*Article* **Using Machine Learning Methods for Predicting Cage Performance Criteria in an Angular Contact Ball Bearing**

**Sebastian Schwarz 1,\*, Hannes Grillenberger 2, Oliver Graf-Goller 2, Marcel Bartz 1, Stephan Tremmel <sup>3</sup> and Sandro Wartzack <sup>1</sup>**


**Abstract:** Rolling bearings have to meet the highest requirements in terms of guidance accuracy, energy efficiency, and dynamics. An important factor influencing these performance criteria is the cage, which has different effects on the bearing dynamics depending on the cage's geometry and bearing load. Dynamics simulations can be used to calculate cage dynamics, which exhibit high agreement with the real cage motion, but are time-consuming and complex. In this paper, machine learning algorithms were used for the first time to predict physical cage related performance criteria in an angular contact ball bearing. The time-efficient prediction of the machine learning algorithms enables an estimation of the dynamic behavior of a cage for a given load condition of the bearing within a short time. To create a database for machine learning, a simulation study consisting of 2000 calculations was performed to calculate the dynamics of different cages in a ball bearing for several load conditions. Performance criteria for assessing the cage dynamics and frictional behavior of the bearing were derived from the calculation results. These performance criteria were predicted by machine learning algorithms considering bearing load and cage geometry. The predictions for a total of 10 target variables reached a coefficient of determination of *<sup>R</sup>*<sup>2</sup> <sup>≈</sup> 0.94 for the randomly selected test data sets, demonstrating high accuracy of the models.

**Keywords:** rolling bearing dynamics; cage instability; regression; machine learning; neural networks; random forest; gradient boosting; evolutionary algorithms
