Holistic Precision Error Model for 5 Axis HSC Machining Centre with Rotating Rolling Units In Direct Drives

The paper presents a holistic model of thermal and dynamic load errors for a five axis machining centre. The reasons for using such a model are presented, focusing on the interaction between the behaviours of the machine tool modules. A strategy for reducing the thermal errors subject to compensation is presented and discussed. Relations for power losses in the centre's rotating rolling units are given. The relations describe the power losses and friction torque caused by load and by the elastohydrodynamic phenomena in the lubricating oil at minimal lubrication. Modelling based on the authors’ own research and literature reports is applied to high speed spindle bearings, tilting table bearings and ball screw units. The paper also presents a model showing how changes in the position of the high-speed spindle tip arise under centrifugal forces as the speed changes.