Casting Cores Research Articles

Production of high-quality casting cores from lignin-based binders using blow-out method

Production of high-quality casting cores from lignin-based binders using blow-out method

Determining the foundry area of bronze chariot-horse excavated from Yang’an Han Tomb in Qionglai, Sichuan Province: Based on the scientific analysis of residual casting cores

The bronze chariot-horses excavated from the Yang’an Han tomb in Qionglai, Sichuan Province, was a high-ranking burial object. In order to address their provenance, X-ray fluorescence (XRF), X-ray diffraction (XRD), petrographic and phytolith analyses were conducted to characterize the major elements, trace elements, mineral crystals types and phytoliths in the casting core residues of the bronze horses. We found that the chemical and petrographic compositions of the casting cores were significantly different from those of the primary soils and the pottery artefacts from Xi’an, but similar to those of Chengdu, which indicated that the raw materials of the casting cores of the bronze chariot-horses derived from local sources. In other words, the Yang’an bronze chariot-horses were cast locally rather than transported as finished products from the central government of the Western Han Dynasty.

The Technique of Inorganic Core Sand Shooting with Reduced Pressure in Venting System

The publication presents a new shooting technique with reduced pressure in venting system for manufacturing foundry cores using inorganic sand mixture with Cordis binder. Traditional technologies for producing casting cores using blowing methods, despite their undeniable advantages, including the ability to produce cores in series, also come with some disadvantages. The primary drawbacks of the process involve uneven compaction structure of the cores, with denser areas primarily located under the blow holes, and under-shooting defects, which often occur in regions away from the blow hole or in increased core cross-sectional areas. In an effort to improve core quality, a concept was developed that involves incorporating a reduced pressure in the core box venting system to support the basic overpressure process. The solutions proposed in the publication with a vacuum method of filling the cavities of multi-chamber core boxes solve a number of technical problems occurring in conventional blowing technologies. It eliminates difficulties associated with evacuating the sand from the chamber to the shooting head and into technological cavity and increases the uniform distribution and initial degree of compacting of grains in the cavity. The additive role of this “underpressure” support is to enhance corebox venting by eliminating 'air cushions' in crevices and structural elements that obstruct the flow of evacuated air. The publication presents the results of studies on core manufacturing using blowing methods conducted in three variants: classic overpressure, utilizing the core box filling phenomenon by reducing pressure, and an integrated approach combining both these methods.

Pengaruh curing time dan pemanasan cetakan pasir kering terhadap kadar air, kuat tekan, dan lost of ignition (LOI) untuk aplikasi sand casting

Sand molding has the advantage of being able to cast metals with high melting points, such as steel and nickel. Sand for the mold media generally uses a lot of silica sand. Some sand molds contain alphaset binders as well as other binders. Alphaset sand molding is a technique for making molds and metal casting cores that use resin as a binder and catalyst between sands. The addition of a catalyst as a mixture of resin. The process of making specimens for the sand mold test using silica sand SiO 2 with a weight of 1000 g using 2.1% alphaphenolic resin and 25% catalyst from resin as additional elements for the resin hardening process. with a manual mixing process and making a sample with a diameter of 50mm in the form of a silencer with the tests carried out are water content, lost of ignition compressive strength and sand size distribution. Good moisture content data on alphaset molds are shown in temperature variations with heating. the results of testing the value of increasing compressive strength with variations in heating curing time 30, 60, 90 get results of 20.45, 22.8 and 31.85. data from the lost of ignition test sample curing time 30 get results of 2.05 The results of the distribution of sand are suitable for steel castings with large, medium and small sizes of castings, water content of curing time of 120, get results of more than 1%, namely 1.06 factors causing the mixin process. The above test shows an increase in compressive strength with variations in heating with lost of ignition testing temperature. The more often sand is used as the mold produces a higher LOI value.

Casting, gilding and corrosion mechanisms in two gilded hollow bronze statues from ancient Egypt

This research aims to study two gilded hollow bronze statues from pharaonic Egypt excavated in a karnak temple. The two objects had an unusual casting core and one of them was gelded on the ground. Various parts and layers, including the casting core, gold layer, gilding ground, corrosion products, and metallic structures, were characterized via scanning electron microscopy (SEM), polarized light microscopy (PLM), and USB digital microscopy. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and SEM coupled with energy-dispersive spectroscopy (EDS) were employed for the analysis. The features related to manufacturing and gilding technologies of the two statues are presented. Specifically, the casting core consisted of an external lime layer on the clay-based internal core, contrarily to the typical casting cores in ancient Egypt and other ancient civilizations consisting of a clay-based mixture. The study proposed a specific method of hollow casting to obtain the casting core, reasonably adopted by the ancient Egyptians to replicate analogous hollow objects from a master mold, whereas the mold of usual hollow casting methods was destroyed after casting. Moreover, the gilding of one of the statues is a unique example of gilded bronze with ground calcite as filler material and beeswax as blinding medium. Finally, the chemistry and structure of the corrosion layers were characterized to gain insights into the morphology and corrosion mechanisms in the presence of calcite ground and gold layers.

