Machining Electrode Used: 1
Time Cost: 4h45min
Translation Time: 30min
Electrode Used: 2
Time Cost: 10h25min
Translation Time: 4h30min
Total Electrode Used 3 8
Total Time Cost 19h15min 61h40min
Wear and Tear R<0.25mm R<1.0mm
Polishing Abrasive Paste Diamond Rasp+Oilstone+Abrasive Paste
Cost <0.5A supposed to be A

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