Pushing the Limits of 3D Color Printing: Error Diffusion with Translucent Materials

Accurate color reproduction is important in many applications of 3D printing, from design prototypes to 3D color copies or portraits. Although full color is available via other technologies, multi-jet printers have greater potential for graphical 3D printing, in terms of reproducing complex appearance properties. However, to date these printers cannot produce full color, and doing so poses substantial technical challenges, from the shear amount of data to the translucency of the available color materials. In this paper, we propose an error diffusion halftoning approach to achieve full color with multi-jet printers, which operates on multiple isosurfaces or layers within the object. We propose a novel traversal algorithm for voxel surfaces, which allows the transfer of existing error diffusion algorithms from 2D printing. The resulting prints faithfully reproduce colors, color gradients and fine-scale details.Comment: 15 pages, 14 figures; includes supplemental figure

A Comparison of Three-Dimensional Printing Technologies on the Precision, Trueness, and Accuracy of Printed Retainers

Purpose: The aim of this study was to evaluate the differences in the precision, trueness, and accuracy of 3D printed orthodontic clear retainers produced using printer systems with various printing technologies. Methods: Retainers (n=15) were printed using four different 3D printers: a stereolithography (SLA) printer, two different digital light processing (DLP and cDLP) printers, and a polyjet photopolymer (PPP) printer. The 3D printed retainers were transformed into a digital file through a cone-beam computed tomography scan that was compared to the original image using a 3D superimposition analysis software. At previously chosen landmarks (R6, L6, R3, L3, R1, L1) retainers were compared to the reference model. The intercanine and the intermolar width measurements were also analyzed for deviations between the samples and the original file. A discrepancy up to 0.25mm was considered clinically acceptable. Precision of printers was evaluated on 5 randomly chosen samples. Trueness was determined by comparing the measurements on printed retainers to those on the original image file. Root mean square (RMS) and percent of points within the tolerance level (inTOL) were also calculated with respect to precision and trueness for each retainer. Samples were analyzed for intra-printer reliability (precision), and inter-printer trueness. Statistical significance was set at P\u3c0.05. Results: Interrater correlation coefficient indicated good agreement and all measurements were within 0.10mm at least 95% of the time. Statistically significant differences were found between printer types among each of the 6 landmarks and the arch widths. When evaluating inTOL and RMS, statistically significant differences in both median precision and trueness among each printer type were found. SLA and PPP printing technologies exhibited both excellent precision and trueness. Conclusion: Retainers fabricated by SLA, DLP, cDLP, and PPP technologies were shown to be clinically acceptable and accurate compared to the standard reference file. SLA and PPP printers showed greater accuracy, and the DLP and cDLP printers exhibited greater precision. The PPP printer had the most accurate intra-arch measurements followed by the SLA printer, and therefore, based on their high trueness and precision values, were deemed to be the most accurate overall

Tunable Digital Material Properties of 3D Voxel Printers

Digital materials are composed of many discrete voxels placed in a massively parallel layer deposition process, as opposed to continuous (analog) deposition techniques. We explore the material properties attainable using a voxel-based freeform fabrication process and simulate how the properties can be tuned for a wide range of applications. By varying the precision, geometry, and material of the individual voxels, we obtain continuous control over the density, elastic modulus, CTE, ductility, and failure mode of the material. Also, we demonstrate the effects of several hierarchical voxel “microstructures”, resulting in interesting properties such as negative poisson’s ratio. This implies that digital materials can exhibit widely varying properties in a single desktop fabrication process.Mechanical Engineerin

A Content Analysis of 3D Printing Policies at Academic Libraries

Many academic libraries are adopting 3D printing programs and researching, writing, and implementing policies for these programs. This article analyzes the content of 50 academic library 3D printing policies looking for commonalities. Five major themes emerged from the analysis: the policy\u27s purpose, potential users of the 3D printers, 3D printing procedures, the acceptable uses of the 3D printers, and user privacy considerations. This article provides a breakdown of these five major themes

Модель оценки экономической эффективности использования 3D-принтера при создании изделий из стеклопластиковой арматуры периодического профиля

MODEL OF ECONOMIC EVALUATION USE A 3D-PRINTER IN THE CREATION OF PRODUCTS OF FIBERGLASS REINFORCEMENT PERIODIC PROFILE D. SHABANOV, V. STAHEIKO, S. TEREKHOV, N. AVERCHENKOНа основе изучения и анализа использования новой технологии изготовления стеклопластиковой арматуры дается описание подхода к оценке экономического эффекта от использования 3D-принтера при производстве стеклопластиковой арматуры периодического профиля и печати изделий на её основе по отношению к уже существующим технологиям. Рассматриваются вопросы технологии изготовления стеклопластиковой арматуры периодического профиля с использованием существующих технологий и 3D-принтера. На основе анализа данных предлагается описательная модель оценки эффективности использования 3D-принтера при создании изделий из стеклопластиковой арматуры периодического профиля. Увязываются вопросы экономической целесообразности использования 3D-принтера при армировании цементобетонных покрытий автомобильных дорог.= On the basis of the study and analysis of the use of new manufacturing technologies fiberglass reinforcement the approach to the assessment of the economic effects of the use of 3D-printers in the production of glass-fiber reinforcement with periodic profile and printing products based on it in relation to existing technologies is described. The problems of production of fiberglass reinforcement with periodic profile technology with existing technology and of 3D-printers are examined. On the basis of the data analysis the descriptive model evaluating the effectiveness of the use of 3D-printers to create products made of fiberglass fittings periodic profile is proposed. The issues of economic feasibility of the use of 3D-printers for reinforcing concrete slabs roads are solved

A level set based method for fixing overhangs in 3D printing

3D printers based on the Fused Decomposition Modeling create objects layer-by-layer dropping fused material. As a consequence, strong overhangs cannot be printed because the new-come material does not find a suitable support over the last deposed layer. In these cases, one can add some support structures (scaffolds) which make the object printable, to be removed at the end. In this paper we propose a level set method to create object-dependent support structures, specifically conceived to reduce both the amount of additional material and the printing time. We also review some open problems about 3D printing which can be of interests for the mathematical community