Induction Heating Metal
What is induction heating?
Induction heating is an accurate, fast, repeatable, efficient, non-contact technique for heating metals or any other conductive material.
Induction heating is used very effectively in many processes such as brazing, soldering and heat shrink fitting. From the smallest hypodermic needle to the big wheels on a tank. Many companies in the automotive, medical device and aerospace industries utilize induction heating efficiently in their processes.
How does it work?
Induction heating is a precise, repeatable, non-contact method of heating electrically conductive materials such as brass, aluminum, copper or steel or semiconducting materials such as silicon carbide.
What's in an induction heating system?
Our induction heaters convert AC line power to higher frequency AC power, which is transmitted via specially designed cables to a workhead containing a set of capacitors and custom-designed work coils. This combination utilizes the principle of resonance to create an electromagnetic field within the coils to efficiently transfer energy to the workpiece.
Placing the workpiece in this electromagnetic field induces eddy currents in the workpiece. The friction created by these currents produces precise, clean, non-contact heating. A water cooling system is typically required to cool the work coil and the induction heating system.
What is the operating frequency?
The operating or resonant frequency of an induction system is the point at which energy is most efficiently transmitted.
The operating frequency is determined by the capacitance of the energy storage circuit, the inductance of the induction coil and the material properties of the workpiece.
In general, the larger the workpiece, the lower the frequency, and the smaller the workpiece, the higher the frequency.
Induction heating of magnetic materials?
If your workpiece material is magnetic, such as carbon steel, it can be easily heated by the two heating methods of induction (eddy current heating and hysteresis heating). Hysteresis heating is very effective at Curie temperatures (1100°F (600°C) for steel) when the permeability is reduced to 1 and eddy currents are left to heat.
What is heat penetration depth?
This is the depth at which the workpiece is heated by induction.
The induced current in the part will flow at the surface and 80% of the heat generated in the part is generated in the outer layer (skin effect). Higher operating frequencies have a shallower skin depth, while lower operating frequencies have a thicker skin depth and greater penetration depth.
How important is coupling efficiency?
The relationship between the current flowing in the workpiece and the distance between the workpiece and the induction coil is key; the closer the coil, the higher the current in the workpiece.
However, the distance between the coil and the workpiece must first be optimized for the desired heating and the actual workpiece handling. Many factors in the induction heating system can be adjusted to match the coil and optimize coupling efficiency.
Is coil design important in an induction heating system?
Induction heating efficiency is maximized if your workpiece can be placed inside the induction coil. If your process does not allow the workpiece to be placed inside the coil, the coil can be placed inside the workpiece.
The size and shape of the water-cooled copper induction heating coil will follow the shape of the workpiece and will be designed to apply heat to the workpiece in the correct location.
The power required to heat the workpiece depends:
The quality of the workpiece
The material properties of the workpiece
The temperature rise you need
The heating time required to meet your process requirements
The effectiveness of the magnetic field due to the coil design
Any heat loss during the heating process