Session: 14-06-01: Applied mechanics and materials in micro- and nanosystems

Paper Number: 166372

Parametric Analysis of the Solidification Process of Polymethyl Methacrylate (PMMA) in Injection Molding 

The plastic industry is experiencing rapid growth, with a market valuation in billions, driven by increasing demand for injection-molded components. Injection molding is a highly efficient process that produces precise plastic parts with complex geometries at low cost and with high throughput. In the general injection molding process, the steps includes injection of the molten polymer into mold cavities, molding (applying pressure and heat), cooling, and ejection. The cooling step plays a pivotal role, accounting for over 70% of the cycle time and significantly influencing product quality. The material solidifies as it cools, and an optimized cooling system design is crucial for minimizing defects such as warping and shrinkage. Finally, the solidified part is ejected from the mold. Thereby enhancing productivity and product reliability highly depends upon cooling process.

 

This study presents a numerical analysis conducted using ANSYS FLUENT V22 to investigate the solidification of polymeric parts during injection molding through a parametric study. The research is divided into two parts: The first part concerns the heat transefer enhancement at the cooling ducts in the master unit die (MUD) and the second part involves the solidification of molten PMMA filled in the mold cavities. In order to enhance the heat transfer rate at the cooling duct, metallic porous foams were partially filled in the the cooling duct, which was modeled with a 2D axisymmetric geometry. The resulting heat transfer coefficient was then applied as a boundary condition for a micromold containing 100 micropillars (each 100 microns in height and width) filled with molten PMMA. The solidification process of the molten polymer was simulated under various conditions to minimize cooling time. Parameters studied included the heat transfer coefficient, thermal conductivity of the mold and thermal block, and volumetric flow rate.

 

The results demonstrated that, while the use of metal foams in the cooling duct significantly improved the heat transfer rates, it also led to increased pressure drops., The analysis revealed that, although the heat exchanger was increased in the coolant ducts, further enhancement of the cooling process beyond a certain point did not result in reduced solidification time any longer, which was attributed to the limited thermal diffusion capacity of the mold and thermal block materials. To address this limitation, the study explored a range of materials with varying thermal conductivities for the mold and thermal block. The findings indicated that the thermal conductivity of the thermal block had a substantial impact on cooling efficiency, with higher thermal conductivity materials outperforming stainless steel. In contrast, increasing the thermal conductivity of the mold itself had a negligible effect on cooling time.

 

Presenting Author: Mohammad Derikvand Mechanical & Industrial Engineering Department and Center of BioModular Multi-Scale Systems for Precision Medicine (CBM²), Louisiana State University, Baton Rouge, LA 70803, United States

Presenting Author Biography: Mohammad Derikvand is a doctoral candidate in the Department of Mechanical Engineering at Louisiana State University, specializing in micro- and nanofabrication and replication for biomedical applications. He previously earned a Master’s degree in Mechanical Engineering from Iran.

Authors:

Mohammad Derikvand Mechanical & Industrial Engineering Department and Center of BioModular Multi-Scale Systems for Precision Medicine (CBM²), Louisiana State University, Baton Rouge, LA 70803, United States
Sunggook Park Mechanical & Industrial Engineering Department and Center of BioModular Multi-Scale Systems for Precision Medicine (CBM²), Louisiana State University, Baton Rouge, LA 70803, United States