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 machini ng performance if the bearing stiffnesses are below their specified design values. Alternatively, the life of the bearings may be reduced if the beari ngs stiffnesses are above the design values because of excessive preload. T his paper describes a method of checking the spindle assembly by making vib ration measurements. From these measurements it is possible to determine wh ich bearings (if any) are not at their design stiffness. This then allows a ppropriate adjustments to be made to ensure the assembled spindle is close to the design specifications.