Extrusion Line Research Articles

Experimentation, identification, and simulation of polymer swelling at extrusion die outlets

AbstractThe behavior of polyamide PA12 melt extrudates at die outlets is modeled to determine swelling process and rate. It is assessed as a function of imposed input parameters, process parameters, and die geometries. The modeling is carried out using Comsol Multiphysics® platform to simulate the swelling; in particular, its progression in time is investigated for different extrusion process parameters. The experimental swelling observed in extrusion lines tests is compared with the Tanner and Carreau‐Yasuda rheological models. A database is built up with all experiments carried out; the comparison between numerical and experimental results shows close agreement. A parametric analysis of the experimental and numerical swelling is performed. It confirms the important role of the die diameter on swelling rate, independently of shear rate. Increase in temperature lowers swelling rate at constant shear rates and geometric aspect ratio of the dies.Highlights Experimental and numerical study of polymer swelling at capillary die outlets. Behavior of PA12 polymer extrudate modeled to determine its swelling. Rheological models implemented to simulate the swelling phenomenon. Simulation results validated with experimental tests for two millimetric dies. Influence of die geometrical parameters investigated and justified.

Real-time temperature control in rubber extrusion lines: a neural network approach

In rubber extrusion, precise temperature control is critical due to the process’s sensitivity to fluctuating parameters like compound behavior and batch-specific material variations. Rapid adjustments to temperature deviations are essential to ensure stable throughput and extrudate surface integrity. Based on our previous research, which initiated the development of a feedforward neural network (FNN) without real-world empirical application, we now present a real-time control system using artificial neural networks (ANNs) for dynamic temperature regulation. The underlying FNN was trained on a dataset comprising different ethylene propylene diene monomer (EPDM) rubber compounds, totaling 14,923 measurement points for each temperature value. After training, the FNN achieves remarkable precision, evidenced by a mean absolute percentage error (MAPE) of 0.68% and a mean squared error (MSE) of 0.63°C2 in predicting temperature variations. Its integration into the control system enables real-time responsiveness, allowing for adjustments to temperature deviations within an average timeframe of 68 ms. A key advantage over proportional-integral-derivative (PID) controllers is the ability to continuously learn and adjust to complex, non-linear, and batch-specific process dynamics. This adaptability results in enhanced process stability, as evidenced by inline manufacturing validation. Our paper presents the first ANN-based rubber extrusion control, demonstrating how machine learning techniques can be effectively leveraged for real-time, adaptive temperature control. Beyond rubber extrusion, this strategy has potential applications in various polymer processing and other industries requiring precise temperature control. Future trends may involve the integration of online learning techniques and the expansion of interconnected manufacturing processes.

Force controlled printing for material extrusion additive manufacturing

In material extrusion additive manufacturing, the extrusion process is commonly controlled in a feed-forward fashion. The amount of material to be extruded at each printing location is pre-computed by a planning software. This approach is inherently unable to adapt the extrusion to external and unexpected disturbances, and the quality of the results strongly depends on a number of modeling and tuning parameters. To overcome these limitations, we propose the first framework for Force Controlled Printing for material extrusion additive manufacturing. We utilize a custom-built extruder to measure the extrusion force in real time, and use feedback on this quantity to continuously control the material flow in closed-loop. We demonstrate the existence of a strong correlation between extrusion force and line width, which we exploit to deposit lines of desired width in a width range of 33% up to 233% of the nozzle diameter. We also show how Force Controlled Printing outperforms conventional feed-forward extrusion in print quality and disturbance rejection, while requiring little tuning and automatically adapting to changes in the hardware settings. Our results demonstrate that Force Controlled Printing can deposit lines of desired width under severe disturbances in bed leveling, such as at layer heights ranging between 20% and 200% of the nominal height.

