{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:42:22Z","timestamp":1760060542985,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2025,8,30]],"date-time":"2025-08-30T00:00:00Z","timestamp":1756512000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science Council of Taiwan, R.O.C.","award":["NSTC 113-2221-E-032-003"],"award-info":[{"award-number":["NSTC 113-2221-E-032-003"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental platform. One set used a balanced runner (BR) system, and the other used a non-balanced runner (NBR) system. Each cavity in the four-cavity systems contained an ASTM D638 standard specimen with dimensions of 63.5 mm \u00d7 9.53 mm \u00d7 3.5 mm. Both CAE simulation and experimental methods were applied. The results show that the filling patterns from the simulation analysis closely matched those from the experimental study for both BR and NBR systems. Furthermore, by comparing the geometric shrinkage of the injected parts, significant differences were observed in the dimensional deformation in three directions (x, y, and z) between the NBR and BR systems. Specifically, at the end of the filling region (EFR), there was no noticeable difference in shrinkage along the flow direction, but the shrinkage in the cross-flow and thickness directions was reduced in the NBR system. Additionally, for the same cavity (1C) in both BR and NBR systems, the melt-rotation effect significantly reduced shrinkage in both the cross-flow and thickness directions. These findings strongly suggest that melt rotation can effectively modify the dimensional shrinkage of injection-molded parts. Moreover, fiber orientation analyses of the 1C cavity were also performed using CAE simulation for both BR and NBR systems. The results show that in the NBR system, the melt-rotation effect substantially alters the fiber orientation. Specifically, the fiber orientation tensors in the cross-flow (A22) direction exhibit a decreasing trend. It can be speculated that the melt rotation alters the flow field, which subsequently changes the fiber orientation by reducing the flow-fiber coupling effect, thereby reducing the upstream-to-downstream asymmetry in the cross-flow direction. Through in-depth analysis, it is demonstrated that the correlation between the macroscopic geometric shrinkage and the microscopic fiber orientation changes is highly consistent. Specifically, in the EFR, \u0394A22 decreased by 0.0376, improving upstream\/downstream shrinkage asymmetry in the cross-flow direction (Ly). Future work will investigate alternative melt-rotation designs and the optimization of model-internal parameters in FOD prediction.<\/jats:p>","DOI":"10.3390\/polym17172360","type":"journal-article","created":{"date-parts":[[2025,9,1]],"date-time":"2025-09-01T14:02:46Z","timestamp":1756735366000},"page":"2360","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Investigation of the Melt-Rotation Effects on Fiber Orientation Variation and Geometrical Shrinkage in FRP Injection-Molded Parts"],"prefix":"10.3390","volume":"17","author":[{"given":"Jing-Kai","family":"Gao","sequence":"first","affiliation":[{"name":"Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 251301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fang-Lin","family":"Hsieh","sequence":"additional","affiliation":[{"name":"Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 251301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Min-Yuan","family":"Chien","sequence":"additional","affiliation":[{"name":"Department of Vehicle Engineering, Chien Hsin University of Science and Technology, Taoyuan City 320678, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chao-Tsai","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 251301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,30]]},"reference":[{"key":"ref_1","unstructured":"(2025, July 17). Composites World Report. Composites End Markets: Automotive. Available online: https:\/\/www.compositesworld.com\/articles\/composites-end-markets-automotive-2025."},{"key":"ref_2","first-page":"144","article-title":"Application of carbon fiber reinforced plastics in automotive industry: A review","volume":"1","author":"Othman","year":"2018","journal-title":"J. Mech. Manuf."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1007\/s40684-021-00412-w","article-title":"Integration of energy oriented manufacturing simulation into the life cycle evaluation of lightweight body parts","volume":"9","author":"Der","year":"2022","journal-title":"Int. J. Precis. Eng. Manuf. Green Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1007\/s40684-018-0028-3","article-title":"Fabrication and performance of segmented thermoplastic composite wind turbine blades","volume":"5","author":"Garate","year":"2018","journal-title":"Int. J. Precis. Eng. Manuf. Green Technol."},{"key":"ref_5","unstructured":"(2025, July 10). Composites World Report. Composites end Markets: New Space (2025). Available online: https:\/\/www.compositesworld.com\/articles\/composites-end-markets-new-space-(2025)."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1016\/1359-835X(95)00065-A","article-title":"Influence of fiber length and concentration on the properties of glass fiber-reinforced polypropylene: Part 1-Tensile and flexural modulus","volume":"27 Pt A","author":"Thomason","year":"1996","journal-title":"Composites"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1016\/j.compositesa.2006.01.007","article-title":"The influence of fibre length and concentration on the properties of glass fibre reinforced polypropylene: Interface strength and fibre strain in injection moulded long fibre PP at high fibre content","volume":"38","author":"Thomason","year":"2007","journal-title":"Compost. Part A Appl. Sci. Manuf."