Development of a non-uniform heating system for micro hot embossing / C.-H. Yang in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 2 (05/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 2 (05/2013) . - p. 236-243 Titre : Development of a non-uniform heating system for micro hot embossing Type de document : texte imprimé Auteurs : C.-H. Yang ; S.-Y. Yang Année de publication : 2013 Article en page(s) : p. 236-243 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Gaufrage à chaud Microstructures Nanostructures Polyméthacrylate de méthyle Le poly(méthacrylate de méthyle) (souvent abrégé en PMMA, de l'anglais Poly(methyl methacrylate)) est un polymère thermoplastique transparent obtenu par polyaddition dont le monomère est le méthacrylate de méthyle (MMA). Ce polymère est plus connu sous son premier nom commercial de Plexiglas (nom déposé), même si le leader global du PMMA est Altuglas International9 du groupe Arkema, sous le nom commercial Altuglas. Il est également vendu sous les noms commerciaux Lucite, Crystalite, Perspex ou Nudec. Index. décimale : 668.9 Polymères Résumé : In recent years, many replication methods of microstructures on large-area substrates have been reported. The plate-to-plate hot embossing process is a low cost, fast, high throughput and the most possibility of mass production method for replication of micro/nano structures with high precision and high quality. However, micro hot embossing is not practical to use in mass production due to the many difficulties. This paper reports a innovative non-uniform heating hot embossing system for fabrication of large-size, high precise and high brightness light guide plate. Steam is used as heating medium, and water of 12 °C is used for cooling. The v-groove patterns in the stamper have been replicated to the light guide plates (LGPs) with an area of 488 mm by 277 mm. The experimental results show that the non-uniform heating system could achieve a transcription rate of over 99 %, compared with 95 % using conventional uniform heating system. Furthermore, less warpage, the less thickness variation, the higher average luminance and the higher brightness field distribution have been found. The results indicate that non-uniform heating system is likely to be a promising technique for the fabrication of optical elements. Note de contenu : - EXPERIMENTAL SETUP : Machine, mold and substrate - Two different types of heating - Cooling systems - Measurements - RESULTS AND DISCUSSIONS : Replication uniformity using two systems - The warpage of embossed products fabricated by two systems - The thickness variation at various locations of substrates using two systems - The luminance and brightness field distribution of LGPs fabricated using two systems - Numerically simulated and experimentally measured temperature distribution of two types of heating - Cooling channels of hot plates - Discussions of the performance of two systems DOI : 10.3139/217.2702 En ligne : https://drive.google.com/file/d/1LQ_7iW6c_bfbUCDrYv26eKpMwoJ0S7Fg/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18437 [article]

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Fabrication of double-sided micro-lens array using UV injection molding / X.-L. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 1 (03/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 1 (03/2019) . - p. 20-29 Titre : Fabrication of double-sided micro-lens array using UV injection molding Type de document : texte imprimé Auteurs : X.-L. Chen, Auteur ; K.-C. Ke, Auteur ; N.-W. Chang, Auteur ; Y.-H. Chen, Auteur ; S.-Y. Yang, Auteur Année de publication : 2019 Article en page(s) : p. 20-29 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Electroformage Gaufrage à chaud Lentilles (optique) Mesure Moules d'injection Polycarbonates Polyméthacrylate de méthyle Le poly(méthacrylate de méthyle) (souvent abrégé en PMMA, de l'anglais Poly(methyl methacrylate)) est un polymère thermoplastique transparent obtenu par polyaddition dont le monomère est le méthacrylate de méthyle (MMA). Ce polymère est plus connu sous son premier nom commercial de Plexiglas (nom déposé), même si le leader global du PMMA est Altuglas International9 du groupe Arkema, sous le nom commercial Altuglas. Il est également vendu sous les noms commerciaux Lucite, Crystalite, Perspex ou Nudec. Rayonnement ultraviolet Index. décimale : 668.4 Plastiques, vinyles Résumé : This paper reports the fabrication of double-sided micro-lens arrays using a UV injection molding process. The apparatus for UV injection molding is designed and implemented. Because the double-sided micro-lens array is fabricated using a UV-curable resin, the molds must be transparent. An alignment system is also required to align the cavities. In preparing the transparent molds, the cavities for the concave micro-lens and the alignment marks are first machined on the aluminum block. Using electroforming and hot embossing, transparent polycarbonate (PC) molds that have cavities for the MLAs and the alignment marks are fabricated. The PC molds are mounted on the UV injection molding apparatus using a pneumatic clamp. A real-time optical alignment system that comprises a CCD and an X-Y table is used to align the marks in the upper and lower molds. After alignment, the UV-curable resin is injected into the molds using a pneumatic dispenser. When the resin is cured with UV light, a double-sided micro-lens array is fabricated. The cycle time is 45 s. The respective degrees of replication for a convex and a concave micro-lens array are 99.74 % and 99.00 %. The respective standard deviation values for the diameter and the height are 1.3 μm, and 1.5 μm. The optical properties of the double-sided micro-lens array are measured. The average effective focal length is 1.686 mm, with a standard deviation of 0.007 mm, which demonstrates good formability and uniformity. Using the fabricated micro-lens array, the 1.2 mm diameter of the original light source is reduced to a 50 μm spot diameter. The images of an “A” pattern are complete and clear. This study demonstrates that a UV injection molding process that uses transparent PC molds can be used to fabricate a micro-lens array and other double-sided microstructures. Note de contenu : - EXPERIMENTS : Fabrication of the aluminum mold - Fabrication of the transparent polycarbonate (PC) molds - EXPERIMENTAL SETUP : Fabrication process for UV injection molding - Properties of the UV-curable resin - Measurements - RESULTS AND DISCUSSION : The effect of temperature and pressure on the transparent PC molds - The UV-curable resin product - The effect of pressure on the formability and filling time - Fabrication of the MLAs - The optical performance of the fabricated MLA DOI : 10.3139/217.3633 En ligne : https://drive.google.com/file/d/1UPtq6Q1QCfRzbdX97rTADoKFh8xRkO2r/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31908 [article]