Integration of soft tooling by additive manufacturing in polymer profile extrusion process chain

Integrating additive manufacturing (AM) into polymer extrusion offers process chain flexibility and design freedom. It reduces the need for time-consuming iterations and trial-and-error in the die design process. Consequently, polymer AM of extrusion (i.e., soft tooling) allows for a shorter product development cycle and cost-effectiveness for small-scale production and highly customized products. In this study, carbon fibre (CF)-polyether-ether-ketone (PEEK) dies were manufactured using the fused filament fabrication (FFF) AM process, employing a streamlined die design achieved through freeform transition planes. Calibration slides were produced using masked stereolithography (MSLA), FFF, and conventional manufacturing techniques (i.e., machining) to preserve the final product’s cross-section during the cooling process. The dimensional and surface characteristics of these calibration slides were evaluated to assess the dimensional accuracy and surface topography of various materials and manufacturing processes. The dimensional evaluation reveals that MSLA-printed parts exhibit deviation from the nominal dimension closer to the conventionally manufactured part. The integrated soft tooling in the polymer extrusion line was tested with polypropylene (PP) and acrylonitrile butadiene styrene (ABS) as extruded materials. The surface topography of the CF-PEEK die displays distinctive ripple features resulting from the FFF process, identified by relatively flat peaks and deep valleys. The overall surface texture parameter values of CF-PEEK were higher due to the presence of deep valleys. Considering that the areas around the peaks interacted more with polymer molecules during the extrusion, the surface texture parameters of the extrudates were closer to the value observed in 90 µm region areas around the peaks. Notably, extrudates of AM calibration slides have lower surface texture parameters than extrudates of conventionally manufactured calibration slides, even though surface defects in the form of dimple sink marks were observed in extruded material of PP from extrudates using AM calibration slides.

Effects of high gravity on properties of parts fabricated using material extrusion system by additive manufacturing

Additive manufacturing (AM) has gained significant attention in recent years owing to its ability to fabricate intricate shapes and structures that are often challenging or unattainable using conventional manufacturing techniques. This high-quality development trend entails higher requirements for the structural design of 3D printers. In this study, polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) filaments were fed through a heated extrusion nozzle, which melted the material and deposited it onto a build platform. This study's objectives are high-gravitational material extrusion (HG-MEX) systems development, analyzing the high gravity influences on the flow behavior of materials during extrusion, and understanding the effects of gravitational on material flow and overall extrusion performance. HG-MEX systems have great potential for addressing various challenges in additive manufacturing, such as precise manufacturing. The highlight of the progress is that we developed an HG-MEX system and applied surface science to material extrusion in different gravity. We established a system and obtained results on different gravity, we analyzed the analogy between different gravity phenomena. We analyzed the interplay between the behavior of the fabricated parts and gravity. We analyzed high gravity effects on extrusion processes. The results confirmed the characteristics and feasibility of the developed system. The results suggest that a material extrusion line operating under 15 G conditions resulted in better printing quality compared to one operating under 1 G conditions. This observation implies that high gravity had a positive effect on the extrusion process, leading to improved material extrusion performance.

Assessment of property profile of post‐industrial polypropylene recyclates through a multivariable recycling process

AbstractThis study provides key insights into the extrusion of a post‐industrial feedstock primarily composed of polypropylene (PP) and reveals its influence on the property profile of the recyclate. The objective of this study was to gain a fundamental understanding of complex process‐property relationships. Therefore, a two‐part experimental design was established. The first part aimed to analyze the feedstock variability by investigating key material properties of recyclates produced under constant processing conditions. The second part aimed to systematically evaluate the effect of the screw speed, filtration setup, and degassing setup on the properties of the recyclates. An industrial‐scale recycling extrusion line was used. The material evaluation included melt mass‐flow rate (MFR), ash content, oxidation induction temperature, tensile and impact properties, degassing performance, and residual volatile organic compounds (VOCs). Higher melt temperatures led to chain scission of the PP fraction, resulting in increased MFR and higher material stiffness. Additionally, a finer filtration positively contributed to the enhanced material stiffness. Furthermore, the mechanical properties were also influenced by the levels of inorganic fillers in the material composition of the feedstock. Finally, the filtration setup had a greater impact on degassing performance and residual VOC levels than the degassing setup and screw speed.

