The influences of process parameters on residual stress of injection moulded microlens array

Micro injection moulding process is a non-linear and multifactor interaction manufacturing process. Residual stress is a vital quality index for micro injection moulded optics with the strictly request for high precision. In this study, the numerical analysis of residual stress of microlens array made of PMMA was carried out. The Factorial Design method was firstly employed to identify the key process parameters that affect residual stress among a large number of potential parameters with the consideration of interactions. Melt temperature, mould temperature, injection time and packing time were then determined as the most important process parameters. Then, the Taguchi analysis method was introduced to obtain the relative strengths of the effects of the four parameters. The optimal process condition with minimum value of residual stress was further tested.