An investigation of the influence of 3d printing parameters on the tensile strength of PLA material

Fused Deposition Modelling (FDM), also known as 3d printing, is one of the most widespread Additive Manufacturing (AM) technologies based on the extrusion of a thermoplastic filament. This layerwise technology allows lightweight products to be built using different infill strategies and percentages. Furthermore, by varying other parameters, such as temperature, printing speed or layer thickness, it is possible to obtain components with different characteristics. Polylactic Acid (PLA) is one of the cheapest and most sustainable materials for 3d printing because it is a biobased and biodegradable plastic. Its use in 3D printing is widely spread among hobbyists and in the communities, such as the ones of Fablabs or the Makers movement.Nevertheless, to reduce the number of uncompliant parts that may fail into operation since they do not meet the expectations of the user, it is important to know in advance the mechanical performance that different 3d printing strategies can ensure for PLA parts.In this paper, Design of Experiment (DOE) is applied to investigate how main 3D printing parameters influence the tensile strength of PLA products. For this purpose, a 3x3 factorial plane with one replication was constructed and used for 3d printing tensile specimens of PLA Tough material using a Makerbot Replicator machine. The tensile test results show that the layer thickness is more significant than the infill percentage for the resistance of PLA products. A regression model is also proposed to allow the user to predict the ultimate tensile strength of PLA products depending on the values of those two parameters.Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Third International Conference on Aspects of Materials Science and Engineering

An investigation of the influence of 3d printing defects on the tensile performance of ABS material

Recently, the popularity of 3d printing for industrial and consumer use has spread across many different sectors. For this reason, quality assurance of 3d printed parts is becoming increasingly important. The extrusion and layer-by-layer deposition of a polymer filament on the print bed can introduce defects such as pores and voids into the internal structure of 3d printed parts. The relation between 3d printing defects and tensile performance of 3d printed samples is studied in this paper. The study considers tensile specimens of acrylonitrile butadiene styrene (ABS) that were 3d printed by varying the infill strategy and percentage to simulate different levels of strength for the part. Before the tensile tests, the ABS samples were inspected by X-ray tomography to identify the presence of internal voids generated by the 3d printing process. For each sample, data and statistics about the internal defects were used for determining a relation with the tensile test results. The local deformation of the sample and the position of the final fracture were observed using a digital camera and digital image correlation (DIC). In most cases, the experimental results confirmed the matching between the presence of internal voids and the areas of high deformation. However, the position of the specimen fracture did not always coincide with the largest defects. Nevertheless, this study highlights the importance of non-destructive inspection in quality assurance of 3d printed parts when in-situ monitoring of the 3d printing process is not applied. Copyright (C) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Third International Conference on Aspects of Materials Science and Engineering

Experimental validation of laser powder bed fusion simulation

In many industrial sectors, laser powder bed fusion (L-PBF) is the main additive manufacturing technology for producing end-usable metal parts. Although L-PBF technique has been developed in the last twenty years, ensuring process feasibility and achieving maximum product quality at the first building session is still a difficult goal to pursue. Simulation software packages are available in the market for the prediction of induced stresses and deformation in LPBF products to help the user getting the part right at the first time. In this paper, Amphyon software by Additive Works is tested and experimentally validated for the production of Ti6Al4V parts in an EOSINT M270 Dual Mode machine. First, the sensitivity of the software is evaluated by changing the main process parameters by +/- 20% with respect to Ti64 reference values. After calibration, the software is validated by comparison of the predicted deformed shape of a reference part with the real geometry using 3D scanning. Experimental results show that Amphyon software is able to predict the deformed shape for L-PBF parts correctly. The deviations from the real geometry depend on a simplified simulation model that considers a limited set of parameters for the L-PBF process

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelvefluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelve-fluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner