Extrusion System Research Articles

Scale-up fabrication of a biodegradable PBAT/PLA composite film compatibilized with a chain extender for industrial agricultural mulch film application

Low-density polyethylene (LDPE) mulch films have become a prevalent practice in agriculture to increase crop yield. However, because of their high environmental impact after use, biodegradable plastic films are considered desirable alternatives in agroecosystems. Herein, a polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) composite film compatibilized with a chain extender (CE) was prepared via a two-step extrusion process. First, PBAT and PLA were blended at different ratios in a laboratory-scale twin-screw extruder, and the PBAT/PLA blends (80/20 wt.%) compatibilized with 1 phr of CE exhibited the most comparable physicochemical properties. The CE integration into the PBAT/PLA binary blend significantly increased mechanical rigidity and strength (p ≤ 0.05). The enhanced compatibility between the immiscible polymers was verified through thermal and phase morphological analyses. The optimum composite was then produced using a pilot-scale extrusion system. The pilot-scale extruded optimal biodegradable mulch composite exhibited excellent water barrier properties, as evidenced by a water vapor permeability of 0.83 g mm/m2·day·kPa and a water contact angle of 93.77° These values surpassed those of commercially available biodegradable mulch films. Furthermore, it demonstrated a weight reduction of 2.9% during a 3-month period of soil burial, exhibiting durability compared to commercial biodegradable mulch films. These results suggest that the developed film has great potential for practical food and agricultural applications.

Adaptive Toolpath Generation for Material Extrusion Additive Manufacturing Using a Nozzle with Rectangular Orifice

Material Extrusion Additive Manufacturing has greatly simplified the production of complex designs, but it is often accompanied by a trade-off between build resolution and build rate. A higher build resolution can improve the quality of the finished product, but it also slows down the production process. This compromise can be fine-tuned between production runs via alternative sizes of the primary manufacturing tool (i.e., the nozzle), but, in-process reconfiguration of the nozzle is not utilized in the usual Fused Filament Fabrication (FFF) applications. An extrusion system featuring a rotatable rectangular-orifice nozzle can be employed to tune the build resolution. The effective size of the extrusion can be altered through rotational guidance, where a single nozzle acts as if it possesses various orifice sizes. This method holds the potential to introduce variable bead width and height in the process by employing intermediate orientations of the rectangular cross-section. Nevertheless, the implementation of this concept necessitates the development of a customized tool path planning approach. This paper presents methods for planning the trajectory and spin of a rectangular-orifice nozzle to effectively control the position and width of the printed trace. The intention is to promote rapid extrusion of interior regions and enable the printing of finer details with more accuracy. Due to the critical nature of shell manufacturing and infill generation in FFF, dedicated modes of operation have been developed for these tasks. Versatile test cases are developed for the purpose of evaluating the introduced strategies. The results of these test cases demonstrate the applicability of the proposed method for achieving controllable resolution in FFF.

In-situ additive manufacturing deposition trajectory monitoring and compensation with thermal camera

Modern additive manufacturing systems still suffer from low fabrication accuracy and speed. This issue is particularly severe for thermal reaction bonding material extrusion systems, where the motion and the deposition processes are coupled. To enhance the deposition accuracy, this work established a method to use real-time in-situ thermal images to capture and compensate for the geometrical accuracy of the printed parts and establish the spatial and temporal relationship between the inaccuracy and the deposition trajectory commands. The paper derives an analytical slender condition to process the printing regions with low curvature while establishing deposition direction allocation methods to account for the trajectory regions with high curvature. Real-time thermal image localization is performed with key printing feature detection and calibration. The localized and calibrated thermal images are aligned with the defined deposition direction to acquire the deposition inaccuracies. With the deposition dynamics considered, the deposition inaccuracy is reduced via dynamic deposition rate compensation. The proposed thermal imaging and compensation techniques have been experimentally verified with a material extrusion experimental platform to illustrate its capabilities to alleviate the deposition inaccuracy during the corner regions.

