Abstract
Weld lines not only detract from an injection-molded part’s surface quality, but also significantly reduce its mechanical strength. It is not always easy to completely eliminate weld lines by simply adjusting the relevant injection mold design or the molding conditions. One solution is to prevent the weld lines from forming in regions that are structurally or aesthetically sensitive. The influence of weld lines on the quality of injection-molded parts cannot be overlooked and weld lines should be regarded as an important design constraint, especially for parts with aesthetic concerns. Since precisely predicting the number of weld lines and their positions and lengths is difficult without executing simulation routines, especially when part geometry is considered a design variable, this study adopts an enhanced genetic algorithm, referred to as distributed multi-population genetic algorithm (DMPGA), combining an optimization algorithm and commercial MoldFlow software with a dominance-based constraint-handling technique and a master–slave distributed architecture. MoldFlow obtains relevant data regarding warpage and weld lines and evaluates the corresponding designs. The dominance-based constraint-handling technique handles the weld line design constraint without needing additional penalty factors. Finally, the master–slave distributed architecture reduces the formidable computational time required for injection molding optimization. To illustrate the high viability of DMPGA, this study provides an outer frame of a digital photo frame as an optimization example. The results of this study show that DMPGA cannot only effectively decrease maximum part warpage without violating the weld line constraint, but also conquer hurdles attributed to constraint handling and computational demand.
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References
Gao Y, Wang X (2008) An effective warpage optimization method in injection molding based on the Kriging model. Int J Adv Manuf Technol 37:953–960
Kurtaran H, Erzurumlu T (2006) Efficient warpage optimization of thin shell plastic parts using response surface methodology and genetic algorithm. Int Adv Manuf Technol 27(5–6):468–472
Lee BH, Kim BH (1995) Optimization of part wall thicknesses to reduce warpage of injection-molded parts based on the modified complex method. Polym Plast Technol Eng 34(5):793–811
Ozcelik B, Erzurumlu T (2006) Comparison of the warpage optimization in the plastic injection molding using ANOVA, neural network model and genetic algorithm. J Mater Process Technol 171:437–445
Liu SJ, Wu JY, Chang JH, Hung SW (2000) An experimental matrix design to optimize the weldline strength in injection molded parts. Polym Eng Sci 40(5):1256–1262
Lee BH, Kim BH (1995) Automated selection of gate location based on desired quality of injection molded part. Polym Plast Technol Eng 35(2):253–269
Zhai M, Lam YC, Au CK (2006) Runner sizing and weld line positioning for plastics injection moulding with multiple gates. Eng Comput 21:218–224
Deng YM, Britton GA, Lam YC (2006) Towards automatic shape modification in injection-moulded-plastic-part design. Int J Adv Manuf Technol 28:495–503
Deng YM, Lam YC, Britton GA (2004) Optimisation of injection moulding conditions with user-definable objective functions based on a genetic algorithm. Int J Prod Res 42(7):35–88
Lam YC, Deng Y-M, Au CK (2006) A GA/gradient hybrid approach for injection moulding conditions optimisation. Eng Comput 21(3):193–202
Pandelidis I, Zou Q (1990) Optimization of injection molding design. Part II: molding conditions optimization. Polym Eng Sci 30(15):883–892
Zhou J, Turng LS (2007) Process optimization of injection molding using an adaptative surrogate model with gaussian process apptoach. Polym Eng Sci 47(5):684–694
Deng YM, Zheng D, Lu XJ (2008) Injection moulding optimization of multi-class design variables using a PSO algorithm. Int J Adv Manuf Technol 39:690–698
Deb K (2000) An efficient constraint handling method for genetic algorithms. Comput Meth Appl Mech Eng 186:311–338
Holland JH (1975) Adaptation in natural and artificial systems. University of Michigan Press, Ann Arbor, MI
Lam YC, Zhai LY, Tai K, Fok SC (2004) An evolutionary approach for cooling system optimization in plastic injection moulding. Int J Prod Res 42(10):2047–2061
Potts JC, Giddens TD, Yadav SB (1994) The development and evaluation of an improved genetic algorithm based on migration and artificial selection. IEEE Trans Syst Man Cybern 24(1):73–86
Mera NS, Elliott L, Ingham DB (2004) A multi-population genetic algorithm approach for solving ill-posed problems. Comput Mech 33:254–262
Chen XF, Gui WH, Cen LH, Hu ZK (2004) A multi-population genetic algorithm based on chaotic migration strategy and its application to inventory programming. Proceedings of the WCICA 3:2159–2162
Chen L, Chang FJ (2007) Applying a real-coded multi-population genetic algorithm to multi-reservoir operation. Hydrol Process 21:688–698
Cantú-Paz E (1998) A survey of parallel genetic algorithms. Calculateurs Parallèles, Réseaux et Systèmes Répartis 10(2):141–171
MoldFlow Corporation (2004) MoldFlow plastic insight 5.0. Moldflow Corporation, Wayland, MA
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Wu, CY., Ku, CC. & Pai, HY. Injection molding optimization with weld line design constraint using distributed multi-population genetic algorithm. Int J Adv Manuf Technol 52, 131–141 (2011). https://doi.org/10.1007/s00170-010-2719-y
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DOI: https://doi.org/10.1007/s00170-010-2719-y