Experimental Study on Gas Penetration Characteristics in a Spiral Tube during Gas-Assisted Injection Molding

Chen, Shia C.; Hsu, K. S.; Huang, Jiashun

doi:10.1021/ie00040a048

Cited by 35 publications

(31 citation statements)

References 4 publications

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“…So far, most literatures mainly focused on the mathematic simulation of gas penetration, [4][5][6][7][8][11][12][13][14][15] the effect of the gas channel design on the gas penetration behavior, 3,4,6,16 molding window, 3,10,17 the influence of gas channel shape on the mechanical properties [18][19][20] and so on, while studies on the morphology development in GAIM part and the relationship between microstructure and macroproperties are limited. Chien 21 explored the influence of gas channel shape on the mechanical properties of GAIM moldings as well as the crystallnity of polyamide (PA), and found that maximum tensile load and ultimate tensile stress of PA moldings exhibited significant dependence on part thickness because of higher degree of crystallinity.…”

Section: Introductionmentioning

confidence: 99%

Morphology of gas‐assisted and conventional injection molded polycarbonate/polyethylene blend

Zheng

Yang

Yin

et al. 2006

J of Applied Polymer Sci

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The skin-core structure of the gas-assisted and conventional injection molded polycarbonate (PC)/polyethylene (PE) blend was investigated. The results indicated that both the size and the shape of the dispersed PC phase depended not only on the nature of PC/PE blend and molding parameters, but also on its location in the parts. Although the gas-assisted injection molding (GAIM) parts and conventional injection molding (CIM) part have the similar skin-core structure, the morphology evolution of PC phase in the GAIM moldings and the CIM moldings showed completely different characteristics. In the section perpendicular to the melt flow direction, the morphology of the GAIM moldings included five layers, skin intermediate layer, subskin, core layer, core intermediate layer as well as gas channel intermediate layer, according to the degree of deformation. PC phase changed severely in the core layer of GAIM moldings, as well as in the subskin of CIM moldings. In GAIM parts, PC phase in the core layer of the nongate end changed far more intensely and aligned much orderly than that in the gate end. The morphology of PC phase in the GAIM part molded with higher gas pressure changed more severe than that in the GAIM part molded with lower gas pressure. In a word, PC phase showed more obvious fibrillation in the GAIM moldings than that in the CIM moldings.

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Section: Introductionmentioning

confidence: 99%

Morphology of gas‐assisted and conventional injection molded polycarbonate/polyethylene blend

Zheng

Yang

Yin

et al. 2006

J of Applied Polymer Sci

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“…11 In the fullshot GAIM process, the gas penetration length decreased as the gas delay time increased. The major penetration mechanisms of full-shot and shortshot GAIM processes are different.…”

Section: Summary On the Effects Of The Processing Conditions On The Gmentioning

confidence: 99%

Secondary gas penetrations in ribs during full‐shot gas‐assisted injection molding

2003

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Although gas-assisted injection molding (GAIM) eliminates sink marks and prevents warpage, many problems are encountered during gas-assisted filling owing to gas-melt flow interactions. Large voids created by gas penetration during gas-assisted filling result in degraded rigidity. To avoid gas-assisted filling, the shot weight is increased to 100%. Gas is injected after the cavity is completely filled. The so-called "full-shot gas-assisted injection molding" process is investigated in this paper. The effects of the processing conditions and rib geometry on the behavior of gas penetration are systematically investigated. High melt temperature and a short gas injection delay time are found to increase the length of gas penetration during full-shot GAIM. Wide ribs and ribs with fillets cause the gas penetration length to decrease. Although the mechanisms of gas penetration for short-shot and full-shot GAIMs are not identical, the resulting penetration patterns of the gas void shape are similar.

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“…5 The correlation of hollowed core ratio with gas pressure for spiral tubes 8 and 10 mm diameter under injection strokes of 81% and 87% at a delay time of 1 . 0 s, are shown in Fig.…”

Section: Characteristics Of Gas Penetration In Spiral Tubementioning

confidence: 99%

“…The correlation of the processing parameters, including gas pressure, delay time, melt temperature, and mould temperature with gas penetration length and skin-melt thickness ratio was investigated. 5 In addition, quantitative design guidelines for gas channel section geometry were also investigated. Plate parts of different thicknesses, semicircular gas channels with different radii, and rectangular gas channels with different width to height ratios were used in gas-assisted injection moulding to investigate the effects of geometry on gas penetration characteristics.…”

Section: Introductionmentioning

confidence: 99%

Study of mouldability in gas-assisted injection moulded fibre-reinforced Nylon parts

Chen¹,

Chien²,

Chen³

et al. 2004

Plastics, Rubber and Composites

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Investigation of the characteristics of gas penetration in gas-assisted injection moulding (GAIM) of parts plays an important role in the successful application of gas-assisted injection moulding. Although these have been proposed by various investigators, quantitative rules based on well designed experiments on fibre-reinforced plastic materials have not been reported previously. Additions of glass-fibre bring about rather dramatic changes in material viscosity and heat conductivity, etc. In the present paper, spiral tube moulds with uniform diameters of 8 and 10 mm, respectively, and a plate mould of 3 mm thickness with gas channel design of semicircular crosssection were moulded using glass-fibre reinforced Nylon resin. The effects of fibre content, tube diameter, and processing parameters, including gas pressure, delay time, and injection stroke on gas penetration characteristics and mouldability for fibre-reinforced Nylon parts were investigated experimentally. It was found that the coating melt thickness decreases with increasing gas pressure, until the gas pressure reaches a critical value, when the coating melt thickness becomes relatively constant for the spiral tube. Meanwhile, using a longer delay time for gas injection will increase the skin melt thickness. The hollowed core ratio increases with increasing diameter of spiral tube. Alternatively, the hollowed core ratio of GAIM plate and spiral tube parts increases when the content of glass-fibre is increased. However, when the fibre content is over 10 wt-%, it shows less influence on the hollowed core ratio for plate parts. Furthermore, although the area of the moulding window decreases with increasing content of fibre, they all show good mouldability. From these results, one can provide an empirical formula to CAE simulation designers and part/mould designers for GAIM fibre-reinforced Nylon parts to achieve suitable mouldability and accurate CAE simulation.

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Experimental Study on Gas Penetration Characteristics in a Spiral Tube during Gas-Assisted Injection Molding

Cited by 35 publications

References 4 publications

Morphology of gas‐assisted and conventional injection molded polycarbonate/polyethylene blend

Morphology of gas‐assisted and conventional injection molded polycarbonate/polyethylene blend

Secondary gas penetrations in ribs during full‐shot gas‐assisted injection molding

Study of mouldability in gas-assisted injection moulded fibre-reinforced Nylon parts

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