Large-scale hollow-core 3D printing (HC3DP): A polymer 3D printing technology for large-scale ultralightweight components

Material extrusion (ME) has become a popular 3D printing method for large-scale applications such as in the automotive, naval, aerospace, and architecture sectors. It allows the production of complex, customized parts without the need of labour-intensive molds. The increasing need to produce larger and larger parts has been addressed with the introduction of large pellet extrusion systems to increase the extrusion rate. With these extruders the production time is not limited by the extrusion rate of the extruder (kg/h) but by the time the material needs to cool down before the next layer can be printed consecutively. Furthermore, larger bead dimensions result in increased material usage and, therefore, might affect the environmental impact of the printed element. In this study, a method for large extrusion 3D printing based on hollow beads is proposed, to address the limitations of speed, cooldown and maximize the extrusion rate of thermoplastic 3D printing. This paper introduces Hollow-Core 3D printing (HC3DP) and compares it to off-the shelf large-scale pellet extruders and their maximum achievable extrusion rate for a given geometry. A comparative analysis of cooldown characteristics between conventional thermoplastic extrusion 3D printing and HC3DP validates that the latter increases the maximum possible extrusion rate. Additionally, the successful 3D printing of large-scale beads with multiple polymer feedstocks is demonstrated. Then the data associated with printing speed and material usage is presented and discussed in comparison with thermoplastic and other large-scale 3D printing methods. The fabrication of large-scale hollow-core beads at a dimension of 24×20mm is showcased with an extrusion rate of 7250 mm3/s (1308 material, 5941 air). HC3DP for large-scale applications is validated through the production of 2-meter tall cylinders with a diameter of 400 mm in less than two hours. Furthermore, bespoke die geometries that subdivide the inside of hollow 3D-printed beads are presented. To successfully print those, the concept of differentiated internal air pressure per print point is introduced. Finally, 3PT bending tests are conducted to compare different die geometries. In conclusion, this study presents a printing method that highlights the benefits of hollow core 3D printing for large-scale applications, showcasing its positive impact on both the printing process and resulting part properties. By addressing the limitations of traditional approaches, HC3DP pushes polymer 3D printing into a scale relevant for architecture and construction, offering similar extrusion rates as concrete 3DP.

Evaluating the potential of millets as blend components with soy protein isolate in a high moisture extrusion system for improved texture, structure, and colour properties of meat analogues

This study explored the use of millets flours as a secondary ingredient with soy protein isolate (SPI) to develop fibrous high moisture meat analogue (HMMA). Three millets (sorghum, pearl millet, and finger millet) with three incorporation levels (10%, 20%, and 30%) were extruded at 60%, 65%, and 70% moisture content. The results showed that millet type, incorporation level, and moisture content significantly influenced the system parameters and textural properties. Good visual texturization was achieved at addition of pearl millet up to 30% incorporation level and sorghum and finger millet up to 20% incorporation level. Furthermore, the textural properties of HMMA made from SPI-millet blends were compared against HMMA made from SPI-gluten blend and real chicken. The HMMA made from SPI-millet flour had lower hardness, chewiness, resilience, springiness, tensile strength, cutting strength than that for SPI and SPI-wheat gluten blend and were much closer to corresponding values for real chicken. The results also showed that each of the three millet types generated distinctly different fibre patterns (thick to thin fibres) and colour (whiter to darker) of HMMA. Thus, HMMA produced from SPI-millet flour blends can offer a wide textural, fibre pattern and colour space for different plant-based meat applications. Since millets do not have gluten, they also offer an opportunity to make gluten-free HMMA’s.

