Sources of nonlinearities, chatter generation and suppression in metal cutting

Abstract

The mechanics of chip formation has been revisited in order to understand functional relationships between the process and the technological parameters. This has led to the necessity of considering the chip-formation process as highly nonlinear, with complex interrelations between its dynamics and thermodynamics. In this paper a critical review of the state of the art of modelling and the experimental investigations is outlined with a view to how the nonlinear dynamics perception can help to capture the major phenomena causing instabilities (chatter) in machining operations. The paper is concluded with a case study, where stability of a milling process is investigated in detail, using an analytical model which results in an explicit relation for the stability limit. The model is very practical for the generation of the stability lobe diagrams, which is time consuming when using numerical methods. The extension of the model to the stability analysis of variable pitch cutting tools is also given. The application and verification of the method are demonstrated by several examples.

Automated lateral sectioning for Knife-Edge Scanning Microscopy

“…In addition, as the cutting depth increases, there is more contact between the edge of the knife and the neighboring tissue. This can cause tearing of the tissue and induce knife vibrations [6].…”

Influence of frictional mechanism on chatter vibrations in the cutting process–analytical approach

“…While the frictional mechanism is based on friction between the tool and the workpiece, the regenerative effect is related to the wavy workpiece surface generated by the previous cutting tooth pass. Wiercigroch et al define four chatter mechanisms [12,13]. Besides regenerative and frictional chatter, they also report mode coupling and termomechanical mechanisms.…”

A simulated investigation on the machining instability and dynamic surface generation

“…The machining instability coined here is a new generalized concept, which includes all phenomena making the machining process departure from what it should be. For instance, a variety of disturbances affect the machining system such as such as self-excited vibration [10], thermomechanical oscillations in material flow [11], Feed drive hysteresis [12] etc., but the most important one is self-excited vibrations resulted from dynamic instability of the overall machine-tool/machining-process system [5]. However, sometimes the machining process is carried out with a relative vibration between the workpiece and the cutting tool especially in heavy cutting and rough machining in order to obtain high material removal rates.…”