Machine tool spindle error monitoring

This paper presents the results of a number of case studies with respect to the dynamic measurement of machine tool spindles. For these tests a special two-sphere mandrel was fitted to the spindle under test while a fixture or 'probe nest' capable of holding five displacement transducers was clamped to the worktable. Five capacitance non-contact probes were then located in the fixture, providing for five orthogonal displacements and two tilt measurements to be recorded, Tests were then performed at certain prescribed spindle speeds to assess total, average, and asynchronous error, along with thermal drift information. The results generated provide valuable condition monitoring information on spindle wear and the likely general machining performance of the machine tool. These tests are soon to be adopted in a British Standard for machine tool performance assessment.