Improvement of Powder Metallurgy Gears for Engines and Transmissions

This paper presents the progress in Powder Metallurgy (PM) Gears, including examples of how to combine the disciplines of materials-, design- and process technology to push the limits towards increased performance, reduced weight, energy consumption and total manufacturing cost. Advancements in materials and manufacturing technology for PM gears will be presented as well as the result from simulations and reverse engineering work on existing automotive transmissions. The results from this work show that the amount and type of load on the individual gears in auto transmissions are very different and this gives room for optimized selection of material and manufacturing process. PM gears do not have the same geometrical design limits as conventional gears machined from wrought steel, and in this paper it is exemplified how modifications of macro- and micro gear geometries of PM gears can reduce weight, inertia and stress levels and in such a way contribute to improved transmissions for cars and motorcycles.