scholarly journals Molecular Dynamics Study on the Deformation Behaviors of Nanostructures in the Demolding Process of Micro-Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 470 ◽  
Author(s):  
Can Weng ◽  
Jin Yang ◽  
Dongjiao Yang ◽  
Bingyan Jiang
Keyword(s):  
Molecular Dynamics ◽  
Injection Molding ◽  
Mold Insert ◽  
Adhesion Energy ◽  
Molded Parts ◽  
Replication Quality ◽  
Deformation Behaviors ◽  
Dynamics Simulations ◽  
Polymer Nanostructure

Polymer parts with nanostructures have broad applications, possessing excellent optical, electrochemical, biological, and other functions. Injection molding technology is one of the main methods for mass production of polymer parts with various shapes and sizes. The demolding process is vital to the replication quality of molded parts with nanostructures. For this study, molecular dynamics simulations of polypropylene (PP), polymethyl methacrylate (PMMA), and cycloolefin copolymer (COC) were conducted for the demolding process. The average velocity, density distribution, adhesion energy, and demolding resistance were introduced to analyze the deformation behaviors of polymer nanostructure from a nickel nano-cavity with an aspect ratio of 2:1. The shoulders of nanostructures were firstly separated from the nickel mold insert in the simulation. Under the external demolding force of 0.07 nN, PP and PMMA could be successfully demolded with some deformations, while COC could not be completely demolded due to the greater adhesion energy between COC and Ni. It was found that the maximum adhesion energy occurred in the separation process between the shoulder of the nanostructure and Ni and the huge adhesion energy was the main cause of demolding defects. The velocity difference of the whole polymer layer and polymer nanostructure was further analyzed to explain the nanostructure deformation. In order to improve the quality of demolding, the external force applied on polymers should be properly increased.

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 Molecular Dynamics Simulations on the Demolding Process for Nanostructures in Injection Molding

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 636 ◽  
Author(s):  
Can Weng ◽  
Dongjiao Yang ◽  
Mingyong Zhou
Keyword(s):  
Molecular Dynamics ◽  
Injection Molding ◽  
Molecular Dynamics Simulations ◽  
Interaction Mechanism ◽  
Mold Insert ◽  
Sharp Decrease ◽  
Average Density ◽  
Radius Of Gyration ◽  
Good Shape ◽  
Dynamics Simulations

Injection molding is one of the most potential techniques for fabricating polymeric products in large numbers. The filling process, but also the demolding process, influence the quality of injection-molded nanostructures. In this study, nano-cavities with different depth-to-width ratios (D/W) were built and molecular dynamics simulations on the demolding process were conducted. Conformation change and density distribution were analyzed. Interfacial adhesion was utilized to investigate the interaction mechanism between polypropylene (PP) and nickel mold insert. The results show that the separation would first happen at the shoulder of the nanostructures. Nanostructures and the whole PP layer are both stretched, resulting in a sharp decrease in average density after demolding. The largest increase in the radius of gyration and lowest velocity can be observed in 3:1 nanostructure during the separation. Deformation on nanostructure occurs, but nevertheless the whole structure is still in good shape. The adhesion energy gets higher with the increase of D/W. The demolding force increases quickly to the peak point and then gradually decreases to zero. The majority of the force comes from the adhesion and friction on the nanostructure due to the interfacial interaction.

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.

Characterization Methods of Nano-Patterned Surfaces Generated by Induction Heating Assisted Injection Molding

2015 ◽  
Vol 9 (4) ◽  
pp. 349-355
Author(s):  
Stefano Menotti ◽  
◽  
Giuliano Bissacco ◽  
Hans Nørgaard Hansen ◽  
Peter Torben Tang ◽  
...  
Keyword(s):  
Injection Molding ◽  
Induction Heating ◽  
Process Condition ◽  
Heating System ◽  
Patterned Surfaces ◽  
Quantitative Characterization ◽  
Characterization Methods ◽  
Replication Quality

An induction heating-assisted injection molding (IHAIM) process developed by the authors is used to replicate surfaces containing random nano-patterns. The injection molding setup is developed so that an induction heating system rapidly heats the cavity wall at rates of up to 10°C/s. In order to enable the optimization of the IHAIM process for nano-pattern replication, it is necessary to develop robust methods for quantitative characterization of the replicated nano-patterns. For this purpose, three different approaches for quantitative characterization of random nano-patterns are applied and compared. Results show that the use of IHAIM is an efficient way to improve replication quality. All three measurement methods are capable of detecting the trend of the replication quality of the surface changing the process condition.

