Large-scale Casting Research Articles

Bridging the Past and Present by Skill: Exploring Medieval Bell Casting by Experiment

This paper presents key results from experimental work on traditional bronze casting, focusing on early to high medieval bells, roughly between the 8th and 12th century AD. It demonstrates that combining craft, historical sources, and modern science can effectively revive lost technologies. The reconstruction is based on Theophilus Presbyter’s Schedula Diversarum Artium, dated to the early 12th century, whose precise instructions were critical, though several field-scale experiments were required to refine the process.These experiments are part of broader research into medieval large-scale casting methods in central Europe. The paper argues that more than experimental archaeology or traditional craft is needed to understand and recreate lost technologies. Researchers must invest significant time mastering materials, tools, and techniques to grasp craft processes fully. Brief experimental engagements fail to capture the depth of these traditions. This approach bridges archaeology and hands-on practice, challenging conventions in both traditional craft and mainstream academia.

Topology optimization based on combined mechanical analysis and variable density method for casting structure

In this study, a topology optimization method based on combined mechanical analysis and variable density is presented for a large-scale casting structure with complex thin-walled structures. First, the mechanical analysis model of the frame is established, the first-order bending and torsional modes and stiffness values of the all-cast aluminum frame are obtained, and the basic mechanical parameters such as bending/torsional mode and stiffness constraints needed for topology optimization are defined. Using the variable density method, unneeded material that can be removed from the casting structure is identified. According to the design requirements, the optimization objective function and constraint conditions are established, and the variable density method is used to solve the problem. Analysis of the mechanical results before and after topology optimization reveals that the modes and stiffness values are larger than the target values, and the mass of the frame is reduced by 10.2 kg (i.e. 13.9%) compared with the original design. The application of the combined mechanical analysis and variable density method to a casting structure can effectively achieve lightweight design.

Optimal Design of the Gating and Riser System for Complex Casting Using an Evolutionary Algorithm.

The gating and riser system design is essential for both quality and cost in large-scale casting and is expected to reach several objectives simultaneously. However, even with the help of commercial simulation software, the design of gating and riser systems is still the result of a long-term trial-and-error optimal process owing to the conflict between the objectives. Several evolutionary algorithms (EAs) have been reported to be helpful in the selection of the geometrical dimensions of gating and riser systems. In this study, a route with sequential use of a multi-objective EA and single-objective optimization algorithm was developed to help design gating and riser systems, respectively. This route was applied in an actual case and verified using commercial simulation software. The results showed a dramatic decrease in the time cost in design and acceptable casting quality. Thus, the proposed design method is time-saving.

Optimization of driven waveform of piezoelectric printhead for 3D sand-printing

Abstract Micro-droplet injection forming technology demonstrates considerable potential with regard to additive manufacturing of complex casting sand molds. However, the influence of micro-droplet injection characteristics on the forming accuracy and injection regulation strategies is relatively weak during the process of promoting the industrialization of three-dimensional sand printing. Moreover, the practical requirements of precision rapid prototyping of complex sand molds have not been adequately addressed through investigations on the aforementioned influence. A jetting experiment platform is developed herein to optimize the driving waveform of a piezoelectric printhead. On the basis of theoretical simulations and experimental verification, the influence of the printhead waveform on its jetting characteristics is discussed. A method for driving the waveform is presented to improve and optimize the casting sand mold performance. Several case studies are presented to illustrate the effectiveness of the optimized driving waveform for enhancing the casting sand mold performance via systematic printing of a standard sand mold test block. Moreover, the optimal driving waveform’s contribution to the forming accuracy and efficiency of a large-scale casting sand mold is investigated through experiments using a three-dimensional sand printer. On the basis thereof, the effectiveness of the optimal driving waveform is demonstrated to improve not only the forming accuracy of the sand mold but also the production efficiency. This development can transform the industry of sand casting to produce high-quality castings.

