Lost-wax Research Articles

Based on chemical and mineralogical examination of casting cores to determine the foundry area of bronze vessels from the Xiaxiangpu site in Nanyang city, Henan Province, China

XRF and XRD analysis were conducted on clay cores inside seven bronze artifacts belonged to E State from the Xiaxiangpu site (c. 885–650 BCE). The aims of the study are to discuss whether it is the metal raw materials or the finished bronze artifacts were imported, and whether the E State still had political and technical conditions to make sacrificial vessels after its rebellion. The contrastive analysis of major compositions and trace elements with other reference objects indicates that the raw materials of clay cores were came from local sources. Contrary to the outside lead ore, it is highly likely that E State imported the metal raw materials and cast bronze artifacts in local workshops independently. The autonomy of such act confirms that E State still kept the aristocracy and economic and political strength after the military unrest in the late Zhou Dynasty.

Design and Thermal Comparison of Random Structures Realized by Indirect Additive Manufacturing

Additive manufacturing (AM) processes are used to fabricate three-dimensional complex geometries. There are several technologies that use laser or electron beam over metal powder beds. However, the direct AM processes have inconveniences such as specific set of materials, high thermal stress traced, high local energy absorbed, poor surface finish, anisotropic properties, high cost of material powder, and manufacturing with high-power beams. In this paper, an alternative process was developed. An indirect additive manufacturing (I-AM) combining a 3D print of castable resin and metal casting in order to obtain a cellular structure similar in shape to commercial metal foams but completely definable as design features was developed. Design of the cellular structure was made by the graphical algorithm editor Grasshopper®. Designed structures were realized by a lost-wax casting process and compared with commercial foam specimens by a system designed for this work. The designed metal foams showed a performance superior to that of commercial metal foam; in particular, the heat thermal coefficient of designed metal foams in the better case was 870 W/m2·K, almost doubled in comparison with the commercial foam tested in this work.

Influence of surface airborne-particle abrasion and bonding agent application on porcelain bonding to titanium dental alloys fabricated by milling and by selective laser melting

Statement of problemComputer-aided design and computer-aided manufacturing (CAD-CAM) technologies have provided alternatives to lost-wax casting for the fabrication of titanium frameworks in metal-ceramic fixed dental prostheses (FDPs). The findings on varying metal surface characteristics resulting from application of different fabrication technologies indicate a need to reevaluate the traditional titanium surface conditioning protocols. PurposeThe purpose of this in vitro study was to investigate the effects of surface airborne-particle abrasion (APA) and bonding agent application on the porcelain bond to titanium dental alloys fabricated by subtractive computer numerical controlled (CNC) milling and by additive selective laser melting (SLM) methods. Material and methodsEight groups of Ti-6Al-4V substrates (n=11) were fabricated—half of them by CNC milling and half by SLM. The groups represented a fully crossed experimental protocol of APA with 110-μm Al2O3 particles under a pressure of 0.2 MPa (intact—controls or abraded) and bonding agent application (with or without bonding agent) for the CNC milled and SLM titanium substrates. Ultra-low fusing dental porcelain was applied to the differently prepared titanium substrates, and the titanium-ceramic bond strength was determined by a 3-point bend test according to the International Organization for Standardization (ISO) standard 9693-1:2012. Average profile roughness (Ra) values were obtained for intact and APA titanium substrates fabricated by CNC milling and by SLM. Representative titanium-ceramic interfaces were analyzed by using a field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS). Titanium-ceramic bond strength data were analyzed statistically by 3-way ANOVA and the Tukey HSD test. Ra data were analyzed by 2-way ANOVA, followed by regression analyses (α=.05). ResultsThe method applied for the digital fabrication of titanium (either subtractive CNC milling or additive SLM) did not affect the titanium-ceramic bond (P=.247). APA (P<.001), as well as the application of a bonding agent (P<.001), increased the titanium-ceramic bond strength. When these 2 procedures were combined, the porcelain bond strength to CNC milled titanium was 37.3 ±4.1 MPa and that to SLM titanium was 36.7 ±4.9 MPa. APA increased the surface roughness of CNC milled titanium (P=.002) but decreased the roughness of the SLM substrates (P<.001). ConclusionsA protocol comprising APA and application of a bonding agent ensures the highest porcelain bond strength to both CNC milled and SLM titanium, with the obtained values being well above the minimal value for metal-ceramic systems as specified by ISO 9693-1:2012.

