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The material extrusion process is one of the most popular additive manufacturing processes. The presence of porosity in the MEX printed parts, which ultimately deteriorates the mechanical properties, is one of the main drawbacks of the MEX process. The porosity in the structure is related to the shape of the adjacent beads and overlapping during the material deposition. Due to the deposition nature of the MEX process, the porosity cannot be entirely removed from the printed parts. Understanding the influence of process parameters on material deposition and the rheological properties is crucial to improving the quality of the final product. In this study, the two-phase-flow numerical approach with the level-set equations has been used for the first time to model the material deposition on the moving platform in 3D. The influence of the viscosity and printing parameters, including travel speed, inlet velocity, viscosity, nozzle diameter, and layer height, on the width of the deposited bead has been investigated. The simulation results are validated against experimental measurements with an average error of 5.92%. The width measured by the experimental study shows good agreement with the results of the numerical simulation. The comparison between the results of the 3D numerical simulation and 2D simulation reveals that the 2D simulation is not appropriate and accurate enough to predict the geometry of the deposited bead with the given set of parameter settings. The key novelty of this research paper is the application of the level-set method in a 3D context for material deposition on a moving substrate.

Background The purpose of this study was to investigate the effects of screw configuration on chemical properties and ginsenosides content of extruded ginseng and to select the most suitable screw configuration for the processing of ginseng. Method The extrusion conditions were set as follows: moisture content (20%), barrel temperature (140°C), screw speed (200 rpm), and feeding rate (100 g/min). Result The extruded ginseng of screw configuration 6 has the highest DPPH free radical scavenging rate, reducing power and total phenol, which is the most suitable configuration for the development of ginseng extract products. In addition, the extruded ginseng of screw configuration 9 has the highest content of total saponin, and the content of rare ginsenoside Rg3 which is scarcely present in the ginseng raw material powder was significantly increased. This intended that twin‐screw extrusion process enables the mutual conversion between ginsenosides and rare ginsenoside Rg3 had achieved. Conclusion The extrusion process promotes the development and utilization of ginseng and provides theoretical basis for the design and development of screw configuration of twin‐screw extruded ginseng. The twin‐screw extruding function obviously improves the antioxidant ability of Ginseng extract. The content of total saponins in ginseng extract was increased by twin‐screw extruder. The content of rare ginsenoside Rg3 increased significantly after extrusion. Extensive additional research is necessary prior to industrial implementation.

The objective of this work is to evaluate the reprocessing of PLA 3D printing waste from different origins, into filaments and films, and without the addition of any additive. Two types of waste were considered: a blend of different printing wastes (masks, visors, other components) of personal protective equipment coming from an association of Spanish coronamakers, and PLA waste from a single known commercial source. Both types of materials were subjected to repeated extrusion cycles and processed into films by compression molding. Samples were characterized after each cycle and their mechanical and viscosity properties evaluated. Diffusion-ordered NMR spectroscopy (DOSY) experiments were also carried out to estimate molecular weights. The results show a better performance for the PLA waste from the known origin, capable of withstanding up to three re-extrusion cycles per two for the waste blending, without significant degradation. Additionally, a model to address collection and mechanical recycling cycles under two different scenarios (full traceability and not full traceability) was proposed.

Selected, peer reviewed papers from the International Conference on Extrusion and Benchmark (ICEB 2013), October 8 - 9, 2013, Dortmund, Germany.

Extrusion is a thermomechanical technology that has been widely used in the production of various starch-based foods and can transform raw materials into edible products with unique nutritional characteristics. Starch digestibility is a crucial nutritional factor that can largely determine the human postprandial glycemic response, and frequent consumption of foods with rapid starch digestibility is related to the occurrence of type 2 diabetes. The extrusion process involves starch degradation and order–disorder structural transition, which could result in large variance in starch digestibility in these foods depending on the raw material properties and processing conditions. It provides opportunities to modify starch digestibility by selecting a desirable combination of raw food materials and extrusion settings. This review firstly introduces the application of extrusion techniques in starch-based food production, while, more importantly, it discusses the effects of extrusion on the alteration of starch structures and consequentially starch digestibility in various foods. This review contains important information to generate a new generation of foods with slow starch digestibility by the extrusion technique.

