Previous work was reported on the induction hardening process for a 1541 steel axle shaft. This presentation compares the previous results with the stress formation dynamics in the same shaft made from steels with lower hardenability. Hardened using a scan heating method and a trailing PAG spray quench, several steels having lower hardenability were modeled using the same heating schedule so that the depth of austenite formation is similar in all cases. During spray quenching, the hardened case is shallower as steel hardenability is reduced. This leads to differences in the magnitude of compressive and tensile stresses and their distributions. In turn, the potential for internal cracking is reduced as the stress transition zone is altered by the thickness of the diffusive phase layer between the martensitic case and the ferrite-pearlite core of the shaft. The next step is to investigate these effects on the torque carrying ability of the shaft.

A new technology has been introduced to the North American market as a potential replacement for conventional gas carburizing. This new approach, called Through Surface Hardening (TSH) technology, utilizes a low hardenability (LH) steel and induction hardening to create a contoured hardened pattern, similar to a traditional gas carburizing process. In this study, TSH-processed and conventional gas-carburized SAE 8620 fatigue samples were subjected to reverse torsional loading, generating comparative stress to cycle curves. This paper outlines the torsional fatigue performance and metallurgical characteristics of each process type.

In this paper, a complete rethinking of induction hardening for CV Joints (constant velocity joints) is introduced. The new machine concept is based on a pick-up principle for hardening these workpieces. The conventional hardening solution is characterized by high floor space requirements, sequentially processing the Stem (shaft) hardening from one machine to another hardening the inner bowl of the Bell, including complex workpiece handling systems. The new, innovative process combines these discreet operations into one machine set-up with inverted spindle and two inductor coils. The VLC 100-IH machine is a solution with minimum floor space required, hardening with one chuck and without flipping the part end-to-end, giving a high degree of flexibility, easy in-line integration, as well as short cycle times. We are describing the innovations for hardening CV Joints with this combined process approach made possible by the inverted Pick-Up spindle and integrated part handling.

Induction heating is a very controlled and cost effective way of heating parts for bonding or joining applications. This presentation will talk about what induction is and why manufacturers are switching to induction over other heating processes for their joining and bonding needs. Applications covered include brazing and soldering, weld pre-heating, seam welding, shrink fitting, hard surfacing alloy bonding, adhesive and paint curing, heat staking, and heat sealing. Advantages to manufacturers include flexibility to process a variety of parts with relatively rapid changeover, efficient use of energy, time, and shop floor space, and economical processing of both large continuous production runs or small batch jobs.

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.

M-42 is Molybdenum-series high speed steel used as a cutting tool material because of its hot hardness and toughness properties. With the better hot hardness and wear resistance, M-42 is one of the most widely used tool materials for cutting tools. These Molybdenum steels are heat treated conventionally in four steps viz., preheating, austenitizing, quenching along with two stages of tempering. The main step in heat treatment, austenitizing is done with the aid of salt bath furnace by heating the tool steel to the austenitizing temperature (1260°C) with three stages of preheating. This method is often a time consuming process with most of the time and energy utilized for the achievement of the required temperature. This study deals with the rapid heat treatment of the aforementioned M-42 steel samples by the action of microwaves from a hybrid microwave furnace. The quenching is done as of in a conventional method using a neutral salt bath maintained at a temperature of 550 °C. Comparison between the rapidly heat treated specimen and the conventionally heat treated specimen With similar dimensions is carried out. The tempering processes for both the specimens were carried out conventionally. Mechanical properties such as hardness, microstructure, etc., are compared between the conventional and the rapid heat treated specimens. Scanning electron microscopy was also taken to study the grain refinement of the microwave heat treated steel specimen at a higher magnification. The comparison between the properties and the microstructure revealed minute changes in mechanical properties of the rapid heat treated specimen and also resulted in the marked drop of the heating time and the energy saving thereby reducing the costs incurred for the heat treatment process.