DEPLOYMENT OF A VISION SENSOR AND AN EXPERT SYSTEM TO MINIMIZE PLASTIC WASTE: A CASE STUDY IN COLORED OPTICAL TUBES EXTRUSION

Industry 4.0 has expanded the alternatives to design more sustainable processes. Among the technologies of this industrial phase, IoT (Internet of Things) technology allows the linkage of devices that generate data at high volumes (big data), supporting the creation of Artificial Intelligence (AI) models to perform optimal operating standards to minimize waste in the production. By means of vision sensor and AI deployment, this study aimed to reduce the polybutylene plastic waste in an extrusion line of colored tubes, in which most of the waste is generated during the color transition. For that, a vision sensor that transfers the tube color in real-time was installed, which made it possible to set acceptance ranges for the standard colors of the tubes based on the elicitation of the operators' knowledge. These ranges allowed the setup of an expert system that warns the operator, by a light signal, the right time to start the production. The suggested technology demonstrated to be 11.47% more efficient in waste reduction in color transitions. It also allowed the identification of the requirements for the deployment of this technology in plastic extrusion, so it can promote overall waste reduction, which requires improvements in operation, standardization, and employee training.

Scheduling parallel extrusion lines

This paper introduces the problem of scheduling jobs on parallel plastic extrusion lines where each line is composed of one or more than one extruder. Although there are some similarities between the introduced problem and the non-identical parallel machines scheduling problems with sequence-dependent setup times, limited additional resources and machine eligibility restrictions, the problem considered in this paper is a generalization of the parallel machine scheduling problem. This is because in parallel machines scheduling each job requires only one machine but in our case some jobs require more than one machine. Thus, our problem reduces to the parallel machine scheduling problem if all jobs require only one machine. This paper describes the problem of scheduling parallel extrusion lines, its industrial context, and develops a mixed-linear formulation to model the problem. This formulation allowed solving instances of up to 15 jobs. In addition, we developed four metaheuristics: a simulated annealing algorithm, a tabu search heuristic, a genetic algorithm, and a greedy randomized adaptive search procedure. These metaheuristics can be used to solve real-life instances of the problem. A numerical experiment shows that the proposed metaheuristics produce excellent solutions. Some of the proposed simulated annealing adaptations and of the tabu search heuristics obtained solutions with less than 2% deviation from the optimum.

Assessing the Sensitivity of the Heat Transfer Coefficient at the Polymer-Calibrator Interface in Profile Extrusion

One of the major challenges in modeling the cooling stage of the thermoplastic profile extrusion process is defining the heat transfer coefficient at the polymer-calibrator interface (hint), which significantly affects the cooling rate. Accurate values for the hint are essential for improving process efficiency using numerical modeling codes. In the existing literature, values of hint are only available for a limited number of cases, and there are no systematic studies regarding the influence of processing conditions on this parameter. This study focuses on the determination of accurate values for hint and on the influence of processing parameters, namely: cooling fluid temperature, pulling velocity, and vacuum pressure. To accomplish this, a previously developed calibrator prototype, and associated methodology, targeting the measurement of hint for thermoplastic materials, is utilized in a conventional profile extrusion line. The results obtained show hint values in the range of 200–1500 W·m−2·K−1, which is in accordance with the results published in the available literature. The results also reveal that the cooling fluid temperature and the pulling velocity have the most substantial influence on hint, while vacuum pressure has minimal impact within the range of the experiments conducted.

Experimental Validation of a Micro-Extrusion Set-Up with In-Line Rheometry for the Production and Monitoring of Filaments for 3D-Printing.

