Quality Of 3D Printing Research Articles

Rheological study on 3D printability of alginate hydrogel and effect of graphene oxide

In recent years, hydrogels have been used as important biomaterials for 3D printing of three dimensional tissues or organs. The key issue for printing a successful scaffold is the selection of a material with a good printability. Rheological properties of hydrogels are believed to pay an important role in 3D printability. However the relations between rheological properties of hydrogels and 3D printability have not been extensively studied. In this study, alginate-based hydrogels were prepared as a model material for an extrusion-based printer and graphene oxide was added to modify the rheological properties and 3D printability of the hydrogels. Rheological studies were performed for the hydrogel samples with different formulas. The range of shear rates that the hydrogels suffered during the printing process was deduced. This range of shear rates helped us to select a proper shear rate to investigate the thixotropic properties of the hydrogels. Furthermore, we also defined some measureable parameters to describe and discuss the quality of 3D printing. The present study shows a new approach to analysis of 3D printability of a hydrogel and also provides some suggestion for 3D printing of 3D scaffolds.

The application of dairy products and their derivatives as edible inks in 3D printing technology: A review

SummaryThree‐dimensional (3D) printing technology digitally designs and manufactures objects through computer‐controlled processes. It requires raw materials with specific rheological properties for extrusion and shape retention. Dairy products hold promise for 3D printing due to their ability to form structures and their nutritional value. However, the quality of 3D printing with dairy products relies on the properties of the printing ink and printer parameters, presenting challenges for practical applications. This work provided a summary of the suitability of dairy‐based 3D printed products, discussing physicochemical modifications and additives to enhance their suitability and nutritional properties. The internal structure and composition of printing inks derived from dairy products are closely linked to their printing performance. Physicochemical modifications and additives effectively improve printability and the nutritional aspects of dairy inks. The 3D printing suitability of dairy inks can be enhanced through physical, chemical or enzymatic treatments. The gel properties of dairy products can be improved by mixing them with hydrophilic gels, introducing calcium, and incorporating lipids to enhance the 3D printing performance of dairy products. 3D printing technology enables the customisation of dairy products with personalised control of nutritional content, meeting the increasing consumer and market demand for healthier foods. In the future, 3D printed dairy products are expected to constitute convenient and quick nutritious food and enter home kitchens.

Investigating the effect of lattice design on sauce adhesion in 3D printed durum wheat pasta

Pasta has been one of the beloved foods for many years, and recently, attempts have been made in the industry to utilize 3D printing to create various designs of pasta noodles. This study investigated the effect of freeze-dried spinach powder on the quality of pasta dough used for 3D printing while focusing on improving the quality of 3D printing and post-processing characteristics and also the sauce adhesion capacity of pasta dough under various traditional Korean lattice infill patterns. Common durum wheat flour was substituted with 0, 4, 8, 12 and 16 g/54 g freeze-dried spinach powder. As wheat flour was progressively substituted with spinach powder, the rheological behavior of the dough ink changed from a long paste to a short paste. Pasta dough containing 12% spinach powder exhibited good resolution in the printing test while maintaining a stable network structure due to appropriate starch gelatinization with spinach granules after drying and cooking, ultimately resulting in a high-quality product. However, exceeding a certain threshold (16% spinach content) leads to adverse effects. Wanjasal, Guigapsal, and Ttisal muntin units were used as patterns for spinach-containing pasta, and increased sauce viscosity correlated with a greater retention of sauce within pattern holes. By successfully enhancing the nutritional value and printing resolution of durum wheat pasta using spinach powder, this study provides quantitative guidelines for the development of 3D printable pasta.

Research on Accuracy Enhancement Scheme for Home 3D Printers Based on Vision Sensors

Nowadays, with the rapid development of technology, more and more new technologies are being developed, but how to make these technologies accessible to factories at an affordable price and at a cost that is acceptable to all parties is a huge and complex comprehensive research. This paper focuses on two new technologies. They are 3D printers and vision sensors. After discussing how they work and the advantages and disadvantages about them. This paper focuses on how these two new technologies can be combined to improve the quality of 3D printing, increase the compatibility of building complex geometries, and reduce the reliance on manual calibration. Finally, a model for combining these two novel technologies is presented along with its operational logic. However, the challenges of cost, sensor integration and algorithm optimization will be addressed in further development and finally a partial analysis of how it can be further developed in the future.

