Mancang Song

Quality Defects and Analysis of the Microfluidic Chip Injection Molding

Compared with hot embossing, microfluidic chips injection molding is higher efficiency process and more suitable for mass production, but the quality control for injection molding is much more complex. Experiments indicate that the incomplete replication of the micro-channel and the sink mark for microfluidic chips are the chief defects to the molding. Simulation and theoretical analysis show that the stagnant flow of the melt in micro-channel and the shrinkage difference of the chips in different directions are the main reasons for molding defect. A set of new methods that how to control process parameter, design mold, and select polymer material is proposed to reduce or avoid the defects.

Numerical simulation and experimental study of polymer micro extrusion flow

The uniformity of polymer melt flow in micro extrusion die determines the quality of products directly. It is the base of extrusion die design. According to rheology testing theory and with the help of capillary rheometer, the reasonable extrusion parameters have been achieved. The comparative micro scale viscosity model is built based on Kelvin-Voigt constitutive equation and the wall slip model is built based on Navier slip law. The extrusion of double-lumen is taken for example. By use of both numerical simulation and orthogonal experiment, the effects of main structure parameters on flow uniformity are studied. The conclusions show that shunting angle affects the uniformity most, then length of center stereotyping part, compression angle and compression ratio. Meanwhile, the best lumen structure parameters are determined. After that, double-lumen catheter die is fabricated by precision machining technology. The results of experiment validate the correctness and validity of numerical simulation for polymer micro extrusion flow.