Identification of sensitive dimensions of rotating auxiliary elements for a high-speed spindle shaft assembly

Machine tool spindles, complex dynamic systems under thermal growth, are significantly influenced by the shaft assembly's dimensions, including the spindle shaft and various press-fit auxiliary elements. Despite the importance of these dimensions, their effects on the spindle's dynamic and thermo-mechanical behavior have yet to be sufficiently explored. This study employed a detailed sensitivity analysis on auxiliary components-shaft dimensions to identify dimensions that most effectively improve the frequency response function (FRF) and minimize thermal growth. The dynamic and thermal analyses were conducted using the Receptance Coupling Substructure Analysis (RCSA) and a Reduced-Order Model of Finite Element Model (ROM-FEM), respectively. The findings revealed that, for the considered design, the front stepped sleeve, spindle tail components, and the shaft's central hole are the most sensitive components and offer a further and significant improvement on spindle performance after bearing optimization.