Search Results for induction heating

The handling of billets or bars is an essential part of an induction heating system. This article describes two types of handling systems available for bar heating lines: inclined ramps with escapement, and sling feeder with inclined ramp and escapement. It focuses on the various infeed billet handling systems such as bin tippers, elevator feeders, rotary feeders, vibratory bowl feeders, magazine loaders, and rod feeders. The article provides information on the main categories of billet feeding systems, namely, dual pinch roll drive assemblies, tractor drive assemblies, billet pusher systems, walking beam assemblies, and index/continuous conveyor systems. It also discussed the hot billet handling systems used to deliver heated billets to the forging cell. These methods include billet extractor conveyors, accept/reject systems with pyrometer measurements, extractor rolls, discharge chutes, pinch roll extractors, pick-n-place systems, and robots.

Induction heating is a combination of several interrelated physical phenomena, including heat transfer, electromagnetics, and metallurgy. This article presents a brief review of different heat transfer modes, namely, heat conduction, thermal radiation, and convection. It focuses on the specifics of induction heating and heat treating applications. The article discusses the nonlinear and interrelated nature of a particular heat transfer phenomenon, physical property, and skin effect. It also presents simple case studies and general physical laws governing different heat transfer modes. The article also discusses the basic concepts of direct current and alternating current circuits, and reviews the theory of electromagnetic fields.

This article reviews the performance of power electronics components, namely, power rectifiers, insulated-gate bipolar transistors, metal-oxide semiconductor field-effect transistors, diodes, and silicon-controlled rectifiers. It provides information on induction heating power supplies with multiple heat stations, such as switching units and multiple (zone) outputs. The article describes power supply operational control and power supply protection circuits. It details duty cycle, power factor, and harmonics of power supplies. The article also describes system parameters, software analysis-calculations, human analysis-decisions, multiple system arrangements, and zone control systems for power supply selection. It provides information on the maintenance of induction power supplies, detailing the safety precautions to be taken and the need for routine inspection and servicing.

Induction heating has the ability to concentrate the electromagnetic field and heat within a certain area of the workpiece. This article provides a detailed discussion on the end heating of bars, rods, and billets using solenoid inductors, oval inductors, and channel inductors. It reviews the importance of computer modeling in predicting the impact of different, interrelated, and nonlinear factors on the transitional and final thermal conditions of billets and bars. The article describes the most appropriate processes to improve end heating process effectiveness. Induction bending of narrow circumferential band of pipe or tube is also discussed. The article concludes with a discussion on stress relieving of pipe ends and welded areas.

The basic elements of control design are safety, process control, process verification, machine control, productivity, repeatability, and ease of setup. Effective systems of quality control/quality assurance are essential for heat treating practices. This article provides information on process control modes, as well as on process signatures of some items that require control, monitoring, verifying, and logging methods. It provides information on programmable logic controllers that have become efficient in machine control and monitoring. The article describes possible noise issues, National Electric Code clearance requirements, monitoring requirements, and machine accuracy that need to be considered when designing induction equipment.

This article provides an overview of the basic theory of infrared (IR), including emissivity and E slope. It explains how the IR thermometer works, and provides guidance on choosing a thermometer, in particular, deciding between a two-color and a single-wavelength thermometer and installing and maintaining them. The article discusses typical applications of induction heating, and describes how the IR thermometer controls the temperature. While the majority of the article discusses spot thermometers, thermal imagers, which are fast and are used for both research and control of the induction process, are also addressed.

Induction heating system control is straightforward after the design and application of the coil and power supply required for the job. This article provides an overview of the basic components of an induction heating system, including a machine controller (computer or programmable logic controller), interface wiring, an operator interface, and safety controls. It also provides information on programming devices and temperature controllers, such as manual, auto, and auto-manual temperature controllers.