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the drying process and the achievable properties in slurry-based 3D printing of casting cores. This study aims at contributing to a better understanding of the interrelations between the drying conditions in the 3D printing process and the properties of sintered specimens relating thereto. The drying intensity influenced by an IR heater as well as the drying periods are varied for layer thicknesses of 50, 75, and 100 µm. Within this study, a process window applicable for 3D printing of sinterable casting cores is identified and further indications are given for optimization potentials. At layer heights of 75 µm, bending strengths between ~8 and 11 MPa as well as densities of around 50% of the theoretical density were achieved. Since the mean roughness depth Rz is determined to be <30 µm in plane, an application of slurry-based 3D printing in investment casting is conceivable.

Micromachining porous alumina ceramic for high quality trimming of turbine blade cores via double femtosecond laser scanning

Turbine blade cores are made of porous alumina ceramic and determine the molding accuracy of the cavity of turbine blades, which strongly affect thermal diffusion performance and service life of turbine engines. To get a high quality ceramic core, accurate trimming for a preliminarily processed core is needed and therefore, micromachining porous alumina ceramic, which differs from general alumina substrates, is crucial. This paper dealt with a processing technology for the special material via double femtosecond laser scanning. The materials ablation threshold was firstly determined through parameter fitting and then this material was machined at a combination of different laser processing parameters. Considering the produced debris blocks the lasers further propagation into the material, double femtosecond laser scanning was newly proposed and experimentally verified with the comparison of gas jet assist and underwater laser processing ways. The removal profiles of the machined material were characterized in terms of cutting width, cutting depth, deviation of linearity and surface morphology, which exhibited high dependence on the femtosecond laser processing parameters. The optimal laser operating window was identified and high quality laser cutting of the porous alumina ceramic was demonstrated. The developed processing technology has potential application in trimming for ceramic casting cores. In addition, it might also give a novel view for high quality laser micromachining another materials.

Study on the casting cores to identify the manufacturing place of Chinese bronze vessels excavated in the Qiaojiayuan tombs from Spring and Autumn period

To date, few large-scale bronze foundry sites of the Bronze Age have been found in the middle and lower reaches of the Yangtze River in Southern China, but highly developed bronze cultures have occurred here. For instance, in Qiaojiayuan, Yunxian County, northwestern Hubei Province, on the border of Southern and Northern China, a high-level tomb cluster of Spring and Autumn period (8th–5th c. BC) has been unearthed. The location of the site is identical with the Ancient Jun 麇 State recorded in the historical documents. Thus, figuring out where these bronzes were made can shed light on the status of the Jun State and its potential links to other great powers. X-ray fluorescence (XRF) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were conducted to characterize the major elements, trace elements, and rare earth elements in the casting core residues of the Qiaojiayuan bronze ritual vessels. They are largely different from the loess in the Yellow River Basin, but very similar to the laterite in southern China. Moreover, from the chemical characteristics, the samples from Qiaojiayuan are well resembled with those from Panlongcheng and Zuozhong, but differ from the casting core residues or clay molds manufactured in Northern China, and they are not consistent with the local soil geochemical characteristics. It can be further speculated that the Qiaojiayuan bronzes were first cast and finished in the Chu State before being transported to the area of Jun.

Trimming for alumina-based ceramic casting cores for turbine blade by double picosecond laser scanning

Ceramic cores determine the moulding accuracy of a turbine blade’s cavity, which strongly affects thermal diffusion performance and the service life of a turbine engine. To get a high quality ceramic core after the preliminary process, this paper deals with a laser trimming technology for ceramic casting cores via double picosecond laser scanning for the first time. Instead, the core ceramic foils were firstly machined at a combination of different laser processing parameters to determine the necessary laser trimming technology. Three different laser pulse duration regimes including femto-, pico- and nanosecond were examined and picosecond laser was selected for trimming of the core considering a serious recast layer occurrence in nanosecond laser processing and large amounts of faintly bonded aerosols on the side-wall of the machined surface in femtosecond laser processing. The removal profiles of the machined ceramic foils were characterized in terms of depth, deviation of linearity and surface morphology, which exhibited high dependence on the picosecond laser processing parameters. Double picosecond laser scanning for trimming was further put forward, schematically analysed and experimentally verified. Compared to the conventional trimming ways, the proposed technology allows a much smoother and denser edge and side-wall of the machined surface of ceramic casting cores, which helps to form high accuracy turbine blades cavity. What is more, it also provides a novel view for high quality laser micro-machining.

