Predictive Cutting Model for Forces and Power in Self-Propelled Rotary Tool Turning Operations

A predictive model for the three force components and power in the ingenious self-propelled rotary tool turning operations is presented and experimentally verified for both TiN coated and uncoated carbide tools. The model based on the ‘unified mechanics of cutting approach’ and the fundamental rotary tool cutting processes reported earlier incorporates all the tool and cut variables. It is shown that this operation can be represented by a number of equivalent ‘classical’ oblique cutting elements of positive and negative inclination angles about an equivalent ‘classical’ orthogonal cutting element which controls the rotary tool speed and whose location is at the point where the torque on the rotary tool is zero for a frictionless tool spindle axis. The model predictions have encompassed and confirmed the few reported experimental trends noted in the literature and shown that the TiN coating only marginally reduces the power but with larger reductions in the radial and feed force components. The importance of modelling complex practical machining operations is highlighted in this work.