Even a cursory look at a comparison of network meshes used by different numerical methods reveals that depending upon specifics of a particular induction application; a particular type of mesh generation technique could be a decisive factor in a selection of numerical simulation techniques that would suit the best to modeling of a particular induction application: Finite Difference (FDM), Finite Elements (FEA), and Boundary Elements (BEM).
Without a concentrator, the mag- netic flux would spread around the coil or current-carrying conductor and link with the electrically conductive surroundings (auxiliary equipment, metal supports, tools, and fixtures, for example). The concentrator forms a magnetic path to channel the coil’s main magnetic flux in a well-defined area outside the coil.
The skin and proximity effects — as well as the “ring,” “slot,” and edge effects — lead to a nonuniform current distribution within a copper coil. Areas of high current density within this distribution are the primary candidates for localized hot spots, which can result in premature coil failure.
Rapid induction heating appreciably affects the kinetics of austenite formation and carbon distribution within it. Results of computer modeling of induction scan hardening of shaft using numerical computer modeling are shown here as well.
There are three ways to quench gears in spin hardening applications (Ref. 1):
• Submerge the gear in a quench tank. This technique is particularly applicable for large gears.
• Quench “in place” using an integrated spray quench. Small- and medium-size gears are usually quenched using this technique.
• Use a separate, concentric spray-quench block (quench ring) located below the inductor.
In induction heating applications longevity of inductor depends upon several factors, including coil copper selection. This article discusses how different copper grades used for fabrication of induction heating coils affect physical properties, main electrical parameters, copper losses, reliability and longevity of induction heaters. Among other phenomena article discusses copper stress-corrosion cracking, stress-fatigue cracking, galvanic corrosion, and some other important phenomena that have a marked effect on coil failure. Effect of copper residual elements and alloying elements on performance of induction coil is discussed here as well.
Non-uniform coil current distribution resulting from various electromagnetic phenomena has a dramatic effect on induction coil life and crack development in the coil copper. This article is one of series of articles devoted to a systematic scientific/engineering analysis of failures of induction heating coils and prevention. Article concentrates on coil copper electromagnetic edge effect, effect of frequency and coil copper tubing geometry on current density distribution. Other factors that affect electromagnetic edge effect (i.e., flux concentrators, magnetic flux intensifiers, flux controllers, frequency selection, etc.) are discussed here as well.
Whenever someone is talking about induction heating, reference is often made to the phenomenon of skin effect. In most publications devoted to induction heating distributions of current density and power density (heat source distributions) along the workpiece thickness/radius are simplified, and described as exponentially decreasing from the surface into the workpiece. However, in some applications, surface hardening in particular, the power density distribution along the radius/thickness has a unique “wave” shape, which differs significantly from the commonly assumed, classical exponential distribution. Here, the power density is maximum at the surface, and decreases toward the core. But then, at a certain distance from the surface, the power density increases, reaching a maximum value before again decreasing. Article discusses frequency selection for induction surface hardening as well as electromagnetic “wave” phenomenon.
Magnetic flux concentrators (also called flux intensifiers, diverters, or flux controllers) are made from high permeability, low-power-loss materials. They are used in induction heat treating applications in a manner similar to that of magnetic cores in power transformers. Article concentrates on effect of magnetic flux concentrators on life of induction coils.