High gravity material extrusion system and extruded polylactic acid performance enhancement

Additive manufacturing (AM) has gained significant attention in recent years owing to its ability to quickly and easily fabricate complex shapes and geometries that are difficult or impossible to achieve with traditional manufacturing methods. This study presents the development of a high-gravity material extrusion (HG-MEX) system, which generates a high-gravity field through centrifugal acceleration. In this process, the material is dissolved by heating the nozzle and subsequently deposited on the construction platform. The primary objective of this research is to evaluate the positive effects of gravity on material extrusion (MEX), which is a key aspect of AM. To accomplish this, a combined machine comprising a MEX unit and centrifuge is constructed. This HG-MEX system is used to analyze and reflect the influence of gravity on the material extrusion. The experimental evaluations demonstrate that the application of high gravity is a promising approach to improve the shape accuracy and performance of the parts fabricated through MEX. Notably, our results confirm the feasibility of utilizing MEX under high gravity to enhance performance in AM processes.

Additive-manufactured anisotropic magnets for harsh environments

We describe the fabrication of SrFe12O19-based filaments, using polyphenylene sulphide (PPS) as the binder for the magnetic particles, and the subsequent printing of this filament with a 3D printer. PPS is an ideal polymer for applications in harsh environments, making it applicable for the automotive industry, where it is widely used with injection moulding. However, 3D printing this polymer introduces a major challenge. Because PPS is more difficult to extrude than polyamide, the filling factor in this study was set to 70 wt. %, which is lower than when used in injection moulding (close to 90 wt. %). The filament with a diameter of 2.75 mm was printed into a disk-shaped magnet with a diameter of 10 mm and a height of 4 mm using a HAGE 3D printer that uses a belt system for the filament extrusion. The magnets were printed onto a glass surface and onto a bulk Nd-Fe-B permanent magnet with an external magnetic field, parallel to the printer’s z-axis. Printing in the presence of a magnetic field was found to increase the magnet’s remanent magnetization by 61%, compared to an isotropic print. Without an external magnetic field we achieved a remanence of 23.9 emu/g for the 70 wt.% filling fraction, while when printing in a magnetic field, the value of the remanence improved to 39.7 emu/g because of the improved magnetic texture.

Thermal and Mechanical Properties of Reprocessed Polylactide/Titanium Dioxide Nanocomposites for Material Extrusion Additive Manufacturing.

Polylactic acid (PLA) is a biodegradable polymer that can replace petroleum-based polymers and is widely used in material extrusion additive manufacturing (AM). The reprocessing of PLA leads to a downcycling of its properties, so strategies are being sought to counteract this effect, such as blending with virgin material or creating nanocomposites. Thus, two sets of nanocomposites based respectively on virgin PLA and a blend of PLA and reprocessed PLA (rPLA) with the addition of 0, 3, and 7 wt% of titanium dioxide nanoparticles (TiO2) were created via a double screw extruder system. All blends were used for material extrusion for 3D printing directly from pellets without difficulty. Scanning electron micrographs of fractured samples' surfaces indicate that the nanoparticles gathered in agglomerations in some blends, which were well dispersed in the polymer matrix. The thermal stability and degree of crystallinity for every set of nanocomposites have a rising tendency with increasing nanoparticle concentration. The glass transition and melting temperatures of PLA/TiO2 and PLA/rPLA/TiO2 do not differ much. Tensile testing showed that although reprocessed material implies a detriment to the mechanical properties, in the specimens with 7% nano-TiO2, this effect is counteracted, reaching values like those of virgin PLA.

Understanding and modelling the aquafeed extrusion process for Atlantic salmon feed with an empirical model

