Abstract
Machining process productivity is adversely impacted by the unstable chatter vibrations causing poor surface quality, excessive loads, and premature tool and machine failures. Depending on the position of the cutting edge element (CEE) along the vibration wave on the part surface, its flank face and hone radius dynamically indent into the material and cause process damping (PD), which improves the machining stability. This article proposes a generalized analytical PD model by lifting the straight flank face limitation of authors’ previously developed approach and extends it to any clearance face geometries used in machining operations. The proposed model employs the dimensionality reduction method by discretizing the two-dimensional (2D) contact between the CEE and the part surface with series of springs to simulate the contact mechanics between the two. Elasto-plastic material model of the workpiece is used to calculate the contact pressure considering the work material properties, cutting edge geometry, machining and vibration parameters as inputs. The PD force is evaluated by removing the effect of the static indentation from the overall contact force. The equivalent viscous damping coefficient is calculated to linearize the PD force and can be used for accurate machining stability prediction of difficult-to-cut materials. The model has been validated with the experimentally identified and finite elements-based PD coefficients, and a stability lobes diagram in orthogonal machining. Initial results reveal that the newly proposed analytical model can eliminate the empirical values identified from time-consuming machining tests and computationally expensive numerical simulations. Next, the introduced method will be extended to PD in three-dimensional (3D) machining processes such as milling with general tool geometries having varying cutting speeds and geometries along the tool axis.
