Investigation of Flow and Sink Initiation Process in Mold Shapes in Injection Molding
Tetsushi Kaburagi*, Masashi Kurose**, Takahiro Ogawa***,
Hiroki Kuroiwa*, and Tomoyuki Iwasawa*
*Gunma Industrial Technology Center, 884-1 Kamesato-machi, Maebashi, Gunma 379-2147, Japan
**Institute of National College of Technology, Gunma, 580 Toriba-machi, Maebashi, Gunma 371-8530, Japan
***Yamaguchi Co., Ltd., 2309-25 Kamiuekihon-machi, Isesaki, Gunma 372-0013, Japan
Injection molding has faults, or sinks, caused by the shrinkage ofmaterials. Sinks should be inhibited since they greatly affect the dimensions of moldings. In this study, a mold that allows visual observation is employed, and the sink initiation process is analyzed and predicted based on the results of that analysis. This mold has two sections, one flat and one curved. The difference between the deformations in the flat and curved sections is investigated. Methods of inhibiting sinks are considered from the results of the analysis and injection molding experiments. Packing pressure is found to have a great effect on sinks.
Hiroki Kuroiwa, and Tomoyuki Iwasawa, “Investigation of Flow and Sink Initiation Process in Mold Shapes in Injection Molding,” Int. J. Automation Technol., Vol.9, No.1, pp. 10-18, 2015.
-  H. Yokoi, “Visualization and Measurement Technologies inside Injection Mold(Intelligent Dies, and Measurement and Visualization of In-Mold Phenomena),” J. of the Japan Society of Precision Engineering, Vol.73, No.2, pp. 188-192, 2007.
-  T. Matsumori, K. Yamazaki, and Y. Doi, “A Study on Optimal Layout Design of Cooling Channels for Plastic Injection Molding Die : Optimal Layout Design Based on Evaluation ofWarpage and Molding Time(Machine Elements, Design and Manufacturing),” Trans. of the Japan Society of Mechanical Engineers. C, Vol.75, 760, pp. 3347-3354, 2009.
-  D. P. Gruber, J. Machera, D. Habaa, G. R. Bergerb, G. Pachera, andW. Friesenbichlerbet, “Measurement of the visual perceptibility of sink marks on injection molding parts by a new fast processing model,” Polymer Testing, Vol.33, pp. 7-12, 2014.
-  K. Satoh, T. Wada, and M. Yamabe, “Mechanism of Warpage Generation in Injection Molding for a Product with a Complex Shape,” Seikei-Kakou, Vol.18, No.8, pp. 593-599, 2006.
-  K. Sagae and M. Yamakawa, “Numerical Analysis of Thermal Deformation in Polymer Products after Injection Molding,” Trans. of the Japan Society of Mechanical Engineers. A, Vol.59, No.567, pp. 2635-2640, 1993.
-  T. Matsuoka and H. Takahashi, “Measurement and Analysis of Polymer Temperature within theMold in the Cooling Stage of lnjection Molding,” The Japan Society of Mechanical Engineers. A57, No.540, pp. 1971-1876, 1991.
-  H. Yokoi, “Visualization and In-process Sensing Techniques for Injection Molding,” J. of the Japan Society of Precision Engineering, Vol.66, No.10, pp. 1518-1523, 2000.
-  Y. Murata, S. Abe, and H. Yokoi, “Measurement of Melt Temperature Distribution along the Cavity Thickness Direction by Using Integrated Thermocouple Sensor,” Seikei-Kakou, Vol.14, No.4, pp. 257-264, 2002.
-  H. Yokoi, “Visiualization experimental technique for analysis of the injection molding 1.,” J. of The Japan Society of Electrical Machining Engineers, Vol.33, No.74, pp. 1-8, 1999.
-  H. Yokoi, H. Umeyama, Y. Utaka, and Y. Murata, “Visual Analysis of Three Dimensional Melt Flow Behavior Using a Glass-Inserted Mold,” Seikei-Kakou, Vol.9, No.3, pp. 232-237, 1997.