Semi-Solid Rheological Squeeze Casting Process of ZL114A Aluminum Alloy Thin-Wall Complex Casting

High-strength aluminum alloy with large-scale and thin-walled complex castings have broad application prospects in aerospace, weapons, electronics, defense and military industries. However, due to the uneven thickness of the plate, the casting defects are inevitable by the ordinary casting method, and it is impossible to accurately control the shape and performance of the casting in the casting process. Previous studies have found that the semi-solid rheological extrusion casting technology with short process and near-end type can help solve this technical problem. Therefore, this paper studies the semi-solid rheological extrusion casting process of thin-walled complex casting of ZL114A aluminum alloy. The combination of numerical simulation and experimental research is used to simulate and optimize the filling and solidification process of thin-walled specimens. Based on this, a semi-solid rheological extrusion casting test was conducted. The result showed that, (1) The optimized model can well reflect the filling and solidification process under different rheological extrusion casting parameters, and obtain defect-free castings through process optimization. (2) The thin-walled parts of the thin plate casting produced by semi-solid rheology extrusion have excellent mechanical property and ductility.

Development of (Nb0.75,Ti0.25)C-Reinforced Cast Duplex Stainless Steel Composites

Improvements to the wear performance of CD4MCu (a cast Fe-Cr-Ni-Cu-Mo duplex stainless steel grade) would be of great benefit in pump applications. This study demonstrates that CD4MCu stainless steels reinforced with (Nb0.75,Ti0.25)C particles can be fabricated by simply melting the elements required for the CD4MCu stainless steel together with the amounts of Nb, Ti and C required to achieve a specific volume fraction of (Nb0.75,Ti0.25)C particles in a miniature laboratory argon arc furnace. Their potential as erosion resistant materials was evaluated through microstructural characterization, hardness testing, and sliding wear tests. The formation of (Nb0.75,Ti0.25)C particles was found to improve the bulk hardness of the CD4MCu stainless steels without significantly altering its duplex microstructure, which then led to better wear performance. The results indicate that large-scale casting of the proposed materials should be possible and that they have potential as erosion resistant materials.

Casting Design Optimization Using Numerical Simulation of Precision Forging Die for Large Titanium Alloy Integral Bulkhead

In this paper, the competing requirements of material strength, casting formation and residual stress are considered in the design of a large bulkhead integral isothermal forging die using a design approach that incorporates an outer ring plus a die body. Thermal stress assembly was conducted to resolve the various manufacturing issues encountered in the production of this large-scale casting. This paper also proposes a design method for an expansion joint and material-saving holes to homogenize the cross-sectional thickness of the casting die by solving problems associated with defects and hot cracking during the casting process. The finite element method was used based on the equivalent liquid level descending method, the Niyama criterion, etc., to analyze the pouring of the sand model with different risers to choose the casting process. To resolve the occurrence of hot cracks during production, the design was optimized and the process was improved in combining with the simulation analysis result, after which carrying out another finite element analysis and by re-verifying the production process again. The results show that the simulated porosity, shrinkage and stress distribution are in accord with the practical production status. Based on the mechanical properties and a microstructure analysis, the tension strength of the K3 casting die at 950 °C is approximately 635 MPa, and the microstructures are typical dendrites. However, through the simulation, practical production, and analysis of the mechanical properties and microstructure, the die design method proposed in this paper offers benefits in solving casting forming problems and hot cracking of an integral oversized titanium bulkhead casting die, and a K3 superalloy die with a weight of 7.8 tons was successfully cast.

3D sand mould printing: a review and a new approach

PurposeThe purpose of this paper is to review available technologies, analyse their features, propose a new approach of 3D sand mould printing based on line forming, introduce the manufacturing principle and show advantages of this approach, especially for larger parts with large Z steps in the build, such as 2 mm stepwise.Design/methodology/approachThis paper introduces 3D sand mould printing, compares and analyses technological process and existing fabrication approaches among available technologies first. Then, a new approach of 3D sand mould printing is proposed to improve build speed. In addition, the proposed system will be analysed or benchmarked against existing systems.FindingsA new approach based on line forming of sand mould printing is put forward by reviewing and analysing available technologies, to improve build speed from the aspect of basic moulding movement instead of optimization of moulding methods and process parameters. The theoretical calculation and analysis shows that build speed can be improved greatly, and it is more suitable for the manufacture of large-scale casting’s sand mould when considering dimensional accuracy and printing error, as well as uniformity of each layer.Research limitations/implicationsThe specific implement scheme of line forming and nozzle’s specific structure of this new approach need further study.Practical implicationsMuch higher build speed of 3D sand mould printing with new approach brings evident implication for moulds companies and manufacturing industry, having a far-reaching influence on the development of national economy.Originality/valueThis paper reviews available technologies and presents a new approach of 3D sand mould printing for the first time. Analysis of the new approach shows that this new method of sand mould printing can boost build speed greatly. So, its application prospect is great.

