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http://fluxtrol.com Composite Materials for Magnetic Field Control in EPM
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Composite Materials for Magnetic Field Control in EM Processing of Materials
V. Nemkov, R. Ruffini (Fluxtrol Inc., USA) A. Kolesnichenko (Net Shape Cast, USA)
Effects of Magnetic Flux Controllers
• Field Pattern Control
• Better Power Utilization in the Part (mainly in heating processes)
• Coil Efficiency Improvement
• Coil Power Factor Improvement
• Reduced Coil Current Demand
• Loss Reduction in Power Supplying Circuitry
• Shielding
Effect of magnetic flux concentrator
made of Fluxtrol A
Materials for Magnetic Flux Control
Available materials belong to three major groups:
• Soft Magnetic Composites (SMC) or Magnetodielectrics (MD)
• Laminations
• Ferrites
Fluxtrol Inc. produces 3 primary MD materials:
• Fluxtrol A
• Fluxtrol 50
• Ferrotron 559 H
Primary Fluxtrol Products
Note: frequency ranges and resistivity values are only for reference
Magnetic Properties of Fluxtrol Products
Compared to laminations and
ferrites, Fluxtrol materials are
almost linear.
Fluxtrol A material can support
permeability above 50 at high
magnetic loading (flux density
up to 14000 Gs), which is
important for high power and
low frequency applications.
Relatively low permeability of
MDM compared to laminations
does not influence their
performance in non-closed
magnetic circuits.
Flux Density vs Magnetic Field Strength
0
2000
4000
6000
8000
10000
12000
14000
0 50 100 150 200
Field Strength, A/cm
Flu
x D
en
sit
y, G
s
Fluxtrol A
Fluxtrol 50
Ferrotron 559 H
Permeability vs Flux Density
0
25
50
75
100
125
0 3000 6000 9000 12000
Flux Density, Gs
Perm
eab
ilit
y
Ferrotron 559
Fluxtrol 50
Fluxtrol A
Comparison of Laminations
and MDM Properties Characteristics Laminations Ferrotron/Fluxtrol
Frequency, kHz up to 20 kHz Any
Effective saturation, T 1.5 – 1.6 1.2 – 1.5
Initial permeability Above 1000 18 - 63
Max permeability Around 5000 20 - 120
Permeability grades No 4 grades
Anisotropy Very strong Low to Middle
Temperature resistance, C Probably 300 – 400 C Long – 250 C
Performance in 3D field Very bad Good
Complex geometry Difficult Easy
Installation Laborious Easy
Cooling Difficult Easy – many methods
In-field adjustment Difficult Easy
Use as construction part Problematic Good
Fluxtrol Material Blocks for Large Installations
Fluxtrol MDM for magnetic flux concentration and shielding. Self-gluing film
insulation may be applied to the blocks if required. Largest plates at present
time are 6” x 8.5” x 2”
Copper Tubes with Matching Netshape
LRM Concentrators
Advantages:
1. More effective copper
and Fluxtrol cooling
2. Higher mechanical
strength
3. Minimized
manufacturing costs
4. Possibility to work
effectively in 3D
magnetic fields
Selected Material Processing Technologies
Technology Frequency
range,
Power
range, kW
Magnetic core material
Existing Proposed
Induction melting 50 -10000 Hz 50 -10000 Air or Lams Lams + MDM in
3D area
Cold-crucible melting of
metals 500 – 5000 Hz 50 - 2000 Air MDM shunts
EM pouring control 50 – 150 kHz 25 – 100 Ferrite MDM
Vacuum or controlled
atmosphere furnaces 50-3000 100 -10000 No or lams
MDM or MDM +
Lams
Liquid coating wiping 100-200 kHz 25-50 Lams or air MDM
Semi-levitation and
levitation 50 – 10000 Hz 50 - 500 Air MDM
Pulse treatment in
casting 1-2 Hz 100 - 200 Lams Lams + MDM
EFG Crystal growth 10-30 kHz 10 - 30 Ferrite or
MDM MDM
Monocrystal growth 10-500 kHz 10 - 30 Air MDM
Magnetic Control in
Cold Crucible Melting Furnace
With No controller With Fluxtrol controller
Advantages:
• Improvement of coil efficiency and power factor
• Reduction of losses in the furnace chamber and other
components
• Possibility to use smaller chamber
Melting Inductor for Glove Box Environment
Example of shielding effect and
efficiency improvement
Fluxtrol A shields on the side and
bottom coil surfaces allowed to:
•Strongly reduce losses in the
chamber walls and bottom plate
•Increase the furnace volume in
the same chamber
•Increase coil efficiency from 23 to
63% due to reduced losses in
chamber walls, bottom plate and
in the coil
Fluxtrol
plates
Induction coil for melting of radioactive
materials in protective atmosphere
Magnetic field lines and color map of
power density in a shielded coil
Glove Box walls
Fluxtrol plates
Molten metal
Shielding in Furnaces with Special Atmosphere
Due to the magnetic field
shielding it is possible:
• reduce the furnace size
or
increase the furnace
loading
• improve efficiency and
power factor of the
inductors, especially for
the bottom ones
• Fluxtrol Inc. has very good
experience in such designs
Possible Combinations of Lams and MDM
3D area
Use of MDM in combination with
laminations in 3D areas of shunts MDM inserts in magnetic core for gradient
field formation in pulse magnetic device for
steel stirring in continuous slab casting
Due to machinability, ability to work in 3D areas and serve as structural
components, MDM may be effectively used in combination with laminations
Magnetic “Wiper” Concept
Electrodynamic forces created by magnetic field help to “blow out” excess of
coating material (Zn or other) from the surface of wire (left) or strip (right).
Required frequency is usually high (up to 200 kHz) and MDM material is the
only choice for magnetic material
Recommended