Analysis of the Physical Quantity Variation in the Cavity and the Quality of the Molded Product According to the Injection Speed in Injection Molding

  • Kwon, Soon Yong (Samyang Central R & D Center) ;
  • Cho, Jung Hwan (Samyang Central R & D Center) ;
  • Roh, Hyung Jin (Samyang Central R & D Center) ;
  • Cho, Sung Hwan (Samyang Central R & D Center) ;
  • Lee, Yoo Jin (Department of Mechanical System Design Engineering, Seoul National University of Science and Technology) ;
  • Lyu, Min-Young (Department of Mechanical System Design Engineering, Seoul National University of Science and Technology)
  • Received : 2017.12.03
  • Accepted : 2017.12.14
  • Published : 2017.12.31


Molding conditions can be described as factors that determine the quality of a product obtained from injection molding. Many studies have been performed on the injection molding pressure, injection temperature, packing pressure and other molding conditions related to part quality. However, the most accessible factor among the adjustable molding conditions during actual injection is the injection speed. In this study, we simulated the variation of the physical quantity according to injection speed and performed experiments to understand the effect of injection speed on the actual product. A CAE analysis program (Moldflow) was used to simulate and analyze the results using PC and PBT for two models. In order to compare these results with the experimental results, an actual injection molding was performed for each injection speed, and the correlation between simulation and injection molding, especially for the shrinkage of the molded article, was discussed.


Supported by : 서울과학기술대학교


  1. M. Lee, H. Kim, and M.-Y. Lyu, "A Study on the Warpage of Glass Fiber Reinforced Plastics for Part Design and Operation Condition", The Polymer Society of Korea, 36, 555 (2012).
  2. M. Fujiyama and T. Wakino, "Molecular orientation in injection-molded Polypropylene Copolymers with Ethylene", Intern. Polymer Processing, 7, 159 (1992).
  3. N. Prabhu, J. Schultz, and S. G. Advani, "Role of Coupling Microscopic and Macroscopic Phenomena During the Semicrystalline Polymers", Polymer Engineering and Science, 41, 1871 (2001).
  4. M. C. Huang and C. C. Tai, "The effective factors in the warpage problem of an injection-molded part with a thin shell feature", Journal of Materials Processing Technology, 110, 1 (2001).
  5. H. O. Hardenberg and F. W. Hase, "An empirical formula for computing the pressure rise delay of a fuel from its cetane number and from the relevant parameters of direct-injection diesel engines", SAE Technical Paper (1979).
  6. D. Yao and B. Kim, "Increasing flow length in thin wall injection molding using a rapidly heated mold", Polymer-plastics Technology and Engineering, 41, 819 (2002).
  7. P. F. Bright, R. J. Crowson, and M. J. Folkes, "A study of the effect of injection speed on fibre orientation in simple mouldings of short glass fibre-filled polypropylene", Journal of Materials Science, 13, 2497 (1978).
  8. H. H. Chiang, C. A. Hieber, and K. K. Wang, "A unified simulation of the filling and postfilling stages in injection molding. Part I: Formulation", Polymer Engineering & Science, 31, 116 (1991).
  9. M. L. Williams, R. F. Landel, and J. D. Ferry, "The temperature dependence of relaxation mechanisms in amorphous polymers and other glass-forming liquids", Journal of the American Chemical Society, 77, 3701 (1955).
  10. P. E. Rouse Jr, "A theory of the linear viscoelastic properties of dilute solutions of coiling polymers", The Journal of Chemical Physics, 21, 1272 (1953).
  11. J. D. Ferry, "Mechanical properties of substances of high molecular weight. VI. Dispersion in concentrated polymer solutions and its dependence on temperature and concentration", Journal of the American Chemical Society, 72, 3746 (1950).
  12. H. Yaguchi, H. Hojo, D. G. Lee, and E. G. Kim, "Measurement of planar orientation of fibers for reinforced thermoplastics using image processing", Int. Polym. Processing, 10, 262 (1995).
  13. K. M. B. Jansen, D. J. Van Dijk, and E. V. Burgers, "Experimental validation of shrinkage predictions for injection molded products", Int. Polym. Processing, 13, 99 (1998).
  14. M.-Y. Lyu, J. G. Choi, and Y. Pae, "Investigation of the Jetting Phenomena in Injection Molding for Various Injection Speeds, Resins and Mold Shapes", Transactions of Materials Processing, 12, 3 (2003).