http://fluxtrol.com Influence of Magnetic Flux Controllers on Induction Heating Systems

1. 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

2. 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

3. 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

4. Materials for Magnetic Flux
Control
• Laminations
2
Laminations
1.6
MDM's
• Ferrites 1.2
Flux Density (T)
0.8
• Magnetodielectric 0.4
Ferrites
Materials (MDMs)
0
0 50 100 150 200 250
Magnetic Field Strength
(A/cm)
B-H Curves for MFCs

5. Considerations for MFC
Selection
• Relative magnetic permeability
• Operating frequency
• Core Losses
• Thermal resistance
• Ease of installation and removal
• Machinability
• Electrical resistivity
• Chemical resistance
• Cost

6. 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

7. Magnetic Permeability of
MDM’s for Induction Heating
150
125
100
Fluxtrol A
Permeability
75
50
Fluxtrol A'
25 Fluxtrol B
Ferrotron
0
0 50 100 150 200
Magnetic Field Strength
(A/cm)

8. 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)

9. Camshaft Lobe Sintering Power
InductorTM

10. Clutch Plate Hardening Power
InductorTM

11. Camshaft Hardening Power
InductorTM

12. I.D. Hardening Power Inductor TM

13. 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

14. 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
controller influence

15. Demonstration Stand
1. Workpiece - S-shaped 1/2” thick steel plate water-
cooled on the back side
2. Specially designed hair-pin coil with Fluxtrol A
magnetic flux controller applied
3. ABB industrial robot
4. Hand-hold coaxial transformer with a flexible cable
(EFD)
5. EFD power supply Minac: 30 kW, 10 - 25 kHz
6. Close loop cooling system (Dry Coolers, Inc.)

16. Induction Coil Comparison
Coil without a concentrator Coil with Fluxtrol A
concentrator

17. Induction Coil with Magnetic
Flux Controller

18. Computer Simulation for
Process Design

19. Computer Simulation for
Process Design

20. Computer Simulation for
Process Design

21. Robot Guided Induction Scanning
Conclusions
• Magnetic Flux Controllers Make a Dramatic
Effect on Hair-Pin Coil Performance
• Computer Simulation Allows the Designer
Accurately Predict the System Parameters and
Heating Results
• Robotic Scanning Systems Can Be Used
Effectively in Flexible Production Line