The cavitation erosion of ultrasonic sonotrode during large-scale metallic casting: Experiment and simulation

Ultrasonic sonotrodes play an essential role in transmitting power ultrasound into the large-scale metallic casting. However, cavitation erosion considerably impairs the in-service performance of ultrasonic sonotrodes, leading to marginal microstructural refinement. In this work, the cavitation erosion behaviour of ultrasonic sonotrodes in large-scale castings was explored using the industry-level experiments of Al alloy cylindrical ingots (i.e. 630 mm in diameter and 6000 mm in length). When introducing power ultrasound, severe cavitation erosion was found to reproducibly occur at some specific positions on ultrasonic sonotrodes. However, there is no cavitation erosion present on the ultrasonic sonotrodes that were not driven by electric generator. Vibratory examination showed cavitation erosion depended on the vibration state of ultrasonic sonotrodes. Moreover, a finite element (FE) model was developed to simulate the evolution and distribution of acoustic pressure in 3-D solidification volume. FE simulation results confirmed that significant dynamic interaction between sonotrodes and melts only happened at some specific positions corresponding to severe cavitation erosion. This work will allow for developing more advanced ultrasonic sonotrodes with better cavitation erosion-resistance, in particular for large-scale castings, from the perspectives of ultrasonic physics and mechanical design.

Large-scale simulation of dendrite growth in directional solidification castings (Phys. Status Solidi B 10/2017)

The modified shape function dendritic (MSFD) model was built to simulate the growth of a large number of dendrites in directional solidification (DS) in casting scale. The cover figure (cf. article no. 1600860 by Hang Zhang and Qingyan Xu) shows experimental dendritic morphologies in cross and longitudinal sections fitted by the numerical results with different pre-set Euler angles (φ1, ψ, φ2). The results agreed well, which proved that the transform matrix M was suitable for the dendritic morphology description. For the DS process, an MSFD model coupled with macro models was proposed to simulate the growth of thousands of micro dendrites and their distribution. Furthermore, the crystal selection of the spiral selector is clearly represented by the simulation method that employed the MSFD model, and the findings reveal the distribution of dendrites within the thinnest wall of a single-crystal turbine blade and the solidification sequence of the dendrites. Hence, the modified model coupled with macro-simulation models can be used to predict the morphology and distribution of DS dendrites with respect to large-scale castings produced by the DS process.

Large-scale simulation of dendrite growth in directional solidification castings

In this study, the growth and distribution of directional solidification (DS) dendrites in entire cross-sections of DS superalloy castings are simulated based on a modified shape function dendritic (MSFD) model coupled with the cellular automaton-finite difference (CA-FD) method. The macro-thermal transfer and columnar grain growth are calculated using CA-FD with a macro time-step, and then, the original and boundary conditions for the dendrite-growth simulation are determined via the interpolation of the macro temperature and the projection of the 3D preferential grain orientation using a matrix, M. The dendrite growth calculation cyclically proceeds based on the MSFD model. It is used to predict the growth of hundreds of dendrites throughout the cross-section of a DS casting by considering the macro-solidification parameters. The MSFD model is further applied to predict the competitive growth of DS dendrites and their distribution in the cross-sections of a spiral selector and a fake single crystal turbine blade. The results of the simulation correlate with the results of the DS experiment. Hence, the modified model coupled with the macro-simulation models can be used to predict the morphology and distribution of DS dendrites with respect to large-scale castings produced by the DS process.

Directly cast bulk eutectic and near-eutectic high entropy alloys with balanced strength and ductility in a wide temperature range

High entropy alloys (HEAs) usually possess weak liquidity and castability, and considerable compositional inhomogeneity, mainly because they contain multiple elements with high concentrations. As a result, large-scale production of HEAs by casting is limited. To address the issue, the concept of eutectic high entropy alloys (EHEAs) was proposed, which has led to some promise in achieving good quality industrial scale HEAs ingots, and more importantly also good mechanical properties. In the practical large-scale casting, the actual composition of designed EHEAs could potentially deviate from the eutectic composition. The influence of such deviation on mechanical properties of EHEAs is important for industrial production, which constitutes the topic of the current work. Here we prepared industrial-scale HEAs ingots near the eutectic composition: hypoeutectic alloy, eutectic alloy and hypereutectic alloy. Our results showed that the deviation from eutectic composition does not significantly affect the mechanical properties, castability and the good mechanical properties of EHEAs can be achieved in a wide compositional range, and at both room and cryogenic temperatures. Our results suggested that EHEAs with simultaneous high strength and high ductility, and good liquidity and castability can be readily adapted to large-scale industrial production. The deformation behavior and microstructure evolution of the eutectic and near-eutectic HEAs were thoroughly studied using a combination of techniques, including strain measurement by digital image correlation, in-situ synchrotron X-ray diffraction, and transmission electron microscopy. The wavy strain distribution and the therefore resulted delay of necking in EHEAs were reported for the first time.

