Polymer melt flow and gas penetration in gasassisted injection molding of a thin part with gas channel design

Chen, Shia Chung; Hsu, K. F.; Hsu, K. S.

doi:10.1016/0017-9310(95)00379-7

Cited by 23 publications

(6 citation statements)

References 4 publications

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“…H~0 : 5 (implicit Crank À Nicolson scheme) (11) With the initial melt and water temperatures given and the boundary temperature assigned at the mould/ polymer interface, the numerical iteration provides the temperature distribution inside the moulded article at different elapsed times.…”

Section: Numerical Simulation Of Heat Transfer Theory Of Transient He...mentioning

confidence: 99%

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Liu¹,

Chen²

2004

Plastics, Rubber and Composites

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This report investigated, both experimentally and numerically, the cooling process in water assisted injection moulded parts. Experiments were carried out on a laboratory developed water assisted injection moulding system, which included an injection moulding machine, a water pump, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The resin used was semi-crystalline polypropylene. The in-mould temperature of the polymeric materials during the cooling process was measured. A transient heat transfer finite element model was adopted to simulate and predict the temperature variation within water assisted injection moulded products. Simulated results matched well with the experimental data. Experimental investigation and numerical simulations of a water assisted injection moulding cooling process can provide an improved understanding of the influence of water related parameters on the cooling process of water assisted injection moulded parts.

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Section: Numerical Simulation Of Heat Transfer Theory Of Transient He...mentioning

confidence: 99%

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Liu¹,

Chen²

2004

Plastics, Rubber and Composites

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“…In recent years, significant progress has been made towards the simulation of the polymer/gas interface distribution in GAIM moldings. Potente and Hansen [11], Cheng et al [12–16], Barton and Turng [17], Turng [18], Li and Isayev [19], Lin et al [20] and Polynkin et al [21] have studied extensively the influence of processing variables on the polymer/gas interface distribution for various polymers and mold geometries. The literature in relation to the influence of the processing variables on the polymer/gas interface distribution in GAIM has been discussed earlier [19, 22, 23].…”

Section: Introductionmentioning

confidence: 99%

Flow and thermally induced birefringence in gas‐assisted tubular injection moldings: Simulation and experiment

Carrillo

Isayev

2012

Polymer Engineering & Sci

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Various components of birefringence in polystyrene (PS) and polycarbonate (PC) tubular moldings, obtained by gas‐assisted injection molding (GAIM), are measured and simulated considering both flow‐ and thermally induced stresses. The flow‐ and thermally induced stresses are calculated using nonlinear and linear viscoelastic theories, respectively, based on the flow and temperature histories that the polymer experiences during the GAIM cycle. Flow‐induced birefringence components are calculated from flow stresses using the stress optical rule, while thermally induced birefringence components are calculated from thermal stresses using a photoviscoelastic model. The simulated total residual birefringence takes into account the contributions of both flow‐ and thermally induced birefringence generated during the melt injection, gas injection, and cooling stages of GAIM. The simulated results are in better agreement with the measured birefringence in PS moldings than in PC moldings. Considering both thermal and flow birefringence, simulations provides a better description of the experimental results indicating that, in GAIM moldings, the birefringence near the mold was caused mainly by flow stresses while that located towards the polymer/gas interface was caused mainly by thermal stresses. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

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“…At the present stage, process simulation for the melt filling and gas-assisted filling stages [3][4][5][6][7][8] has been developed, and some of them were incorporated into several commercial packages, such as C-GASFLOW, Moldflow/Gas, and CADMOLULD-MEGIT, etc. Two key factors that affect the simulation accuracy most are the algorithm used for the calculation of skin melt thickness and the geometrical modeling approach used to represent gas channels.…”

Section: Introductionmentioning

confidence: 99%

“…Such analysis approach has been verified for melt flow in thin cavity with channels of semicircular and quadrantal cross-sections reported recently. [7][8][9] Although the approach of assigning variable thickness to gas channels was used by CADMOLULD-MEGIT 4 and STRIMFLOW/Gas, it meets the difficulty for describing gas channels with a thin and long rib attached on their top. Basically, gas is not easy to penetrate this thin rib on the top of the gas channel.…”

Section: Introductionmentioning

confidence: 99%

Integrated simulations of structural performance, molding process, and warpage for gas-assisted injection-molded parts. III. Simulation of cyclic, transient variations in mold wall temperatures

Chen

Jong

1999

J. Appl. Polym. Sci.

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Whether it is feasible to perform an integrated simulation for structural analysis, process simulation, as well as warpage calculation based on a unified CAE model for gas-assisted injection molding (GAIM) is a great concern. In the present study, numerical algorithms based on the same CAE model used for process simulation regarding filling and packing stages were developed to simulate the cooling phase of GAIM considering the influence of the cooling system. The cycle-averaged mold cavity surface temperature distribution within a steady cycle is first calculated based on a steady-state approach to count for overall heat balance using three-dimensional modified boundary element technique. The part temperature distribution and profiles, as well as the associated transient heat flux on plastic-mold interface, are then computed by a finite difference method in a decoupled manner. Finally, the difference between cycle-averaged heat flux and transient heat flux is analyzed to obtain the cyclic, transient mold cavity surface temperatures. The analysis results for GAIM plates with semicircular gas channel design are illustrated and discussed. It was found that the difference in cycle-averaged mold wall temperatures may be as high as 10°C and within a steady cycle, part temperatures may also vary ϳ 15°C. The conversion of gas channel into equivalent circular pipe and further simplified to two-node elements using a line source approach not only affects the mold wall temperature calculation very slightly, but also reduces the computer time by 95%. This investigation indicates that it is feasible to achieve an integrated process simulation for GAIM under one CAE model, resulting in great computational efficiency for industrial application.

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Polymer melt flow and gas penetration in gasassisted injection molding of a thin part with gas channel design

Cited by 23 publications

References 4 publications

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Flow and thermally induced birefringence in gas‐assisted tubular injection moldings: Simulation and experiment

Integrated simulations of structural performance, molding process, and warpage for gas-assisted injection-molded parts. III. Simulation of cyclic, transient variations in mold wall temperatures

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