Improved dynamic simulation of end-milling process using time series analysis

Milling is a competitive manufacturing process that is widely used in automotive, aerospace, biomechanical and die/mould industries. Due to the complex geometry and intricate mechanics of milling, the realistic simulation of various milling processes is a challenging research task. Accurate simulation of the milling process requires a proper knowledge of its dynamics. In this paper, a method is developed for the accurate prediction of cutting forces and surface texture in the end-milling operation, based on Time Series Analysis (TSA). In the proposed approach, an equivalent damping ratio is defined for the cutting zone, while the damping ratio of the non-cutting zone is determined by experimental modal analysis. Using a correlation sum criterion, the simulation and experimental force signals are compared to anticipate the value of process damping inside the cutting zone, by assessing the variations in correlation dimensions for both signals. The simulation algorithm incorporates the Time Finite Element Analysis (TFEA) for predicting the dynamics of the milling system. It also takes into account the effect of cutter deflections and run out. The feasibility of the proposed algorithm is verified experimentally for the side wall machining of aluminum 7075-T6, using a High Speed Steel (HSS) helical end mill. The implemented model can accurately predict cutting forces and a 3D surface texture for low radial immersion cutting.