The use of vibration measurements for quality control of machine tool spindles

The assembly of machine tool spindles results in a degree of variability in the effective stiffness of the bearings. This may result in a poor machining performance if the bearing stiffnesses are below their specified design values. Alternatively, the life of the bearings may be reduced if the bearings stiffnesses are above the design values because of excessive preload. This paper describes a method of checking the spindle assembly by making vibration measurements. From these measurements it is possible to determine which bearings (if any) are not at their design stiffness. This then allows appropriate adjustments to be made to ensure the assembled spindle is close to the design specifications.