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

Area of Science:

• Biomaterials Engineering
• Polymer Science
• Manufacturing Technology

Background:

• Microinjection molding of degradable polymer stents shows promise but faces challenges in optimizing process parameters for quality.
• Complex relationships between process parameters and molding quality hinder achieving optimal stent properties, specifically low residual stress and minimal warpage.

Purpose of the Study:

• To propose and validate an adaptive optimization method utilizing kriging surrogate models to minimize residual stress and warpage in polymer stent microinjection molding.
• To establish an efficient approach for determining optimal process parameters in polymer stent manufacturing.

Main Methods:

• An adaptive optimization strategy integrating design of experiment (DOE) and kriging surrogate models was developed.
• The kriging surrogate model approximates the relationship between process parameters and stent quality metrics (residual stress, warpage).
• Finite element method (FEM) simulations were employed to analyze the microinjection molding process, with expected improvement (EI) guiding the optimization search.

Main Results:

• The proposed method effectively reduced residual stress and warpage in the microinjection molding of a polymer vascular stent (ART18Z).
• The integration of DOE and kriging surrogate models provided an efficient alternative to computationally expensive reanalysis.
• Numerical results confirmed the capability of the adaptive optimization method in enhancing stent molding quality.

Conclusions:

• The adaptive optimization method based on kriging surrogate models is a viable and effective approach for improving the quality of microinjection molded polymer stents.
• This technique offers a significant advantage in optimizing complex manufacturing processes by reducing computational cost and improving defect control.
• The study demonstrates a pathway to enhance the development and production of high-quality degradable polymer stents for medical applications.