-  H. Kuroiwa, Y. Fukushima, Y. Murata, and F. Ichikura, “Examination of rib shape optimization of injection molded article by CAE,” Die and Mold in Injection Molding, Vol.25, No.12, pp.88-89, 2010.
-  T. Ogawa and M. Kurose, “Effect of Molding Pressure for Sink Initiation Process using Visualized Die and Mold in Injection Molding,” Proc. of 53rd Bachelor Thesis Presentations by the Student Members of the Kanto Branch of the JSME, pp. 515-516, 2012.
-  H. Inaba, K. Ozaki, and H. Ikegami, “Solidification and Flow Characteristics of Molten High-Density Polyethylene Injected into a Rectangular Cavity,” Trans. of the Japan Society of Mechanical Engineers, Vol.B61, No.581, pp. 223-230, 1995.
-  H. Kimura, F. Teraoka, M. Sugita, and Y. Kumazawa, “Residual Stress in Injection Molded Resin Base Denture: Part 3.Relation between Residual Stress and Gate Positions,” J. of the Japanese Society for Dental Materials and Devices, Vol.6, No.2, pp. 190-195, 1987.
-  M. Kurose, K. Hasumi, T. Kaburagi, T. Noguchi, and Y. Fukushima, “Effect of Warpage deformation by Gate Arrangement in Injection Molding,” JSME annual meeting 2010, Vol.6, pp. 269-270, 2010.
-  T. Ogawa, M. Kurose, H. Kuroiwa, and T. Kaburagi, “Investigation of Flow and Sink Initiation Process at plate shape using Visualize,” Die and Mold in Injection Molding, Vol.28, No.12, pp.24-25, 2013.
-  H. Inaba, H. Ikegami, and K. Ozaki, “Solidification Characteristics of Molten Polymer Plastics Injected in a Narrow Annular Cavity,” Trans. of the Japan Society of Mechanical Engineers, Vol.B 60, No.574, pp. 2195-2202, 1994.
-  D. Mathivanan, M. Nouby, and R. Vidhya, “Minimization of sink mark defects in injection molding process – Taguchi approach,” Int. J. of Engineering, Science and Technology, Vol.2, No.2, pp. 13-22, 2010.
-  D. Tsugawa and H. Yokouchi, “Analysis of Flow of Polymer Melt in Molds Considering Temperature Distribution on Injection Molding,” J. of the Japan Society of Precision Engineering, Vol.58, No.12, pp. 2031-2036, 1992.
-  M. Hirai, T. Hirai, T. Katayama, and H. Dobashi, “Flow Analysis in Consideration of Unstable Flow for Injection Moulding,” J. of the Society of Materials Science, Vol.42, No.474, pp. 228-232, 1993.
-  Y. Kurosaki, I. Satoh, and H. S. Kim, “Visualization of Extra Melt Motion Induced in the Packing Stage and Its Effect on the Residual Stress Frozen in an Injection-Molded Polymer Product,” Seikei-Kakou, Vol.4, No.4, pp. 256-264, 1992.
-  T. Kuroda and H. Hidetoshi, “Measuring 3-D Shape Based on Specular Image Processing with CG-Based Projection of Pattern Light Source,” ITEJ Technical Report, Vol.20, No.63, pp. 15-20, 1996.
-  D.P. Gruber, G. Berger, G. Pacher, and W. Friesenbichler, “Novel approach to the measurement of the visual perceptibility of sink marks on injection molding parts,” Polymer Testing, Vol.30, No.6, pp. 651-656, 2011.
-  T. Kameda, T. Takahashi, and K. Koyama, “Effect of Packing Pressure on Molding Shrinkage Distribution of Injection Molded Parts of Acrylonitrile-Styrene (AS) resin,” Seikei-Kakou, Vol.17, No.8, pp. 571-579, 2005.
-  Y. Tachi, “Trend of plastic mold steel,” Sanyo Technical Report, Vol.18, No.1, pp. 42-49, 2011.
-  T. Takahara and K. Koyama, “Influence of Talc Concentration on Angular Deformation in Injection Molded Parts of Talc and Rubber Filled Polypropylene,” Vol.21, No.4, pp. 223-231, 2010.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 International License.