This article describes the effects of furnace atmospheric elements, including air, water vapor, molecular nitrogen, carbon dioxide, and carbon monoxide, on steels. It provides useful information on six groups of commercially important prepared atmospheres classified by the American Gas Association on the basis of the method of preparation or on the original constituents employed. These groups are designated and defined as follows: Class 100, exothermic base; Class 200, prepared nitrogen base; Class 300, endothermic base; Class 400, charcoal base; Class 500, exothermic-endothermic base; and Class 600, ammonia base. These are subclassified and numerically designated to indicate variations in the method by which they are prepared. The article also contains a table that lists significant furnace atmospheres and typical applications.

Magnetic flux controllers are materials other than the copper coil that are used in induction systems to alter the flow of the magnetic field. This article describes the effects of magnetic flux controllers on common coil styles, namely, outer diameter coils, inner diameter coils, and linear coils. It provides information on the role of magnetic flux controllers for whole-body and local area mass-heating applications, continuous induction tube welding, seam-annealing inductors, and various induction melting systems, namely, channel-type, crucible-type, and cold crucible systems. The article also describes the benefits of the flux controllers for induction heat treating processes such as single-shot and scanning.

The optical fiber preform is a long cylinder of glass that contains core and cladding glasses. This article describes the relationship between the peak furnace temperature, fiber draw tension, and fiber draw speed. It focuses on temperature requirements such as product viscosity, hot zone length, temperature profile, and heating cycle to draw the glass. The article provides information on process gases in the draw induction furnace, insulation package for induction heating operations, and furnace design and scalability. It reviews the key factors for the selection of susceptor materials, namely, cost, temperature cycling, and the impact on the product.

This article provides a rough estimate of the basic parameters, including coil efficiency, power, and frequency in induction heating of billets, rods, and bars. It focuses on the frequency selection for heating solid cylinders made of nonmagnetic metals, frequency selection when heating solid cylinders made from nonmagnetic alloys, and frequency selection when heating solid cylinders made from magnetic alloys. The article describes several design concepts that can be used for induction billet heating, namely, static heating and progressive/continuous heating. It presents the four major factors associated with the location and magnitude of subsurface overheating: frequency, refractory, final temperature, and power distribution along the heating line. The article summarizes the pros and cons of using a single power supply. It also reviews the design features of modular systems, and concludes with information on the temperature profile modeling software.

The most popular metal hot working processes for which induction heating is applied are forging, forming, extrusion, and rolling. This article focuses on estimation techniques to determine basic induction heating process parameters, including coil power, length of heating line, and frequency selection. It discusses three modes of heat transfer: conduction, convection, and radiation, in induction heating. The article describes the factors affected by a distortion of the magnetic field at the coil end through a schematic illustration of distribution of three magnetic force components experienced by the turns of the coil. It concludes with information on some case studies of numerical simulation.

Hyperthermia is a type of cancer treatment that requires directing a carefully controlled dose of heated nanoparticles to the cancerous tumor that leads to the destruction of cancer cells. Nanoparticles are used as the heat generating sources within the cancer cells and the tumors. The problem in controlling the temperature of nanoparticles is solved by the use of induction heating, which uses a high-frequency alternating magnetic field localized in the area of interest. This article provides an overview of this technique along with the description of its major components, namely, nanoparticles, induction heating setup, and magnetic field strength.

This article is a compilation of best practices, materials, and techniques for the design and manufacture of modern induction forge coils. It presents the basics of induction coil design along with various design considerations, namely, copper tube selection, water flow considerations, and brazing and fabricating the copper coil winding for heating billets, bars, and slabs. The article describes refractory selection criteria and the methods of mounting and securing the induction coil winding, and presents general refractory installation guidelines for induction heating applications. It provides information on curing, form removal, dryout, and coil refractory seasoning. Wear rails that are designed to prevent damage to the coil refractory and subsequent coil winding are also discussed. The article concludes with a discussion on preventive maintenance practices for induction forging coils.