Study on the Stiffness, Longevity and Reliability of the Spindle Unit of Eclipse 300 CNC Lathe with Different External Load

Abstract

The stiffness of the spindle assembly of machine tools in general and also CNC machines in particular is an important criteria to evaluate the quality of machining. The initial stiffness of the spindle assembly is due to pre-load. During operating, the spindle assembly is wear under the influence of external loads including cutting force and speed. It reduces the stiffness of the spindle assembly, as well as decreasing machining accuracy. This study presents the results of various stiffness of the spindle assembly under external loads in laboratory conditions. Based on the relationship between the stiffness and the amount of axial wear of the spindle assembly according to the working time, as well as the permissible stiffness limit to predict remaining time, reliability and time of adjusting the pre-load to maintain stability and machining accuracy.

A Method to Evaluate Wear and Vibration Characteristics of CNC Lathe Spindle

“…The axial displacement for preload is divided into two parts on a class B basis [6]. A method has been proposed to determine the life and reliability of the spindle assembly under random loads based on the allowable stiffness [7]. The research results show that the life expectancy increases by 12-15% compared to the case calculated according to the total axial wear.…”