In-situ ultrasonic measurement of molten polymers during injection molding

Zhao, Peng; Ji, Kaipeng; Zhang, Jianfeng; Chen, Yuhong; Dong, Zhengyang; Zheng, Jianguo; Fu, Jianzhong

doi:10.1016/j.jmatprotec.2021.117081

Cited by 22 publications

(9 citation statements)

References 35 publications

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“…Recently, in 2021, Zhao et al [ 34 ] used ultrasound sensors to measure the melt temperature inline. A new approach was proposed by the correlation of ultrasound principles and the PVT equation in ( 4 ).…”

Section: Conventional Ultrasonic Transducer (Ut) Applications In the Injection Moulding Processmentioning

confidence: 99%

Ultrasound Sensors for Process Monitoring in Injection Moulding

Kariminejad

Tormey

Huq

et al. 2021

Sensors

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Injection moulding is an extremely important industrial process, being one of the most commonly-used plastic formation techniques. However, the industry faces many current challenges associated with demands for greater product customisation, higher precision and, most urgently, a shift towards more sustainable materials and processing. Accurate real-time sensing of the material and part properties during processing is key to achieving rapid process optimisation and set-up, reducing down-times, and reducing waste material and energy in the production of defective products. While most commercial processes rely on point measurements of pressure and temperature, ultrasound transducers represent a non-invasive and non-destructive source of rich information on the mould, the cavity and the polymer melt, and its morphology, which affect critical quality parameters such as shrinkage and warpage. In this paper the relationship between polymer properties and the propagation of ultrasonic waves is described and the application of ultrasound measurements in injection moulding is evaluated. The principles and operation of both conventional and high temperature ultrasound transducers (HTUTs) are reviewed together with their impact on improving the efficiency of the injection moulding process. The benefits and challenges associated with the recent development of sol-gel methods for HTUT fabrication are described together with a synopsis of further research and development needed to ensure a greater industrial uptake of ultrasonic sensing in injection moulding.

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Section: Conventional Ultrasonic Transducer (Ut) Applications In the Injection Moulding Processmentioning

confidence: 99%

Ultrasound Sensors for Process Monitoring in Injection Moulding

Kariminejad

Tormey

Huq

et al. 2021

Sensors

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“…This is because the parts of the measurement device in contact with the molten polymer must have high heat and pressure resistances under the process’s repetitive, nonsteady-state operation. Scientists have proposed ultrasonic sensors − and near-infrared spectroscopic (NIR) sensors − for in-line measurements of process variables that are not easy to measure with conventional sensors. Ultrasonic sensors have attracted attention because they can be attached directly to the outer surface of molds or barrels without the need to modify the equipment.…”

Section: Introductionmentioning

confidence: 99%

In-Line Monitoring of the Physical Blowing Agent Concentration by Transmission Near-Infrared Spectroscopy with High-Pressure Resistance Fiber Optic Probes for Foam Injection Molding Processes

Yoshikawa

Hosoe

Hikima

et al. 2023

Ind. Eng. Chem. Res.

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Control of the physical blowing agent (PBA) concentration in polymers is critical in achieving stable production of polymeric foams. However, there are very few in-line chemical monitoring techniques for foam injection molding (FIM) processes. The difficulty in sensor application with regard to FIM comes from nonsteady-state operations, where the temperature and pressure temporarily change dynamically. We invented an in-house fiber optic near-infrared (NIR) probe with high-pressure and high-temperature resistances and applied it to the transmission NIR spectroscopy of FIM processes to monitor the PBA, i.e., CO 2 , dissolved in the molten polymer. The CO 2 concentration was successfully monitored from the CO 2 absorption spectra at 4952 cm −1 and the polymer's absorption spectra even at a 120 MPa injection pressure and 200 °C processing temperature. Furthermore, the phase separation of CO 2 from the polymer before injection was detected from the decrease in transmittance of the NIR spectra.

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“…During conventional processes of injection molding, constant-temperature injection molds are used. The difference between temperatures of flowing stream of plastic and molding surface causes the plastic melt to cool down and its viscosity to increase along with the distance traveled [30]. The formation of frozen layers reduces the cross-section of the cavity, making it impossible to fill the forming areas, which are the farthest from the injection point.…”

Section: Introductionmentioning

confidence: 99%

Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges

et al. 2021

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Injection molding is a polymer processing technology used for manufacturing parts with elastic hinges. Elastic hinges are widely used in FMCG (Fast Moving Consumer Goods) packaging (e.g., bottle closures of shampoos, sauces) and in the electrical engineering industry. Elastic hinge is a thin film that connect two regions of the injection molded part, where significant shear rates are present, which can lead to the degradation of polymers and the decrease in mechanical properties. Selective induction heating is the method that improves the flow of the polymer melt through thin regions by the local increase in mold temperature. In this study, selective induction heating was used to improve mechanical properties of elastic hinges by the reduction of material degradation due to high shear rates. To verify the change of shear rates, selective induction heating simulation and injection molding simulations were performed. The linear relation between mold temperature and maximum shear rate in the cross-section was identified and the mechanical tests showed significant differences in hinge stiffness, tensile strength and elongation at break.

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In-situ ultrasonic measurement of molten polymers during injection molding

Cited by 22 publications

References 35 publications

Ultrasound Sensors for Process Monitoring in Injection Moulding

Ultrasound Sensors for Process Monitoring in Injection Moulding

In-Line Monitoring of the Physical Blowing Agent Concentration by Transmission Near-Infrared Spectroscopy with High-Pressure Resistance Fiber Optic Probes for Foam Injection Molding Processes

Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges

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