The inferential monitoring of screw load torque to predict process fluctuations in polymer extrusion

Abeykoon, Chamil; McAfee, Marion; Li, Kang; Martin, Peter; Kelly, Adrian L.

doi:10.1016/j.jmatprotec.2011.05.002

Cited by 22 publications

(16 citation statements)

References 7 publications

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“…Previous work by the author [21] reported an attempt to predict process thermal stability inferentially. Correlations between screw load torque, melt pressure, and melt temperature fluctuations were examined by analyzing experimentally measured signals.…”

Section: B Previous Work On Inferential Monitoring Of Point/bulk Melmentioning

confidence: 99%

A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

Abeykoon

2014

IEEE Trans. Ind. Electron.

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Polymer extrusion is the most fundamental technique for processing polymeric materials, and its importance is increasing due to the rapid growth of worldwide demand for polymeric materials. However, the process thermal monitoring is experiencing several problems resulting in poor process diagnostics and control. Most of the existing process thermal monitoring methods in industry only provide point/bulk measurements, which are less detailed and low in accuracy. Physical thermal profile measurements across the melt flow may not be industrially compatible due to their complexity, access requirements, invasiveness, etc. Therefore, inferential thermal profile monitoring techniques are invaluable for obtaining detailed, accurate, and industrially compatible measurements and, hence, to achieve improved process control. In this paper, a novel soft sensor strategy is proposed to predict the real-time temperature profile across the die melt flow in polymer extrusion for the first time in industry or research. It is capable of determining the melt temperature at a number of die radial positions only based on six readily measurable process parameters. A comparison between the simulation results of the novel melt temperature profile prediction soft sensor and the experimental measurements showed that the soft sensor can predict the real-time melt temperature profile of the die melt flow with good accuracy. Therefore, this will offer a promising solution for making real-time melt temperature profile measurements noninvasively in polymer extrusion, and also, it should be applicable to other polymer processes only with a few modifications. Moreover, this technique should facilitate in developing an advanced process thermal control strategy.Index Terms-Dynamic modeling, inferential measurements, melt temperature profile, polymer extrusion, process monitoring, soft sensor, process control. 0278-0046

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Section: B Previous Work On Inferential Monitoring Of Point/bulk Melmentioning

confidence: 99%

A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

Abeykoon

2014

IEEE Trans. Ind. Electron.

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“…The torque was recorded as a percentage (100% equals 24 Nm), and pressure was measured in bar (TM, 2006). It was reported that pressure and torque fluctuations change extrusion processing behavior (Abeykoon et al, 2011). In this study, different trends in torque and die pressure were observed.…”

Section: Resultsmentioning

confidence: 99%

Influence of degassing on hot-melt extrusion process

Alshahrani

Morott

Alshetaili

et al. 2015

European Journal of Pharmaceutical Sciences

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The present study aimed to evaluate the effect of degassing on an extrusion process, with respect to extrudate quality and drug release properties. Processed formulations were extruded with and without a degassing vent port at various locations along the barrel. All the experiments were performed under constant processing temperature, feeding rate, and screw speed. During the extrusion process, torque and pressure were monitored and recorded. The degassing process was beneficial when used over a conveying section after a mixing section. This is attributed to the large surface area available on the conveying elements, which minimizes the internal volume of the processed material, thereby facilitating the escape of entrapped gases. Degassing enhanced the homogeneity, physical appearance, and drug release properties of all the formulations. Furthermore, the degassing process also enhanced the cross-sectional uniformity of the extruded material, which is beneficial for visual monitoring during processing. Degassing considerably reduced the post-extrusion moisture content of Formula D3, which contains the highly hygroscopic polymer Kollidon® 17 PF, suggesting that the greatest influence of this process is on hygroscopic materials. The reduction in post-extrusion moisture content resulting from the inclusion of a degassing vent port, reduced fluctuations in the values of in-line monitoring parameters such as pressure and torque. Employing a degassing unit during hot-melt extrusion processing could help increase process efficacy and product quality.

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“…The typical variability of the melt temperature profile across the die melt flow over different processing conditions was discussed previously by the author [3,77,78,79,80,81,82] and a few other researchers [13,17,83]. If the melt flow is fully homogeneous in temperature, it should have flat melt temperature profile across the flow cross-section under all processing conditions (i.e., the ideal situation).…”

Section: A New Approach For Extrusion Controlmentioning

confidence: 97%

Single screw extrusion control: A comprehensive review and directions for improvements

Abeykoon

2016

Control Engineering Practice

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Polymer extrusion is usually a complex process, particularly due to the coupled nature of process parameters, and hence highly prone to fluctuations. Although a number of different approaches have been attempted in research/industry over the last few decades for extrusion control, it is still experiencing some problems in achieving consistent product quality. Presently, most of the polymer processing extruders are equipped with PID controllers mainly for the control of the screw speed and barrel temperatures in their set limits. It seems that only both of these controllers are commonly used as the major aids of process control to achieve the required melt quality. Although, the quality of the melt output (i.e., a thermally homogeneous melt output which is constant in quantity and quality over the time) is the key variable in polymer extrusion, only a few control techniques are available which make control decisions by observing the actual melt flow quality. Therefore, the development of new control strategies which consider the actual melt quality, perhaps incorporating industrially popular nonlinear techniques such as artificial intelligence, should be highly valuable. In this work, a critical evaluation is made on the state-of-the-art of the previous control approaches in polymer extrusion in industry and research while identifying their limitations. Then, some of the possible directions for future research and also to develop an advanced process control strategy are presented by eliminating a few of the existing limitations.

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The inferential monitoring of screw load torque to predict process fluctuations in polymer extrusion

Cited by 22 publications

References 7 publications

A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

Influence of degassing on hot-melt extrusion process

Single screw extrusion control: A comprehensive review and directions for improvements

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