A number of modifications were made to a batch quenching process for pinion gears to reduce the amount of size change in the ID. This paper assesses the impact of adding vertical plates to the load elevator to better condition oil flow to the stacked part baskets. Data collected from pinion gears before and after the modification show a reduction in the average and range of ID bore change, indicating an improvement in quench uniformity. CFD analyses suggest that improvement is due to a significant reduction in turbulence, resulting from the addition of the vertical plates. As the authors explain, high levels of turbulence promote collapse of the vapor film that occurs at the start of the quench process, and disparity in the timing causes unwanted variation in part size change throughout the load.

This presentation explores a proven and cost-effective induction technology designed for contour hardening of bevel, hypoid, and pinion gears, as well as gear-like components with complex geometries, using inexpensive steels. Developed specifically to replace the carburizing process, this unique technology offers significant advantages. The presentation includes case studies that demonstrate the chemical composition of the steels used, the achieved hardness patterns, and the microstructure of the hardened area, transition zone, and core of the workpiece. The technology’s uniqueness lies not only in its ability to induction contour harden complex-geometry parts but also in its capacity to produce fine-grained martensitic structures (with typical grain sizes ranging from 8 to 11) and substantial compressive residual surface stresses (up to 600 MPa, or 85 ksi). These features dramatically enhance the mechanical properties of induction-hardened components.