Assessment of the surface and structure of elements produced in additive manufacturing technology after chemical treatment

Samples made of ABS material were produced on devices from three different manufacturers: Stratasys, Velleman, 3Novatica. The quality of the printed surface was improved by vaporization with acetone vapours. Roughness measurements were performed, which proved the improvement of the surface after vaporization. The structure of the produced samples was also tested using a computer microtomography. It has been shown that excessive exposure to the solvent significantly changes the geometrical dimensions of models exposed to the vaporization process

Wpływ parametrów procesu druku metodą FFF i jednorodności makrostruktury na udarność PLA

The article presents studies of the additive manufacturing printing parameters influence on the impact strength of PLA samples obtained by the fused filament fabrication (FFF) method. Two process variables were taken into account in the research program: the height of the printed layer and the printing temperature. An optical microscope was used to analyze the cross-section image (breakthrough) of the samples. The impact strength was determined at −40°C and 23°C. Selected geometric features of the macrostructure (uniformity and thickness of individual layers, voids) determined on the basis of the sample cross-section image analysis, enhanced the possibility of assessing the PLA impact strength, depending on the adopted process variables and the temperature at which the experiment was carried out.W artykule przedstawiono badania wpływu parametrów druku addytywnego na udarność próbek z PLA otrzymanych metodą FFF (fused filament fabrication). W programie badań uwzględniono dwie zmienne procesowe: wysokość drukowanej warstwy i temperaturę druku. Do analizy obrazu przełomu próbek wykorzystano mikroskop optyczny. Oznaczono udarność w temperaturze -40°C oraz 23°C. Wybrane cechy geometryczne makrostruktury (równomierność i grubość poszczególnych warstw, puste przestrzenie) wyznaczone na podstawie analizy obrazu przekroju próbek, pogłębiły możliwość oceny udarności PLA w zależności od przyjętych zmiennych procesowych, a także temperatury w jakiej zrealizowano eksperyment

Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding

Repeatability of the Vibroarthrogram in the Temporomandibular Joints

Current research concerning the repeatability of the joint’s sounds examination in the temporomandibular joints (TMJ) is inconclusive; thus, the aim of this study was to investigate the repeatability of the specific features of the vibroarthrogram (VAG) in the TMJ using accelerometers. The joint sounds of both TMJs were measured with VAG accelerometers in two groups, study and control, each consisting of 47 participants (n = 94). Two VAG recording sessions consisted of 10 jaw open/close cycles guided by a metronome. The intraclass correlation coefficient (ICC) was calculated for seven VAG signal features. Additionally, a k-nearest-neighbors (KNN) classifier was defined and compared with a state-of-the-art method (joint vibration analysis (JVA) decision tree). ICC indicated excellent (for the integral below 300 Hz feature), good (total integral, integral above 300 Hz, and median frequency features), moderate (integral below to integral above 300 Hz ratio feature) and poor (peak amplitude feature) reliability. The accuracy scores for the KNN classifier (up to 0.81) were higher than those for the JVA decision tree (up to 0.60). The results of this study could open up a new field of research focused on the features of the vibroarthrogram in the context of the TMJ, further improving the diagnosing process

Recykling części eksploatacyjnych z ABS wykorzystywanych w przemysłowych drukarkach 3D

