Influence of Magnetic Flux Controllers on Induction Heating Systems, Computer Simulation and Practice Robert T. Ruffini, President Fluxtrol Manufacturing, Inc. Auburn Hills, MI Dr. Valentin S. Nemkov, Chief Scientist; Robert C. Goldstein, Research Engineer Centre for Induction Technology, Inc. Auburn Hills, MI
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Influence of Magnetic Flux Controllers on Induction Heating Systems
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Influence of Magnetic Flux Controllers
on Induction Heating Systems, Computer
Simulation and Practice
Robert T. Ruffini, President
Fluxtrol Manufacturing, Inc. Auburn Hills, MI
Dr. Valentin S. Nemkov, Chief Scientist; Robert C. Goldstein, Research Engineer
Centre for Induction Technology, Inc. Auburn Hills, MI
Overview
• Magnetic Flux Control in Induction Heating
• Magnetic Flux Controller Application Technique
• Examples of Induction Coils with Magnetic Flux Controllers
• Conclusions
• Robot Guided Induction Heating Application
Technological Effects of MFC
Application
• Improved induction coil efficiency
• Better utilization of the workpiece power
• Magnetic field and heat pattern control
• Protection against unintended heating
• Improved power supplying circuitry
performance
• Elimination of external magnetic fields
Materials for Magnetic Flux
Control
• Laminations
• Ferrites
• Magnetodielectric
Materials (MDMs) 0
0.4
0.8
1.2
1.6
2
0 50 100 150 200 250Magnetic Field Strength
(A/cm)
Flu
x D
en
sity (
T)
MDM's
Laminations
Ferrites
B-H Curves for MFCs
Considerations for MFC
Selection • Relative magnetic permeability
• Operating frequency
• Core Losses
• Thermal resistance
• Ease of installation and removal
• Machinability
• Electrical resistivity
• Chemical resistance
• Cost
Typical properties of MDM’s
• Operating frequency: 50 Hz-5 MHz
• Temperature resistance: 150 - 350 C
• Initial relative permeability: 10 - 65
• Maximum permeability: 10 - 150
• Saturation flux density: 0.3 - 1.6 T
• Electrical resistivity: 100-10^7 Ohm-cm
Magnetic Permeability of
MDM’s for Induction Heating
0
25
50
75
100
125
150
0 50 100 150 200
Magnetic Field Strength
(A/cm)
Perm
eability Fluxtrol A
Fluxtrol A'
Fluxtrol B
Ferrotron
How to Apply MDM’s to Induction
Heating Coils
• Epoxy/Glue/Adhesive MFC to Copper Coil
– Prepare copper surface by removing machining oil or residual
quenchant
– Use thermally conductive, electrically non conductive epoxy
– Use epoxy with high temperature and thermal shock resistance
• Mechanically Fasten
– Soft solder or braze a brass bolt to copper inductor and drill clearance
hole in MFC
– Use a thermally conductive grease between copper coil and MFC
• Soft Solder (Fluxtrol A)
Camshaft Lobe Sintering Power
InductorTM
Clutch Plate Hardening Power
InductorTM
Camshaft Hardening Power
InductorTM
I.D. Hardening Power InductorTM
Conclusions
• Magnetic Flux Controllers Are an Important
Part of the Induction Technique
• Examples of Induction Heating Coils with
MDM controllers applied were shown
• Computer Simulation Can Accurately
Predict the Performance of Magnetic Flux
Controllers
Robot Guided Induction Scanning
Application Demonstrates:
1. The ability to treat complex shape parts with induction
robotic technique
2. Modern induction equipment suitable for robotic
scanning
3. Ability of computer simulation to predict the results of
heating
4. Demonstration of the magnitude of magnetic flux