Induction Heating Guide

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What is Induction Heating ?
Eddy currents internally produced on the work piece by an
alternating magnetic field, causes the heating effect.
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Behind the Mystery !
u
Proximity Effect
u
Skin Depth
u
Curie
u
Martensite
u
Transformation
u
dΦ
e = −N
dt
u
u
Energy Density
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Power Density
3
Magnetic Field Theory
CONDUCTOR
CURRENT
MAGNETIC
FIELD
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Electromagnetic Induction Theory
Eddy currents internally produced on the workpiece by an
alternating magnetic field, causes the heating effect.
CURRENT
MAGNETIC FIELD
X
X
X
X
X
X
X
X
INDUCTOR
WORKPIECE
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X
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Faraday’s Law
Induction refers to the electromagnetic
phenomenon discovered by Michael Faraday.
dΦ
e = −N
dt
e = Voltage
N = Number of Turns
Φ = Magnetic Field [webers]
dΦ Rate of change of
=Magnetic Field
dt
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Skin Depth
Effect of frequency on current penetration.
HIGH FREQUENCY
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LOW FREQUENCY
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Reference Depth
ρ
d = 3160
µf
d =5030
µ =1
ρ=
f =
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ρ
( English units [in] )
( Metric units [cm] )
µf
Above Curie for non-magnetic materials
Electrical Resistivity
Frequency ( Hz)
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Efficiency versus Frequency
δ = Reference Depth
Diameter Fixed
EFFICIENCY
Diameter / δ = 4
FREQUENCY
LOW FREQUENCY
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High frequency is
more efficient,but
requires longer
heat time for
conduction to
center
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Permeability
A measure of how magnetic a material is.
It is the unit less measure of flux density in the
material divided by what the density would have
been in air.
µ
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[ Unit less ]
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Induction Hardening
Q
U
E
N
C
H
I
N
G
H
E
A
T
I
N
G
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Advantages of Induction Heating
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Rapid Heating
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High Power Densities
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Accurate Location of the Heated Area
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Accurate Time and Temperature Control
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Clean Operating Conditions
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Minimal Stand-by Power
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Easily Adapts to Automation
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Considerations for New Equipment
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Material
u
Power Required
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Hardness Desired
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Output Voltage
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Pattern Desired
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Part Rotation
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Production Rate
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Efficiency
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Means of Locating
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Quality Control
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Quench Media
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Power Factor
u
Frequency
u
Utility Requirements
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Inductor Configuration
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The Overall Process
Inductor
u Quench Barrel
u Part
u Locator
u
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What is an Inductor ?
u
INDUCTOR EXAMPLE
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Example of a Two Turn Inductor
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Use of Flux Concentrators
WORKPIECE
INDUCTOR
FLUX CONCENTRATOR
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Example of Flux Concentrator
FLUX CONCENTRATOR
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Difficult Heat Treating Pattern
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Bell
Inductor Design
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Difficult Heat Treating Pattern
u
Bell
Actual Pattern
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Typical Applications For Induction Heating
- Billet heating
- Extruding
- Soldering, Brazing
- Heat treatment, including case hardening,
tempering and annealing
- Shrink fitting
- Strip heating
- Tube and Wire heating
- Continuous annealing
- Epitaxial growth (crystal growing)
- Forging
- Stress relieving
- Plasma applications
- Cap sealing
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So What Next?
Now you are hopefully more aware of induction heating, the
only thing left for you to do is to contact one of our sales
team.
Pick up the phone and call Inductoheat Banyard on 01202
627800 or email induction@inductoheat.co.uk
Alternatively, fill out the project specification enquiry form or
request a brochure from our website.
You can be sure of a fast response with one of our sales
team happy to help you in answering any further questions,
or offering any advice regarding induction heating.
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