Effect of processing on weld line strength in five thermoplastics

Seldén, R.

doi:10.1002/pen.11663

Cited by 86 publications

(98 citation statements)

References 15 publications

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“…Flow-fronts usually contain foreign substances, such as gases and moisture, which reduces good interfacial bonding and leads to the formation of V-notches, which serve as stress concentrators and crack initiators during the product lifetime. [2][3][4]7,8,11,12 Lastly, even without orientation or inclusion related problems, weldlines would be weaker regions, anyway, as with conventional cooling the flow-fronts that meet at these locations are at relatively low temperatures and do not possess sufficient heat energy for effective self-welding. [3][4][5] Thus, the afore-mentioned problems not only reduce product quality, but also cause inconsistencies in the properties from cycle to cycle result, which can cause major losses in both the time and money associated with product manufacture.…”

Section: Introductionmentioning

confidence: 96%

“…These are "frozen-in" before completely relaxing, and the result is a localized anisotropic and mechanically weak structure. [3][4][5]8 The second problem associated with weldlines is poor localized bonding resulting from insufficient entanglement of the molecular chains at the weld interface. Flow-fronts usually contain foreign substances, such as gases and moisture, which reduces good interfacial bonding and leads to the formation of V-notches, which serve as stress concentrators and crack initiators during the product lifetime.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the effect of processing variables on the mechanical response of polysytrene molded using vibration‐assisted injection molding process

Kikuchi

Coulter

Gomatam

2005

J of Applied Polymer Sci

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ABSTRACT:The present work is focused on the study of vibration-assisted injection molding (VAIM) process, using polystyrene as a model polymeric system. This recently developed polymer processing operation is based on the concept of using motion of the injection screw to apply mechanical vibration to polymer melt during the injection and packing stages of injection molding process, to control the polymer behavior at a molecular level, which would result in improvements/alterations to the mechanical behavior of molded products. In this study, the afore-mentioned concept was verified experimentally from monotonic tensile experiments and birefringence measurements of VAIM molded polystyrene in comparison with those of conventional injection molding process. The results of our study indicate that the actual degree of strength improvement depends on at least four parameters, namely, vibration frequency, vibration amplitude, vibration duration, and the delay time between the injection start and the vibration start. Furthermore, when these parameters were optimized, as much as a 28% strength improvement was observed, accompanied by an increase in toughness. Furthermore, birefringence measurements revealed that VAIM processing significantly altered the residual stress distribution throughout final products, but it did not, however, change the material density in the products.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Assessing the effect of processing variables on the mechanical response of polysytrene molded using vibration‐assisted injection molding process

Kikuchi

Coulter

Gomatam

2005

J of Applied Polymer Sci

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“…One of the design problems is to estimate the strength at the weld line [1], which is formed by two counter flows from injection gates. The fiber near the weld line is gradually changing its orientation with depth.…”

Section: Introductionmentioning

confidence: 99%

Exact closed form solution for an anti-plane deformation of anisotropic media

Watanabe

Nawi

2005

Quart. Appl. Math.

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Abstract.A closed form solution for the ordinary differential equation of Hill's type,is found and is applied to the stress analysis for an anisotropic medium whose axis of anisotropy is varying periodically with depth. Introduction.Recently, injection molded fiber-reinforced plastics have been widely used as mechanical parts. One of the design problems is to estimate the strength at the weld line [1], which is formed by two counter flows from injection gates. The fiber near the weld line is gradually changing its orientation with depth. Watanabe and Adachi [2] have employed an anisotropic solid with periodic variation of axis of anisotropy as a model of the material with the weld line. They have obtained an approximate solution (high frequency approximation) and discussed propagation of SH wave. The governing equation they tackled was complex and even for its static version was not tractable. Fortunately, the authors have found a closed form solution for the governing equation of its static version after considering a static solution around a crack edge in an anisotropic solid. The present paper shows how the exact solution is found and discusses its application to the stress analysis of an anisotropic solid with periodic variation of off-angle.