Evaluation of Marginal Misfit of Implant-Supported Fixed Prostheses Made Using Different Techniques.

To evaluate the vertical marginal (VM) and horizontal marginal (HM) misfit of frameworks made using different techniques. A total of 30 frameworks were divided into three groups of 10 samples each based on manufacturing technique: nichrome cast (G1), milled in zirconia (G2), and milled in wax and fused to metal (G3). Marginal misfit was measured using a three-dimensional optical microscope. The highest VM misfit was in G3 (83.5 μm), followed by G1 (55 μm) and G2 (42 μm). The highest HM misfit was in G2 (118 μm), followed by G3 (102 μm) and G1 (-85 μm). Frameworks milled in zirconia resulted in the lowest VM misfit, while frameworks filled in wax and fused to metal resulted in higher VM. The HM misfit was favorable in the lost-wax technique.

로스트 왁스에 의한 석고주조기법 연구 - 회전체를 중심으로 -

로스트 왁스에 의한 석고주조기법 연구 - 회전체를 중심으로 -

DEPOSITS OF BRONZE SMALL TWIGS IN MIDDLE ROS BASIN

In the article the noticeable role of bronzocasting production is considered on the settler monuments of scythian time in the Tarashchanskiy district of the Kyiv area.&#x0D; Among the numerous testimonies of bronze casting production and trade in metals the two most interesting items are bronze treasures, recently discovered in the villages of Lisovichi and Dibrovka in Kyiv region. Each contained about 300 bars with a length of 40.5 and 22 cm (Lisovichi), 41 cm (Dibrovka), total weight about 30 kg. We can assume a different purpose of bronze bars: blanks for specific products, raw materials for smelting, the equivalent of money. Spectral analysis of the products showed that they are made of high-quality tin bronze with a high admixture of iron (2.58 %, Lisovichi). Titanium content (4.39 %, Lisovichi) remains unclear (is it a natural impurity in raw materials?) According to the place of discovery (on settlements), treasures of bars can be dated to Scythian time (the end of 6th—5th century BC?), although more late dates are not excluded.

La imagen modelada. Conversación con Antonio Pujía

La conversación con Antonio Pujía nos permitió apreciar la importancia que elartista ha dado al conocimiento técnico de la fundición a la cera, primero, plasmadaen su proyecto de una Cooperativa de Técnicas de la Escultura y, luego, através de su curso de modelado en cera (que aún hoy dicta). Al mismo tiempo,hemos revisitado, a través de su relato, una parte importante de su vida y desu carrera artística.

Imported or indigenous? The earliest forged tin foil found in China

Abstract It was during the early Eastern Zhou period (7th–5th centuries BCE) that forged tin foil turned up suddenly as an “exotic” novelty. This paper investigates archaeological finds of tin foil with decorating patterns from Caojiagang and Zhaoxiang, the two Eastern Zhou tombs found in Dangyang, Hubei, Central China. The results of scientific examination reveal the application of remarkable forging and working techniques to manufacturing the patterned tin foil, demonstrating a new trend toward diversity in metalwork in Eastern Zhou China, signalling a departure from the dominance of piece-mould casting bronze technology in the earlier periods of the Shang and Western Zhou. It is argued that the appearance of tin foil and the widespread adaption of forging technology in the Eastern Zhou period were most likely motivated by the desire to pursue social distinction or display individual preference. The cultural links to the Eurasian steppe could have played a role in the process also.

Capacitive Bio-Inspired Flow Sensing Cupula.

