MYD Proheat300

The basic of induction heating principle have been understood and applied to manufacturing since the 1920s. During World War II, the technology developed rapidly to meet urgent wartime requirements for a fast, reliable process to harden metal engine parts. More recently, the focus on lean manufacturing techniques and emphasis on improved quality control have led to a rediscovery of induction technology, along with the development of precisely controlled, all solid state induction heating power supplies.

Induction heating takes place in an electrically conducting object (not necessarily magnetic steel) when the object is placed in a varying magnetic field. Induction heating is due to the hysteresis and eddy-current losses.

Hysteresis losses only occur in magnetic materials such as steel, nickel, and very few others. Hysteresis loss states that this is caused by friction between molecules when the material is magnetized first in one direction, and then in the other. The molecules may be regarded as small magnets which turn around with each reversal of direction of the magnetic field. Work (energy) is required to turn them around. The energy converts into heat. The rate of expenditure of energy (power) increases with an increased rate of reversal (frequency).

Eddy-current losses occur in any conducting material in a varying magnetic field. This causes heading, even if the materials do not have any of the magnetic properties usually associated with iron and steel. Examples are copper, brass, aluminum, zirconium, nonmagnetic stainless steel, and uranium. Eddy currents are electric currents inducted by transformer action in the material. As their name implies, they appear to flow around in swirls on eddies within a solid mass of material. Eddy-current losses are much more important than hysteresis losses in induction heating. Note that induction heating is applied to nonmagnetic materials, where no hysteresis losses occur.

For the heating of steel for hardening, forging, melting, or any other purposes which require a temperature above Curie temperature, we cannot depend upon hysteresis. Steel loses its magnetic properties above this temperature. When steel is heated below the Curie point, the contribution of hysteresis is usually so small that it can be ignored. For all practical purposes, the I2R of the eddy currents is the only way in which electrical energy can be turned into heat for induction heating purposes.

Two basic things for induction heating to occur:

A changing magnetic field

An electrically conductive material placed into the magnetic field

What is advantages of induction heating,brazing,hardening,melting and forging,etc?

Why choose induction heating over open flame,convection,radiant or another heating method?Here’s a short summary of the major advantages that modern solid state induction heating offers for lean manufacturing:

*Heating Fast

Induction heating is induced within the part itself by alternating electrical current. As a result, product warpage, distortion and reject rates are minimized. For maximum product quality, the part can be isolated in an enclosed chamber with a vacuum, inert or reducing atmosphere to eliminate the effects of oxidation. Production rates can be maximized because induction works so quickly; heat is developed directly and instantly (>2000º F. in < 1 second) inside the part. Startup is virtually instantaneous; no warm up or cool down cycle is required. The induction heating process can be completed on the manufacturing floor, next to the cold or hot forming machine, instead of sending batches of parts to a remote furnace area or subcontractor. For example, a brazing or soldering process which previously required a time-consuming, off-line batch heating approach can now be replaced with a continuous, one-piece flow manufacturing system.

*Heating Consistent

Induction heating eliminates the inconsistencies and quality issues associated

with open flame, torch heating and other methods. Once the system is properly calibrated and set up, there is no guess work or variation; the heating pattern is repeatable and consistent. With modern solid state systems, precise temperature control provides uniform results; power can be instantly turned on or shut off. With closed loop temperature control, advanced induction heating systems have the capability to measure the temperature of each individual part. Specific ramp up, hold and ramp down rates can be established & data can be recorded for each part that is run.

*Heating Clean

Induction heating systems do not burn traditional fossil fuels; induction is a clean, non-polluting process which will help protect the environment. An induction system improves working conditions for your employees by eliminating smoke, waste heat, noxious emissions and loud noise. Heating is safe and efficient with no open flame to endanger the operator or obscure the process. Non-conductive materials are not affected and can be located in close proximity to the heating zone without damage.

*Save Energy

Tired of increasing utility bills? This uniquely energy-efficient process converts up to 90% of the energy expended energy into useful heat; batch furnaces are generally only 45% energy-efficient. And since induction requires no warm-up or cool-down cycle, stand-by heat losses are reduced to a bare minimum. The repeatability and consistency of the induction process make it highly compatible with energy-efficient automated systems.