Dimensional Analysis of the Wear of 3D Printed Dies Used to Form PC and PVC Sheets by Thermoforming

Polymers have been around for a while now, and for the time being they play a fundamental role in our society. As time passes, the number of polymer-based items increases. Thermoforming is a conventional polymer manufacturing process with high potential. This paper explores the surface quality of 3D printing dies after being used in a thermoforming process. A polylactic acid (PLA) die was printed using a Fused Deposition Modelling (FDM) The polymeric blanks formed were Polycarbonate (PC) and Polyvinyl chloride (PVC) sheets of 1.5 mm. The results reveal the effects of the temperature, the thermoforming process time and vacuum time on the wear of the top surface dis not surpass 1mm in the worst zone, and does not affect the polymeric formed sheets.

Immersion polishing post-treatment of PLA 3D printed formed parts on its surface and mechanical performance

Steps were taken to improve the surface and mechanical performance of PLA 3D printed formed parts, reduce the “step texture” produced by the fused deposition process, and improve the quality of 3D printing by means of post-treatment. The PLA 3D formed parts were immersion polished with chloroform solution to investigate the effects of immersion polishing on the surface roughness, surface gloss, mechanical properties, and other factors of PLA formed parts. The results of the pre-experiment showed that 90% of the effect was due to the optimal concentration value of chloroform solution and 10% was the optimization of time for immersion polishing. Under the pre-experimental conditions, the surface roughness of the formed parts was reduced by 87%, and the surface gloss was increased by 510%, the surface quality and gloss were significantly improved, and the “step texture” was significantly reduced; meanwhile, the tensile and compressive ultimate strength of the formed parts were increased by 9.41% and 13.09%, respectively, and the mechanical performance were improved, and the quality of 3D printing post-treatment was significantly improved.

JUSTIFICATION OF THE DESIGN OF A 3D PRINTER EXTRUDER NOZZLE USING GRANULES AND CUT POLYMER PARTICLES AS INPUTS

The article defines extrusion as a continuous process of converting a solid bulk polymer into a viscous state followed by pushing it through a molding tool. It is emphasized that extruders are one of the most promising types of equipment for processing polymer materials and are used in various industries, including 3D printing. Attention is focused on the fact that one of the important parts of each extrusion unit is the extrusion head. It is the main tool that determines the final shape of extruded products. It is emphasized that the extruder nozzle has a significant impact on the quality of 3D printing. Four parameters characterizing the nozzle are highlighted: its external size, internal structure, diameter of the hole for extruding the polymer, and the material from which it is made, and each is considered in detail. The main physical and mechanical properties of nozzles made of different materials are presented. A classification of nozzles was developed on the basis of the conducted review. The formula for determining the volumetric productivity of a 3D printer extruder is given, depending on the design of its dosing zone and nozzle resistance. An expression for determining the total resistance coefficient of the nozzle is given, which is defined as the sum of the resistance coefficients of individual geometrically simple sections of its internal structure. It is proposed to use in the extruder of a 3D printer that uses granules or crushed polymer particles as raw materials for the construction of nozzles for 3D printers that print with filament. With their use, a new nozzle design for screw extruders was developed and presented. Based on the analysis of the internal structure of nozzles for 3D printers that print with filament and forming devices of plastic processing equipment, the design of the extruder nozzle using a mandrel was developed and presented.

A multiobjective optimization parameters applied to additive manufacturing: DOE-based approach to 3D printing

The performance and quality of 3D printing, as well as the mechanical properties of the final part, depend on its printing parameters, such as layer thickness, printing speed, infill density, filling pattern, printing material, and many others. In this study, the influence of printing parameters on the mechanical properties of the final printed part is investigated, and at the end, a multi-objective optimization was performed on the experimental responses. To study the effects of printing parameters, the Design of Experiments methodology was used, where five parameters considered essential were evaluated: layer thickness, printing speed, infill density, filling pattern, and printing material. Once everything was printed, mechanical tests of traction, compression, and bending were used to obtain the experimental curves. After obtaining the experimental responses by extracting the test curves, the ANOVA method was applied, through which it was possible to obtain a behavior equation, a relation of the main effects, and Pareto graphs of each experimental result on the studied parameters. Finally, the multi-objective optimization allowed obtaining printing parameters that allowed improvements in several mechanical properties in addition to the minimization of time and total mass. Results indicated a reduction of 72.39% in the average time of printing and an increase of 9.06% in the mass after the optimization where the mechanical properties were substantially optimized.