The article presents new application of the material obtained from the recycling of acrylonitrilebutadiene-styrene (ABS) – the material acquired from operating parts of industry Dimension Elite 3D printer by Stratasys. The operating parts were used to prepare the regranulate and to produce filament, the latter of which was applied used in the FFF technology (Fused Filament Fabrication). Manufactured in the FFF technology, test specimens were used to determine the selected mechanical properties and to compare the obtained results with the properties characteristic of molded pieces made of ABS regranulate that were produced by injection molding. The paper presents results of tests performed on a filament, obtained from the ABS regranulate and indicates characteristic processing properties of that material. It also discusses beneficial processing parameters for injection molding (IM) and 3D printing (FFF). The study also presents selected results of tests of functional properties of ABS products in the FFF technology. The research results have allowed to assess the possibility of recycling of the operating parts of 3D printers in FFF.Przedstawiono nowe zastosowanie materiału uzyskanego z recyklingu ABS (akrylonitryl-butadien-styren) pochodzącego z elementów eksploatacyjnych przemysłowych drukarek 3D Dimension Elite (Stratasys). Z elementów eksploatacyjnych przygotowano regranulat i wyprodukowano filament, który następnie zastosowano w technologii przyrostowego wytwarzania FFF (ang. Fused Filament Fabrication). Wytworzone w technologii FFF próbki posłużyły do oznaczenia wybranych właściwości mechanicznych oraz porównania ich z właściwościami charakteryzującymi wypraski z regranulatu ABS, uzyskane metodą wtryskiwania. Oceniano cechy filamentu otrzymanego z regranulatu ABS, wskazano także na charakterystyczne właściwości przetwórcze tego surowca. Określono korzystne pod względem wytrzymałości mechanicznej parametry procesów wytwarzania: wtryskiwania ciśnieniowego (IM) oraz drukowania 3D (FFF), wyznaczono też właściwości użytkowe wytworów z ABS, otrzymanych w technologii FFF. Wyniki badań pozwoliły na ocenę możliwości recyklingu zużytych elementów eksploatacyjnych przemysłowych drukarek 3D w technologii FFF

Influence of Extruder’s Nozzle Diameter on the Improvement of Functional Properties of 3D-Printed PLA Products

The dynamic growth of the use of polymer construction parts manufactured individually and in a small series makes it necessary to improve additive methods in the areas of materials, equipment and processes. By observing selected phenomena occurring during the processing of polymer materials in other production technologies (e.g., extrusion and injection molding), it is possible to obtain solutions that positively affect the final performance properties of the products obtained in additive manufacturing technologies using thermoplastic filament. The aim of this research was to determine the effect of the diameter of the print head nozzle on the spatial structure (path width) and selected mechanical properties of samples produced by the FFF method with PLA material. The obtained results were compared to the samples with a solid structure produced using injection molding technology. In the experiment, the RepRap device for additive manufacturing was used, with the use of nozzles with diameters of 0.2 mm, 0.4 mm, 0.8 mm and 1.2 mm. The test objects were produced with a layer height of 0.2 mm, full filling (100%) and with constant remaining printing parameters. The conducted research allowed us to conclude that the use of layer heights lower than the standard ones gives favorable results for selected mechanical properties. The use of an extruder nozzle diameter of 0.8 mm allows one to obtain a macrostructure with a high degree of interconnection of layers and paths and favorable mechanical properties. The test results can be used in the construction of functional elements that are produced by fused deposition modeling (FDM) and fused filament fabrication (FFF) methods in prototype, unit and small-lot production

Application of Finite Element Analysis in Oral and Maxillofacial Surgery—A Literature Review

In recent years in the field of biomechanics, the intensive development of various experimental methods has been observed. The implementation of virtual studies that for a long time have been successfully used in technical sciences also represents a new trend in dental engineering. Among these methods, finite element analysis (FEA) deserves special attention. FEA is a method used to analyze stresses and strains in complex mechanical systems. It enables the mathematical conversion and analysis of mechanical properties of a geometric object. Since the mechanical properties of the human skeleton cannot be examined in vivo, a discipline in which FEA has found particular application is oral and maxillofacial surgery. In this review we summarize the application of FEA in particular oral and maxillofacial fields such as traumatology, orthognathic surgery, reconstructive surgery and implantology presented in the current literature. Based on the available literature, we discuss the methodology and results of research where FEA has been used to understand the pathomechanism of fractures, identify optimal osteosynthesis methods, plan reconstructive operations and design intraosseous implants or osteosynthesis elements. As well as indicating the benefits of FEA in mechanical parameter analysis, we also point out the assumptions and simplifications that are commonly used. The understanding of FEA’s opportunities and advantages as well as its limitations and main flaws is crucial to fully exploit its potential