Spindle position influence on milling operation stability

Machine tool is the most used manufacturing means in automotive industry. This kind of manufacturing machine is very expensive and has immediate influence on produced workpiece quality. During machining process design, a tool machine specification sheet is written for each machining operation depending on workpiece required quality, material hardness and cutting conditions. In this way, in order to optimize investments, new machining center should be able to manufacture the quality set by workpiece specification sheet. The main aim of the work presented in this paper is to define and test a new method for spindle dynamic stiffness comparing. The used approach is firstly based on dynamic criteria attained through FRF (Frequency Response Function) measured experimentally on machining center spindle. Secondly, stability limits are calculated and then obtained experimentally. In this case the criterion of st eady state limit is used to compare different spindle configurations regarding the tool.