LESSONS LEARNT ON 3D PRINTING MICHELANGELO’S DAVID REPLICA

Abstract. This paper reports and discusses the results of some experimental investigations carried out with the aim to identify the best conditions for a safe exposure of the 3D printed large-scale replica of Michelangelo’s David during its exhibition in the Italian Pavilion of the Expo 2020 Dubai.The whole project posed numerous challenges due to the dimension of the Michelangelo’s David (which is over seven metres high and weighs more than five ton). As a matter of fact, on the one hand, no standardized procedures have been still established to define accuracy and quality of 3D printing. On the other hand, the large-scale printing opens up new issues concerning the mechanical properties requested of the printing material and the printing set-up that is necessary to ensure the stability and durability of the printed replica.After a general picture of the whole project, thermal characterization of the material used to print the replica and mechanical tests of samples obtained form the replica are reported and discussed. Thermal characterisation showed that the stiffness of the material was strongly influenced by temperature and that it decreased continuously as this parameter increased. Mechanical tests showed a brittle behaviour, with a collapse load approximately 10 times higher than the internal loads resulting from the self-weight alone.The analyses here presented constitute some of the groundwork carried out for the realisation and installation of the 3D printed replica of Michelangelo’s David. This conceptualisation, considering both the extreme environmental conditions and the large-size of the replica, has been particularly challenging and the adopted procedure was useful to verify the different phases of the realisation of the replica.

Optimized Control Method for Fused Deposition 3D Printing Slice Contour Path Based on Improved Hopfield Neural Network

ABSTRACT This paper presents a novel approach for optimizing the contour path of fused deposition 3D printing slices to mitigate the limitations of inefficiency and time consumption associated with the process. The proposed algorithm leverages the Hopfield Neural Network (HNN) and an improved whale optimization algorithm to plan the printing order of each contour and optimize the network parameters, respectively. In particular, the algorithm transforms the running trajectory planning problem of the assembled tool head into a travel problem, which allows for a more efficient path planning approach. The HNN is then employed to determine the optimal path for each contour, with the network optimization process utilizing a nonlinear weight update method to overcome the drawbacks of the traditional HNN that is prone to generating invalid paths and falling into local optimality during operation. The network optimization process is designed to automatically adjust the link weights between neurons within a specific range, thereby ensuring that the network reaches the desired energy minima and outputs the optimal path for 3D printed slice contours. The proposed algorithm was tested in part printing experiments, and the results demonstrated a significant reduction in single-layer contour path lengths, printing times, and an enhancement in dimensional accuracy and surface quality of the printed parts compared to the traditional parallel scanning method. The proposed algorithm represents a significant contribution to the field of 3D printing, as it provides an efficient and effective approach for optimizing the contour path of fused deposition 3D printing slices. The findings of this study hold significant implications for improving the efficiency and quality of 3D printing and could potentially lead to further advancements in the field.

Improving printed products manufacturing technology using 3D printing

The aim of the paper is to analyze the state of the printing industry in the current conditions, learn reproduction technologies on non-absorbent surfaces, and study modern technological processes of obtaining products based on 3D printing, which is the research object. The problem lies in the lack of general recommendations for using the above technology to produce printed products or their elements. The main factors affecting the quality of finished products have been determined. The criterion to compare possible options for creating printed products was selected, namely, the examination method was considered. After processing the expert group summary, the consistency degree of opinions was determined using Kendall’s concordance coefficient. The most significant factor was identified, and further research is focused on it. Layer-by-layer deposition modeling was chosen as the technology for creating the test. Test fragments were developed, and materials and equipment to run the experiment were selected. A quantitative and qualitative assessment of the quality of 3D printing was carried out. Following the conducted research, the shortcomings were taken into account, and a number of recommendations for further creation of the forthcoming high-quality product were made. Those recommendations refer to the optimal line width (1.5 points and more), typeface origin and font size (20 points and above) for the reproduction of text information, and thickness of the element base of printed products (minimum 2.5–3 mm). The above recommendations allow a 3D printing product and its elements to achieve a remarkable quality level and visual appeal, as well as enable enterprises to use it as the basis of technological instructions for applying modern technologies.