An empirical model was applied to quantitatively model the effects of extrusion variables and recipe compositions on quality of feed pellets. Lab extrusion trials were performed with an Atlantic salmon feed recipe with using a central component design (CCD). Comparing with a coated commercial feed made with the same recipe, the lab extrusion pellets had similar bulk density, hardness, and durability properties. A Response Surface Method (RSM) was also used to regress the extrusion trial data and compared with the empirical model results. The respective Absolute Average Deviation (AAD %) values of the empirical model and RSM regression were 4.1 % and 1.8 % for pellet bulk density, 7.4 % and 4.9 % for pellet hardness, 10.4 % and 10.0 % for pellet oil absorption, 13.7 % and 8.3 % for pellet water stability, and 11.3 % and 5.5 % for pellet durability. Using the model coefficients obtained from the extrusion results, the empirical model can partly extrapolate the pellet qualities of an additional extruded recipe, which has a slightly adjusted wheat gluten and wheat. The model performance was evaluated based on. R2, RSME (root-mean-square deviation), AAD % of the empirical model was better than the RSM model to predict the effects of extrusion variables on pellet quality parameters. The effects of the extrusion process variables and recipe composition on pellet quality parameters are predicted by the empirical model. Its demonstrates that the empirical model is a new method to understand extrusion trial results in different extrusion systems and recipes without changing its mathematical form of expression, which gives a common reference to compare an extruded recipe in different systems and has practical engineering applications.

Fractional computations for free convective flow of Casson-hybrid nanofluid flow with sodium alginate and water as based materials

The hybrid nanofluid is the modified class of nanomaterials with impressive thermal impact and preserves significant applications in extrusion systems, thermal management systems, engineering processes, cooling and heating materials and many more. The aim of this research is to communicate the thermal enhancement of water (H2O) and sodium alginate (C6H9NaO7) base fluids with interaction of hybrid nanofluids. The Casson fluid model is used to endorse the properties of such base liquids. The titanium dioxide and silver nanoparticles incorporate the thermal impact of hybrid nanofluid properties. The fractional simulations are performed by using the Caputo–Fabrizio (CF) time-fractional derivatives. The integration of problem is computed via Laplace technique. It is observed that the velocity profile enhanced the Grashof number. The increasing observations for Nusselt number and wall shear force due to fractional parameters are obtained.

Additive Manufacturing of Thermoplastic Polyurethane-Cork Composites for Material Extrusion Technologies.

Among the material extrusion technologies of additive manufacturing, fused granular fabrication is playing a bigger role in the industry. The increase in the size of printers demands extrusion systems with higher deposition rates that facilitate printing larger parts in shorter times with a need for cost reduction. This cost reduction in fused granular fabrication systems is due to the utilisation of pellets as the material source for the prints, such as pellets that are the most common way of distributing polymeric materials in industry and do not need the usual previous transformation into filaments. Most of the polymers in the industry can be found in the shape of pellets, so the opportunities for developing new materials beside the traditional filaments found in the market are expanding. In this research, a novel composite material has been developed based on the blending of commercial thermoplastic polyurethane (TPU) and cork particles obtained from industrial waste at different concentrations. These materials have been processed at a laboratory scale, and their mechanical, thermal and rheological properties have been studied. Despite a 53.52% reduction in the maximum stress on the x-axis, an 81.82% decrease in the values obtained with specimens oriented on the z-axis and a shortage in the deformation values, the results reveal a remarkable weight reduction leading to 21.31% when compared to the TPU of the blends,. These results may open a path to further explore these blends and find suitable applications in industry as proposed.

Accelerating flow for engine oil base fluid with graphene oxide and molybdenum disulfide nanoparticles: modified fractional simulations

Thermal assessment of hybrid nanofluid presents novel applications in enhancing heat transfer devices, solar energy production, extrusion systems, chemical processes, nuclear reactors, cooling processes, etc. Owing to such conveying applications of hybrid nanomaterials, the aim of current research is to justify the impressive thermal mechanism engine oil with the utilization of hybrid nanoparticles. The molybdenum disulfide and graphene oxide nanoparticles are used to reflect the improvement in engine oil thermal performances. The motivations for considering such hybrid nanofluid model are to improve the thermal aspect of engine oil which play a key contribution in the vehicle systems and automobile industry. The problem is further improved with mixed convection and Newtonian heating applications. The oscillating surface is used to endorse the flow. The fractional simulations with the implementation of Caputo–Fabrizio (CF) technique are performed. In contrast to traditional attempts, the modern -Laplace transform is used to compute the integration task.