},{"key":"ref_8","first-page":"65","article-title":"Thermal, tensile and dynamic mechanical properties of short carbon fibre reinforced polypropylene composites","volume":"21","author":"Wang","year":"2013","journal-title":"Polym. Polym. Compos."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"706","DOI":"10.3144\/expresspolymlett.2012.76","article-title":"Injection moulding of long glass fibre reinforced poly(ethylene terephtalate): Influence of carbon black and nucleating agents on impact properties","volume":"6","author":"Cilleruelo","year":"2012","journal-title":"Express Polym. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"292","DOI":"10.3139\/217.2442","article-title":"Influence of processing parameters on the fiber length and impact properties of injection molded long glass fiber reinforced polypropylene","volume":"26","author":"Rohde","year":"2011","journal-title":"Int. Polym. Process."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4058","DOI":"10.1002\/pc.24466","article-title":"A novel fiber length measurement technique for discontinuous fiber-reinforced composites: A comparative study with existing methods","volume":"39","author":"Goris","year":"2018","journal-title":"Polym. Compos."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1003","DOI":"10.1177\/0021998308088606","article-title":"Fiber length and orientation in long-fiber injection-molded thermoplastics-Part I: Modeling of microstructure and elastic Properties","volume":"42","author":"Nguyen","year":"2008","journal-title":"J. Compos. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2002","DOI":"10.1016\/j.compscitech.2012.08.018","article-title":"Analysis of fibre orientation distribution in short fibre reinforced polymers: A comparison between optical and tomographic methods","volume":"72","author":"Bernasconi","year":"2012","journal-title":"Compos. Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1696","DOI":"10.1177\/0892705715584411","article-title":"Method to measure orientation of discontinuous fiber embedded in the polymer matrix from computerized tomography scan data","volume":"29","author":"Gandhi","year":"2015","journal-title":"J. Thermoplast. Compos. Mater."},{"key":"ref_15","unstructured":"Teuwsen, J., Goris, S., and Osswald, T.A. (2017, January 8\u201310). Impact of the process-induced microstructure on the mechanical performance of injection molded long glass fiber reinforced polypropylene. Proceedings of the SPE ANTEC Annual Tech Paper, Anaheim, CA, USA."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1007\/s40684-020-00226-2","article-title":"Flow-induced orientations of fibers and their influences on warpage and mechanical property in injection fiber reinforced plastic (FRP) Parts","volume":"8","author":"Huang","year":"2021","journal-title":"Int. J. Precis. Eng. Manuf. Green Technol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Quintana, M.C., Bernath, A., Schajer, G., Reiter, M., Leitner, M., and Steinm\u00fcller, H. (2020). Fiber orientation distribution predictions for an injection-molded Venturi-shaped part validated against micro-CT. Front. Mater., 7.","DOI":"10.3389\/fmats.2020.00169"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1177\/073168448400300201","article-title":"Orientation behavior of fibers in concentrated suspensions","volume":"3","author":"Folgar","year":"1984","journal-title":"J. Reinf. Plast. Compos."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"751","DOI":"10.1122\/1.549945","article-title":"The use of tensors to describe and predict fiber orientation in short fiber composites","volume":"31","author":"Advani","year":"1987","journal-title":"J. Rheol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6719","DOI":"10.1016\/j.polymer.2005.05.026","article-title":"Description and modeling of fiber orientation in injection molding of fiber reinforced thermoplastics","volume":"46","author":"Vincent","year":"2005","journal-title":"Polymer"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1360","DOI":"10.1002\/pc.22262","article-title":"Prediction of fiber orientation in the Injection molding of long fiber suspensions","volume":"33","author":"Ortman","year":"2012","journal-title":"Polym. Compos."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/j.jnnfm.2008.08.002","article-title":"An anisotropic rotary diffusion model for fiber orientation in short- and long-fiber thermoplastics","volume":"56","author":"Phelps","year":"2009","journal-title":"J. Non-Newton. Fluid Mech."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1179","DOI":"10.1122\/1.2946437","article-title":"An objective model for slow orientation kinetics in concentrated fiber suspensions: Theory and rheological evidence","volume":"52","author":"Wang","year":"2008","journal-title":"J. Rheol."},{"key":"ref_24","unstructured":"Wang, J., and Jin, X. (2010, January 4\u20138). Comparison of recent fiber orientation models in autodesk moldflow insight simulations with measured fiber orientation data. Proceedings of the Polymer Processing Society 26th Annual Meeting (PPS-26), Banff, AB, Canada."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1597","DOI":"10.1122\/1.4821038","article-title":"Phenomenological improvements to predictive models of fiber orientation in concentrated suspensions","volume":"57","author":"Tseng","year":"2013","journal-title":"J. Rheol."