Multi-Material Metamaterial Topology Optimization to Minimize the Compliance and the Constraint of Weight: Application of Non-Pneumatic Tire Additive-Manufactured with PLA/TPU Polymers.

In non-pneumatic tires, metamaterial cells could replace the pneumatic part of the tire. In this research, to achieve a metamaterial cell suitable for a non-pneumatic tire with the objective function of increasing compressive strength and bending fatigue lifetime, an optimization was carried out for three types of geometries: a square plane, a rectangular plane, and the entire circumference of the tire, as well as three types of materials: polylactic acid (PLA), thermoplastic polyurethane (TPU), and void. The topology optimization was implemented by the MATLAB code in 2D mode. Finally, to check the quality of cell 3D printing and how the cells were connected, the optimal cell fabricated by the fused deposition modeling (FDM) method was evaluated using field-emission scanning electron microscopy (FE-SEM). The results showed that in the optimization of the square plane, the sample with the minimum remaining weight constraint equal to 40% was selected as the optimal case, while in the optimization of the rectangular plane and the entire circumference of tire, the sample with the minimum remaining weight constraint equal to 60% was selected as the optimal case. From checking the quality of 3D printing of multi-materials, it was concluded that the PLA and TPU materials were completely connected.

3D-printing bionic-patterned zirconia via stereolithography promotes soft tissue integration for ceramic implants

Due to the desirable aesthetic performance, zirconia abutments attract tremendous attention in implant related restoration of the anterior zone. However, the inadequate soft tissue integration originated from the inertia surface of zirconia severely limits its application. Fabricating bionic-patterned zirconia abutments is believed to be a promising strategy to solve this puzzle. The main obstacle to fabricating bionic-pattern lies in that conventional zirconia manufacturing technology cannot precisely engineer complex micro-pattern. Notably, modern 3D printing presents a feasible way to obtain various sophisticated topological architecture. In the present study, series of bionic-patterned zirconia were fabricated by 3D printing, simulating lotus leaf, butterfly wings, shark skin, and gecko foot. The features of micro-patterns and quality of 3D printing were systematically characterized. In addition, the effect of various bionic-patterned zirconia on the behaviors of gingival fibroblasts was investigated. Results showed that zirconia with various micro-scale bionic patterns was successfully and precisely fabricated by 3D printing. Among the four types of bionic patterns, the ones that resembled the geckos’ feet or lotus leaves were the most recommended topography for cell growth and spreading, while the pattern mimicked shark skin upgraded the expression of fibroblast functional genes including Col-I, Fn, and Itgb-1 most obviously. The bionic-patterned zirconia can efficiently promote adhesion, proliferation, and related gene expression of gingival fibroblasts, indicating that bionic-patterned zirconia has great potential to promote soft tissue integration.

Compressive strength of metamaterial bones fabricated by 3D printing with different porosities in cubic cells

This research focuses on the compressive strength of metamaterial bones, fabricated by 3D printing with different porosities in cubic cells. For this objective, compressive testing was done on standard samples besides bones, both 3D-printed and real ones. To fabricate a metamaterial bone, the cubic cell was chosen in this research. Since the yield strength and the ultimate stress of the vertical solid standard specimen had better performance than the horizontal solid standard one, the vertical metamaterial sample with a cubic cell was designed for four porosity states of 25%, 30%, 50%, and 55%. The obtained results illustrated that 30% of porosity was introduced as the optimal specimen. Therefore, this percentage of porosity was used to fabricate a metamaterial bone. In addition, the rabbit tibia bone in two solid and metamaterial states was prepared by 3D printing and compared with the real rabbit bone. The results showed that the real bones withstood more force compared to the solid and metamaterial 3D-printed bone samples. The weight of the metamaterial bone decreased by 5.97%, compared to the solid bone specimen. Finally, the quality of 3D printing was checked by microscopy. Then, the quality of 3D printing decreased by increasing the thickness of the strut.

