how induction heating work | Manufacturer of induction heating machine ,ultrasonic welding machine

How Induction Heating works?

Induction Heating is a flame-free, no-contact heating method that can turn a precisely defined section of a metal bar cherry red in seconds. How is this possible?

How Induction Heating works?

Alternating current flowing through an induction coil generates a magnetic field. The strength of the field varies in relation to the strength of the current passing through the coil. The field is concentrated in the area enclosed by the coil; while its magnitude depends on the strength of the current and the number of turns in the coil. (Fig. 1) Eddy currents are induced in any electrically conductive object—a metal bar, for example—placed inside the induction coil. The phenomenon of resistance generates heat in the area where the eddy currents are flowing. Increasing the strength of the magnetic field increases the heating effect. However, the total heating effect is also influenced by the magnetic properties of the object and the distance between it and the coil. (Fig. 2) The eddy currents create their own magnetic field that opposes the original field produced by the coil. This opposition prevents the original field from immediately penetrating to the center of the object enclosed by the coil. The eddy currents are most active close to the surface of the object being heated, but weaken considerably in strength towards the center. (Fig. 3) The distance from the surface of the heated object to the depth where current density drops to 37% is the penetration depth. This depth increases in correlation to decreases in frequency. It is therefore essential to select the correct frequency in order to achieve the desired penetration depth.

What Is Induction Heating?

What Is Induction Heating?

Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, where eddy currents (also called Foucault currents) are generated within the metal and resistance leads to Joule heating of the metal.Induction heating is a form of non-contact heating,when alternating current flows in the induced coil, varying electromagnetic field is set up around the coil, circulating current(induced, current, eddy current) is generated in the workpiece(conductive material), heat is produced as the eddy current flows against the resitivity of the material.The basic principles of induction heating 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 power supplies.

induction_heating_principle
induction_heating_principle

How Induction Heating Work?

An induction heater (for any process) consists of an induction coil (or electromagnet), through which a high-frequency alternating current (AC) is passed. Heat may also be generated by magnetic hysteresis losses in materials that have significant relative permeability. The frequency of AC used depends on the object size, material type, coupling (between the work coil and the object to be heated) and the penetration depth.High Frequency Induction heating is a process which is used to bond, harden or soften metals or other conductive materials. For many modern manufacturing processes, induction heating offers an attractive combination of speed, consistency and control.

What’s Induction Heating Applications

Induction heating is a rapid ,clean, non-polluting heating form which can be used to heat metals or change the conductive material’s properties. The coil itself does not get hot and the heating effect is under controlled. The solid state transistor technology has made induction heating much easier,cost-effective heating for applications including soldering andinduction brazing ,induction heat treating, induction melting,induction forging etc.