Study of the effective case depth on the gear tooth root for low pressure carburizing and gas carburizing

Study of the effective depth of the gear tooth root for aeronautical applications. Some of the gear’s thermal treatments which are carried out in AvioAero (Rivalta di Torino) are checked out through the use of flat test samples, suitable to exemplify the tooth flank of a toothed profile. This allows you to be sure of the effective depth reached on the side of the tooth, while often there is no information about another critical area of the gear itself: the gear tooth root, more difficult to reach for the carburizing atmosphere and therefore with an effective depth thinner than what you get on the flank of the corresponding tooth. About the thermal process itself, it is estimated an effective case depth loss ranging from 25% to 45% compared to the tooth flankThe objective of this work is to verify this decay and observe its dependence on factors such as: tooth geometry (tooth height), tooth root radius, material (AISI 9310 at Pyrowear 53), carburizing process (gas carburizing and low pressure carburizing). This study will therefore provide additional information on the decay of the effective depth of the tooth root compared to the tooth flank, allowing to establish if the estimated decay turns out to be conservative, especially for tooth root radii regularly used to make gears (from 0.4 mm to 1.6 mm).