Physical interference of magnetic dipole for retardation type nanofluid with bioconvection phenomenon

The bioconvection aspect for the rate type nanomaterial under dynamic of induced magnetic force has been numerically worked out. The Oldroyd-B nonlinear model is incorporated to inspect the interesting rheological dynamic of rate type classifications. Following nonlinear models, the relaxation and retardation features are observed. The numerical proposed data is fundamentally achieved via the shooting method. After developing the dimensionless problem expressions, the shooting numerical algorithm is followed for the computations. The physical onset of parameters is graphically listed with interesting applications. It is observed that a more strong induced magnetic field profile has been observed due to the presence of bio-convective Lewis number and Rayleigh number. An enriched profile of thermal phenomenon due to Grashof number is observed. The composed reflected outcomes present importance in thermal management systems, extrusion systems, plasma physics, chemical processes, nuclear systems, extrusion mechanism, biofuels, etc.

Minimally invasive in situ bioprinting using tube-based material transfer

Abstract Minimally invasive in situ bioprinting can potentially enhance the advantages of bioprinting, allowing the surrounding healthy tissue to be maximally preserved. However, the requirements for such a device are manifold and challenging to fulfill. We present an experimental bioprinting platform consisting of an extrusion system based on a tube mounted between an extrusion syringe and a dispensing nozzle. We investigated the influence of material transfer through a tube on the printing outcome. The results showed that it is feasible to form a continuous filament and print 3-dimensional structures using the developed platform.

Numerical Study of the Effect of High Gravity in Material Extrusion System and Polymer Characteristics during Filament Fabrication.

Polymer science plays a crucial role in the understanding and numerical study of material extrusion processes that have revolutionized additive manufacturing (AM). This study investigated the impact of high-gravity conditions on material extrusion and conducted a numerical study by referring to the development of a high-gravity material extrusion system (HG-MEX). In this study, we evaluated the polymeric characteristics of HG-MEX. By analyzing the interplay between polymer behavior and gravity, we provide insights into the effects of high gravity on extrusion processes, including filament flow, material deposition, and the resulting fabrication characteristics. The established numerical study of high-gravity material extrusion in additive manufacturing is a meaningful and valuable approach for improving the quality and efficiency of the process. This study is unique in that it incorporates material surface characteristics to represent the performance and contact with polymer science in additive manufacturing. The findings presented herein contribute to a broader understanding of polymer science and its practical implications for HG-MEX under various gravitational conditions.

Manganese Sulfate Nanocomposites Fabricated by Hot-Melt Extrusion for Chemodynamic Therapy of Colorectal Cancer.

The development of metal salts-based nanocomposites is highly desired for the Fenton or Fenton-like reaction-based chemodynamic therapy of cancer. Manganese sulfate (MnSO4)-dispersed nanoparticles (NPs) were fabricated with a hot-melt extrusion (HME) system for the chemodynamic therapy of colorectal cancer in this study. MnSO4 was homogeneously distributed in polyethylene glycol (PEG) 6000 (as a hydrophilic polymer) with the aid of surfactants (Span 80 and Tween 80) by HME processing. Nano-size distribution was achieved after dispersing the pulverized extrudate of MnSO4-based composite in the aqueous media. The distribution of MnSO4 in HME extrudate and the interactions between MnSO4 and pharmaceutical additives were elucidated by Fourier-transform infrared, X-ray diffractometry, X-ray photoelectron spectroscopy, and scanning electron microscopy analyses. Hydroxyl radical generation efficiency by the Fenton-like chemistry capability of Mn2+ ion was also confirmed by catalytic assays. By using the intrinsic H2O2 in cancer cells, MnSO4 NPs provided an elevated cellular reactive oxygen species level, apoptosis induction capability, and antiproliferation efficiency. The designed HME-processed MnSO4 formulation can be efficiently used for the chemodynamic therapy of colorectal cancer.

