Experimental Validation of Injection Molding Simulations of 3D Microparts and Microstructured Components Using Virtual Design of Experiments and Multi-Scale Modeling

Abstract

<jats:p>The increasing demand for micro-injection molding process technology and the corresponding micro-molded products have materialized in the need for models and simulation capabilities for the establishment of a digital twin of the manufacturing process. The opportunities enabled by the correct process simulation include the possibility of forecasting the part quality and finding optimal process conditions for a given product. The present work displays further use of micro-injection molding process simulation for the prediction of feature dimensions and its optimization and microfeature replication behavior due to geometrical boundary effects. The current work focused on the micro-injection molding of three-dimensional microparts and of single components featuring microstructures. First, two virtual a studies were performed to predict the outer diameter of a micro-ring within an accuracy of 10 µm and the flash formation on a micro-component with mass a 0.1 mg. In the second part of the study, the influence of microstructure orientation on the filling time of a microcavity design section was investigated for a component featuring micro grooves with a 15 µm nominal height. Multiscale meshing was employed to model the replication of microfeatures in a range of 17–346 µm in a Fresnel lens product, allowing the prediction of the replication behavior of a microfeature at 91% accuracy. The simulations were performed using 3D modeling and generalized Navier–Stokes equations using a single multi-scale simulation approach. The current work shows the current potential and limitations in the use of micro-injection molding process simulations for the optimization of micro 3D-part and microstructured components.</jats:p>

Rapid Numerical Estimation of Pressure Drop in Hot Runner System

“…The pressure drop is especially important in microsystem. Injection molding of a micro-device requires a high pressure at the gate to drive the filling flow in the micro-cavity [ 2 , 3 , 4 , 5 ]. To maintain the required pressure at the gate, the pressure drop through the runner should be suppressed.…”

Atomistic Investigation on the Wetting Behavior and Interfacial Joining of Polymer-Metal Interface

“…Injection molding, or the direct joining method is one of the most commonly used technologies in the fabrication of polymer products [ 7 , 8 , 9 ]. With metallic part as an insert assembled in the cavity of injection mold, the polymer-metal hybrid structure can be easily fabricated in mass production.…”

Submillimeter features on injected acrylonitrile butadiene styrene parts: Visualization of the flow and numerical simulation

“…The injection of a part with traditional dimensions (> 10 mm and > 0.1 g), named macro, having micrometric surface textures (< a few hundred μm) is a process which corresponds to one of the microinjection molding categories. [3], [4] The main difficulty of this type of part is to combine the mechanical requirements along with the dimensional qualities of the part at a macroscopic scale, and a perfect replication of those micrometric shapes on its surface. The functionalization of the surface is primarily linked to the quality of filling of those micro-textures, in particular of its replication height.…”

“…This difficulty can be explained by the meshing quality along with the definition of the boundary conditions of the calculation. Rytka et al [9] established that it was essential to use a 3D mesh in microinjection and that multi-scale [4] meshing is one of the adopted solutions to study macroscopic parts containing microscopic elements. In this case, the runner system of the macroscopic is refined as it approaches the micrometric part.…”

“…Most often, its behavior is modeled after a Cross WLF model for the polymer viscosity with its different coefficients, for the PVT the coefficient of a two domain-Tait model, the transition temperature, T trans , value for the polymer, the shrinkage… Afterward, the data regarding the injection process have to be implemented with the melt polymer temperature, T Melt , the mold temperature, T Mo , the injection rate, the dynamic injected volume, the pressure and holding time, the cooling time, and the in-between cycle time. Lastly, the data regarding the mold with the mold/ polymer thermal exchange coefficient, h tc , for the different phases of the injection cycle, the precise dimensions of the cavity [4] and the runner system, the temperature and flow rate of the cooling fluid, and a perfect knowledge of cavity venting… All of these items will impact the simulation results to different degrees. A particularly sensitive point concerns the choice of the threshold value which allows the calculation to stop the flow of the polymer [9] in connection with the characteristics of the mold/ polymer heat exchanges.…”