Submersible robotics have improved in efficiency and versatility by incorporating features found in aquatic life, ranging from thunniform kinematics to shark skin textures. To fully realize these benefits, sensor systems must be incorporated to aid in object detection and navigation through complex flows. Again, inspiration can be taken from biology, drawing on the lateral line sensor systems and neuromast structures found on fish. To maintain a truly soft-bodied robot, a man-made flow sensor must be developed that is entirely complaint, introducing no rigidity to the artificial “skin.” We present a capacitive cupula inspired by superficial neuromasts. Fabricated via lost wax methods and vacuum injection, our 5 mm tall device exhibits a sensitivity of 0.5 pF/mm (capacitance versus tip deflection) and consists of room temperature liquid metal plates embedded in a soft silicone body. In contrast to existing capacitive examples, our sensor incorporates the transducers into the cupula itself rather than at its base. We present a kinematic theory and energy-based approach to approximate capacitance versus flow, resulting in equations that are verified with a combination of experiments and COMSOL simulations.

Virtual Evaluation of the Accuracy of Fit and Trueness in Maxillary Poly(etheretherketone) Removable Partial Denture Frameworks Fabricated by Direct and Indirect CAD/CAM Techniques.

To compare the accuracy of fit and trueness of maxillary poly(etheretherketone) (PEEK) removable partial denture (RPD) frameworks fabricated by direct and indirect computer-aided design/computer-aided manufacturing (CAD/CAM) techniques. A definitive maxillary class I master epoxy model was duplicated to create a stone cast. The cast was scanned, and an RPD was designed. Standard tessellation language (STL) data were used to fabricate 20 identical RPD frameworks using two CAD/CAM techniques: direct milling of PEEK and indirect additive manufacturing (resin printing combined with PEEK thermopressing using the lost-wax technique). All the frameworks for each technique (n = 10) and the reference cast were scanned. To assess the accuracy of fit, a color map was constructed using metrology software, and the misfit (distance between each framework and the reference cast) was measured at 25 standardized points. To assess the overall trueness, each framework STL file was superimposed over the original design's STL file, and the average deviation was recorded in microns. Data were statistically analyzed using t-test. Color mapping showed distinct pressure areas in the anterior and posterior straps of the major connector in the indirect technique, while a more uniform distribution of the color map was observed in the direct technique. A significant difference was found between the two techniques regarding the overall accuracy of fit. Compared with the indirect technique, the milled frameworks showed significantly better overall trueness (p < 0.001). Although a significant difference in the overall fit accuracy was noted between both techniques, the fit was an acceptable clinical fit. The fabrication method affects the fit in the anterior and posterior strap areas. The frameworks of the direct technique revealed better overall trueness values compared with the indirect technique.

3D Printing in Dentistry-State of the Art.

Three-dimensional (3D) printing is a rapidly developing technology that has gained widespread acceptance in dentistry. Compared to conventional (lost-wax technique) and subtractive computer numeric controlled methods, 3D printing offers process engineering advantages. Materials such as plastics, metals, and ceramics can be manufactured using various techniques. 3D printing was introduced over three decades ago. Today, it is experiencing rapid development due to the expiration of many patents and is often described as the key technology of the next industrial revolution. The transition to its clinical application in dentistry is highly dependent on the available materials, which must not only provide the required accuracy but also the necessary biological and physical properties. The aim of this work is to provide an up-to-date overview of the different printing techniques: stereolithography, digital light processing, photopolymer jetting, material jetting, binder jetting, selective laser sintering, selective laser melting, and fused filament fabrication. Additionally, particular attention is paid to the materials used in dentistry and their clinical application.

Self-Healing Performance Comparison Between Two Promising Vascular Vessel Systems of the Wind Turbine Blade

