from 1 kHz to 400 kHz. Higher and lower frequencies are available but typically these will be used for specialist applications. The relationship between operating frequency and current penetration depth and therefore hardness depth is inversely proportional. i.e. the lower the frequency the deeper the case. The above table is purely illustrative, good results can be obtained outside these ranges by balancing power densities, frequency and other practical considerations including cost which may influence the final selection, heat time and coil width. As well as the power density and frequency, the time the material is heated for will influence the depth to which the heat will flow by conduction. The time in the coil can be influenced by the traverse speed and the coil width, however this will also have an effect on the overall power requirement or the equipment throughput. It can be seen from the above table that the selection of the correct equipment for any application can be extremely complex as more than one combination of power, frequency and speed can be used for a given result. However in practice many selections are immediately obvious based on previous experience and practicality. Advantages Fast process, no holding time is required, hence more production rate No scaling or decarburizing More case depth, up to 8 mm Selective hardening High wear and fatigue resistance Applications The process is applicable for electrically conductive magnetic materials such as steel. Long work pieces such as axles can be processed. See also Case hardening Induction forging Induction heater Induction shrink fitting References Notes Bibliography . . . External links Frequently Asked Questions About The Induction Hardening Process with examples of Induction Heating Applications The National Metals Centre offering Design, Modeling & Simulation (DMS) technologies relating to Induction Hardening processes - NAMTEC Metal heat treatments it:Tempra#Tempra ad induzione