Induction Heating: An Amazing Twist of Technology

What Is Induction Heating?

Induction heating relies on the existence of eddy currents discovered by Léon Foucault in . Briefly, when a changing magnetic field passes through any conductive object, current flow is induced in the object. That current flow creates a secondary electric field in the conductor. The secondary electric field, in turn, produces another flow of current which is known as the eddy current, so named because it flows in a circular pattern, much like water can swirl in a slow-moving stream when it encounters an obstacle. The push-pull between these fields&#;literally, the kinetic energy caused by electrons being shuttled back and forth&#;produces heat in the conductor.

For more information, please visit our website.

This use of eddy currents can not only cook a meal; it can melt steel and other metals.

Induction Heating Applications

Induction heating is used to manufacture end items as diverse as bulldozers, spacecraft, faucets and sealing plastic lids on pharmaceutical bottles. The fundamental design of an induction heating device uses a coil of wire and an AC current to induce a changing magnetic field in the item to be heated&#;the work piece. The coil can measure only a few centimeters in diameter, or any other dimension suited to the job at hand.

The work piece is placed inside the magnetic field generated by the coil, but not in contact with it, then heated to the desired level by the eddy currents. Depending upon the material being heated, temperatures as high as 2,200° F (1,200° C) can be achieved.

Induction heating is clean, requiring no fossil fuels. Parts exposed to induction heating simply heat up, so there&#;s no cleanup afterward and no worry about contamination of the work piece. It&#;s also fast. For example, manufacturers of pipes and tubular channels use induction heating to weld a seam along the longitudinal dimension of pipes passing by at high speed on a conveyor.

A few other processes that use induction heating include: 

• Induction hardening and tempering, which alters the physical characteristics of materials to meet the needs of various applications.
• Induction melting can be used to melt any ferrous or non-ferrous metal, including nuclear material and various alloys used in medicine and dentistry.
• Metal and carbon fiber materials can be bonded together by heating them, thereby curing adhesives placed between two surfaces.
• Soldering, brazing and welding are all natural applications for induction heating where precise temperature control and accurately confining heat to the desired area is important.

Induction Heating Solves Real Problems

The so-called Tylenol Murders took place in Chicago during when someone, never identified, laced Tylenol bottles with cyanide. The subsequent events led to a nationwide recall of Tylenol products. The poisoning also forced the entire over-the-counter pharmaceutical industry to package their products in tamper-proof containers.

The aluminum foil that&#;s commonly used to seal OTC drugs is part of the industry&#;s solution, and it uses induction heating. The process begins by placing the foil, which is electrically conductive, into the cap. The cap is screwed down, then the entire package is placed inside an induction heating coil. As the foil heats up, adhesives around its edge adhere it to the lip of the bottle.

Designers of induction cap sealing equipment must take several factors into account. The induction heater&#;s physical dimensions need to be tailored to the containers to be sealed. The electromagnetic field needs a depth suitable for heating the foil. The heating should take place as quickly as possible for productivity reasons. The efficiency of the induction heater needs to achieve a specific performance level.

These and other design constraints can be reduced dramatically when the wire used to make the coil is custom-manufactured. New England Wire Technology, a long-time supplier to the induction heating market, provides wire specially made to solve such design problems.

For instance, NEWT can supply round, square and rectangular conductors. Their exact size can be tailored specifically for the AC current and frequency to be used. And, because the efficiency can be optimized in the wire itself, the induction cap sealer design engineer has much greater flexibility in choosing the spacing, shape and size of the sealing head. In fact, that same flexibility benefits designers of any induction heating device.

The Case for Litz Wire

Induction heaters can run on AC power ranging from a few Hertz to 500 kHz and higher. The frequency chosen determines the heat&#;s penetration depth, with lower frequencies penetrating deeper. Frequencies for induction heaters are chosen at design time according to the particular work to be accomplished. For instance, an application that calls for hardening and a deep penetration uses low frequency. Another application that calls only for surface heating would use high frequency.

Higher frequencies passing through a wire cause the skin effect where much of the current flow travels along the outside of the wire, increasing its AC resistance and creating unwanted heat. Using NEWT&#;s unique Litz wire to build the coil virtually eliminates the skin effect, making the coil more efficient and allowing for more modest, lower cost power supply designs. (Read more about Litz wire).

