Limiting precision distortions in spindle unit of HSC machining centre

The paper presents causes of excessive precision distortions, appearing in electrospindles of HSC machining centres. The influence of changing ambient temperature is shown, as well as the precision of its modelling. Phenomena, which appear in the electrospindle unit during large rotational speed changes, have been presented and the functioning of bearing loading sleeve has been shown, which has the task of compensating thermal expansions of a spindle. Conditions of proper functioning of the sleeve have been presented, which should assure minimal displacements of a spindle. Also, possibilities of increasing bearing life span have been pointed out.