Warpage optimization with dynamic injection molding technology and sequential optimization method

Warpage is one of the serious defects for thin wall plastic injected component. This paper employs dynamic filling and packing process parameters as the new design variables to perform the optimization on warpage for the first time. In this paper, several numerical implementations for dynamic filling and packing are discussed in detail. The unclear functional relationship between the objective (maximum warpage) and 12 process parameters is characterized by the Kriging surrogate model approximately. These process parameters not only include the conventional process parameters, like melt temperature, filling time, packing pressure etc., but also include the new dynamic process parameters involving amplitude, frequency, and phase of vibration. Subsequently, the efficient global optimization method (expected improvement-based method) is used for searching the optimum solution sequentially. Final results suggest a set of process parameters of the dynamic injection molding technology with which the maximum warpage of a plastic part is greatly reduced. By comparison with the corresponding conventional injection, injecting pressure of the optimized system fluctuates with the same frequency as dynamic flow rate during filling, which plays a significant role for the warpage reduction.