scholarly journals Experimental Investigation and Molecular Dynamics Simulation on the Anti-Adhesion Behavior of Alkanethiols on Nickel Insert in Micro Injection Molding

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1834
Author(s):  
Can Weng ◽  
Jiachen Chen ◽  
Jin Yang ◽  
Mingyong Zhou ◽  
Bingyan Jiang
Keyword(s):  
Molecular Dynamics ◽  
Injection Molding ◽  
Md Simulation ◽  
Mold Insert ◽  
Dynamics Simulation ◽  
Injection Molding Process ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Adhesion Behavior ◽  
Self Assembled

Due to the adhesion between the polymer melt and nickel (Ni) mold insert in the micro injection molding process, deformation defects frequently occur when the microstructures are demolded from the insert. In this study, self-assembled alkanethiols were applied to modify the surface of Ni mold insert to reduce its surface energy. Experimental trials were undertaken to explore the effect of alkanethiols coating on the replication quality. After that, molecular dynamics (MD) simulation was then used to investigate the adhesion behavior between the self-assembled coating and polypropylene (PP) by establishing three different types of alkanethiol material. The interaction energy, the potential energy change and radial distribution function were calculated to study the anti-adhesion mechanism. Experimental results show that all the three coatings can effectively decrease the adhesion and therefore promote the replication fidelity. It is demonstrated in MD simulation that the adhesion mainly comes from the van der Waals (vdW) force at the interface. The arrangement of sulfur atom on the Ni surface results in different absorbing behaviors. Compared with that of the PP–Ni interface, the interfacial energy and adhesion work after surface treatment is significantly reduced.

scholarly journals Molecular Dynamics Simulation on the Influences of Nanostructure Shape, Interfacial Adhesion Energy, and Mold Insert Material on the Demolding Process of Micro-Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1573 ◽  
Author(s):  
Jin Yang ◽  
Can Weng ◽  
Jun Lai ◽  
Tao Ding ◽  
Hao Wang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Injection Molding ◽  
Interfacial Adhesion ◽  
Mold Insert ◽  
Adhesion Energy ◽  
Dynamics Simulation ◽  
Micro Injection Molding ◽  
Interfacial Adhesion Energy

In micro-injection molding, the interaction between the polymer and the mold insert has an important effect on demolding quality of nanostructure. An all-atom molecular dynamics simulation method was performed to study the effect of nanostructure shape, interfacial adhesion energy, and mold insert material on demolding quality of nanostructures. The deformation behaviors of nanostructures were analyzed by calculating the non-bonded interaction energies, the density distributions, the radii of gyration, the potential energies, and the snapshots of the demolding stage. The nanostructure shape had a direct impact on demolding quality. When the contact areas were the same, the nanostructure shape did not affect the non-bonded interaction energy at PP-Ni interface. During the demolding process, the radii of gyration of molecular chains were greatly increased, and the overall density was decreased significantly. After assuming that the mold insert surface was coated with an anti-stick coating, the surface burrs, the necking, and the stretching of nanostructures were significantly reduced after demolding. The deformation of nanostructures in the Ni and Cu mold inserts were more serious than that of the Al2O3 and Si mold inserts. In general, this study would provide theoretical guidance for the design of nanostructure shape and the selection of mold insert material.

scholarly journals Self-Assembled Monolayers of Alkanethiols on Nickel Insert: Characterization of Friction and Analysis on Demolding Quality in Microinjection Molding

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 636
Author(s):  
Jiachen Chen ◽  
Jin Yang ◽  
Mingyong Zhou ◽  
Can Weng
Keyword(s):  
Injection Molding ◽  
Surface Effect ◽  
Mold Insert ◽  
Self Assembled Monolayers ◽  
Injection Molding Process ◽  
Molding Process ◽  
Adhesion Properties ◽  
Assembled Monolayers ◽  
Self Assembled

