Measurement and Evaluation of Asynchronous Radial Error of a High Speed Spindle

Rotational accuracy of a high speed spindle is critical concern in a miniaturized machine tool for achieving desired precision of the components. It is difficult to evaluate the asynchronous radial error of the high speed spindles due to its random and non repeatable nature. This paper presents a new method for assessing asynchronous radial error of a high speed spindle used in a miniaturized machine tool. Spindle error measurements were carried out using a capacitive sensor and a master cylinder. In the proposed method, components of asynchronous radial error is decomposed using a mathematical model consisting of a Fourier series function and assumed to follow normal probability distribution. Standard deviation of the asynchronous components is used to indicate the variations in multiple spindle revolutions. Proposed method is also useful in selecting the number of spindle revolutions for evaluating the asynchronous radial error of the miniaturized machine tool spindle.