Analysis of influence on process parameters of flow imbalance of H⁃shaped channel filling in microscale

doi:10.19491/j.issn.1001-9278.2022.01.015

Abstract

Abstract:

To explore the influence of the key factors on the imbalance of polymer melt filling at a micro scale， a numerical simulation experiment was conducted using polyoxymethylene as a raw material in a semi?circular H?shaped symmetrical distribution microchannel system with the consideration of the mold temperature， melt temperature， injection rate and microchannel size. The temperature difference data between the symmetrical points at the sprue was analyzed.The obtained results indicated that there was a temperature asymmetry in the flow channel system during the process of microinjection， and the temperature difference between the symmetrical points increased with an increase in injection rate. The larger the melt inlet temperature， the greater the temperature difference between the symmetry points， and the more obvious the filling imbalance. The smaller the microchannel size， the smaller the temperature difference between the symmetrical points. The filling imbalance was also improved. Increasing the mold temperature can reduce the convective heat transfer between the melt and the wall surface. This could reduce the temperature difference between the symmetrical points and improve the imbalance of filling.

Key words: mold temperature, melt temperature, injection rate, microchannel size, filling imbalance

CLC Number:

TQ320.66

YANG Bo, XU Bin, YANG Chaolong. Analysis of influence on process parameters of flow imbalance of H⁃shaped channel filling in microscale[J]. China Plastics, 2022, 36(1): 100-106.

Figures/Tables 8

Fig.1. Relationship curves between viscosity and shear rate of POM material

材料	n	η₀/Pa·s	A₁/K	A₂/ K	T^*/K	λ	C_p/J·（kg·K）^-1	κ /W·（m·K）^-1	ρ /kg·m^-3
POM	0.24	27 360	1.69	51.6	409.15	0.111 9	2 952	0.21	1 158

Tab.1. Viscosity model coefficient and Material parameters

Fig.2. Flow passage system layout and grid division

材料	熔体温度/K	注射速率/s^-1	模具温度/K
POM	500	5 000	393
	500	7 000	393
	510	9 000	403
	510	11 000	403
	520	13 000	413

Tab.2. The simulation experiment parameters are set horizontally

Fig.3. Temperature distribution of the whole runner system and the gate section

Fig.4. Influence of melt temperature on temperature difference at symmetry point

Fig.5. Influence of runner size on temperature difference at symmetry point

Fig.6. Influence of mold temperature on temperature difference at symmetry point

References 14

1	LIU J H， CHEN X D， DIAO SH P. Ultrasonic vibration technology for the polymer replication of high aspect ratio micro⁃structured surface［J］.Microsystem Technologies， 2018， 24（5）： 2 253⁃2 264.
2	GAO S， QIU Z J， MA Z. Development of high efficiency infrared⁃heating⁃assisted micro⁃injection molding for fabricating micro⁃needle array［J］. International Journal of Advanced Manufacturing Technology， 2017， 92（1⁃4）：831⁃838.
3	SURACE R， BELLANTONE V， TROTTA G， et al. Replicating capability investigation of micro features in injection moulding process［J］. Journal of Manufacturing Processes， 2017， 28：351⁃361.
4	DESANTIS F， PANTANI R. Development of a rapid surface temperature variation system and application to micro⁃injection molding［J］. Journal of Materials Processing Technology， 2016， 237：1⁃11.
5	MÉLÉ P， GIBOZ J. Micro⁃injection molding of thermoplastic polymers： proposal of a constitutive law as function of the aspect ratios［J］. Journal of Applied Polymer Science， 2017， 135（4）： 45719.
6	ZHANG N， GILCHRIST M. D. Characterization of thermo⁃rheological behavior of polymer melts during the micro injection moulding process［J］. Polymer Testing， 2012， 31（6）：748⁃758.
7	YOUSFI M， ALIX S， LEBEAU M， et al. Evaluation of rheological properties of non⁃Newtonian fluids in micro rheology compounder： experimental procedures for a reliable polymer melt viscosity measurement［J］. Polymer Testing， 2014， 40（10）：207⁃217.
8	MENG L， WU D， HE X， et al. Effect of surface tension on filling flow of carboxymethyl cellulose solution in microchannel［J］. Materials Research Innovations， 2015， 18（S2）： 1 034⁃1 039.
9	徐斌，邓鈴苹，杨宏韬，等.球形转角形状对于改善微结构塑件填充不平衡的实验研究［J］.中国塑料，2021，35（1）：67⁃72.
	XU B， DENG L P， YANG H T， et al. Experimental study on effect of spherical corner shape on improvement of filling imbalance of microstructural plastic parts［J］. China Plastics， 2021，35（1）：67⁃72.
10	WILCZYNSKI K， NAROWSKI P. Experimental and theoretical study on filling imbalance in geometrically balanced injection molds［J］. Polymer Engineering and Science， 2019， 59（2）： 233⁃245.
11	JAEYOUNG K， SEOKYOUNG A， SUNDAR V， et al. Imbalance filling of multi⁃cavity tooling during powder injection molding［J］. Powder Technology，2014，257：124⁃131.
12	BEAUMONT J， YOUNG J. Mold filling imbalances in geometrically balanced runner systems ［J］. Injection Molding Technology， 1997， 1（3）： 133⁃138.
13	杨卫民，谢鹏程. 注塑成型多模腔充填不平衡现象的产生机理（Ⅰ）［J］.中国塑料， 2004， 18（11）： 93⁃99.
	YANG W M， XIE P C. Mechanism of filling imbalance of plastics injection molding in multi⁃Cavity molds （Ⅰ）［J］. China Plastics， 2004， 18（11）：93⁃99.
14	杨卫民，谢鹏程. 注塑成型多模腔充填不平衡现象的产生机理（Ⅱ）［J］.中国塑料， 2004， 18（12）： 81⁃85.
	YANG W M， XIE P C. Mechanism of filling imbalance of plastics injection molding in multi⁃cavity molds （Ⅱ）［J］. China Plastics， 2004， 18（12）：81⁃85.