Study of the Structural Characteristics of Mold for Precise Injection Molding

2011 ◽  
Vol 291-294 ◽  
pp. 610-613
Author(s):  
Hong Lin Li ◽  
Zhi Xin Jia
Keyword(s):  
Injection Molding ◽  
Process Parameters ◽  
Structural Characteristics ◽  
Injection Mold ◽  
Industrial Products ◽  
Balance System ◽  
Molded Parts ◽  
Manufacturing Accuracy ◽  
Injection Molded

With the improvement of accuracy requirements for industrial products, the precise injection molding is replacing the traditional injection molding quickly and widely. Many factors influence the quality of injection-molded parts greatly, such as the property of the plastics, mold structure and the manufacturing accuracy, injecting machine and the injecting process parameters. In this paper, the work is emphasized for the influence of mold structure on the quality of injection-molded parts. Eight portions of injection mold are analyzed, including the cavities and cores, the guide components, the runner system, the ejection system, the side-core pulling mechanism, the temperature balance system, the venting system and the supporting parts. The structural characteristics of the above eight portions are presented.

Filling-to-Packing Switchover Mode Based on Cavity Pressure for Injection Molding

2012 ◽  
Vol 501 ◽  
pp. 168-173 ◽  
Author(s):  
Jian Wang
Keyword(s):  
Injection Molding ◽  
Crucial Role ◽  
Mold Temperature ◽  
The Other ◽  
Injection Time ◽  
Cavity Pressure ◽  
Part Quality ◽  
Molded Parts ◽  
Screw Position

Filling-to-packing switchover control during injection molding plays a crucial role in ensuring the quality of the molded parts. In this study, a filling-to-packing switchover mode based on cavity pressure was presented, and it was compared with other two switchover modes by injection time and screw position. The objective of this study was to validate the accuracy of the switchover mode based on cavity pressure, and examine its consistency. Weight of the molded parts served as the main measure to probe the process capabilities. In this study, the change in mold temperature was monitored; variation of mold temperature affecting the process was examined. The results of the verification experiments revealed that the switchover mode based on cavity pressure could yield a better part quality and consistent part weight compared with the other two traditional switchover modes. It was proved that the switchover mode by cavity pressure can be used to improve the precision of the injection molding. However, a suitable switchover pressure must be used for achieving such high process capability, and the position to get the pressure signal and mold temperature should also be considered.

scholarly journals Effect of substrate temperature on quality of copper film catalyst substrate: A Molecular Dynamics Study

2017 ◽  
Vol 2 (2) ◽  
pp. 183 ◽  
Author(s):  
Rinaldo Marimpul
Keyword(s):  
Molecular Dynamics ◽  
Substrate Temperature ◽  
Film Growth ◽  
Copper Film ◽  
Deposition Process ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential

Copper film growth using thermal evaporation methods was studied using molecular dynamics simulations. The AlSiMgCuFe modified embedded atom method potential was used to describe interaction of Cu-Cu, Si-Si and Cu-Si atoms. Our results showed that the variations of substrate temperature affected crystal structure composition and surface roughness of the produced copper film catalyst substrate. In this study, we observed intermixing phenomenon after deposition process. The increasing of substrate temperature affected the increasing of the total silicon atoms had diffusion into copper film.

scholarly journals Investigation on Product and Process Fingerprints for Integrated Quality Assurance in Injection Molding of Microstructured Biochips

2018 ◽  
Vol 2 (4) ◽  
pp. 79
Author(s):  
Nikolaos Giannekas ◽  
Yang Zhang ◽  
Guido Tosello
Keyword(s):  
Injection Molding ◽  
Quality Monitoring ◽  
Efficient Production ◽  
Replication Fidelity ◽  
Part Quality ◽  
Replication Quality ◽  
Micro Features ◽  
Product And Process ◽  
Plastic Parts

Injection molding has been increasing for decades its share in the production of polymer components, in comparison to other manufacturing processes, as it can assure a cost-efficient production while maintaining short cycle times. In any production line, the stability of the process and the quality of the produced components is ensured by frequently performed metrological controls, which require a significant amount of effort and resources. To avoid the expensive effect of an out of tolerance production, an alternative method to intensive metrology efforts to process stability and part quality monitoring is presented in this article. The proposed method is based on the extraction of process and product fingerprints from the process regulating signals and the replication quality of dedicated features positioned on the injection molded component, respectively. The features used for this purpose are placed on the runner of the moldings and are similar or equal to those actually in the part, in order to assess the quality of the produced plastic parts. For the purpose of studying the method’s viability, a study case based on the production of polymer microfluidic systems for bio-analytics medical applications was selected. A statistically designed experiment was utilized in order to assess the sensitivity of the polymer biochip’s micro features (μ-pillars) replication fidelity with respect to the experimental treatments. The main effects of the process parameters revealed that the effects of process variation were dependent on the position of the μ-pillars. Results showed that a number of process fingerprints follow the same trends as the replication fidelity of the on-part μ-pillars. Instead, only one of the two on-runner μ-pillar position measurands can effectively serve as product fingerprints. Thus, the method can be the foundation for the development of a fast part quality monitoring system with the potential to decrease the use of off-line, time-consuming detailed metrology for part and tool approval, provided that the fingerprints are specifically designed and selected.

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