Hollows produced by wires and borosilicate tubes are two significant approaches for the storage and transport of healing agent for self-healing wind turbine blades. To compare the performance for the two approaches, sheet samples and prototype blades were molded with vacuum-assisted resin transfer molding (VARTM) and max-flexural strength was evaluated before and after the self-healing process. One millimeter outer diameter with 0.5 mm inner diameter borosilicate tubes were used to store and transport the healing agent. Dicyclopentadiene was used as the healing agent and Grubbs' first-generation catalyst was used to initiate polymerization. To obtain the same structure of the tube, a lost-wax method was applied twice to form hollows with 1 mm outer diameter and 0.5 mm inner diameter. Since the samples need to be heated to form the hollows, the effect of the heating process on flexural strength was investigated. The flexural strength of the samples showed to be enhanced with the heating process. The percentage improval for flexural strength was 14.18% at 120 °C, 21.79% at 135 °C, and 10.89% at 150 °C. The growth trend continued until 135 °C and decreased after 135 °C. The toughness of the samples was also weakened. With the heating process, the initial and post self-healing flexural strength between samples with tubes and samples with hollows showed little difference. The recovery percentage of samples with tubes was 81.55%, while that of samples with hollows was 81.92%. Without the heating process, the initial and post self-healing flexural strength between samples with tubes and samples with hollows also showed little difference. The recovery percentage of samples with tubes was 89.52%, while that of samples with hollows was 89.46%. The space between the tubes/hollows greatly affected the flexural strength. The flexural strength of samples with a larger space between tubes/hollows was higher than that of samples with a smaller space between tubes/samples. For the prototype wind turbine blade, the initial and post self-healing flexural strength followed the same trend. For samples with hollows, the ratio of the inner diameter to outer diameter can be close to one so the walls can be very thin improving storage and transport efficiency.

Novel fatty acid anion-based ionic liquids: Contact angle, surface tension, polarity fraction and spreading parameter

This work deals with the determination of several wetting properties (contact angle, surface tension, polarity fraction and spreading parameter) of six novel fatty acid anion-based ionic liquids (FAILs): methyltrioctylammonium hexanoate [N8881][C6:0], methyltrioctylammonium octanoate [N8881][C8:0], methyltrioctylammonium laurate [N8881][C12:0], methyltrioctylammonium palmitate [N8881][C16:0], methyltrioctylammonium stearate [N8881][C18:0] and methyltrioctylammonium oleate [N8881][C18:1]. Surface tension was determined at temperatures from 293 to 333K, exhibiting a linear decrease within the temperature range. Contact angle measurements were performed on five different surfaces (steel, aluminum, tungsten carbide, cast iron and bronze) using 3 test liquids (water, diiodomethane and ethylenglycol) and each of the synthesized FAILs. Polarity fraction (PF) and the spreading parameter (SP) were calculated in order to gain a deeper understanding of wetting characteristics of these FAILs. Despite the similarity of the obtained results with all FAILs and surfaces, [N8881][C6:0] and [N8881][C8:0] with both cast iron and bronze surfaces were the best surface-FAIL combinations regarding wettability.

Mechanical Characterization of Different Aluminium Foams at High Strain Rates.

Samples having nominal compositions of AlSi12 and Al6082-T4 were prepared using a lost wax casting process, with nominal relative densities of 20%, 40%, and 60%, as well as arrangements of a uniform cell structure (US) or a dual-size cell (DS). For comparison, samples of aluminium foam-filled tubes having the same nominal composition were also prepared with the same technique, with nominal relative densities of 20% and similar arrangements (US and DS). Impact tests at different velocities were performed using a split Hopkinson pressure bar (SHPB). It is possible to conclude that Al6082-T4 foams have better performance, in both configurations, than the AlSi12 ones. Considering a uniform cell structure and a density of 20%, the absorbed energy by the Al6082-T4 foams was around 25% higher than the value observed for the AlSi12 ones. In terms of arrangement, the US structure presents absorbed energy around 57% lower than the DS ones, while the AlSi12 foams with a relative density of 20% were compared. Finally, the absorbed energy growths from 2.8 × 105 to 5.2 × 105 J/m3, when the density increased from 20% to 60%. However, when these foams were involved with a tube, the performances increased substantially.

Technological Observations on Two-Part Stone Jewelry-Casting Molds of the Late Bronze Age in the Near East

AbstractTwo-part stone jewelry molds were intended for casting of small and delicate precious metal jewelry and were common primarily during the Late Bronze Age in the ancient Near East. Published examples bear witness to the technological sophistication of the ancient craftsmen who used them as versatile tools for casting of a variety of solid rings, bezels, earrings, pendants, diadems, beads, pins, figurines, and amulets. As most stones crack when exposed to the extreme heat of molten metal, solid casting using stone molds may actually have been intended for fabrication of wax models using the “lost wax” technique, which allows for their repeated use for production of wax anti-types. The largest number of these molds originates from coastal sites of the northern Levant, drawing attention to this region as a nexus of specialized metalworking during this period and probably also for the spread of this technology in the eastern Mediterranean.