The main objective of this work is to validate an in-line micro-slit rheometer and a micro-extrusion line, both designed for the in-line monitoring and production of filaments for 3D printing using small amounts of material. The micro-filament extrusion line is first presented and its operational window is assessed. The throughputs ranged between 0.045 kg/h and 0.15 kg/h with a maximum 3% error and with a melt temperature control within 1 °C under the processing conditions tested for an average residence time of about 3 min. The rheological micro slit is then presented and assessed using low-density polyethylene (LDPE) and cyclic olefin copolymer (COC). The excellent matching between the in-line micro-rheological data and the data measured with off-line rotational and capillary rheometers validate the in-line micro-slit rheometer. However, it is shown that the COC does not follow the Cox-Merz rule. The COC filaments produced with the micro-extrusion line were successfully used in the 3D printing of specimens for tensile testing. The quality of both filaments (less than 6% variation in diameter along the filament's length) and printed specimens validated the whole micro-set-up, which was eventually used to deliver a rheological mapping of COC printability.

Digital twins for the rapid startup of manufacturing processes: a case study in PVC tube extrusion

In this work, a soft sensor–based digital twin (DT) was developed to reduce the startup time in manufacturing plastic tubes and enable real-time product quality monitoring, i.e., the weight per unit length and the inner and outer diameters of the tube. An experimental campaign was conducted on a real tube extrusion line using three polyvinyl chloride (PVC) compounds and different process conditions, and machine learning regression algorithms were trained and tested to create the models of the extruder and the extrusion die the DT is based on. The characterization of the considered material, whose properties were given as input to the digital models, was carried out according to a procedure based only on the data collected by the production line. The DT was tested for the startup of the production of a single-layer tube and allowed to achieve the specified customer requirements (thickness and weight) in a few minutes. The proposed solution thus proved to be a valuable tool for reducing the setup time, thus increasing the efficiency of the process.

Improved extrusion of PP-R and PP-RCT pipes

Plastics processing company Bausano, based in Italy, describes how its new extrusion lines can produce improved PP-R and PP-RCT composite pipes.

Multi-Source-CT for inline inspection of extruded profiles

The market for extruded profiles for different applications (automotive, construction sector) is a big part of the plastics processing industry. Currently, the whole production process runs almost without quality checks. Only random tests are done to check the profile for its geometry, dimensions and defects. For extruded pipes and other rotation-symmetric products, there are special inline-inspection systems. However, none of these systems is capable of checking the whole inner and outer geometry of an arbitrarily formed profile. Due to this, we evaluate a concept for a multi-source-CT system, which is able to inspect the whole geometry of extruded profiles during the production process. In this work, we evaluate a concept and build a prototype system to validate the functional capability. Considerable attention is paid to the use of commercially available components because of the cost-effectiveness of the whole system. On the whole, the system comprises 16 x-ray-sources and two polygon-shaped detectors. The components are separated into two rings, each with eight x-ray sources and one detector. The rings are arranged around the extrusion line so that extruded profile traverses through the rings during the extrusion. The whole system is semi-static, which means the components are rigid relative to each other, but the system makes an eccentric movement perpendicular to the direction of extrusion. Due to this, the number of projection angles increases from 16 to about 420 projection angles, which is sufficient for reconstruction. To further increase the sampling rate, three x-ray-sources are pulsed simultaneously. Therefore, we are able to do a full 3D scan of extruded profiles with an extrusion feed of up 100 mm/sec.

3D Printing and Performance Study of Porous Artificial Bone Based on HA-ZrO2-PVA Composites.

An ideal artificial bone implant should have similar mechanical properties and biocompatibility to natural bone, as well as an internal structure that facilitates stomatal penetration. In this work, 3D printing was used to fabricate and investigate artificial bone composites based on HA-ZrO2-PVA. The composites were proportionally configured using zirconia (ZrO2), hydroxyapatite (HA) and polyvinyl alcohol (PVA), where the ZrO2 played a toughening role and PVA solution served as a binder. In order to obtain the optimal 3D printing process parameters for the composites, a theoretical model of the extrusion process of the composites was first established, followed by the optimization of various parameters including the spray head internal diameter, extrusion pressure, extrusion speed, and extrusion line width. The results showed that, at the optimum parameters of a spray head diameter of 0.2 mm, extrusion pressure values ranging from 1-3 bar, a line spacing of 0.8-1.5 mm, and a spray head displacement range of 8-10 mm/s, a better structure of biological bone scaffolds could be obtained. The mechanical tests performed on the scaffolds showed that the elastic modulus of the artificial bone scaffolds reached about 174 MPa, which fulfilled the biomechanical requirements of human bone. According to scanning electron microscope observation of the scaffold sample, the porosity of the scaffold sample was close to 65%, which can well promote the growth of chondrocytes and angiogenesis. In addition, c5.18 chondrocytes were used to verify the biocompatibility of the composite materials, and the cell proliferation was increased by 100% when compared with that of the control group. The results showed that the composite has good biocompatibility.