Improvement of the Quality of 3D Printing in the Mass Production of Parts

The article highlights the experience of using 3D printing at automotive enterprises manufacturing automotive wiring. The primary attention was paid to optimizing technologies and modernizing equipment in 3D printing in production conditions. This helped to improve the printing quality at the enterprise and reduce energy consumption during mass printing of parts. The article aims at improving quality and reducing energy consumption during 3D printing in serial production conditions. The technique’s novelty consists of a complex of production optimizations combined into a production rack to improve 3D printing. During the research, negative factors affecting print quality and their elimination were analyzed. An experimental setup for 9 printers was created. As a result, ways to increase energy efficiency according to environmental standards were implemented under the mass production of 3D parts. Overall, the applied technology allowed for reducing the time for the development of new prototypes. This made it possible to reduce the produced parts cost and allowed for implementing urgent changes in manufacturing enterprises.

Numerical Simulation and Experimental Study the Effects of Process Parameters on Filament Morphology and Mechanical Properties of FDM 3D Printed PLA/GNPs Nanocomposite.

The selection of optimal process parameters has a decisive effect on the quality of 3D printing. In this work, the numerical and experimental methods were employed to investigate the FDM printing deposition process of PLA/GNPs nanocomposite. The effect of process parameters on cross-sectional morphology and dimension of the deposited filament, as well as the mechanical property of the FDM printed specimens were studied. The extrusion and the deposition process of the molten PLA/GNPs nanocomposite was simulated as a fluid flow by the paradigm of CFD, the effects of printing temperature and shear rate on thermal-physical properties, such as viscosity and surface tension, were considered in models. Under the assumptions of non-Newtonian fluid and creep laminar flow, the deposition flow was controlled by two key parameters: the nozzle temperature and the nozzle velocity. The numerical model was verified by experiments from four aspects of thickness, width, area, and compactness of the deposited PLA/GNPs nanocomposite filament cross-section. Both the numerical simulation and experiment results show that with the increase of nozzle temperature and nozzle velocity, the thickness, area, and compactness of the deposited filament decreases. While the width of deposited filament increased with the increase of nozzle temperature and decrease of nozzle velocity. The decrease in thickness and the increase in width caused by the change of process parameters reached 10.5% and 24.7%, respectively. The tensile strength of the printed PLA/GNPs specimen was about 61.8 MPa under the higher nozzle temperatures and velocity condition, an improvement of 18.6% compared to specimen with the tensile strength of 52.1 MPa under the lower nozzle temperatures and velocity condition. In addition, the experimental results indicated that under the low nozzle velocity and nozzle temperature condition, dimensional standard deviation of the printed specimens decreased by 52.2%, 62.7%, and 68.3% in X, Y, and Z direction, respectively.

Parametric optimization for dimensional correctness of 3D printed part using masked stereolithography: Taguchi method

PurposeMasked stereolithography (MSLA) or resin three-dimensional (3D) printing is one of the most extensively used high-resolution additive manufacturing technologies. Even though, the quality of 3D printing is determined by several factors, including the equipment, materials and slicer. Besides, the layer height, print orientation and exposure time are important processing parameters in determining the quality of the 3D printed green state specimen. The purpose of the paper is to optimize the printing parameters of the Masked Stereolithography apparatus for its dimensional correctness of 3D printed parts using the Taguchi method.Design/methodology/approachThe acrylate-based photopolymer resin is used to produce the parts using liquid crystal display (LCD)-type resin 3D printer. This study is mainly focused on optimizing the processing parameters by using Taguchi analysis, L-9 orthogonal array in Minitab software. Analysis of variance (ANOVA) was performed to determine the most influencing factors, and a regression equation was built to predict the best potential outcomes for the given set of parameters and levels. The signal-to-noise ratios were calculated by using the smaller the better characteristic as the deviations from the nominal value should be minimum. The optimal levels for each factor were determined with the help of mean plots.FindingsBased on the findings of ANOVA, it was observed that exposure time plays an important role in most of the output measures. The model’s goodness was tested using a confirmation test and the findings were found to be within the confidence limit. Also, a similar specimen was printed using the fused filament fabrication (FFF) technique; it was compared with the quality and features of MSLA 3D printing technology.Practical implicationsThe study presents the statistical analysis of experimental results of MSLA and made a comparison with FFF in terms of dimensional accuracy and print quality.Originality/valueMany previous studies reported the results based on earlier 3D printing technology such as stereolithography but LCD-based MSLA is not yet reported for its dimensional accuracy and part quality. The presented paper proposes the use of statistical models to optimize the printing parameters to get dimensional accuracy and the good quality of the 3D printed green part.

