In single-shot hardening applications, heat treated components often feature a variety of geometric complexities including variable wall thicknesses, sharp diameter transitions, lightening holes, slots, etc. Due to the inherent 3D electromagnetic nature of single-shot coils and the complex geometry components which they must accommodate, the design and optimization of single-shot hardening coils is typically a demanding and intricate task. This paper presents combined electromagnetic-thermal and thermal-mechanical FEA simulation results for the single-shot induction hardening of a power transmission shaft. The simulation results, including electromagnetic, thermal, metallurgical, and mechanical data demonstrate the value of computer simulation in the design and development of single-shot induction hardening systems.

The recently published ASM Handbook , Volume 4C is specifically devoted to meeting the needs of the induction heating and heat treating community. It is a long-awaited expansion of the ASM Handbook series to cover induction technology in depth. Heating by electromagnetic induction is a topic of major technological significance that continues to grow at an accelerated rate in a variety of thermal applications such as hardening, tempering, stress relieving, brazing, soldering, shrink fitting, melting, normalizing, annealing, coating, as well as re-heating ferrous and non-ferrous metallic materials prior to warm and hot working. The new ASM Handbook volume reflects an ambitious undertaking to compile an all-new, comprehensive resource on 21 st -century induction thermal processes. World-recognized experts from leading universities, national research laboratories, and industrial corporations from 10 countries contributed to this volume, making it a truly international work to address leading-edge induction technologies.

This presentation reviews selected innovations related to induction hardening of various automotive powertrain transmission and engine components, including but not limited to induction surface hardening of complex geometry shafts. Thanks to several innovative designs (patented and patent pending), important goals were achieved. Process flexibility in shaft scan hardening has been substantially enhanced thanks to a novel inverter design that allows controlling independently frequency and power during scanning. This innovation allows improving quality of induction hardened components maximizing production rate and process flexibility. When applying single-shot hardening for heat treatment of output shafts, flanged shafts, yoke shafts, sun shafts, intermediate shafts, drive shafts and others, coil life is often limited due to a necessity to “squeeze” coil current in a certain area, maximizing power density. This seemingly unavoidable feature of the great majority of single-shot inductors represents a “weak link”, limiting coil life expectancy. Thanks to innovative design (patent-pending) of a single-shot inductor, its life was increased approximately nine times. Process sensitivity has been dramatically reduced. Other benefits include measurable improvement in process robustness, coil reliability and maintainability.