A Soft Ring-Shaped Actuator for Radial Contracting Deformation: Design and Modeling.

Bioinspired movements such as elongation/shortening and bending are extensively studied in the field of soft robotics. However, radial contracting deformation has been overlooked, another typical deformation in nature, such as the constrictive deformation in the human esophagus and bladder. We present a novel soft ring-shaped actuator that generates radial contraction and examine its quasi-static performance under pressurization. This actuator consists of a soft ring-shaped body and a rigid casing. A single circular air chamber embedded concentrically inside the actuator is created through the lost-wax method. A theoretical model of the quasi-static state of the actuator's contracting deformation was formulated in light of the minimum total potential energy principle. Meanwhile, a finite-element method (FEM) model was constructed to stimulate the radial contraction of the actuator. In addition, experiments were conducted to identify the maximum input pressure and measure the deformations at the specific input pressure. When the actuators were pressurized under 20.0 kPa, axisymmetric contractions were achieved. The theoretical model and FEM models produced the predictions in good agreement with experimental results, with slight mean relative differences regarding peak points, 3.4% and 5.4%, respectively. In addition, pilot tests suggest that the ring-shaped actuator can achieve the key tasks of robotic manipulators, such as gripping and holding.

Adaptation of removable partial denture frameworks fabricated by selective laser melting

Statement of problemSelective laser melting (SLM) is a novel 3-dimensional (3D) printing technology that can directly form the metal frameworks of removable partial dentures. The adaptation of SLM frameworks has not been thoroughly evaluated. PurposeThe purpose of this in vitro study was to evaluate the tissue surface adaptation of removable partial denture frameworks fabricated by an SLM technique. Material and methodsFour types of maxillary partial edentulous resin models were custom made: bilateral second premolars and molars missing, bilateral premolars and first molars missing, all teeth missing except 2 canines, and 2 central incisors missing. According to these dentition-defect patterns, 4 types (I, II, III, and IV) of virtual removable partial denture frameworks were designed, and an SLM printer was used for 3D printing using cobalt-chromium (Co-Cr) alloys (repeated 3 times). As a control, refractory casts duplicated from the resin models were used to fabricate denture frameworks by the lost-wax casting technique. Average gaps and maximum gaps between frameworks and models were measured using the silicone impression material. Two-way ANOVA was used to determine the influence of production methods and design types on the gaps (α=.05). ResultsThe 2-way ANOVA showed that average gaps were significantly influenced by the production methods and design types, as well as their interactions (P<.001). With design Types I and II, the average gaps of the SLM-printed frameworks were larger than those of the cast ones (P<.001). However, no such differences were found for design Type III, P=.325, or IV, P=.862. ConclusionsSLM-printed frameworks achieved an acceptable adaptation. However, among frameworks with a large span and relatively more retainers and clasps, the adaptation of those made by the precision casting technique was slightly better than that of those printed by the SLM technique.

Evaluation of the accuracy and stress distribution of 3-unit implant supported prostheses obtained by different manufacturing methods