When the part geometry scaling down from macro to microscale level, the size-induced surface effect becomes significant in the injection molding process. The adhesion between polymer and nickel (Ni) mold insert during the process can lead to defects in necking, warping and deformation of microstructure. In this study, the self-assembled monolayers (SAMs) with low surface energy were deposited on the Ni surface to reduce the adhesion and further improve the demolding quality of the microstructure. Results show that the alkyl mercaptan SAMs with chemical bonds and close alignment can be successfully deposited on the surface of Ni by the solution deposition method. The contact angle, surface free energy, and friction coefficient before and after anti-adhesion treatment on the surface of mold insert were measured. In addition, the anti-adhesion properties of different alkyl mercaptan materials and the correspondingly replication quality of microstructure parts after injection molding were analyzed. It is found that the Ni mold insert treated by the perfluorodecanethiol has the best wear resistance and still shows good reproducibility at the 100th demolding cycle.

scholarly journals Vacuum Venting Enhances the Replication of Nano/Microfeatures in Micro-Injection Molding Process

2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Seong Ying Choi ◽  
Nan Zhang ◽  
J. P. Toner ◽  
G. Dunne ◽  
Michael D. Gilchrist
Keyword(s):  
Injection Molding ◽  
Quantitative Study ◽  
Vacuum Pressure ◽  
Injection Molding Process ◽  
Anodized Aluminum ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Sample Shape ◽  
Final Sample ◽  
Qualitative And Quantitative Study

Vacuum venting is a method proposed to improve feature replication in microparts that are fabricated using micro-injection molding (MIM). A qualitative and quantitative study has been carried out to investigate the effect of vacuum venting on the nano/microfeature replication in MIM. Anodized aluminum oxide (AAO) containing nanofeatures and a bulk metallic glass (BMG) tool mold containing microfeatures were used as mold inserts. The effect of vacuum pressure at constant vacuum time, and of vacuum time at constant vacuum pressure on the replication of these features is investigated. It is found that vacuum venting qualitatively enhances the nanoscale feature definition as well as increases the area of feature replication. In the quantitative study, higher aspect ratio (AR) features can be replicated more effectively using vacuum venting. Increasing both vacuum pressure and vacuum time are found to improve the depth of replication, with the vacuum pressure having more influence. Feature orientation and final sample shape could affect the absolute depth of replication of a particular feature within the sample.

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

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 614 ◽  
Author(s):  
Dario Loaldi ◽  
Francesco Regi ◽  
Federico Baruffi ◽  
Matteo Calaon ◽  
Danilo Quagliotti ◽  
...  
Keyword(s):  
Injection Molding ◽  
Process Simulation ◽  
Current Work ◽  
Injection Molding Process ◽  
Process Conditions ◽  
Virtual Design ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Multi Scale ◽  
Filling Time

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.

scholarly journals Investigation of Interface Thermal Resistance between Polymer and Mold Insert in Micro-Injection Molding by Non-Equilibrium Molecular Dynamics

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2409
Author(s):  
Can Weng ◽  
Jiangwei Li ◽  
Jun Lai ◽  
Jiangwen Liu ◽  
Hao Wang
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Injection Molding ◽  
Thermal Resistance ◽  
Mold Insert ◽  
Micro Injection Molding ◽  
Interface Resistance ◽  
Interface Thermal Resistance ◽  
Packing Pressure ◽  
Non Equilibrium Molecular Dynamics

Micro-injection molding has attracted a wide range of research interests to fabricate polymer products with nanostructures for its advantages of cheap and fast production. The heat transfer between the polymer and the mold insert is important to the performance of products. In this study, the interface thermal resistance (ITR) between the polypropylene (PP) layer and the nickel (Ni) mold insert layer in micro-injection molding was studied by using the method of non-equilibrium molecular dynamics (NEMD) simulation. The relationships among the ITR, the temperature, the packing pressure, the interface morphology, and the interface interaction were investigated. The simulation results showed that the ITR decreased obviously with the increase of the temperature, the packing pressure and the interface interaction. Both rectangle and triangle interface morphologies could enhance the heat transfer compared with the smooth interface. Moreover, the ITR of triangle interface was higher than that of rectangle interface. Based on the analysis of phonon density of states (DOS) for PP-Ni system, it was found that the mismatch between the phonon DOS of the PP atoms and Ni atoms was the main cause of the interface resistance. The frequency distribution of phonon DOS also affected the interface resistance.

