Abstract Summary
Manufacturing and metal cutting processes have a rich body of research on the nature and effects emerging from structural dynamics phenomena. It is well established that excessive (and uncontrolled) vibrations in machining operations hinder productivity and quality of the components being made. In these environments it is common to encounter self-excited vibrations originated by the relationship in dynamic response between the cutting tool and workpiece; referred to as regenerative chatter. To supress these effects, and especially in larger scale components, conventional practices provide the workpiece with as much support as possible and therefore commonly require custom-built fixturing bases, several manual interventions and setup stages. In contrast, for modern reduced fixturing approaches, the workpiece is minimally-held, which gives the benefits of reduction of setup times, fixturing costs and inventory, and improves access to the workpiece thereby avoiding multistage setups. However, minimal fixturing reduces support of the workpiece, and so vibration becomes a greater challenge, along with the subsequent detrimental effects to part quality and material removal rate (MRR). This paper sets out to determine an optimization methodology for layout configurations that maximize milling depths of cut whilst achieving dynamic stability; by means of FEA model-based simulations, particle swarm optimization (PSO) methods, and experimental modal analysis (EMA) updating algorithms. The investigation takes a sequential approach for the evaluation of the system’s structural dynamics. First, the accuracy and effectiveness of the optimization algorithm is tested on simplified setups. EMA testing and model updating is then performed before application onto a single workpiece. Finally, a complete doublesided access fixturing assembly is investigated. The optimization program enables analysis of a wide range of possible setup considerations, and through this it is shown that optimal results can differ from standard practice. The comparative reduction in workpiece stiffness to a traditional approach is mostly unavoidable, however careful placement of workholding elements can visibly improve cutting conditions and increase dynamic stability within an unsupported environment. This motivates industrial adoption of the approach.
