Turning of the thin-walled cylindrical workpiece is technologically highly demanding process due to the high flexibility of the workpiece. In this paper, a mathematical treatment of integral-based model of the cutting force which takes into account feed, cutting speed, depth of cut and tool nose radius leading to a model of tool-workpiece interaction is presented. The force interaction together with the compliant workpiece dynamics leads to a machining stability formulation. The effect of the aforementioned parameters on characteristic exponents is calculated and validated by comparison with experimentally identified exponents. One of the outputs with immediate practical value is identification of the process damping, which is in the studied case shown to be significantly higher than structural damping of the workpiece itself. This means that without loss of reliability in stability prediction the experimental modal analysis of a given workpiece may be omitted and workpiece’s dynamics may be described only by mass and stiffness matrices which can be easily and reliably obtained by a finite element analysis.

Specific cutting force is a key parameter that is important for estimating cutting forces that occur during machining. This information is important for various applications. The most important application is estimation of the stability limit valid for the specific configuration of the machine to...

The cutting forces that occur during machining cause static and dynamic deformations of the machine–tool–workpiece system. In general, the cutting force is spatial. However, knowledge of the tangential component of the cutting force is crucial for the optimum use of the power installed on the spindle. An important parameter for cutting force modeling is the tangential cutting force coefficient. This paper focuses on the approach of the in-process identification of the cutting and edge components of the tangential cutting force coefficient, using the spindle power signal read directly from the machine tool control system. Such procedures have already been described in the available literature. The key point for the successful implementation of these methods is the identification and avoidance of the passive torque signal. This paper describes the operational calibration of the spindle drive system. The calibration procedure is based on the tap test using modal hammer excitation and the spindle power signal response. The proposed procedure was successfully validated using a machine–machine comparison approach and a machine–dynamometer validation approach. The results are consistent with those in the available literature. With this method, we were able to determine the cutting component of the tangential specific cutting force with a deviation of 1% from the reference system and an edge component of 10%. The modal hammer method only enables the avoidance of dynamometers in the machine calibration procedure.