Effects of Wall Slip on Filling Flow for Polymer Melt in Micro Injection Molding

Abstract:

Effect of wall slip on melt filling flow behaviors in micro injection molding are investigated based on analysis of wall slip mechanism for polymer melt flowing at filling stage. By means of comparisons, slip coefficients in different microchannels are confirmed. With finite element method, the relationship between slip velocity and inlet flow rate or length-diameter ratio is analyzed. The results indicate that the wall slip happen for polymeric melt in microchannels, and slip coefficients are related with the size characteristics of microchannels. Moreover, wall slip velocity has the size effect and increase with the decrease of the section size of microchannels, which cause melt velocity distribution to smooth. At the same time, slip velocity is proportional to length-diameter ratio of microchannel, namely when wall shear stress is uniform, the slip velocity rises with increasing length-diameter ratio of microchannel.

• Periodical: Key Engineering Materials (Volumes 609-610)
• Pages: 617-622
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.609-610.617
• Online since: April 2014
• Authors: Jian Zhuang, Ya Jun Zhang, Da Ming Wu*, Li Zhu Liu, Cheng Jun Sun, Wei Wang, Shui Xing Liu
• Keywords: Filling Flow, Micro Injection Molding, Numerical Simulation, Wall Slip

References

[1] S.G. Hatzikiriakos, J.M. Dealy, Wall slip of molten high density polyethylenes II. capillary rheometer studies, J. Rheol. 36(1992) 703-714.

DOI: 10.1122/1.550313

[2] S.G. Hatzikiriakos, J.M. Dealy, Wall slip of molten high density polyethylene I. Sliding plate rheometer studies, J. Rheol. 35(1991) 497-523.

DOI: 10.1122/1.550178

[3] D.G. Yao, B. Kim, Scaling issues in miniaturization of injection molded parts, J. Manu. Sci. Eng. 126(2004) 733-738.

DOI: 10.1115/1.1813479

[4] W.B. Young, Simulation of the filling process in molding components with micro channels, Microsys. Tech. 11(2005) 410-415.

DOI: 10.1007/s00542-004-0474-4

[5] S.G. Hatzikiriakos, J.M. Dealy, The effect of interface condition on wall slip and melt fracture of high density polyethylene, ANTEC SPE Tech. 37(1991) 2311.

[6] C. S. Chen, S.C. Chen, W.L. Liaw, R.D. Chien. Rheological behavior of POM polymer melt flowing through micro-channels, Eur. Polym. J. 44(2008) 1891-1898.

DOI: 10.1016/j.eurpolymj.2008.03.007

[7] H. Hervet, L. Léger, Flow with slip at the wall: from simple to complex fluids, Physique, 4(2003) 241-249.

DOI: 10.1016/s1631-0705(03)00047-1

[8] L. Léger, H. Hervet, G. Massey, et al Wall slip in polymer melts, J. Phys.: Codens. Matter 9(1997) 7719-7740.

DOI: 10.1088/0953-8984/9/37/006

[9] D.G. Yao, B. Kim, Simulation of the filling process in micro channels for polymeric materials, J. Micromech. Microeng. 12(2002) 604-610.

DOI: 10.1088/0960-1317/12/5/314

[10] Y.M. Joshi, A.K. Lele, R. Mashelkar, A unified wall slip model, J. Non-Newtonian Fluid Mech. 94(2000) 135-149.

DOI: 10.1016/s0377-0257(00)00160-9