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Flow visualization of filling process during micro-injection molding / S.-Y. Yang in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 4 (12/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 4 (12/2002) . - p. 354-360 Titre : Flow visualization of filling process during micro-injection molding Type de document : texte imprimé Auteurs : S.-Y. Yang, Auteur ; S. C. Nian, Auteur ; C. Sun, Auteur Année de publication : 2002 Article en page(s) : p. 354-360 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Micro-injection molding has been under development for the mass manufacture of micro parts. This paper presents fundamental research on the filling characteristics during micro-injection molding. Flow visualization was employed to observe the fast filling process. A lab-made impact type micro-injection machine was developed and used in this study. Filling of 4 x 4 x 0.2 mm3 and 2 x 2 x 1 mm3 cavities in quartz glass molds was recorded with a high-speed video camera. The effects of the processing conditions on the filling behaviors are systematically studied. The processing parameters include air pressure, mold temperature, and melt temperature. Based on the analysis of flow patterns, it was found that the melt fronts advanced quickly and filled the cavity in less than 0.1 seconds. The filling process can be divided into impact-filling and pressure-filling stages. Mold temperature and air pressure are found to be the dominant processing parameters. Note de contenu : - EXPERIMENTAL SET-UP : Impact type micro-injection machine - Mold construction - Image capture system and operation procedure - Processing conditions - RESULTS AND DISCUSSION : Flow visualization of the filling process during filling of the shell-shaped cavity - Flow visualization of the filling process during filling of the block-shaped cavity - Effects of processing conditions in filling behaviors during micro-injection molding - Effects of air pressure - Effects of mold temperature - Effects of melt temperature DOI : 10.3139/217.1706 En ligne : https://drive.google.com/file/d/1DCPLSdI11t9o9-8P3ETib79_x-4SfevY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16039 [article]

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Flow visualization of filling with aid of colored billets during impact micro-injection molding / S. C. Nian in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 4 (12/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 4 (12/2004) . - p. 402-407 Titre : Flow visualization of filling with aid of colored billets during impact micro-injection molding Type de document : texte imprimé Auteurs : S. C. Nian, Auteur ; S.-Y. Yang, Auteur Année de publication : 2004 Article en page(s) : p. 402-407 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Injection molding of thermoplastic parts with micro shotweight has been developed for many Micro-Electro-Mechanical (MEMS) applications. A lab-made high speed impact type micro-injection machine was developed to perform the microinjection molding. Many phenomena regarding impact microinjection molding is not clear and needs systematical investigation. In this study, the filling phenomena during impact microinjection was observed and investigated. Molds of spiral cavity of four different depths were constructed and employed. One side of the cavity was implemented with transparent window to observe the filling, and the filling phenomena were recorded with a high-speed video camera. To aid detailed observation, in the injection sleeve of the machine, sequential transparent and colored billets were inserted. The recorded images of filling flows of the colored melt in the spiral cavity were used for visualization and analysis of the filling with impact-type micro-injection molding machine. It is observed that melt behind from the sleeve will flow through the core of melt ahead and lead the melt front. Fountain flow in high speed micro-injection molding is dominant. During penetration, the colored melt, which is behind the transparent melt originally, is comparatively hot and flows along the core, following the inner side of core to seek shortest flow path. DOI : 10.3139/217.1841 En ligne : https://drive.google.com/file/d/1jOY94kWGCc0wJtZyrB3Kqf_5w_CDoz5N/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3274 [article]

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Improving flow balance during filling a multi-cavity mold with modified runner systems / T.-C. Huang in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 4 (09/2008)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 4 (09/2008) . - p. 363-369 Titre : Improving flow balance during filling a multi-cavity mold with modified runner systems Type de document : texte imprimé Auteurs : T.-C. Huang, Auteur ; P.-H. Huang, Auteur ; S.-Y. Yang, Auteur ; T.-Y. Ko, Auteur Année de publication : 2008 Article en page(s) : p. 363-369 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Multi-cavity injection molding has been regarded as low cost mass-production method for producing plastic products such as optical elements. However, the flow imbalance during filling a multi-cavity mold using symmetrical runner system is a serious problem. This paper is devoted to improving the flow balance by modifying the runner system design. For this purpose, four eight-cavity molds with four modified symmetrical runner systems are designed, constructed and tested. They are tapering H-type runners, pinned H-type runners, curved A runners, and curved B runners. The flow imbalance in each runner system is observed and measured with the aid of short-shot experiments. The experimental results indicate that the tapering H-type runner system can improve flow balance. The pinned H-type runner system fails to improve flow balance. The curved A and B runner system can reverse the imbalance trend, but the stability of the curved systems is poor at high melt temperature. DOI : 10.3139/217.2075 En ligne : https://drive.google.com/file/d/1iLprWRv9qTDPxgusQzXTC7QvZuNnKH-1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2617 [article]

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Injection molding of plastic plates combined with boss features on superplastic Zn-22Al sheet / S.-Y. Yang in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 4 (12/2001)  

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Molding of thin sheets using impact micro-injection molding / S. C. Nian in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 4 (12/2005)  

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Polymer-ridge waveguide fabrication by gas-assisted UV embossing with a soft mold / F.-S. Cheng in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 3 (07/2008)  

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