Generative Design and Integrated 3D Printing Manufacture of Cross Joints.

The integrated process of design and fabrication is invariably of particular interest and important to improve the quality and reduce the production cycle for structural joints, which are key components for connecting members and transferring loads in structural systems. In this work, using the generative design method, a pioneering idea was successfully realized to attain a reasonable configuration of the cross joints, which was then consecutively manufactured using 3D printing technology. Firstly, the initial model and generation conditions of a cross joint were constructed by the machine learning-based generative design algorithm, and hundreds of models were automatically generated. Then, based on the design objective and cost index of the cross joint, three representative joints were selected for further numerical analysis to verify the advantages of generative design. Finally, 3D printing was utilized to produce generative joints; the influences of printing parameters on the quality of 3D printing are further discussed in this paper. The results show that the cross joints from the generative design method have varied and innovative configurations and the best static behaviors. 3D printing technology can enhance the accuracy of cross joint fabrication. It is viable to utilize the integrated process of generative design and 3D printing to design and manufacture cross joints.

Study of the fractional composition of powders for 3D printing based on polyamide-12 using statistical methods of dimensional ranking

The quality of 3D printing depends on the properties of consumables, in particular, on the chemical composition of the powders, the size and shape of their particles. To eliminate printing defects, the working mixture of primary and secondary powders based on polyamide-12 should contain no more than 30% of the secondary powder. We present the results of studying the fractional composition of powders by the methods of statistical analysis. Digital images of polymer samples including morphological parameters of particle images were analyzed. To assess the fractional composition of the particles of primary and secondary powders, a statistical method of dimensional ranking and a differential method for determining the boundaries of fractions were used. It is shown that the particle area is the parameter most sensitive to changes in the structure of powders. The results of statistical ranking of effective particle radii are obtained proceeding from the histograms of the particle area distribution. The boundaries of the conditioned fraction are determined by the magnitude of the effective radii. A comparison of the fractional composition of primary and secondary powders, as well as calculation of the percentage of fine, working and large fractions were carried out taking into account the assessment of the fraction boundaries. It is revealed that the content of fractions of powder particles with conditioned dimensions should be about 64% of the total volume of the powder. Reduction of the amount of primary powder can lead to defects in 3D printing. The results obtained can be used to increase the degree of recovery of polyamide-12 based powders during 3D printing.

Influence of rheological characteristics on the quality of 3D printing of food pastes

In extrusion 3D printing, the rheological properties of food are critical to achieving quality printing. The aim of this study is to investigate potential correlations between the printability of food pastes and rheological characteristics. Potato and tomato puree were used as a model system. The rheological properties of mashed potatoes with the addition of potato starch and their behavior during 3D printing have been investigated. A correlation has been established between the formulation and manufacturability in 3D printing. Potato mass without starch had a low yield point, which affected the deformation and subsidence of the mass later. At the same time, the addition of 2% starch showed excellent extrudability and printability, that is, the ability to flow. Under these conditions, the printed objects had a smooth shape, good resolution, and could withstand shape over time. The object with the addition of 4% starch represented good shape retention but poor extrudability due to its high consistency index and toughness. The results obtained using tomato puree showed a linear correlation between ingredient flow stress, zero shear viscosity and corresponding print stability. The extrusion pressure required to extrude tomato paste increases linearly with increasing flow voltage. Modules of viscosity, elasticity, and zero shear rate turned out to be not linearly correlated with the extrusion force, which can be explained by the fact that these parameters reflect the rheological properties of the non-deforming state of the material, in contrast to the flow stresses.