Induction Tempering, Stress Relieving, Normalizing, Annealing [.pdf format]

Systematic analysis of induction coil failures. Part 14: Split-return inductors and butterfly inductors

Author: Valery Rudnev
Publication: Heat Treating Progress, Professor Induction Series
Date: 3/1/2009

The main considerations when choosing an inductor style are the shape of the part, the desired heat-treat pattern, and the material handling to be used for production (i.e., how the part is moved into the coil or the coil indexes into the part, whether rotation of the part is required, or how is the part transferred after heat treatment). Over the years, induction practitioners have established a family of special or specialty inductors. Common names have been coined to describe their appearance or function, such as pancake, channel, hairpin, split-return, and butterfly inductors [1]. This column is devoted to the analysis and prevention of failures of split-return and butterfly-type inductors.

Innovative Induction Heating Technologies

Authors: Valery Rudnev, Doug Brown, Gary Doyon
Publication: Proceedings of Material Science & Technology, Conference & Exhibition (MS&T-08), Pittsburgh, Oct.5-9, 2008
Date: 10/5/2008

Presentation focuses on:

  1. Novel approaches to induction heat treating of critical automotive components, including but not limiting to induction contour hardening of spiral, hypoid and bevel gears with diameters from 6" to 8" (patent pending) and sprockets. Patented CrankPro Technology for non-rotational hardening and tempering of crankshafts (V-4, V-6 and V-8) and camshafts with non-convention journals and lobes.
  2. Specifics of induction hardening of hand tools (i.e., wrench jaws, hammers), fasteners, etc.
  3. Induction heating of large-diameter (8 to 12 in. and larger) billets made from carbon steels, stainless steels and Inconel, including a comparative assessment of progressive multi-stage horizontal induction heating approach vs. static heating using vertical inductors (frequency selection, electrical efficiency, system flexibility, cost, etc.).
  4. FluxManager® - technology for effective heating of carbon steel tubular goods (patented in 2007).
  5. Developing compact and highly-efficient induction tempering and stress relieving systems.

Innovative induction heating of oil country tubular goods

Authors: Peter Ross, Valery Rudnev, Rich Gallik, George Elliott
Publication: Industrial Heating
Date: 5/1/2008

The stress relieve operation is an important step in the manufacture of a quality connection of tubes and pipes. Improper heat treatment could result in several undesirable phenomena from total joint failure to a type of bi-metallic corrosion known as "ring-worm corrosion" that occurs in improperly stress relieved or normalized pipes. Stress relieving is typically done prior to machining of the thread. In order to achieve the best stress relief, the upset end must be uniformly heated along the entire swage length as well as through the entire wall thickness of the pipe. Article discusses novel induction heating technology - FluxManager that provides superior axial and radial temperature uniformity that is imperative for manufacturing quality tubular goods.

SHarP-C is Advanced Non-rotational Induction Crankshaft Hardening and Tempering Technology

Authors: Don L. Loveless, Valery I. Rudnev, GCD, LAL, HM
Publication: Proceedings of Global Powertrain Congress GPC-2001, Advanced Engine Design & Performance]
Date: 6/1/2001

A revolutionary new induction heating system is being introduced to the automotive industry for the heat treatment of crankshafts. This technology involves heat treating the crankshaft journals using stationary inductors. At the same time, SHarP-C process does not use clamp-type coils. Features of V-6 hardening/tempering machine are discussed in this presentation as well as some aspects of computer modeling and features of microstructure.

Intricacies of Induction Tempering for Automotive Industry

Authors: Valery Rudnev, Don L. Loveless, John Powell, R. Escobedo
Publication: Proc. of 20th ASM Heat Treating Conference, St. Louis, October, 2000
Date: 10/1/2000

Article discusses basic principles of induction tempering process and stress distribution during heating and quenching. Variety of the general purpose compact in-line induction tempering machines discussed in this article as well

Shops Warm Up to Induction Heat Treating

Authors: Valery Rudnev, Ray L. Cook, Don L. Loveless, Micah R. Black, John Powell
Publication: American Machinist
Date: 6/1/2000

Many end users are taking advantage of induction hardening and tempering to improve part strength and wear resistance. This article discusses some subtle features of heat treatment by induction, including surface hardening, case depth requirements, through-hardening and induction tempering.

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