Spindle-runout generator devices to evaluate a rotary encoder's ability to detect spindle runout

Abstract This study aims to develop equipment and procedures to test the performance of Self-calibratable Angle device (SelfA) rotary encoder designed to detect spindle runout. Spindle runout decreases the processing and rotating-position accuracy in machine tools and can lead to a mechanical failure of the bearings inside rotary machines. To detect spindle runout, the National Institute of Advanced Industrial Science and Technology in Japan developed Self-calibratable Angle device (SelfA), which can detect the angle error by itself and has the epochal function to detect spindle runout. Experimental equipment is needed to generate a known amount of runout so that the performance of SelfA can be evaluated quantitatively. Therefore, we propose two spindle-runout generators and evaluate the amount of spindle runout generated by these generators. The first generator vibrates the main shaft directly and generates spindle runout within ±0.1 [μm] of the desired amount. The second approach vibrates the sensor side of the SelfA encoder and can generate several arbitrary amounts of spindle runout simultaneously, which are accurate to within ±0.02 [μm].