Still, Challenges Do Arise

Because induction heating is used in so many applications, converting a customer&#;s design needs into a suitable Litz wire product involves many factors. According to NEWT engineers, &#;Almost every induction heating project takes on aspects of a custom job. While building wire and cable to customer specs seems simple, the number of variables that go into a solid design can be numerous.&#;

Suggested reading:
Compare Costco VHS to DVD to Walmart DVD
How many types of hose fittings are there?
Ultimate Buying Guides

If you are looking for more details, kindly visit Duolin.

For instance, the wire size can be adjusted for the AC frequency to avoid skin effect and other losses in the coil. Then, the total number of conductors in the Litz wire can be chosen to accommodate the maximum current flow. Conductors that make up the Litz wire are insulated using a film that needs to accommodate certain temperatures. Case in point: an induction coil used to heat a large vat of steel has to work in a much hotter environment than one used to seal aspirin bottles. Likewise, the outer insulation needs to protect the high voltages often used, as well as environmental conditions.

Custom Design Services to the Rescue

The solution to these challenges lies in NEWT&#;s custom design service staff. That team, consisting of a knowledgeable sales staff supported by design and manufacturing engineers, has helped customers worldwide achieve the best solutions. Be sure to contact us to discuss your next induction heating project.

    Induction heating is the process of heating conductors, (usually metals), by inducing an electric current to flow in the object to be heated. Current is induced into the object in the same manner that current is induced into the secondary of a transformer.

   In induction heating, a coil of copper is wound around an object to be heated. The coil of copper can be compared to the transformer primary, and the object to be heated can be compared to the secondary of the transformer.

   The object to be heated acts like a single turn secondary in a transformer. Additionally, the object acts as if the single turn secondary were short circuited.

   An alternating current is applied to the primary of a transformer, which creates an alternating magnetic field. The secondary of the transformer is located within the magnetic field. Faraday's Law shows that an electric current will be induced into the secondary of the transformer.

   Thus, applying an alternating current to the induction coil induces a current into the object to be heated. Imagine how a short circuit secondary on a transformer would heat up if you connected power to the primary!
   So, you can heat metals without flames and without touching the object to be heated. You can even heat the metal underwater.

   Practical induction heating has been used since the 's. Growth in the induction heating industry expanded very rapidly during World War II.
   Surface hardening, or case hardening, was one of the main growth areas during WWII. Military vehicles and weaponry using case hardening on axles and engine components could outlast those without case hardening.

Thus, applying an alternating current to the induction coil induces a current into the object to be heated. Imagine how a short circuit secondary on a transformer would heat up if you connected power to the primary!So, you can heat metals without flames and without touching the object to be heated. You can even heat the metal underwater.. Growth in the induction heating industry expanded very rapidly duringSurface hardening, or case hardening, was one of the main growth areas during WWII.and weaponry using case hardening on axles and engine components could outlast those without case

   After the war, the technology improvements moved rapidly into the civilian sector as the demand for reliable automobiles increased.

   Induction heating equipment must create alternating currents at frequencies from 60 Hz to over 1 MHz. In the beginning, spark gap oscillators, motor driven generators and vacuum tubes were used to create the alternating current. Technology advanced and soon SCR, (Silicon Controlled Rectifier), based power supplies were used to replace older generators. Very large and powerful transistors are now used in power supplies for induction heating.
   An induction heating system is comprised of several major components.
. Power Supply ( generates the high frequency current)
. Load Matching Station ( matches the impedance of the coil to the power supply)
. Induction Coil (copper coil wrapped around object to be heated
. Water Cooling ( high power systems are water cooled to remove waste heat)

must create alternating currents at frequencies from 60 Hz to over 1 MHz. In the beginning, spark gap oscillators, motor driven generators and vacuum tubes were used to create the alternating current. Technology advanced and soon SCR, (Silicon Controlled Rectifier), based power supplies were used to replace older generators. Very large and powerful transistors are now used in power supplies for induction heating.Anis comprised of several major components.. Power Supply ( generates the high frequency current). Load Matching Station ( matches the impedance of the coil to the power supply). Induction Coil (copper coil wrapped around object to be heated. Water Cooling ( high power systems are water cooled to remove waste heat)

For more Induction Heating Equipmentinformation, please contact us. We will provide professional answers.