A Material-Recycling Unit for the Fused Deposition Modelling of Three-Dimensional Printing Systems

Fused deposition modelling (FDM) three-dimensional (3D) printing technology is one of the most common additive manufacturing (AM) technologies due to the relatively low cost of the printing units and materials. Although cost-effective, this technology is not conceived to convert 100% of the raw material into a complete product, creating a potential plastic waste problem. To recycle the plastic waste from the FDM machine into reusable filaments, the concept of a 3D printer material-recycling machine (3DP-MRM) was developed using CREO Parametric 9.0 software. A prototype with four systems, including a spooler system, extruder system, display system, and filament-positioning system, was manufactured in-house with complete run experiments. The tests of the 3DP-MRM were applied, and the machine worked successfully among all the designed functions with minor issues.

A STUDY ON MULTI-MODELING FOR ARTIFACT RESTORATION

Abstract. Restoration is carried out in order to restore damaged antiquities to their original form. Recently, research has been active in obtaining the target three-dimensional (3D) model by optical scanning and X-ray computed tomography (CT), as well as restoring artifacts via modeling. Because the cultural artifacts are restored in a virtual environment without direct contact with the cultural artifacts, secondary damage can be preserved. Furthermore, the restoration results can be used for the physical restoration of cultural artifacts via 3D printing. In this study, multi-digital modeling technology was used to restoration horse-shaped earthenware artifact that still had its missing part. After 3D printing, the restoration part was applied to the artifact. In order to record the shape of the artifact in detail, a high-precision 3D scanner was used to construct the shape of the artifact into a 3D model. Two models were then built as a reference for restoration: The legs of the excavated horse-shaped earthenware are believed to have been bent during burning, but they were reproduced in their entirety for restoration by conducting rigging and keyframe animation. For the restoration of the missing horse body, horse and rider-shaped vessels excavated from the same site were used as references. However, since the decorations on the reference surfaces obscured the horse body, a 3D model of the horse shape was obtained through X-ray CT segmentation modeling. Using the obtained model, the missing 3D horse body was restored. For the hind legs, the leg geometry reconstructed by the rigging was used as a reference. The hollow space inside the artifact and the structures that could be restored were further modeled. The finished model was completed by outputting a mock-up using a material extrusion system 3D printer, conducting a bonding test with actual artifacts, and finally creating the restoration model. Afterward, a photopolymerization system 3D printer is used to output the restoration part, and then it is applied to the artifacts through post-processing. A study for restoration artifacts based on multi-modeling techniques was proposed in this work. In particular, rigging and x-ray CT segmentation modeling were used to restoration the artifacts based on their original form and historical research. As such, multi-modeling techniques are an effective way to not only restore artifacts, but also to build a reference for restoration.

An unsteady bioconvective non-Newtonian nanofluid model with variable thermal properties and modified heat flux framework

The suspension nanoparticles in non-Newtonian materials convey different applications in the thermal systems, engineering processes, industrial energy developments, extrusion systems, solar system, etc. It is commonly observed that the thermal properties in the various base materials fluctuated and cannot be assumed to be constants. A decomposition of nanofluids is fluctuated and cannot considered as a constant. The objective of this communication is to inspect the thermal mechanism of non-Newtonian nanofluids due to accelerated frame in view of variable thermal conductivity. The modified mathematical relations for Fourier and Fick theories are utilized to model the problem. The nanofluids contain the microorganisms to ensure the thermal stability. The problem is modeled in nonlinear partial differential system which is further communicated via HAM. The convergent analysis is ensured and later on physical illustrations to problem in view of parameters are discussed. It is observed that thermal phenomenon controls due to mixed convection parameter while increasing impact for Williamson fluid parameter is observed. The magnitude of oscillation of Nusselt number due to Prandtl number is enhanced without any phase difference. The obtained results may convey different engineering applications like extrusion systems, chemical processes, thermal management systems, heating and cooling application, plasma, manufacturing processes.

Development of lunar regolith-based composite for in-situ 3D printing via high-pressure extrusion system

Development of lunar regolith-based composite for in-situ 3D printing via high-pressure extrusion system