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"\u017burawik, R., Volke, J., Zarges, J.-C., and Heim, H.-P. (2022). Comparison of real and simulated fiber orientations in injection molded short glass fiber reinforced polyamide by X-ray microtomography. Polymers, 14.","DOI":"10.3390\/polym14010029"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Rienesl, K., Lengauer, C., Jarosch, K., and Pinter, G. (2023). Determination of fiber orientation model parameters for injection-molded short fiber reinforced polymers. Front. Mater., 10.","DOI":"10.3389\/fmats.2023.1152471"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/0377-0257(88)80023-5","article-title":"The flow of fiber suspensions in complex geometries","volume":"26","author":"Libscomb","year":"1988","journal-title":"J. Non-Newton. Fluid Mech."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1093","DOI":"10.1002\/cjce.5450800611","article-title":"Fiber suspensions in complex geometries: Flow\/orientation coupling","volume":"80","author":"VerWeyst","year":"2002","journal-title":"Can. J. Chem. Eng."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Tseng, H.C., and Su, T.H. (2018, January 21\u201325). Coupled flow and fiber orientation analysis for 3D injection molding simulations of fiber composites. Proceedings of the Polymer Processing Society 34th Annual Meeting (PPS-34), Taipei, Taiwan.","DOI":"10.1063\/1.5088279"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.compositesa.2018.09.022","article-title":"A new anisotropic viscous constitutive model or composite molding simulation","volume":"115","author":"Favaloro","year":"2018","journal-title":"Compos. Part A"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1122\/1.5064727","article-title":"The use of informed isotropic constitutive equation to simulate anisotropic rheological behaviors in fiber suspensions","volume":"63","author":"Tseng","year":"2019","journal-title":"J. Rheol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Huang, C.T., and Lai, C.H. (2020). Investigation on the coupling effects between flow and fibers on fiber-reinforced plastic (FRP) injection parts. Polymers, 12.","DOI":"10.3390\/polym12102274"},{"key":"ref_34","first-page":"47","article-title":"Solving Mold Filling Imbalances in Multi-Cavity Injection Molds","volume":"2","author":"Beaumont","year":"1998","journal-title":"J. Inject. Molding Technol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"572","DOI":"10.1177\/073168449901800609","article-title":"Mold filling imbalances in Geometrically Balanced Runner Systems","volume":"18","author":"Beaumont","year":"1999","journal-title":"J. Reinf. Plast. Compos."},{"key":"ref_36","unstructured":"Beaumont, J.P. (2004). Runner and Gating Design Handbook, Hanser. [2nd ed.]."},{"key":"ref_37","unstructured":"Chiang, G., Chien, J., Hsu, D., Tsai, V., and Yang, A. (2005, January 1\u20135). True 3D CAE visualization of filling imbalance in geometry-balanced runners. Proceedings of the SPE Annual Tech Meeting (ANTEC2005), Boston, MA, USA."},{"key":"ref_38","unstructured":"Chien, J., Huang, C., Yang, W., and Hsu, D. (2006, January 7\u201311). True 3D CAE Visualization of \u201cIntra-Cavity\u201d Filling Imbalance in Injection. Proceedings of the SPE Annual Tech Meeting (ANTEC2006), Charlotte, NC, USA."},{"key":"ref_39","unstructured":"Petzold, F., Thornagel, M., and Manek, K. (2009, January 22\u201324). Complex Thermal Hot-Runner Balancing: A Method to Optimize Filling Pattern and Product Quality. Proceedings of the SPE Annual Tech Meeting (ANTEC2009), Chicago, IL, USA."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Wilczy\u0144ski, K., and Narowski, P. (2020). A Strategy for Problem Solving of Filling Imbalance in Geometrically Balanced Injection Molds. Polymers, 12.","DOI":"10.3390\/polym12040805"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1002\/pls2.10080","article-title":"Effect of static mixer on fiber orientation of injection molded fiber-reinforced composites","volume":"3","author":"Shotwell","year":"2022","journal-title":"SPE Polymers"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1515\/ipp-2022-4252","article-title":"Comparison of fibre reorientation of short- and long-fibre reinforced polypropylene by injection molding with a rotating mold core","volume":"38","author":"Land","year":"2022","journal-title":"Int. Polym. Process."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Hsieh, F.-L., Chen, C.-T., Hwang, S.-S., Hwang, S.-J., Huang, P.-W., Peng, H.-S., Jien, M.-Y., and Huang, C.-T. (2024). Study on the influence of runner and overflow area design on flow\u2013fiber coupling in a multi-cavity system. Polymers, 16.","DOI":"10.3390\/polym16091279"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1039","DOI":"10.1007\/s40684-022-00473-5","article-title":"Correlation Between Fiber Orientation and Geometrical Shrinkage of Injected Parts Under the Influence of Flow-Fiber Coupling Effect","volume":"10","author":"Huang","year":"2023","journal-title":"Int. J. Precis. Eng. Manuf. Green Technol."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/17\/2360\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:36:00Z","timestamp":1760034960000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/17\/2360"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,8,30]]},"references-count":44,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["polym17172360"],"URL":"https:\/\/doi.org\/10.3390\/polym17172360","relation":{},"ISSN":["2073-4360"],"issn-type":[{"type":"electronic","value":"2073-4360"}],"subject":[],"published":{"date-parts":[[2025,8,30]]}}}