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“…Selden [60] , en otra línea de investigación, establece la correlación existente entre las características mecánicas de las líneas de soldadura del material con parámetros de proceso como la presión, temperatura de inyección y de refrigerante, y la velocidad de inyección.…”

Section: Guimond Y Simasunclassified

“…• Líneas de soldadura con baja resistencia mecánica (EF02_02) [28,31,[60][61][62] . La baja resistencia mecánica en las líneas de soldadura se explica por la desfavorable orientación y falta de unión de los frentes, así como la formación de pequeñas 4.12 entallas y de microatrapamientos de aire y volátiles del material.…”

Section: Ind01_04vcmn ; Inodo Y Elemento Entrada == C) Efectos Relacunclassified

Estudio y modelización de las condiciones de proceso en el moldeo por inyección de blends ABS/PC procedentes de materiales reciclados

Pérez¹,

Jorge²

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Agradecimientos.A la empresa Acteco, S.A. y, en particular, a D. Francisco J. Pérez Navarro, por facilitar el suministro y preparación del material, sin el que no hubiera podido realizar esta tesis.A la empresa Instrumentos Físicos Iberia, S.A. y, en particular, a D. Roberto Steinbruggen, por la gran ayuda prestada en los análisis de los materiales.A D. Vicente Chirivella, del Dpto. de Estadística e Investigación Operativa de la U.P.V., por el asesoramiento sobre los aspectos estadísticos empleados en la tesis.A D. Carlos Ferrer, Catedrático del Área de Ciencia de los Materiales e Ingeniería Metalúrgica de la UPV, por sus recomendaciones y consejos que han facilitado la tarea de redacción de la tesis.A mis compañeros del Área de Ciencia de los Materiales e Ingeniería Metalúrgica de la E.P.S. de Alcoy, Juan López y Rafael Balart, por el asesoramiento ofrecido durante la realización de la tesis.A todos mis compañeros del Área de Ingeniería de Procesos de Fabricación de la E.P.S. de Alcoy, Santiago, Miguel Ángel S., Teo, Raul, Rafael, Miguel Ángel P., David, Juanma y Javier, por las ayudas prestadas durante la elaboración de la tesis y que han permitido que ésta sea realidad.A mi compañero y amigo Jesús Seguí, por infinidad de cosas que él ya sabe… A mi director de tesis, D. José D. Zamanillo Cantolla, por su apoyo incondicional y por sus sabios consejos.A todos, muchas gracias. SumarioEl proceso de inyección es un proceso de conformado de los materiales poliméricos termoplásticos que, en la actualidad, presenta una notable importancia económica y tecnológica, y cuyo estudio ha supuesto multitud de investigaciones relacionadas con la determinación de condiciones óptimas de proceso.Por otra parte, los materiales poliméricos reciclados, resultado del desecho de productos que han finalizado su vida útil, representan una importante fuente de materias primas que puede ser reaprovechadas para la obtención de productos con calidades aceptables y con costes inferiores a los convencionales.Aglutinando los dos aspectos anteriores, la presente tesis tiene como objetivo el estudio y determinación de las condiciones de proceso mediante moldeo por inyección de blends de ABS/PC obtenidos a partir de materiales reciclados, proponiendo un modelo de procesabilidad de material que minimice la defectología de la pieza en condiciones de máxima estabilidad de variables de proceso. Para la realización de este estudio se han considerado mezclas de ABS con contenidos bajos de PC (0% -5% -10%) y se han comprobado las diferencias que dichos contenidos provocan sobre el comportamiento del material. Este estudio se ha estructurado en dos etapas diferenciadas, cuya secuenciación ha sido necesaria para su desarrollo.La primera fase está dedicada al estudio y modelización del material, con la perspectiva de la determinación de las características y parámetros necesarios para su procesado. A este respecto se ha desarrollado un modelo de comportamiento reológico de las diferentes mezclas del material, evaluable a partir de ensayos simples de labora...

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Effect of processing on weld line strength in five thermoplastics

Cited by 86 publications

References 15 publications

Assessing the effect of processing variables on the mechanical response of polysytrene molded using vibration‐assisted injection molding process

Assessing the effect of processing variables on the mechanical response of polysytrene molded using vibration‐assisted injection molding process

Exact closed form solution for an anti-plane deformation of anisotropic media

Estudio y modelización de las condiciones de proceso en el moldeo por inyección de blends ABS/PC procedentes de materiales reciclados

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