Некоторые особенности сушки литейных форм и стержней в области стоячих волн сверхвысокочастотного излучения

Некоторые особенности сушки литейных форм и стержней в области стоячих волн сверхвысокочастотного излучения

Study on laser sintering of pine/co-PES composites and the investment casting process

Purpose A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting. Design/methodology/approach The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment. Findings 20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns. Research limitations/implications The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device. Originality/value This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

Evaluation of the Possibilities of Sodium Silicate Sands Application in Automated Hot-Box Process of Cores Shooting

AbstractThe paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO2/ Na2O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm3. The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (RgU), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box / hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.

Casting cores of French bronze statues of the 16th and 17th centuries: Identification of regional practices and artistic choices

What can the chemical and petrofabric study of casting cores of early modern large bronzes tell us about the practices of sculptors and foundry men? The technical study of 23 major large French bronzes dated from the 16th and 17th centuries provides some answers. These include three prestigious royal commissions, namely two of the six bronzes copied by Primaticcio from the marble models of the Belvedere for Francis I, two of the six statues from the funeral monument of Henry II and Catherine de Medicis, and the three bronzes from the heart monument of Constable Anne de Montmorency. Among the investigations carried out (alloy composition, X-ray radiography, and so on) [1], the chemical and petrographic analysis of the refractory cores sampled from inside the statues has proved to be crucial. Surprisingly, this approach is far from systematically applied in the field, despite some successful results [2] including the pioneering work of C. Reedy [3]. This paper introduces the new methodology of casting core analysis developed at the C2RMF. Results obtained from a large corpus of French bronze statues will be described, illustrating the complementary role of core analysis alongside the informative potential of metal analysis and the characterization of casting technique through multivariate technological studies. During the 16th and 17th centuries in France, casting cores were generally created from a sandy clay material with a variable addition of organic. The results of the study cast light on two aspects of the nature of the cores. On the one hand, the bulk chemical compositions of cores and mineralogical composition of added sand show a relatively good homogeneity within the region of Paris and its surroundings, thus testifying to a similar provenance of raw materials. Conversely, significant variations were evident in compositions from other regions. Consequently, the casting cores constitute an excellent regional marker. On the other hand, significant variations were observed in the size distributions of aplastic inclusions, thus witnessing local foundry know-how through the use of several sandy–clayey mixtures.

Collapsing Commodities or Lavish Offerings? Understanding Massive Metalwork Deposition at Langton Matravers, Dorset During the Bronze Age-Iron Age Transition

Summary The discovery of 373 intact and broken tin-bronze socketed axes accompanied by 404 fragments in four pits at Langton Matravers collectively represents one of the largest hoards found to date in prehistoric Britain and Ireland. They were very probably never meant to be used as axes as the very high levels of tin they contain would have made them brittle. Many were poorly finished, with the majority still containing their casting cores. The axes are typologically dated to the Llyn Fawr metalwork phase (c.800–600 BC) and span the Bronze Age/Iron Age transition, when the production, circulation and deposition of bronze appear to have been substantially reduced throughout north-west Europe. By placing the Langton Matravers hoard(s) in a broader metallurgical, material and archaeological context, existing theories for this phenomenon, such as the preference for iron, a collapse in bronze supply, or the sharp devaluation of a social or ritual ‘bronze standard’, are evaluated. It is proposed that the Langton Matravers axes belong to a short phase in the centuries-long processes underlying the changing roles of bronze and iron.

Prediction of Properties of Microwave- Hardened Sandmixes Containing Water- Glass with Use of Neural Networks

Abstract Presented are results of a research on the possibility of using artificial neural networks for forecasting mechanical and technological parameters of moulding sands containing water-glass, hardened in the innovative microwave heating process. Trial predictions were confronted with experimental results of examining sandmixes prepared on the base of high-silica sand, containing various grades of sodium water-glass and additions of a wetting agent. It was found on the grounds of obtained values of tensile strength and permeability that, with use of artificial neural networks, it is possible complex forecasting mechanical and technological properties of these materials after microwave heating and the obtained data will be used in further research works on application of modern analytic methods for designing production technology of high-quality casting cores and moulds.

Casting cores used to craft large bronze masterpieces of the Florentine Renaissance and Mannerism

We investigated the casting cores of twelve large bronze masterpieces of the Florentine Renaissance and Mannerism (artworks by Ghiberti, Donatello, Verrocchio, Rustici, and Danti). Materials were characterized in their mineralogical-petrographic features, chemical composition, organic content and fossil traces.The results achieved provide information on the main recipes employed for manufacturing the casting cores, which largely agree with written sources of the time, and shed light on the art foundry processes between the 15th–16th centuries. The data collected point out a pronounced affinity of natural raw materials used in all the casting cores investigated, consisting in silty-sandy clays with a suitable natural fine-grained temper component. A large use of organic fibres and matters of both animal and vegetal origin and a minor use of gypsum in selected workshops (Rustici, Verrocchio) were highlighted. Textural analyses allowed gaining information on direct vs indirect methods of casting, while firing temperatures up to about 1000 °C were estimated from mineralogical and microstructural observations. Despite the strong similarities, significant differences among the various samples analysed were pointed out, providing some initial analytical clues that suggest different practices in separate workshops. Finally, the whole petrographic, geochemical and paleontological data gave information on the provenance of the clayey raw materials.This work represents the first step of a systematic approach to the classification of the core materials used in Florentine foundries along the centuries and shows the significant contribution the petrographic analyses can provide to the interpretation of the execution processes of large bronzes.

