# Finnland Joining 2007 by mSOkHM6

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```									JOINING OF POWDER DETAILS BY
MEANS OF PULSED
ELECTROMAGNETIC FIELD

Victor Mironov, Irina Boyko
Riga Technical University, Riga, Latvia

Lappeenranta, Finland, 21-24 August, 2007
Contents

1. Introduction
2. Theoretical background
3. Pulsed electromagnetic field
4. Equipments
5. MIOM application in PM
6. MIOM for production of composite materials
7. MIOM assembling
8. Conclusion
Introduction

MIOM – Magnet-impulse metal machining (USA,
Germany)
DMC – Dynamic Magnetic Compaction (Russia, USA)
EMF – Electromagnetic forming (USA, Russia,
Germany)
PMW – Pulse Magnetic Welding (Germany, Russia)
MIPP – Magnetic Impulse Pressing of Powder
(Russia, Latvia)
Pulse technological processes and their
parameters
Kinds of pulse      Typical ratline             Pressure and Time
technological
pressure-time     Pm, MPa           ta, s         tk, s
processes
Types of
explosion:                             5∙104           1∙10-6       …1∙10-3
-contact                               1∙104           1∙10-6       …1∙10-3
- in water                             5∙103          500∙10-6      …5∙10-3
- unlimited

Electro-hydraulic                                                    100…
300           1…10∙10-6
effect                                                              200∙10-6

Electromagnetic
impulse (direct)                       100          20…50∙10-6      500∙10-6
Generation of pulse electromagnetic field

1 – transformer           5 – tube
2 – rectifier             6 – detail
3 – capacitor’s battery   7 - coil
4 – discharger
Theoretical background

The electromagnetic force in the coil is determined by following equation:

f v   j  H 
where j and H are the vectors of current density in the coil and
electromagnetic intensity; μ is the magnetic inductivity.
Impulse current
i  I me t sin t
where Im is the current amplitude; ω is the circular frequency of discharge current; t is
the time of current influence.
The electromagnetic field intensity on surface of conductor respectively is determined
as:                             H  H e t sin t
1       m

where Hm is the maximal value of intensity ; α is the attenuation coefficient.
The pressure of electromagnetic forces on the surface of billet with high electric
conductivity can be calculated as:
p  1 H 12
2
Testing and control

The electromagnetic field is induced in the gap between the coil and the plate at
the instant an electric discharge of the capacitors.

Scheme of compaction of a material in a rigid mold.
1 – impact plate; 2 – surge current generator; 3 – surge current generator;
4 – electromagnetic transducer; 5 – inductor with a winding;
6 – compacted material; 7 – mold.
Main parameter range of IEG
Equipment to the magnetic impulse compaction
MIK-500
MIU-40
W = 0,5 kJ
W = 40 kJ
U = 0,8 kV
Umax = 6 kV
1-60 imp/min
1-30 imp/min

MIU-6
W = 6 kJ
Umax = 6 kV         MIK-300
1-600 imp/min       W = 0,3 kJ
U = 0,8 kV
1-30 imp/min
Inductors for concentration
of the magnetic field

Spiral inductor
Inductor with the
concentrator and
water cooling

Flat inductor
MIC for powder coating

Pipe with an internal powder coating

D0 = 16 mm, D1 = 13 mm,
L = 80-300 mm.
Preform of a worm         Shell – copper, capillary - iron
wheel with an external
coating of Fe-C-Cu
Manufacture of complex-shaped components
by the magnetic pulse compaction method
There is proposed method of preparing the multilayer components of tool.
Working part consists of hard alloy (3) or steel (1), another of iron-copper alloy (2).
Dimensions of parts can be increased due to using step pressing. To rise the
density and the efficiency of the used forming envelope, it is expedient to use the
infiltration method.

1
3
2
2

Components consisting of several parts:
a) worm-wheel compact;
b) inserts of mold dies.

1 – wheel, 2 – Fe-C-Cu ring, 3 – WC-Co insert.
Magnetic pulse joining experintal research

1. Assembly diagram
3. Factors of the influence
Assembly diagram

Scheme of the built-up of powder           Scheme of the assembling of powder detail
detail: 1 – detail; 2 – rod; 3 – inductor;   by expansion on the inside: 1 – inductor; 2
4 – pulse current generator                    – powder detail; 3 – bush

Correlation between adhesive shearing strength depending on the energy level of the
capacitive storage device W, rod surface roughness Rz and gap between details δ.
MIOM device of discharge frequency 6 kHz. Energy levels: W=6 (1),W=8 (2), W=10
(3)
Concentration of impulse magnetic field

Concentrator      Changing of magnetic induction
Deformation of powder materials

before sintering

after sintering
and MIC

Changing of electromagnetic pressure on
thickness of the detail from powder
Deformation of sintered materials

1
1. Copper tube
2
D0 = 80 mm, δ0 = 2,0 mm
2. Preform from iron powder
apparent density – 2,45 g/cm3,
green density – 5,8 g/cm3
3. Iron powder after MIC
(green density – 7,2 g/cm3)

3
Assembly of details

One-piece connections of details from diverse materials
Cu-steel, Al-bronze, Cu-Al
MIOM application in powder metallurgy

Part with unidirectional steel fibers in copper   Macrostructure of fibers built-up onto
holder (d = 0.7 mm)                    the copper holder (D = 0,7 mm,
d = 15 mm)

Assembling of bronze filters in            Welds of the pipes (copper-steel,
copper case.                               copper-titanium)
Conclusions

1.   Magnetic pulse joining method makes it possible to extend the field of
application of powder metallurgy.

2.   Features of the method enable one to press powder layers on steel
compacts made by casting or forming.

3. Application of electromagnetic pulsed field in plastic deformation of
metallic materials and in powder metallurgy gives new possibilities
in producing of mechanical engineering and instrument-making
details.

4. MIOM method is more effective in assembling of details from
heterogeneous materials.

5. The optimal parameters must be determined in each MIOM process.

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