The effect of polyethylene glycol sorbitan monostearate on the morphological characteristics and performance of thermoplastic starch/biodegradable polyester blend films

Although thermoplastic starch (TPS) has been developed to mitigate greenhouse gas emissions and environmental and health-related impacts from plastics, high moisture sensitivity and poor mechanical properties limited its practical applications. Blending TPS with biodegradable polyesters, i.e., poly(lactic acid) (PLA) and poly(butylene succinate-co-butylene adipate) (PBSA), is an alternative approach; however, the compatibility among polymer phases needs to be improved. Here, polyethylene glycol sorbitan monostearate (Tween 60), an amphiphilic surfactant, was proposed to improve the compatibility and performance of the TPS/PLA/PBSA 40/30/30 blend. The concentration of Tween 60 varied in the range of 0.5–2.5 wt%. The blends were fabricated using an extruder through two different melt-mixing routes, i.e., direct mixing and masterbatch mixing, and then converted to film using a blown film extrusion line. Tween 60 could improve compatibility between TPS dispersed phase and PLA/PBSA matrix, resulting in increased tensile strength, extensibility, impact strength, thermal stability, and water vapor and oxygen barrier properties of the ternary blend. In addition, better performance of the blend was obtained from the direct mixing route. Tween 60 could thus be considered a potential compatibilizer for the TPS/PLA/PBSA blend film, which can be further used as a biodegradable packaging material.

Swelling phenomenon in rubber weatherstrip manufacturing under real process conditions imposed in a commercial extrusion line

Swelling phenomenon in rubber weatherstrip manufacturing under real process conditions imposed in a commercial extrusion line

Effect of annealing and heat-moisture pretreatment on the quality of 3D-printed wheat starch gels

This paper examines the effects of annealing treatment (ANN) and heat-moisture treatment (HMT) on the physicochemical and structural properties of wheat starch used for 3D food printing. Printing performance, molecular weight (Mw), amylopectin branch chain length distribution, pasting properties, rheology, fourier transform infrared (FT-IR) spectroscopy, texture and scanning electron microscopy (SEM) were used to evaluate the quality of printed products. Compared to untreated wheat starch, HMT improved the accuracy of 3D printing, stacking height of printed samples, and prolonged storage time of printed sample with softer texture. Conversely, ANN decreased printing performance, made sample edges rougher, reduced the stacking height of printed samples, and significantly increased sample hardness in storage. These effects are consistent with changes that these treatments made to the Mw of starch: compared to native starch and ANN, HMT increased the Mw of amylose and significantly decreased average Mw. In turn, this change decreased viscosity and G' of the starch gel, enabling smoother extrusion and better printing lines. In conclusion, HMT can improve 3D printing performance of wheat starch, increasing printing height and accuracy, which provides a simple and effective method to improve 3D printing effect using starch.