Design and Experimental Validation of a Process Chain for Thin Components Manufacturing by Micro Injection Molding Process

2021 ◽  
Author(s):  
Vincenzo Bellantone ◽  
Fulvio Lavecchia ◽  
Rossella Surace ◽  
Onofrio Spadavecchia ◽  
Francesco Modica ◽  
...  
Keyword(s):  
Injection Molding ◽  
Rapid Development ◽  
Micro Milling ◽  
Surface Finishing ◽  
Injection Molding Process ◽  
Manufacturing Cost ◽  
Process Chain ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Micro Features

Abstract Micro applications, especially in biomedical and optical sectors, require the fabrication of thin polymeric parts which can be commonly realized by micro injection molding process. However, this process is characterized by a relevant constraint regarding the tooling. Indeed, the design and manufacturing of molds could be a very time-consuming step and so, a significant limitation for the rapid development of new products. Moreover, if the design displays challenging micro-features, their realization could involve the use of more than one mold for the fabrication of a single thin part. Therefore, a proper integration of different manufacturing micro technologies may represent an advantageous method to realise such polymeric thin micro features. In this work, a micro-manufacturing process chain including stereolithography, micro milling and micro injection molding is reported. The mold for the micro injection molding process was fabricated by means of stereolithography and micro milling, which allowed to produce low-cost reconfigurable modular mold, composed by an insert support and a removable insert. The assessment of the proposed process chain was carried out by evaluating the dimensions and the surface finishing and texturing of the milled mold cavities and molded components. Finally, a brief economic analysis compares three process chains for fabricating the micro mold showing that proposed one reduces manufacturing cost of almost 61% with the same production time.

Micro-injection Molded Polymeric Surfaces for the Maintenance of Human Mesenchymal Stem Cells (hMSCs)

2013 ◽  
Vol 1499 ◽  
Author(s):  
Meghan E. Casey ◽  
John W. Rodgers ◽  
Courtney E. LeBlon ◽  
John P. Coulter ◽  
Sabrina S. Jedlicka
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Injection Molding ◽  
Silicon Wafer ◽  
Human Mesenchymal Stem Cells ◽  
Mold Insert ◽  
High Volume ◽  
Injection Molding Process ◽  
Molding Process ◽  
Micro Features

ABSTRACTIn this work, we take advantage of injection molding as a high volume and repeatable method to create surface areas for the growth of human mesenchymal stem cells (hMSCs). Ultraviolet lithography, combined with deep reactive ion etching, was used to generate micro-features over a relatively large surface area of a silicon wafer. The micro-featured silicon wafer was used as a mold insert for the micro-injection molding process to create polystyrene and low density polyethylene surfaces. Micro-geometry was used to alter the effective surface stiffness of the polymer substrate. Created samples were characterized via scanning electron microscopy and tensile testing. hMSCs were seeded onto samples for initial studies. Actin and vinculin were visualized through ICC to compare cytoskeletal elements. Changes in cell morphology were examined using ICC. Results indicate that injection molding of microfeatured substrates is a viable technique to produce surfaces amenable to stem cell growth.

An Investigation into the Influencing Factors for Polymer Melt at the Filling Stage in Micro Injection Molding

2013 ◽  
Vol 562-565 ◽  
pp. 1380-1386
Author(s):  
Jian Zhuang ◽  
Da Ming Wu ◽  
Ya Jun Zhang ◽  
Lin Wang ◽  
Xiong Wei Wang ◽  
...  
Keyword(s):  
Injection Molding ◽  
Influencing Factors ◽  
Polymer Melt ◽  
Theoretical Models ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Filling Stage ◽  
Conventional Injection Molding

The flow behaviors for polymer melt at the filling stage in micro injection molding are different from those in conventional injection molding due to the miniaturization of plastic parts. This paper focuses on the study of the effects of three main influencing factors, including the microscale viscosity and wall slip, on melt filling flow in microscale neglected those in conventional injection molding process. The theoretical models and the interrelation of these factors in microscale channels were constructed by means of the model correction method. Then, the micro melt flow behaviors were investigated with comparisons of the available experimental data. The results indicate that the dimensions affect the shear rates and viscous dissipation, which in turn affects the apparent viscosity. Finally, the conclusion is that the melt flow behaviors in microchannels are different from those in macrochannels owing to these significant influencing factors.

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