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Review of heat treating seminar. (Heat Treating).

The Tenth International Induction Heating Seminar held in the fall of 2001 by the Inductoheat [R] Group featured a number of workshops and roundtable discussions.

The topics discussed included induction heating basics, power supply choices, induction coil designs and applications, induction heating problems and solutions, quench process and distortion control, unique applications, and many others. Jim Kosniewski, the director of electrical engineering at Inductoheat, kicked off the seminar with a

Induction Heating Power Supplies: Why So Many Choices? (Don L. Loveless, group vice president of research and development, Inductoheat, Inc.). Different power supply types and models have been developed to meet the heating requirements of a nearly endless variety of induction heating tasks. The specific heating to be accomplished dictates the frequency, power level, duty cycle, and other induction heating coil parameters, including coil voltage, current, and power factor ("Q"). System requirements, including size, shape, and location of the heating coil relative to the power supply can dramatically influence the packaging design.

Power Supplies: Flexible Tuning, Reliability, and Maintainability (Stephen Baskerville, research and development manager, Radyne Limited, U.K.). The field of application of induction heating has grown enormously over the last 40 years. Tracking this growth has been an evolution of the unit at the system's heart -- the power supply. Induction heating power supplies have changed to reflect not only technological advances, but also application advances. This discussion notes that, as the application changes, the critical requirements of the power supply change. As a result, the modem induction power supply has to provide a high degree of flexibility, reliability, and maintainability.

Induction Coil Designs and Applications (Micah Black, inductor design supervisor, Inductoheat, Inc.). Induction can be used for many applications. The four basic heating modes are static, scanning, progressive, and pulse. Each mode of heating has a particular induction coil design that pertains to it. Because some induction heating coils seem complex to the presentation on induction heating basics. He noted that induction heating is one area of materials processing that seems to be as much art as science. Essentially, induction hardening is the controlled process of transforming some of the inherent characteristics of metal into a more desirable state. His informative presentation provided a valuable foundation for the technical sessions that followed.

The following synopses are just a few among the more than 15 seminar sessions and roundtable discussions that were conducted Oct. 17-19, 2001, in Clearwater, FL. casual observer, the subject of coil design is sometimes left to the "experts" in the field. This session discussed the basic coil shapes and styles, as well as descriptions of how and why they work best in particular situations.

Process Monitoring and Advanced Controls (Ray Cook, vice president of engineering, Inductoheat, Inc.). Very early techniques for measuring process parameters could be as simple as a pressure switch or a dual set point meter that would indicate if the parameter dropped out of the acceptable range during the cycle. On less critical variables, this can still be the most prudent way to design the system. A circuit in the machine control interrogates and checks the variable during the time that it should be in the normal operating range. For such variables as flow and temperature, this involves the designer's best guess as to the time it may take the flow or temperature to stabilize before making an accept/reject measurement.

For the purist in machine control techniques, the obvious next step in monitoring and controlling the process is to move from the point of observing that a part was not properly hardened to taking corrective action as the problem is encountered. For example, the use of a servo control valve would allow the control to raise or lower the quench flow or pressure when the value drops below the control set point. While technically feasible, the question for most manufacturers is usually, "How much of this high-tech hardware is the customer willing to pay for?" This discussion explores some of the more prudent approaches that utilize some of the techniques available to obtain consistent, reliable results.

Non-Rotational Induction Hardening of Crankshafts (Don Loveless, Dr. Valery Rudnev, Glen Desmier, Loran Lankford, and Hab Medhanie -- Inductoheat, Inc.)

A revolutionary new patented induction heat-treating technology has been introduced to the automotive industry for heat-treating crankshafts. This technology involves heat treating the crankshaft journals using stationary inductors rather than the cumbersome methods of conventional crankshaft hardening processes. In conventional methods, the inductors must follow the offset rotation of the connecting rod journals, requiring the movement of massive induction fixtures as the crankshaft rotates. In the method described in this session, both the crankshaft and the inductors remain stationary during heating and quenching, resulting in a simpler, more cost-effective operation with improved hardness patterns.

The stationary method of heat treating without crankshaft rotation provides several additional practical benefits, including superior reliability, maintainability, and compactness (in some cases, using only 20% of the floor space required by a conventional process). One of the noticeable advantages of this technology is a short heating time, typically 1.5 -- 4 seconds, compared to 7 -- 12 seconds for the conventional process. Due to such a short heat time, only a small mass of metal is heated, and the heat-affected zone is minimized. In addition, the short heating time improves the metallurgical properties of the hardened zone by reducing grain growth, decarburization, and oxidation of the pin! main surface.

Induction Heating of Gears and Critical Components (Madhu Chatterjee, director of gear hardening development and special projects, Inductoheat, Inc.). Before steel gears became popular, gears were made from wood or any material that could be shaped or machined. Today, plastic, nonferrous, ceramic, and composite material gears are being used more every day. Even so, a major share of market relies on gears made from steel, because of its high strength/volume ratio and ready availability. This discussion focused on an overview of gear requirements, designs, and service applications, and examples of material/process substitution data.

Failure Analysis in Heat Treating: Who's to Blame? ( avid A. Moore, P.E.; Dr. Kenneth F. Packer, Ph.D., P.E.; aron J. Jones; Duane M. Carlson -- Packer Engineering, Inc.) Failure analysis has long been a special field of study for metallurgical and materials engineers. Much of what a metallurgical engineer is taught is intended to develop observational an reasoning skills, to understand the interrelationship between observable features and properties or performance. To many, the process of a metallurgical failure analysis is almost an art form since so much of the analysis may be based on the ability of the analyst to identify and recognize important features.

The myth that failure analysis is an a t rather than a science is seemingly supported hen two failure analysts come up with differing conclusions about the same event. Heat treaters, and particularly independent suppliers of h at treatment services, can find themselves involved in the business of failure analysis by virtu of their close relationship with the practice of metallurgical engineering. The heat treater may be he only one involved in the entire design and manufacturing process with any metallurgical engineering expertise. This discussion shows how a complete failure analysis should properly determine e if the customer's specification is being met rather than allocating blame to the parties involved.

Polymer Quenchants for Induction Heat Treating Applications: The Basics (Dr. George E. Totten, senior research scientist, Union Carbide Corp.) Heat treaters have used polymer quenchants in induction heat-treating applications for more than 3 years. Polymer quenchants are used to control distortion and to prevent cracking of steel during the induction hardening process Nevertheless, there continues to be a widespread lack of understanding regarding their selection, use, and performance limitations. This discussion involved an overview of polymer quenchants chemistry, followed by a description of how polymer quenchan s work, and finally the general performance limitations with respect to their use.

Polymer quenchants, such as PAG (poly alkylene glycol)based fluids, have been used for many years to provide improved distortion control and cracking in various heat-treating operations. Polymers work by forming an encapsulating film that exhibits some rate reductions; but more importantly, they facilitate uniform heat transfer around the part, reducing both undesirable thermal and transformational gradients. Although polymer quenchants may undergo some thermal oxidative degradation, this is easily detected by periodic analyses. The discussions presented extensive background and data on polymer characteristics an performance in induction heat-treating applications.

All seminar sessions and roundtable discussions were well attended and enthusiastically received by the many heat-treating specialists and professionals from companies located throughout the U.S. Exhibits adjacent to the discussion rooms provided the attendees with additional information between the seminar sessions.
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Publication:Modern Applications News
Geographic Code:1USA
Date:Jan 1, 2002
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