What Is Induction Heating?

Induction heating is a precise, repeatable, non-contact method for heating electrically-conductive materials like brass, aluminum, copper or steel or semiconducting materials like silicon carbide.

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Solving Your Process Heating Problems

How does induction heating work?

An induction heating system includes a special power supply which converts line power to a high frequency alternating current. This energy is delivered over a cable assembly to a workhead - or tank circuit - which creates an electromagnetic field within the attached coil. A work piece is placed in the coil, inducing a current, friction and heat in it. 

Induction heating is used very effectively in many processes like brazing, soldering and shrink fitting, from something as small as a hypodermic needle to a large wheel on a military tank. Many companies in the automotive industry, medical device industry and aeronautics make efficient use of induction heating in their processes. 

More about how it works:

Does Induction Heat Magnetic Materials?

If your work piece material is magnetic, such as carbon steel, it will be heated easily by induction’s two heating methods, eddy current and hysteretic heating. Hysteretic heating is very efficient up to the Curie temperature (for steel 600°C (°F)) when the magnetic permeability reduces to 1 and the eddy current is left to do the heating.

How Important Is Coupling Efficiency?

The relationship of the current flow in the work piece and the distance between the work piece and the induction coil is key; the closer the coil, the more current in the work piece.

But the distance between the coil and the work piece must first be optimized for the heating required and for practical work piece handling. Many factors in the induction heating system can be adjusted to match to the coil and optimize the coupling efficiency.

Heat losses and uneven, inconsistent application of heat result in increased scrap and diminished product quality, driving up per-unit costs and consuming profits. Best manufacturing economies are seen when the application of energy is controlled.

To bring a batch oven up to temperature and to hold the entire chamber at the required temperature for the process time demands much more energy than is required to process the parts. Flame-driven processes are inherently inefficient, losing heat to the surroundings. Electrical resistance heating can also result in the wasteful heating of surrounding materials. Applying only the energy needed to process your parts is ideal.

Induction selectively focuses energy only on the area of the part that you want to heat. Each part in a process enjoys the same efficient application of energy. Since the energy is transferred directly from the coil to a part, there is no intervening media like flame or air to skew the process.

For more information, please visit Custom Induction Heating Equipment.

Further reading:
2nd Gen buyer's guide - Tacoma World
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The precision and repeatability of induction heating help to reduce process scrap rate and to improve throughput. The selective application of heat to the targeted area of a part enables very tight control of the heating process, also cutting the heating time and limiting energy requirements.

Read: Induction Heating is a Green Technology

Delivering the highest quality parts for the least expense in the least time is accomplished with an efficient process, in which the input elements of materials and energy are tightly and precisely controlled. Induction heating’s targeted application of heat to the part or an area of the part, as well as repeatability, provides the most uniform results for the least cost. Repeatability and throughput are two things that can be greatly improved with induction compared to resistance or flame heating.

Induction heating delivers savings primarily from significant reductions in process scrap rates, improved throughput and from the thrifty use of energy. There is no need for process ramp-up; heat is applied and stopped instantly. In comparison, batch heating in an oven requires an investment of time and energy that serves only the process, not the product. Throughput and efficiency are increased by induction heating with the careful application of energy (heat) in amounts no more than required by the product.

Any heating process carries a risk of operator contact with the heated materials. A technology like induction heating that limits the extent of operator-contacted surfaces does reduce the overall risk. If heating can be limited to only the part and further limited to a zone of the part, safety is improved even more.

What is induction heating?

The heating method known as induction heating occurs when an electrically conductive material is placed in a varying magnetic field. Induction heating is a rapid form of heating in which a current is induced directly into the part being heated. Induction heating is a non-contact form of heating.

What makes up a typical induction heating system?

A typical induction heating system consists of the induction heating power supply, an induction heating coil, and a water-cooling source, which cools the coil and several internal components inside the power supply. The induction heating power supply sends alternating current through the induction coil, thus generating a magnetic field. When a work piece is placed within the coil and enters the magnetic field, eddy currents are induced within the workpiece, generating precise and localized heat without any physical contact between the induction coil and the work piece.

What is an induction heating coil (inductor)?

The varying magnetic field required for induction heating is developed in the induction heating coil via the flow of AC (alternating current) in the coil. The coil can be made in many shapes and sizes to custom fit a specific application. The coils can range from tiny coils made of copper tubing used for precise heating of extremely small parts in applications such as soldering and ferrule heating to large coil assemblies of copper tubing used in applications such as strip metal heating and pipe heating.

What is the importance of the induction heating coil (inductor)?

The induction coil design is one of the most important aspects of an induction heating system. The coil is a custom design to give your work piece or part the proper heating pattern, maximize efficiency of the induction heating power supply’s load matching system, and to accomplish these tasks while still permitting ease of loading and unloading your part.

How can my process benefit from induction heating?

Induction heating can benefit your process in a number of ways. Induction heating is highly repetitive once initial adjustments are made to the power supply. Following this phase, part after part can be heated with identical results so long as the parts are introduced to the coil similarly each cycle. This can also lead to better material utilization and product yield. Induction heating can reduce or eliminate the need for skilled operators in application such as brazing and soldering. The ability of induction heating to heat all parts identically lends itself to automation of the process. Induction heating can also heat the part in a highly localized fashion, which can be extremely beneficial when it is desirable or necessary to limit the heat to only a certain region of the part.

How does induction heating equipment compare to other heating sources?

In addition to some of the points mentioned in the previous FAQ, induction heating is also a clean form of heating which does not emit unpleasant odor or heat. Because the current is induced directly into the part being heated, there is no radiant heating effect into a facilities ambient environment. The location of the desired heat zone can be defined to a specific area on a workpiece in order to achieve accurate and consistent results. Induction heating equipment is instantly on which means it requires no warm-up time as other conventional heating sources do. Induction heating systems are extremely energy efficient.

What is the importance of a power supplies power rating and frequency?

The power rating determines the speed at which a workpiece can be heated. The frequency, along with the electrical resistivity of the workpiece and relative magnetic permeability, determines the skin depth of the eddy currents induced into the work piece. In surface heating, the power rating also plays an important role in skin depth. The higher the frequency, the more shallow the skin depth and the lower the frequency, the deeper the skin depth. Therefore, higher frequencies are more effective for heating smaller parts or parts that require shallow heat penetration, while lower frequencies are more effective for larger materials with deeper heat penetration requirements.

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