Feasibility analysis of active chatter control for stationary and revolving bar boring operations based on magnitude of control forces using fractional order PDλ controller

Due to the factors of limited rigidity and small inherent damping of boring bars, very small depths of cutting can be applied for chatter free machining. Stability lobe diagrams can truly represent that limit. Boring operations are categorized based on the relative motion between the boring bar and workpiece. Modelling of each category is presented in detail using a 3-DOF model. The dynamics of such systems can be successfully represented using ordinary delay differential equations and time periodic delay differential equations. The open loop stability of each type of boring operation is numerically investigated. It has been observed that the stable depth of cut is much more for revolving bar (RB) as compared to stationary bar (SB) boring process. Active chatter control (ACC) techniques can enhance the material removal rates and surface finish of the workpiece. The feasibility of active chatter control for each category is investigated in detail. It is further observed that RB boring process is not a suitable candidate for ACC because much higher harmonic control forces are required for minor improvement in critical depth of cut.