Uniqueness of the cognitive disorganization factor of the symptoms of schizophrenia

We investigated the casting cores of twelve large bronze masterpieces of the Florentine Renaissance and Mannerism (artworks by Ghiberti, Donatello, Verrocchio, Rustici, and Danti). Materials were characterized in their mineralogical-petrographic features, chemical composition, organic content and fossil traces.The results achieved provide information on the main recipes employed for manufacturing the casting cores, which largely agree with written sources of the time, and shed light on the art foundry processes between the 15th–16th centuries. The data collected point out a pronounced affinity of natural raw materials used in all the casting cores investigated, consisting in silty-sandy clays with a suitable natural fine-grained temper component. A large use of organic fibres and matters of both animal and vegetal origin and a minor use of gypsum in selected workshops (Rustici, Verrocchio) were highlighted. Textural analyses allowed gaining information on direct vs indirect methods of casting, while firing temperatures up to about 1000 °C were estimated from mineralogical and microstructural observations. Despite the strong similarities, significant differences among the various samples analysed were pointed out, providing some initial analytical clues that suggest different practices in separate workshops. Finally, the whole petrographic, geochemical and paleontological data gave information on the provenance of the clayey raw materials.This work represents the first step of a systematic approach to the classification of the core materials used in Florentine foundries along the centuries and shows the significant contribution the petrographic analyses can provide to the interpretation of the execution processes of large bronzes.

Radiocarbon dating of ancient bronze statues: Preliminary results from the Riace statues

The low amount of material needed for the measurements makes AMS radiocarbon a technique suitable for the dating of ancient bronze artefacts through the analysis of the organic residues contained into the casting cores. We present the results of the AMS radiocarbon dating analyses carried out on the organic remains extracted from the casting cores of the Riace bronzes, among the most famous and well preserved sculptures of the Greek-Classical period. Although different dating hypotheses have been suggested on the base of stylistic considerations, no conclusive answers are, so far, available. The sample selection and preparation protocols of the different kind of organic materials (charred wood, vegetal remains and animal hairs) are described as well as the interpretation of the results in the frame of the current dating hypotheses and available analytical information about the casting technology.

From the Shell to its Content: the Casting Cores of the Two Bronze Statues from Riace (Calabria, Italy)

The two bronze statues found off the coast of Riace (Statue A and Statue B) are among the few complete bronze Greek originals dating back to the 5th centuryBC. As the casting cores were expected to impair the conservation of the inner bronze surfaces, the core residues were removed by micro-excavation, revealing that both statues were built with a peculiar slab manufacturing technique. This paper describes the results of petrographical, chemical and palaeontological analyses conducted on the cores. There are structural and compositional differences in the materials used for the two statues. The bulk of the material used to manufacture each core appears to be very homogeneous in both cases. Nonetheless, modelled features of the casting cores with different petrographic and chemical composition were identified in both statues. A preliminary attempt was made to restrict the possible areas of provenance of the bulk material used for the cores, by matching petrographical information with the geology of southern Italy and Greece. The statues appear to have been manufactured in Greece; some areas, including the plain of Argos, in the north-eastern Peloponnesus, are more likely candidates than others.

Feature Extraction for Casting Core Development

Feature extraction techniques are presented for the generation of casting core patterns from a boundary representation (B-Rep) solid model. Techniques are presented which would allow for automatic extraction of three classes of core features (internal voids, single and multi-surface holes, and boundary perturbations). The task of extracting casting cores from solid models involves recognizing a collection of entities (i.e., slots, bosses, undercut surfaces, local and global concavities, etc.) from the set of lower level entities (i.e., the B-Rep structure). To this end, a combination of solid modeling B-Rep and graph structures and their associated methods will be used for casting core development. Appropriate local features are identified and extracted from the original object, and are grouped into one or more new object(s) (termed a core-object). If the core-object is multiply connected (i.e., composed of multiple objects), it is graph separated into global feature objects. Each of these global feature objects represents a core in the final pattern. Lastly, the geometry of the original part is augmented to add core prints where core geometries were extracted. The core print, as currently developed, combines the extracted core geometry and its convex hull.