This research takes a feature data model, i.e. STEP-NC as input and determines interactions among the features in the model. The feature interaction data are then appended to the original data model for subsequent uses such as process planning. The method is generic by defining and utilising a set of interaction entities such as removal volumes, common volumes, connection face and bridge faces. This feature interaction data model is developed using the EXPRESS language, making it compatible with the STEP-NC data model. The interaction data are presented in both 3D and feature interaction graph (FIG) format in a developed software system assisted by the Open CASCADE solid modelling kernel.