1. What is Induction heating?
It is a method electrical heating of metallic objects by inducing currents in it, without any physical contact, using alternating electromagnetic fields.
Induced eddy currents circulating through the resistance of the metallic objects, leads to joule heating from within.
2. What makes Induction heating method very special?
3. What are the scopes of application of Induction Heating?
- • Non–contact transfer of large amounts of energy
- • Generation of heat from within conductive materials
- • Rapid rise of temperature
- • Ability to attain very high temperatures
- • Ability to apply heat to confined zone of parts
- • Relatively high efficiency
- • Suitable for integration with modern production lines
- • Very clean and safe
- • No environmental pollution
Scope of application of Induction Heating is unlimited. Many conventional heating methods are being replaced by Induction Heating.
Developments in high frequency power generation and Fall in costs lead to discovery of newer and more effective applications.
Application of IH for Rust/ Paint Removal, Resin drying, Adhesive bonding, Cooking, Steam generation, Fluid heating etc are few of the popular developments in the recent times.
4. What are the different parts of an Induction Heating system?
Power Generator – It is provide the high frequency alternating currents needed for energy transfer. Mains power available at 50/60 hz is converted into high frequency alternating currents. Typical power and frequency ratings of these units range from 3KW 400 khz to 100KW 10 khz for most surface hardening applications. For mass heating and melting applications lower frequency power supplies of ratings ranging from 200kw to 10 MW and more are available.
Heat Station – Many Induction Heating systems are supplied with separate assembly of capacitors and / or load matching transformers which step-up or Step-down the voltages and currents generated by the Power generator to levels as required by the Induction coil.
Induction Coil – This is the final link in the chain that transfer power generated in the Power supplies, thru heat station if any, into the object being heated. It varies From simple single/multi turn circular coils to varied and complex coils to suit the contours of heated zone of different parts.
Cooling Water Sytems – consists one or pumps for circulating cooling water required for cooling the Induction Coil, Load matching transformers, and other Parts that carry large currents.
5. Why most Induction Heaters require cooling water systems?
Since relatively huge amount of power is transferred to a very limited surface Area of parts, Induction Coils and all the elements that carry currents through it are heated up to unacceptable temperatures which require additional cooling to enable continuous operation of IH system.
6. How do you select the frequency rating of the Power Supply?
High frequency currents induced by electromagnetic induction tends to flow only on the surface of the object – confining themselves to shallow depths only.
Higher the frequency of the induced currents, shallower the depth of the penetration. As an example effective heating takes place in ferrous parts to a depth of 3mm with 10 khz currents, Whereas it is restricted to about One mm with 100 khz currents and thus lower current penetration depths needed in smaller parts may requires even higher frequencies , say up to 450 khz.
Since higher frequency currents also result in better coupling or transmission of heating power from Induction coil to the part, for most general purpose heating applications 100 khz Power supplies are being used.
In contrast to the above, Mass heating and melting requires very low frequency currents to extend the Depth of effective heat generation to almost entire cross section of the parts.