ОПТИМІЗАЦІЯ КАСКАДНОЇ СХЕМИ ВИСОКОШВИДКІСНОЇ ЕКСТРУЗІЇ

Plastics are one of the most common materials. Due to its high technical and economical characteristics, this class of materials is used in almost all industries, that is why further growth of the production of plastic products is predicted. Today, the biggest problem in the field of polymer processing by extrusion is to ensure the best possible parameters of resource-energy efficiency of equipment. At the same time, the creating of compounds based on polymers is developing very actively, which requires more flexibility from extrusion lines, since a large number of compositions which differ in their characteristics can be developed on the base of a polymer. The factors listed above have led to cascade extrusion lines become increasingly wide-spread in industry today. Analysis of the extrusion equipment market showed that the schemes with a high-speed double-string extruder at the first stage is more popular. However, the desired mixing quality can be achieved by using a much simpler disc extruder. The article is a review that aims to determine the possibility and feasibility of more efficient arrangement of a cascade scheme for processing composite materials using a disk extruder. Theoretical and experimental studies have shown that melting processes are more efficient in the field of high shear rates at low pressures. Disk extruder is great option for that objective. In this scheme, it is proposed to use a dose feed disk extruder as a homogenizer, and a gear pump as a metering device which allows to reduce pressure and capacity fluctuations before forming device to less than 1%. As a result, it has been determined that the proposed design of the extrusion plant will be more energy efficient than the options on the market and will be able to significantly reduce pressure and performance fluctuations at the inlet to the forming device.

A novel combo‐transmission system of cold energy and electricity for aluminium profile production: Using liquid nitrogen and superconductor technologies

AbstractAluminium production needs the most energy‐intensive technologies among all the metal processing sectors. During the process of aluminium profile extrusion, the whole production line needs bulk electricity, and the mold inside the extrusion equipment needs robust cold energy for rapid cooling of the metal surface. This paper presents a new combo‐transmission that can simultaneously deliver cold energy together with electricity to the aluminium profile extrusion line. Thanks to the superiority of virtually zero loss and compact size, the powerful superconducting cable is used to replace the conventional copper cable. The entire superconducting cable assembly is fully installed into a cryogenic pipeline and cooled by liquid nitrogen at 77 K. In addition to keeping a favourable cryogenic environment for the superconducting cable, liquid nitrogen can also provide a large amount of cold energy for cooling the metal surface. For a typical 100 MN aluminium extrusion production line, the design and optimization of 10 kA class superconducting cable with the pipeline cooling system for aluminium production are presented in detail. The simulation results and comparisons show that the total energy loss of superconducting transmission is about 46% of conventional copper cable, and the energy saved in a year can be up to about 240.6 MWh. Moreover, the net profit increases almost linearly along with the increases of the extrusion speed when the liquid nitrogen cooling is applied to the 100 MN production line. For the case of 23% increase in extrusion speed, the net profit can be up to 1.48 M$ in a year. Overall, the novel design, technical evaluation, and economic analysis of the combo‐transmission system (cold energy + electricity) can provide a promising solution for future high‐dense aluminium production sectors.

Metallic intraocular foreign body removal assisted through the extrusion line

AbstractPurpose: To describe an alternative vitreoretinal surgical manoeuvre, to remove metallic intraocular foreign bodies.Methods: Two patients, at different time lines, underwent vitrectomy to remove a metallic intraocular foreign body (IOFB). A 3‐port vitrectomy was performed, a 23‐G constellation vitrectomy equipment was used in both procedures, careful core vitrectomy was first done, vitreous adhesions and vitreous detachment was carefully done, retina was partially detached at the IOFB location, vitreous adhesions were cut and released gently not to increase the retinal detachment. Liquid prefluorocarbon was placed on the macula. As the vitreous adherences were cut, the IOFB was free from all potential tractional forces, the soft silicone tip cannula was held on to its surface, and at maximal vacuum aspiration, the IOFB was brought up to the anterior chamber, switching the light pipe for forceps in the other hand, and removed out of the eye. A complete as possible vitrectomy was performed, intraocular laser around the retinal brakes was performed, an intraocular lens was placed in the ciliary sulcus with the optic within the anterior capsule, and silicone oil was used as tamponade.Results: No signs of intraocular inflammation were recorded postoperatively. Intraocular silicone oil removal was done at the third post‐operative month in both cases, retina remained attached through follow up, both patients had over 9 months follow‐up visits, visual acuity improved from initial presentation, and also improved after the silicone oil tamponade removal.Conclusions: Active aspiration through the soft silicon tip cannula can be used to reach, and assist removal of metallic intraocular foreign bodies, being this manoeuvre safe, reproducible, possibly time‐saving, and also it could potentially avoid the risk of IOFB mobilization, avoiding further damage to the retina.