Weld line strength factors in a reinforced injection molded part: Relationship with predicted fiber orientation

Quintana, María Camila; Frontini, Patricia María

doi:10.1177/0731684419883941

Cited by 16 publications

(35 citation statements)

References 30 publications

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“…Weld line integrity factor in tensile strength, F w ( σ ) is the ratio of the tensile strengths of weld to a non-weld specimen at particular criteria as in equation (3), which is used to evaluate the depreciative effects of weld line on the composites. 16,18,39,43…”

Section: Resultsmentioning

confidence: 99%

“…However, the most common drawback of short fiber injection molded composites is weld lines in the finished product, which has attracted the wide attention of researchers. 16–20 The weld line is caused by the fusion of two or more flows of material, which form a distinct line after cooling. The presence of weld lines, on the one hand, destroys the external features of the material and attenuates its intrinsic strength, especially tensile strength and flexural strength.…”

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confidence: 99%

“…27 Some other studies differently focused on the effects of varying temperatures and loading conditions on the weld line of SFRTs of PP, polycarbonate (PC), polybutylene succinate (PBS), or PVC. 18,19,28–30 However, there is a significant lack of research information on SFRTs of PET with weld line and long-term durability-dependent prediction by time-temperature superposition analysis. As the weld line is the depreciative factor of the mechanical properties of the composite, long-term durability analysis by TTSP of weld injection polymer would be pretty different from non-weld materials, again adding short glass fibers can infer the mechanism far critical to explain.…”

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confidence: 99%

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Time-temperature-dependent mechanical durability analysis of short (glass) fiber-reinforced polyethylene terephthalate injection molding composites with weld line

Miah

Yang

et al. 2022

Textile Research Journal

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The mechanical property and long-term durable life of short fiber composites are inevitably subjected to internal and external influences during molding and afterwards, such as weld, temperature, stress type, and so on. This study was concerned with the influence of weld on mechanical properties of short glass fiber reinforced polyethylene terephthalate injection molding composites and the investigation of their tensile properties at different temperatures and tensile speeds with varying fiber contents. The weld strength was about 50–60% less than the tensile strength at different temperatures and tensile speeds. As the fiber content increased from 15 wt% to 30 wt%, the weld strength was reduced by 10%. The tensile and weld strength were in general inversely proportional to the temperature and linearly proportional to the tensile speed. Tensile modulus showed an inverse association with temperature and a mostly non-linear relation with the tensile speed. The weld line integrity in tensile strength was independent of tensile speed and temperature below the glass transition temperature level. Morphology evaluation testified that the higher test speed emanated better fracture surface fiber–resin adhesion properties with comparatively brittle fracture tensile behavior. The time-temperature superposition principle was applied to find the scope of long-term durability, lifetime prediction and to describe the viscoelastic properties of the welded glass fiber reinforced polyethylene terephthalate composites. An Arrhenius type of shift factor was obtained to fit the tensile strength data which was independent of the fiber contents of the welds. The experimental results can provide a valuable reference for the design and manufacture of short fiber-reinforced composites in long-term durability applications.

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Section: Resultsmentioning

confidence: 99%

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Time-temperature-dependent mechanical durability analysis of short (glass) fiber-reinforced polyethylene terephthalate injection molding composites with weld line

Miah

Yang

et al. 2022

Textile Research Journal

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“…The second type is flowing weld-lines which form when two flow fronts meet during flowing and usually occur when an obstacle is coming in-between flow. 5,6 When two melt fronts meet each other, the mechanical properties of the mating region are not as that of the parent material, this is because of molecular diffusion of the material, fiber orientation distortion, surface tension effect, etc. 1,7 Most of the time molecular diffusion and fiber orientation distortion reduces the strength of the part.…”

Section: Introductionmentioning

confidence: 99%

Effect of weld-line on tensile properties for thermoplastic glass filled material

Jadhav

Gaval

Divekar³

2022

Journal of Thermoplastic Composite Materials

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In an injection molding process, a weld-line forms when two flow fronts meet each other. Weld-line is a weak area which reduces the strength of the part locally. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. This paper presents the effect of weld-lines on tensile properties of glass fibers reinforced polyamide-6 composite. An injection molding plaque tool has been designed and manufactured with the inputs from mold flow simulation software. The gating system is designed in such a way that the angle between two flow fronts is as minimum as possible, which theoretically gives the lowest strength at weld locations. The plaques are manufactured with BASF material Ultramid B3WG6 grade (glass filled 30%) which is a widely used engineering plastic material. Test specimens have been cut on a plaque for various angular positions. Experimental evaluation for tensile testing, tensile modulus, and stressstrain behavior for specimens with and without weld-line at different angular positions was evaluated as per ISO 527-2 standards. It has been established that the weld line significantly influences the tensile properties of the part. The presence of a weld line results in a significant decrease in the tensile strength of the part. Experimental results show approximately 58% reduction in tensile modulus and 49% reduction in stress at break values in specimen with weld-lines as compared to specimen without weld-lines.

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“…Due to the complexity of analytical solutions, numerical simulations are often used to complete approximate solutions. The mathematical model of the PIM molding cycle before demolding, filling, holding and cooling is as follows [42].…”

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A research method to improve the quality of box-type thin-walled parts by combining parameter optimization and i nverse-deformation design

Zhai

Chang²,

Li³

et al. 2022

Preprint

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In this paper, a five-part study on the molding quality of box-type thin-walled injection molded parts with volume shrinkage and warpage deformation was conducted. In the first part, the molding parameters: filling time, plastic temperature, mold temperature (C), holding time (D), maximum holding pressure (E), and cooling time (F) were selected, and a six-factor, five-level L25 (5 6 ) orthogonal experimental design (OED) was designed. Then, the optimal combination of molding parameters was optimized by using gray correlation (GC) theory analysis. In the second part, the six molding parameters from the first part were further optimized based on the Box Behnken Design (BBD) response surface method (RSM) and BP neural network (BPNN) training, and the results showed that the fitted regression model after BPNN training had a smaller prediction error. In the third part, the regression models fitted with BBD and BPNN-BBD are further optimized globally. The optimization search method uses the NSGA-II genetic optimization algorithm. And comparing the above four optimization methods found that BPNN-BBD-NSGA-II prediction error < BPNN-BBD prediction error < BBD-NSGA-II prediction error < BBD prediction error. The fourth part is based on the anti-deformation design (ADD) theory. The NX/Moldex3D global optimization platform is created to finally almost completely eliminate warpage deformation of box-type thin-walled injection molded parts. In the last part, a trial mold verification analysis was performed, and the molding quality data was obtained by using optical scanning instruments, and the GOM software was used to compare and analyze the deviation values of each appearance surface and the flatness values.

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Weld line strength factors in a reinforced injection molded part: Relationship with predicted fiber orientation

Cited by 16 publications

References 30 publications

Time-temperature-dependent mechanical durability analysis of short (glass) fiber-reinforced polyethylene terephthalate injection molding composites with weld line

Time-temperature-dependent mechanical durability analysis of short (glass) fiber-reinforced polyethylene terephthalate injection molding composites with weld line

Effect of weld-line on tensile properties for thermoplastic glass filled material

A research method to improve the quality of box-type thin-walled parts by combining parameter optimization and i nverse-deformation design

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