Offering ready-to-use tables, diagrams, graphs, and simplified formulas for at-a-glance guidance in induction heating system design, this book contains numerous photographs, magnetic field plots, temperature profiles, case studies, hands-on When the prior microstructure does not have a uniform distribution of phases or elements , complete austenitization requires more time at temperature, or a higher austenitizing temperature.
Induction normally uses a timed heat cycle that For induction surface hardening , it is recommended to use steels with an appropriate carbon content 0. Usually, these steels have an increased silicon 0. Table 4. The shell elements allowed for the examined plate to be meshed with coarse elements regardless of the induction For many modern manufacturing processes, induction heating offers an attractive combination of speed, consistency and control.
The basic principles of induction heating have been understood and applied to manufacturing since the s. 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.
What makes this heating method so unique? In the most common heating methods, a torch or open flame is directly applied to the metal part. But with induction heating, heat is actually "induced" within the part itself by circulating electrical currents. Induction heating relies on the unique characteristics of radio frequency RF energy - that portion of the electromagnetic spectrum below infrared and microwave energy. Since heat is transferred to the product via electromagnetic waves, the part never comes into direct contact with any flame, the inductor itself does not get hot , and there is no product contamination.
When properly set up, the process becomes very repeatable and controllable. How Induction Heating Works How exactly does induction heating work? It helps to have a basic understanding of the principles of electricity. When an alternating electrical current is applied to the primary of a transformer, an alternating magnetic field is created. According to Faraday's Law, if the secondaryof the transformer is located within the magnetic field, an electric current will be induced.
In a basic induction heating setup shown at right, a solid state RF power supply sends an AC current through an inductor often a copper coil ,and the part to be heated the workpiece is placed inside the inductor.
The inductor serves as the transformer primary and the part to be heated becomes a short circuit secondary. When a metal part is placed within the inductor and enters the magnetic field, circulating eddy currents are induced within the part. As shown in the second diagram, these eddy currents flow against the electrical resistivity of the metal, generating precise and localized heat without any direct contact between the part and the inductor. This heating occurs with both magnetic and non-magnetic parts, and is often referred to as the "Joule effect", referring to Joule's first law — a scientific formula expressing the relationship between heat produced by electrical current passed through a conductor.
Secondarily, additional heat is produced within magnetic parts through hysteresis — internal friction that is created when magnetic parts pass through the inductor.
Magnetic materials naturally offer electrical resistance to the rapidly changing magnetic fields within the inductor. 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 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.
Other benefits of this remarkable tech- nology include a measurable improvement in process robustness and dramati- cally reduced process sensitivity. Problems associated with reaching excessive tempera- tures, occurrence of grain boundary liquation incipient melting , grain coars- ening, and other metallurgical factors are reviewed. An introduction to the CamPro Technology is pro- vided, and the achievement of an almost undetectable distortion when hardening camshafts is looked into.
An introduction to FluxManager Technology is provided. Novel semicon- ductor inverter technologies, including but not limited to simultaneous dual- frequency power supplies, and inverters with independent and instant frequency and power regulation IFP-Technology are studied.
This edition embarks on the next step, the design of practical, cost-effective, and energy- efficient induction heating and heat-treating processes and equipment, providing numer- ous case studies, ready-to-use tables, diagrams, rules-of-thumb, simplified formulas, and graphs.
Plots of electromagnetic fields, temperature profiles, and photographs of a variety of production installations are provided to show not only that the task has been previously accomplished but also why and how it has been done.
An extensive list of references is provided here. In order to avoid an unreasonably large number of pages in the second edition, material related to metallographic sample preparation and review of basic temperature measure- ment techniques has been eliminated.
Several excellent texts have been published exclu- sively covering those subjects. Therefore, we refer readers to review those texts, if required. We would also like to acknowledge the contribution of the employees of Inductoheat Inc. Their professional attitude and commitment to quality have made them the benchmark in the induction heating and heat-treating indus- try and have made this work possible. We would like to acknowledge our sincere appreciation to Mr.
It goes without saying that a technical book of this magnitude requires many hours of meticulous work, hours that often have infringed upon or restricted planned family activities. We present this work in the hope that the second edition of the Handbook of Induction Heating will carry on the success of the first edition, providing an aid to practitioners, students, engineers, metallurgists, managers, and scientists revolving around induction heating technologies.
Rudnev was elected as a Fellow of the ASM International in recognition of his distinguished contri- butions to materials science and engineering.
His credits include more than 50 patents and inventions and more than publications. Rudnev contributed materials to 9 handbooks devoted to vari- ous aspects of induction heating, heat treating, materials science, and computer modeling. Don Loveless was group vice president of Technology retired at Inductoheat Inc. He received his electri- cal engineering degree from Western Michigan University.
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