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[2]	. Study on Rapidly Thermal Cycle Injection Molding Using Carbide-bonded Graphene Coating [J]. China Plastics, 2016, 30(10): 55-59 .
[3]	. Injection Molding Filling Disequilibrium Analysis and Runner Design Improvements [J]. China Plastics, 2015, 29(12): 96-100 .
[4]	. Influence of Screw Parameters of Metering Section on the PC Melting Temperature Homogeneity in the Injection Molding of Light Guide Plates [J]. China Plastics, 2013, 27(05): 95-99 .
[5]	HAN Ke LI Zenghe XU Hong WU Daming. Study on Measurement Method for Dynamic Density of Polymer Melts [J]. China Plastics, 2011, 25(04): 98-101 .
[6]	LIU Xiwen YANG Zhongwen. Effects of Injection Molding Parameters on Glossiness of Polypropylene Parts [J]. China Plastics, 2011, 25(01): 76-79 .
[7]	Bing-Yan Jiang HOU Wen-Tan . Crystallization Properties of Injection Molded PE-HD Thin-wall Parts [J]. China Plastics, 2010, 24(08): 55-59 .
[8]	Zhou Ya-Wen LI Qing-Chun. Performance Evaluation of Injection Molding Screws Based on Melt Temperature Homogeneity [J]. China Plastics, 2010, 24(06): 91-96 .
[9]	. Application of Moldflow Software in Warpage Optimization of Injection Molded Parts [J]. China Plastics, 2010, 24(05): 78-80 .
[10]	LIU Xuhui HUANG Hanxiong. Visualization Study on Effect of Melt Temperature on Water Penetration Behavior During Water-assisted Injection Molding [J]. China Plastics, 2010, 24(04): 65-69 .
[11]	ZHUANG Jian;ZHANG Ya-jun;WANG Xiao-na;ZHAO Zhong-li;WU Da-ming. Experiments on the Process of Micro-connectors Based on Mirco-injection Molding [J]. China Plastics, 2009, 23(09): 67-70 .
[12]	WANG Tao;FU Jian;ZHOU Sheng. Effect of Injection Rate on the Breakthrough of Core-melt Front [J]. China Plastics, 2008, 22(9): 0-0 .
[13]	ZHAO Peng;ZHOU Hua-min;CUI Shu-biao;LI Ji-quan;LI De-qun. Determination of the Injection Time in Injection Molding [J]. China Plastics, 2008, 22(4): 62-65 .