High strength injection molding welding and interface crystal phase changes in polyamide 6

Wu, Haonan; Qiu, Jianhui; Zhang, Guohong; SAKAI, Eiichi; Zhao, Wei; Tang, Jianhua; Wu, Hong; Guo, Shaoyun

doi:10.1002/pen.26446

Cited by 3 publications

(1 citation statement)

References 40 publications

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“…And they noted that processing parameters such as mold, melt temperature, injection velocity and packing time have little effect on the weld line factor for PP. For your reference, Wu H et al 20 noted that weld line strength was increasing over 60°C of the molded temperature under the polyamide resins 6. Although melt temperature and mold temperature are different for each material in Table 2, we guess there will be little significant impact on weld line strength because all the mold temperatures were low and the materials are PP in this study.…”

Section: Materials and Boundary Conditionmentioning

confidence: 99%

Simulation‐based analysis of weld line strength of glass fiber‐reinforced polymer in injection molding

Kameya,

Ogata,

Tanohata

2023

Polymer Engineering & Sci

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The injection molding market is expected to grow with the increasing demand from various industries, such as automotive and furniture. However, weld lines in the injection molded part reduce the structural strength and affects its appearance. This study evaluates the effect of the weld line on the structure by shifting the position of the weld line outside the area where the load is applied by manipulating the opening time of the injection gates. We examined the effect of weld lines on the strength of a chair through coupled resin flow and structural analyses. The analysis revealed that the position of the weld lines is crucial for structural strength if the knockdown factor (KDF) is low. Additionally, controlling the opening time of the gate and shifting the position of the weld line improved the structure's appearance, number of weld line and avoid the lower meeting angle. However, depending on the material, the effect may be weak. For example, when the weld line location did not change much despite changing the gate timing, little change was observed in the number of weld lines. Hence, the improvement strategy of weld line should be considered for material types and strength.Highlights Injection molding growth driven by automotive, packaging, furniture demand. Weld lines impact structural strength and appearance. Shifting weld line position outside load area improves the structural appearance and strength. Effects of shifting weld line position depended on the material types. Weld line position is crucial for low knockdown factor and affects strength.

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Section: Materials and Boundary Conditionmentioning

confidence: 99%

Simulation‐based analysis of weld line strength of glass fiber‐reinforced polymer in injection molding

Kameya,

Ogata,

Tanohata

2023

Polymer Engineering & Sci

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Interface enhancement and distribution of carbon fibers in injection welding

Wu,

Qiu,

Zhang

et al. 2024

Polymer Composites

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Injection welding is an excellent adhesive‐free bonding method for thermoplastic resins, demonstrating outstanding connection effectiveness. The incorporation of carbon fibers (CFs) significantly enhances the weld shear strength at the injection interface. This study aims to investigate the reinforcement effect of CF‐reinforced thermoplastic composites (CFRTP) during the injection welding process. And explore the influence of the amount of added CFs on the weld shear strength. Polyamide 6 (PA6)/CF composites with CF contents of 10 wt% and 30 wt% were subjected to injection welding for the first and second molding cycles, respectively. It was observed that the reinforcement effects varied considerably depending on the combinations studied. Under the optimal combination and process parameters, the weld shear strength of PA6/CF composites reached 63 MPa, equivalent to 90% of the shear strength (70 MPa) of the original PA6/CF material. Polarized light microscopy and scanning electron microscopy were utilized to analyze the distribution of CFs at the interface and the reinforcing mechanism during tensile fracture. The significance of maintaining uniform CF content during the welding process of PA6/CF composites was emphasized.Highlights Preparation of PA6 composite materials with different carbon fiber contents. Achieving high welding shear strength of composite materials through injection welding. Identified the optimal injection welding conditions to achieve the highest strength. The positive effect of specific fiber distribution on welding strength was analyzed.

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Optimization of polypropylene high-strength injection molding welding and interface structure analysis

Tang,

Qiu,

Sakai

et al. 2024

Journal of Thermoplastic Composite Materials

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Secondary injection molding is an effective method for joining polymer parts, where the weld interface plays a critical role in the overall performance of the part. This study discusses the influence of injection molding parameters on the interface strength of polypropylene and polypropylene (PP-PP) secondary injection molding and analyzes the welding interface structure. The injection molding parameters for PP-PP were optimized using the Taguchi method and the signal-to-noise ratio (S/N). The optimal injection molding parameters were determined to be a mold temperature of 120°C, injection temperature of 350°C, and injection speed of 100 mm/s. The interface tensile strength was measured at 33.42 MPa, corresponding to 98.1% of the tensile strength of the base material. Among these parameters, mold temperature has the greatest influence on the strength of the welding interface. Secondly, polarizing microscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were employed to observe and analyze the crystal structure and fracture failure modes at the interface. The results indicate that elevated injection molding parameters promote the formation of crystal nuclei and spherulite growth at the secondary melt interface, with the spherulite size at the interface significantly affecting the interface strength. This study offers valuable reference for the welding of other polymers and fiber-reinforced materials.

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High strength injection molding welding and interface crystal phase changes in polyamide 6

Cited by 3 publications

References 40 publications

Simulation‐based analysis of weld line strength of glass fiber‐reinforced polymer in injection molding

Simulation‐based analysis of weld line strength of glass fiber‐reinforced polymer in injection molding

Interface enhancement and distribution of carbon fibers in injection welding

Optimization of polypropylene high-strength injection molding welding and interface structure analysis

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