Experimental and Theoretical Study of Melt Viscosity in Injection Process

The state of melt viscosity in injection process is significantly influenced by the setting parameters due to that the shear rate of injection process is higher than other processes. How to determine plastic melt viscosity during injection process is important to understand the influence of setting parameters on the melt viscosity. An apparatus named as pressure sensor bushing (PSB) module that is used to evaluate the melt viscosity during injection process is developed in this work. The formulations to coupling melt viscosity with fill time and injection pressure are derived and then the melt viscosity is determined. A test mold is prepared to evaluate the accuracy on viscosity calculations between the PSB module and the conventional approaches. The influence of melt viscosity on the tensile strength of molded part is proposed to study the consistency of injection quality.

• Chung-Chih Lin
• Wen-Teng Wang
• Chin-Chiuan Kuo
• Chieh-Liang Wu

• Injection molding
• melt viscosity
• injection quality
• injection speed.

[1] S. Mertes, C. Carlson, J. Bozzelli, andM. Groleau, "What position on the viscosity curve is the most repeatable with respect to end of fill cavity PSI,” in ANTEC conference, USA, 2001, pp. 620–624.
[2] D. M.Dlugas, and A. E.Kountz, "Investigation of differing approaches to determine an optimum injection velocity during mold filling,” in ANTEC conference, USA, 2011, pp. 1627–1635.
[3] S.H.Lee, S.Y.Kim, J.R.Youn, and B.J.Kim, "Warpage of a large-sized orthogonal stiffenedplate produced by injection molding and injection compression molding,” Journal of Applied Polymer Science, vol. 116, pp. 3460–3467, 2010.
[4] M.Kurt,O. S.Kamber, Y.Kaynak,G.Atakok, and O. Girit , "Experimental investigation of plastic injection molding: Assessment of the effects of cavity pressure and mold temperature on the quality of the final products,” Materials and Design, vol. 113, pp. 3217-3224, 2009.
[5] S. C. Chen, W. H. Liao, J. P. Yeh, and R. D. Chien , "Rheological behavior of PS polymer melt under ultra high speed injectionmolding,” Polymer Testing, vol. 31, pp. 864-869, 2012.
[6] J. P. Beaumont, "Runner and gating design handbook: tools for successful injection molding,” 2nd ed. Hanser, Ohio, 2007, pp. 125–132.
[7] C. C. Lin, "Influence of injection velocity on quality of insert molding,” Polymer Engineering and Science, vol. 52, pp. 268–276, 2012.