Ultrasonic investigations of the thermoplastics injection moulding process

Michaeli, Walter; Starke, Christopher

doi:10.1016/j.polymertesting.2004.08.009

Cited by 39 publications

(20 citation statements)

References 4 publications

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“…The use of an ultrasonic source has also been proposed to achieve both the plasticization of the material and the direct injection of the molten material [6][7][8]. This provides a new micro-molding technology that can be a serious alternative to conventional micro-injection techniques.…”

Section: Introductionmentioning

confidence: 99%

Dispersion of Functionalized Silica Micro- and Nanoparticles into Poly(nonamethylene Azelate) by Ultrasonic Micro-Molding

2015

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Ultrasound micro-molding technology has proved useful in processing biodegradable polymers with minimum material loss. This makes this technology particularly suitable for the production of biomedical microdevices. The use of silica (SiO2) nanoparticles is also interesting because of advantages like low cost and enhancement of final properties. Evaluation of the capacity to create a homogeneous dispersion of particles is crucial. Specifically, this feature was explored taking into account micro-and nano-sized silica particles and a biodegradable polyester derived from 1,9-nonanodiol and azelaic acid as a matrix. Results demonstrated that composites could be obtained with up to 6 wt. % of silica and that no degradation occurred even if particles were functionalized with a compatibilizer like (3-aminopropyl) triethoxysilane. Incorporation of nanoparticles should have a great influence on properties. Specifically, the effect on crystallization was evaluated by calorimetric and optical microscopy analyses. The overall crystallization rate was enhanced upon addition of functionalized silica nanospheres, even at the low percentage of 3 wt. %. This increase was mainly due to the ability of nanoparticles to act as heterogeneous nuclei during crystallization. However, the enhancement of the secondary nucleation process also played a significant role, as demonstrated by Lauritzen and Hoffmann analysis.

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Section: Introductionmentioning

confidence: 99%

Dispersion of Functionalized Silica Micro- and Nanoparticles into Poly(nonamethylene Azelate) by Ultrasonic Micro-Molding

2015

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“…Ultrasonic vibrations have been applied in a low-frequency range to injection molding screws [1,2] and mold sprues [3], and studies have analyzed the effects of shearing on orientation, crystallization and mechanical properties [4,5]. Ultrasonic vibration has also been applied to the extrusion of composites [6,7], and an ultrasonic measuring technique was used in the injection molding of thermoplastics [8]. Ultrasonic oscillations can improve the strength of a weld line by facilitating molecular diffusion across the line [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Yang

Huang

Lin

et al. 2014

Journal of Polymer Engineering

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This study investigated the use of ultrasonic technology in assisted injection molding (AIM) and mold design. An ultrasonic device installed in a mold was employed to vibrate a melt, thereby converting kinetic energy into thermal energy. This method enabled maintaining the desired temperature in the melt flow, preventing a high level of shear and the formation of a thick frozen layer surrounding the skin layer; thus, the injection molding efficiency was enhanced and the residual stress inside the injection-molded component was reduced. In this study, a flat sample (75 mm × 47 mm × 1 mm) of an ultrasonic-assisted injection mold was developed. An ultrasonic oscillation device 45 mm in diameter was placed in the center of the cavity and used to vibrate a polycarbonate melt at a frequency of 20 KHz. In addition, cavity pressure sensors were positioned at the front and rear of the vibration region to analyze the melt flow behavior under ultrasonic-AIM (UAIM) conditions. The results showed that ultrasonic oscillations can reduce the amount of melt pressure lost through the cavity. The pressure loss of the flat sample used in UAIM was approximately 29% lower than that of the sample used in conventional injection molding (CIM; nonultrasonic-assisted injection); the power of UAIM did not yield substantial effects. Direct ultrasonic oscillations destroyed the melt flow and thermal stresses, therefore, the region exhibited a low stress distribution. Compared with using CIM, using UAIM reduced the average residual stress by 27%. Ultrasonic oscillation affected the surface roughness during melt solidification. When the ultrasonic power was < 70%, no substantial increase in surface roughness was observed; however, when the ultrasonic power > 70%, the surface roughness was 10 times higher compared with that observed using CIM.

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“…Ultrasonic signatures can reflect physical and rheological properties of materials, process dynamics, material dynamics, process parameters, and product qualities (Gendron et al 1995, Michaeli andStarke 2005). Factor analysis, one of the static-analysis methods, can provide the tools for analyzing the structure of the interrelationships among a large number of variables by defining sets of highly correlated variables (Hair et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Torque value evaluated by ultrasonic technique during polymer melting process

Cheng

Liou

2012

Journal of the Chinese Institute of Engineers

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The torque profile during the melting process of low-density polyethylene (LDPE) pellets in an internal mixer has been estimated by ultrasound. Improved factor analysis was utilized to evaluate the relationship between torque and ultrasonic parameters and to rebuild the torque profile. The estimated torque value had an agreement with the measured data within 11%, which means that the presented ultrasonic measurement contained the same information as the torque measurement, namely viscosity. Therefore, the presented ultrasonic technique and evaluating method might be an optional approach to diagnose the melting process of polymer in the internal mixer and estimate the torque profile.

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Ultrasonic investigations of the thermoplastics injection moulding process

Cited by 39 publications

References 4 publications

Dispersion of Functionalized Silica Micro- and Nanoparticles into Poly(nonamethylene Azelate) by Ultrasonic Micro-Molding

Dispersion of Functionalized Silica Micro- and Nanoparticles into Poly(nonamethylene Azelate) by Ultrasonic Micro-Molding

Characteristics analysis and mold design for ultrasonic-assisted injection molding

Torque value evaluated by ultrasonic technique during polymer melting process

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