Design and fabrication of a device to characterize spindle performance as a function of bearing preload

Abstract

This paper describes the design and fabrication of an apparatus to characterize the performance of lathe spindles as a function of spindle bearing preload. The apparatus will be used to assist undergraduate students enrolled in 2.72 in understanding mechanical design concepts. In order to assess spindle performance, the apparatus measures the radial stiffness, radial error motion, and running torque of a spindle at different preload levels. The data obtained using the apparatus can be used by students to select the optimal preload level for a spindle. The apparatus was designed as four subsystems (one for each measurement) that were integrated into a cohesive measurement system. The apparatus is designed to be as small, light, and user-friendly as possible, in order for students to use it effectively. The apparatus is capable of measuring bearing preload up to 10,000 lbs with a linearity of 0.05% and radial error motion with an accuracy of +/-0.00012 in. (3 [mu]m). It can measure the radial stiffness of the spindle for applied loads up to 500 lbs and running torque up to 443 in-lbs (50 N-m). The fabrication and assembly of the mechanical apparatus, as designed, were completed.