Ductile Iron for Open Gearing - A Current Perspective

摘要

For over three decades, open gearing for many applications has been successfully designed and manufactured from ductile iron. Examples spanning a full range of size and transmitted power are in service in various process industries throughout the world, proving the soundness of this material selection in technical as well as economical terms. The latest metallurgical and manufacturing developments have re-established the practical limits for this material, well beyond what was considered possible as recently as a few short years ago. A ductile iron gear of 16m diameter, 340 BHN (min.) hardness, module 42, with a face width of 1200 mm and having AGMA Q10 teeth quality, capable of transmitting 2×10 000+ kW was previously a concept. Today, such a gear can be manufactured. Despite its long and successful service history, ductile iron remains a somewhat lesser known commodity as an open gearing material. The goal of this paper is to present the current "state-of-the-art" with respect to ductile iron as a gear material, including its mechanical properties as applicable to gear design, structural characteristics, typical manufacturing and inspection plans, and in-service behavior. For each of these aspects, ductile iron will be compared to other available materials for open gearing design and manufacture, such as cast steel, forged/fabricated steel and austempered ductile iron.