Heat Treatment Process Development for Gears using Computer Modeling

Designing a heat treatment schedule for a gear is an iterative process that can be expensive and time consuming. Computer modeling can be used to reduce the guesswork of this process and ensure that desired distortion control, desired residual stress state, hardness, and carbon case-depth are achieved. For a given geometry and material, initial loading models were used to determine the required part case depth and a vacuum carburizing (boost/diffuse) schedule was designed using simulation. Finite element stress models were executed to analyze the residual stress state and final distortion, predicting the overall shape change after the carburizing and quenching process. As the process was iterated, the green shape was refined to meet the desired final shape and residual stress state required by the component specifications. Computer modeling and process simulation provide an engineer with the tools needed to design a heat treatment schedule to meet part requirements, while saving time and expense of an otherwise physical trial and error process.