Observation of instabilities in flow front during micro injection molding process

Kim, Sun Kyoung; Choi, Sung-Ju; Lee, Kwan-Hee; Kim, Dae‐Jin; Yoo, Yeong-Eun

doi:10.1002/pen.21679

Cited by 13 publications

(17 citation statements)

References 9 publications

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“…The microscale rheological properties at a high shear rate, critical stress for wall slip, and so on are required for better process simulation [ 57 , 58 ]. The strong elastic effect, especially at the locations where an abrupt change of channel geometry occurs, and the onset of the flow instability due to channel dimension [ 59 ] need to be taken into consideration. Different polymers were used to make microdevices through microinjection molding, such as PMMA [ 60 ], PS [ 61 , 62 , 63 , 64 ], PP [ 64 ], and COC [ 64 , 65 ].…”

Section: Mold-based Techniquesmentioning

confidence: 99%

Fabrication of Polymer Microfluidics: An Overview

Juang

Chiu

2022

Polymers

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Microfluidic platform technology has presented a new strategy to detect and analyze analytes and biological entities thanks to its reduced dimensions, which results in lower reagent consumption, fast reaction, multiplex, simplified procedure, and high portability. In addition, various forces, such as hydrodynamic force, electrokinetic force, and acoustic force, become available to manipulate particles to be focused and aligned, sorted, trapped, patterned, etc. To fabricate microfluidic chips, silicon was the first to be used as a substrate material because its processing is highly correlated to semiconductor fabrication techniques. Nevertheless, other materials, such as glass, polymers, ceramics, and metals, were also adopted during the emergence of microfluidics. Among numerous applications of microfluidics, where repeated short-time monitoring and one-time usage at an affordable price is required, polymer microfluidics has stood out to fulfill demand by making good use of its variety in material properties and processing techniques. In this paper, the primary fabrication techniques for polymer microfluidics were reviewed and classified into two categories, e.g., mold-based and non-mold-based approaches. For the mold-based approaches, micro-embossing, micro-injection molding, and casting were discussed. As for the non-mold-based approaches, CNC micromachining, laser micromachining, and 3D printing were discussed. This review provides researchers and the general audience with an overview of the fabrication techniques of polymer microfluidic devices, which could serve as a reference when one embarks on studies in this field and deals with polymer microfluidics.

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Section: Mold-based Techniquesmentioning

confidence: 99%

Fabrication of Polymer Microfluidics: An Overview

Juang

Chiu

2022

Polymers

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“…The complex filling field can affect the crystallization phase, which can be seen from the huge difference of the proportion of the skin and core layer in the “skin–core” structure for semi-crystalline materials [ 26 ]. For semi-crystalline materials, physical properties, such as mechanical, optical, electrical, and chemical properties, mainly depend on the crystalline morphology of the materials [ 27 ].…”

Section: Ultrasound-assisted Micro-injection Moldingmentioning

confidence: 99%

Tuning Power Ultrasound for Enhanced Performance of Thermoplastic Micro-Injection Molding: Principles, Methods, and Performances

Zhao

Qiang

et al. 2021

Polymers

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With the wide application of Micro-Electro-Mechanical Systems (MEMSs), especially the rapid development of wearable flexible electronics technology, the efficient production of micro-parts with thermoplastic polymers will be the core technology of the harvesting market. However, it is significantly restrained by the limitations of the traditional micro-injection-molding (MIM) process, such as replication fidelity, material utilization, and energy consumption. Currently, the increasing investigation has been focused on the ultrasonic-assisted micro-injection molding (UAMIM) and ultrasonic plasticization micro-injection molding (UPMIM), which has the advantages of new plasticization principle, high replication fidelity, and cost-effectiveness. The aim of this review is to present the latest research activities on the action mechanism of power ultrasound in various polymer micro-molding processes. At the beginning of this review, the physical changes, chemical changes, and morphological evolution mechanism of various thermoplastic polymers under different application modes of ultrasonic energy field are introduced. Subsequently, the process principles, characteristics, and latest developments of UAMIM and UPMIM are scientifically summarized. Particularly, some representative performance advantages of different polymers based on ultrasonic plasticization are further exemplified with a deeper understanding of polymer–MIM relationships. Finally, the challenges and opportunities of power ultrasound in MIM are prospected, such as the mechanism understanding and commercial application.

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“…Further research on IM parts with micro channels with widths of 30, 60, and 100 µm concluded that using optimum settings for mould temperature and hold pressure, the channels were completely replicated whilst a higher injection pressure caused excessive stress during demoulding [19,20].…”

Section: The Effects Of Process Conditions On Part Demouldingmentioning

confidence: 99%

Characterisation of demoulding parameters in micro-injection moulding

et al. 2014

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Condition monitoring of micro injection moulding is an effective way of understanding the processing effects of variable parameter settings. This paper reports an experimental study that investigates the characteristics of the demoulding behaviour in micro injection moulding (µ-IM) with a focus on the process factors that affect parts' quality. Using a Cyclic Olefin Copolyme (COC) microfluidics demonstrator, the demoulding performance was studied as a function of four process parameters (melt temperature, mould temperature, holding pressure and injection speed), employing the design of experiment approach. The results provide empirical evidences on the effect that processing parameters have on demoulding conditions in µ-IM, and identifies combinations of parameters that can be used to achieve the optimal processing conditions in regards to demoulding behaviour of micro parts. It was concluded that there was a direct correlation between the applied pressure during part filling, holding phases and the demoulding characteristic factors of the µ-IM cycle such as ejection force, integral and time.2

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Observation of instabilities in flow front during micro injection molding process

Cited by 13 publications

References 9 publications

Fabrication of Polymer Microfluidics: An Overview

Fabrication of Polymer Microfluidics: An Overview

Tuning Power Ultrasound for Enhanced Performance of Thermoplastic Micro-Injection Molding: Principles, Methods, and Performances

Characterisation of demoulding parameters in micro-injection moulding

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