Extrusion is the operation of forming and shaping a molten or dough-like material by forcing it through a restriction, or die. It is applied and used in many batch and continuous processes. However, extrusion processing technology relies more on continuous process operations which use screw extruders to handle many process functions such as the transport and compression of particulate components, melting of polymers, mixing of viscous media, heat processing of polymeric and biopolymeric materials, product texturization and shaping, defibering and chemical impregnation of fibrous materials, reactive extrusion, and fractionation of solid-liquid systems. Extrusion processing technology is highly complex, and in-depth descriptions and discussions are required in order to provide a complete understanding and analysis of this area: this book aims to provide readers with these analyses and discussions. Extrusion Processing Technology: Food and Non-Food Biomaterials provides an overview of extrusion processing technology and its established and emerging industrial applications. Potency of process intensification and sustainable processing is also discussed and illustrated. The book aims to span the gap between the principles of extrusion science and the practical knowledge of operational engineers and technicians. The authors bring their research and industrial experience in extrusion processing technology to provide a comprehensive, technical yet readable volume that will appeal to readers from both academic and practical backgrounds. This book is primarily aimed at scientists and engineers engaged in industry, research, and teaching activities related to the extrusion processing of foods (especially cereals, snacks, textured and fibrated proteins, functional ingredients, and instant powders), feeds (especially aquafeeds and petfoods), bioplastics and plastics, biosourced chemicals, paper pulp, and biofuels. It will also be of interest to students of food science, food engineering, and chemical engineering. Also available Formulation Engineering of Foods Edited by J.E. Norton, P.J. Fryer and I.T. Norton ISBN 978-0-470-67290-7 Food and Industrial Bioproducts and Bioprocessing Edited by N.T. Dunford ISBN 978-0-8138-2105-4 Handbook of Food Process Design Edited by J. Ahmed and M.S. Rahman ISBN 978-1-4443-3011-3

In this study, textured vegetable protein (TVP) based on soy protein isolate, wheat gluten, and corn starch was prepared at a 5:3:2 (w/w) ratio using a low-moisture extrusion process. To evaluate the effects of extrusion parameters, die temperature and screw rotation speed, on the properties of TVP, these two parameters were manipulated at a constant barrel temperature and moisture content. The results indicated that increasing the die temperature increased the expansion ratio while decreasing the density of the extrudates. Simultaneously, increasing the screw rotation speed clearly increased the specific mechanical energy of the TVP. Furthermore, mathematical modelling suggested that the expansion ratio increases exponentially to the die temperature. However, extreme process conditions bring about a decrease in water absorption capacity and expansion ratio, as well as undesirable texture and microstructure. The results suggested that the properties of SPI-based TVP are directly influenced by the extrusion process parameters, screw speed and die temperature.

Polylactic acid (PLA) has been widely used in the field of medical devices. However, few studies have been conducted on the extrusion molding of PLA micro tubes for the preparation of biodegradable vascular stents. In this paper, the extrusion die for PLA single-cavity micro tubes was designed and manufactured by micro-extrusion theory. Taking the outer diameter, wall thickness, wall thickness uniformity and ovality of micro tubes as the evaluation index, the influence of the main extrusion process parameters on the evaluation index was studied. The experimental results show that the outer diameter and wall thickness are significantly affected by screw speed, pulling speed and gas flow rate; extrusion process parameters have little influence on wall thickness uniformity and ovality within a certain range, which mainly depends on the processing accuracy and assembly accuracy of the extrusion die. However, excessively high screw speed and low gas flow rate have significant effects on ovality. Finally, according to the influence of extrusion process parameters on the evaluation index, a series of micro tubes that meet the design requirements are extruded and carved into vascular stent structures.

The article presents the research made on the effects of methods of pressure-thermal agglomeration of corn bran, as well as the influence of processing parameters on selected physicochemical properties and biogas efficiency. Corn bran moistened to four levels of moisture content was used for the tests: 20%, 25%, 30% and 35% of dry matter. The pressure-thermal treatment was carried out with the use of a Brikol SJ25 pellet maker and a TS-45 single-screw extruder. In the tests of the extrusion-cooking process, three rotational speeds of the extruder screw were applied: 70, 90 and 110 rpm. The following characteristics were examined: efficiency of the extrusion-cooking and pelleting process, as well as the energy consumption. The water absorption index (WAI), the water solubility index (WSI), bulk density, kinetic strength, structure analysis by the ART/FTIR method, energy potential and the efficiency of cumulated biogas and cumulated methane per dry mass, as well as fresh mass and fresh organic matter and a series of microscopic pictures were completed. The analysis of the ATR/FTIR infrared spectra of the tested pelleted and extruded samples showed clear changes at the molecular level. Biogas production of extruded corn bran increased by several percent, as compared to untreated material.

Quality in a manufacturing process implies that the performance characteristics of the product and the process itself are designed to meet specific objectives. Thus, accurate quality prediction plays a principal role in delivering high-quality products to further enhance competitiveness. In tubing extrusion, measuring of the inner and outer diameters is typically performed either manually or with ultrasonic or laser scanners. This paper shows how regression models can result useful to estimate both those physical quality indices in a tube extrusion process. A real-life data set obtained from a Mexican extrusion manufacturing company is used for the empirical analysis. Experimental results demonstrate that k nearest-neighbor and support vector regression methods (with a linear kernel and with a radial basis function) are especially suitable for predicting the inner and outer diameters of an extruded tube based on the evaluation of 15 extrusion and pulling process parameters.