The purpose of this in vitro study was to measure the vertical, positive-horizontal, and negative-horizontal misfit (VM, PHM, and NHM, respectively) of the zirconia three-element prosthetic framework, fabricated using different methods, and compare them with conventional fabrication methods (lost-wax casting). Furthermore, this study aimed to evaluate the influence of the misfit values on the biomechanical behavior of the 3-unit fixed prosthetic frameworks using three-dimensional finite element analysis (3D-FEA). Forty frameworks (n = 10) were fabricated as follow: G1, Cerec Bluecam; G2, iTero; G3, 3Series; and G4, conventional method. The samples were randomized to measure marginal misfit using a high-precision three-dimensional (3D)-optical microscope. The results were submitted to analysis of variance (ANOVA), with the significance level set at 5%. The mean VM values of each group were used in creating the models by 3D-FEA with the misfit found in optical microscopy. The programs used were the InVesalius, Rhinoceros, SolidWorks, FEMAP and NEiNastran. The von Mises map was plotted for each model. The G4 showed the lowest mean VM value (16.73 μm), followed by G3 (20.71 μm), G2 (21.01 μm), and G1 (41.77 μm) (p < 0.001). G2 was more accurate than G1 (p < 0.05) and similar to G3 (p = 0.319). For PHM, G4 was the most accurate and did not present overextended values. With regard to NHM, the computer-aided design and computer-aided manufacturing (CAD-CAM) systems were more accurate (−61.91 μm) than G4 (−95.36 μm) (p = 0.014). In biomechanical analysis, stress concentration caused by oblique loading is greater than caused by axial loading. In axial loading, G4 was the most favorable while G1 was the least favorable, biomechanically, in oblique loading, similar stress patterns were observed in all the models. The prosthetic screw was the most overloaded structure, but the material did not influence the stress distribution. The misfit prostheses showed a greater degree of stress than the controls (without misfit). The manufacturing method influenced the marginal misfit of the frameworks, with the conventional method being the most accurate and the Cerec Bluecam System (closed system) the least accurate. Biomechanically, fitting prostheses were more favorable than misfit prostheses.

Nataraja Informed through Text and Technique

The imposing Chola-period bronze Shiva Nataraja at the Rijksmuseum is a product of the living tradition of metal casting established over a thousand years ago in the region of Tamil Nadu. Purchased in 1935 from a Parisian dealer, it is one of the highlights of the collection belonging to the Royal Asian Art Society in the Netherlands, which is exhibited at the Rijksmuseum. The interdisciplinary study presented here links an art historical investigation of ancient texts and scholarly literature with scientific analysis in an attempt to refine the art historical context and at the same time flesh out what is known about the fabrication and provenance of the Nataraja in the Rijksmuseum. The Nataraja was cast by the lost-wax method; x-ray images confirm that the Shiva is solid-cast together with the halo. X-ray fluorescence reveals an alloy consistent with other Chola-period bronzes but not necessarily a pañcaloha alloy (five metals), which seems to be a modern tradition; the front hands were apparently cast on separately as a repair, probably during casting or not long after. Further evidence gathered from the sculpture and its soil encrustations (ICP-MS lead and neodymium isotope ratios, SEM-EDX and XRD) is briefly presented, and supports earlier assumptions about the Nataraja. It appears to date from the twelfth century and was under worship for a relatively short time before it was buried at an unknown location in India. The presence of Indian earth and corrosion products typical of burial imply that it did not re-enter a temple context for worship and was not subject to major restoration before entering the art market in the early twentieth century.

CAD/CAM vs Conventional Technique for Fabrication of Implant-Supported Frameworks: A Systematic Review and Meta-analysis of In Vitro Studies.

To compare the marginal vertical misfit between implant-supported frameworks fabricated using CAD/CAM systems and the conventional technique (lost-wax casting). This review was performed according to PRISMA criteria and registered on PROSPERO (CRD42017055685). An electronic search was performed independently by two examiners in the MEDLINE (Pubmed), Embase, Web of Science, and Cochrane Library databases to find studies published up to April 2018. The database search yielded 507 references. After removing duplicate references, 384 studies remained. Eleven in vitro studies were selected according to the eligibility criteria (inter-reader κ = 0.88). Nine different CAD/CAM systems were used to fabricate 172 frameworks of different materials, including zirconia, monolithic lithium disilicate, and metallic alloys. Subgroup analyses were performed for different types and retention systems of the frameworks. In the general analysis, marginal misfit observed with the CAD/CAM systems was lower than with the conventional method (P = .003), as was observed in the subgroup analysis for single-unit frameworks (P < .00001). For fixed (P = .89), cemented (P = .60), and screwed (P = .18) frameworks, no significant difference was observed between the evaluated techniques. The CAD/CAM systems showed improved marginal fit over the conventional lost-wax casting technique for fabricating single-unit frameworks; however, in the subgroup analyses, no difference was observed for the fixed implant-supported type or for the retention systems evaluated.