A stress induced crystallinity model under the microinjection molding process

In the present study, replication of flow-through microfilters in the newly developed microfluidic lab-on-a-chip for blood typing by microinjection molding process was experimentally investigated. As a precise replication of the microfilters was required in order to effectively filter out agglutinated red blood cells, the effects of important processing conditions on the replication of the flow-through microfilters were investigated. By using a mold insert fabricated by a nickel electroplating process and a newly designed mold base, microinjection molding experiments were carried out. A three-dimensional solid model reconstruction method was proposed with the help of specific features characterizing the geometry of microfilters, and accordingly, the feature values of the replicated microfilters were measured by a noncontact optical measurement system. So reconstructed solid modeling result was then used to investigate the effects of various processing conditions, such as a flow rate, a mold temperature, and a packing pressure. Amongst the processing conditions investigated in the present study, the flow rate was found to be the most important one.

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Multi-Objective Optimizations of Biodegradable Polymer Stent Structure and Stent Microinjection Molding Process

Polymers ◽

10.3390/polym9010020 ◽

2017 ◽

Vol 9 (12) ◽

pp. 20 ◽

Cited By ~ 10

Author(s):

Hongxia Li ◽

Xinyu Wang ◽

Yunbo Wei ◽

Tao Liu ◽

Junfeng Gu ◽

...

Keyword(s):

Biodegradable Polymer ◽

Molding Process ◽

Microinjection Molding ◽

Multi Objective

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Multi-Objective Optimizations for Microinjection Molding Process Parameters of Biodegradable Polymer Stent

Materials ◽

10.3390/ma11112322 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2322 ◽

Cited By ~ 2

Author(s):

Hongxia Li ◽

Kui Liu ◽

Danyang Zhao ◽

Minjie Wang ◽

Qian Li ◽

...

Keyword(s):

Residual Stress ◽

Injection Molding ◽

Process Parameters ◽

Optimization Method ◽

Injection Molding Process ◽

Kriging Surrogate Model ◽

Adaptive Optimization ◽

Molding Process ◽

Microinjection Molding ◽

Design Variables

Microinjection molding technology for degradable polymer stents has good development potential. However, there is a very complicated relationship between molding quality and process parameters of microinjection, and it is hard to determine the best combination of process parameters to optimize the molding quality of polymer stent. In this study, an adaptive optimization method based on the kriging surrogate model is proposed to reduce the residual stress and warpage of stent during its injection molding. Integrating design of experiment (DOE) methods with the kriging surrogate model can approximate the functional relationship between design goals and design variables, replacing the expensive reanalysis of the stent residual stress and warpage during the optimization process. In this proposed optimization algorithm, expected improvement (EI) is used to balance local and global search. The finite element method (FEM) is used to simulate the micro-injection molding process of polymer stent. As an example, a typical polymer vascular stent ART18Z was studied, where four key process parameters are selected to be the design variables. Numerical results demonstrate that the proposed adaptive optimization method can effectively decrease the residual stress and warpage during the stent injection molding process.

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