Grain Refinement of a Large-Scale Al Alloy Casting by Introducing the Multiple Ultrasonic Generators During Solidification

Based on the multiple ultrasonic generators, a new technique was reported to produce the large-scale Al alloy castings for downstream deformation processing. The effects of different configurations of ultrasonic generators on the degree and homogeneity of grain refinement were investigated during solidification. Experimental results show that a grain-refined structure with reduced macrosegregation was obtained in the large-scale cylindrical Al alloy ingot (650 mm in diameter, 4800 mm in length). Meanwhile, the role of ultrasonic treatment in the production of large-scale castings was discussed. Additionally, these results raise some new questions regarding the relationship between ultrasonic physics and grain refinement, which require further studies.

Improvement of structural design accuracy using a casting-structural interface (CSI) method in large-scale sand castings

In general, thermal residual stress is generated in casting products as a result of non-uniform cooling, phase transformation from liquid to solid states, and thermo-mechanical constraints. Thus, understanding accurate stress distributions is important in designing a casting part to predict its real structural stability. However, the residual stress that occurs in the casting process is often not considered in the mechanical design process to reduce engineering efforts and time. We conducted a structural analysis that compares two cases with and without considering casting residual stress in large-scale sand castings and obtained significantly different results. We introduced an interfacing algorithm (casting-structural interface) to map the casting residual stress with structural stress and combined the results of finite different analysis for casting and finite element analysis for structural design. This work represents our preliminary studies on improving the design accuracy of a large-scale casting part and shows the importance of considering the casting residual stress. A difference of about 41% in maximal principle stress is obtained with and without considering the casting residual stress.

Dendritic model for macrosegregation prediction of large scale castings

A dendritic model with the consideration of heat transfer conservations, solute transfer conservations, melt convection, grain nucleation and growth, and the sedimentation of crystal was introduced to predict the macrosegregation of large scale casting. The model was validated by a Pb-5wt.% Sn classic benchmark experiment and then used to predict the macrosegregation of a 3.3-ton industrial Fe-4.5wt.% C ingot. Secondary dendrite arm spacing (SDAS) was considered in present model and SDAS was found plays an important role on liquid flow and affects final characteristic of segregation. The quasi A-segregation caused by the instability of interdendritic flow was presented in this study. A negative segregation zone under hot top was presented and the ingot size effect plays more important role than cooling conduction on the formation.

A new ecological model for the ∼565 Ma Ediacaran biota of Mistaken Point, Newfoundland

Ediacaran macrofossils immediately precede the first animal ecosystems of the Cambrian Period and have excited much attention for potentially containing ancestors of the modern animal phyla. Ediacaran fossil surfaces have been variously interpreted as vertically tiered census populations comparable to animal ecosystems, or as osmotrophic ecosystems exploiting turbulent flow regimes. These hypotheses are highly dependent upon the taphonomic interpretation of Mistaken Point, Newfoundland as a consensus population representing the associations of the organisms in life. Reanalyses of these surfaces, however, indicate that this taphonomic model is inconsistent with the range of preservation states seen in each taxon. We present a new taphonomic model, for Mistaken Point surfaces in Newfoundland Canada, and describe it using an index of decay. This reveals a complex history of life, death, and decay at these sites. Data gathered from large scale casting projects in Newfoundland show that only 15–40% of individuals were killed by ash flows, rather than the whole population as previously interpreted. This shows that Ediacaran organisms at Mistaken Point, Newfoundland, had a diverse range of ecological relationships with the microbial mat system. Frondose organisms are engaged in chemical exchange with the sediment and the water column with the stem penetrating through the microbial mat. Reclining forms, such as Fractofusus, lived exclusively above the microbial mat and drew nutrients from the dead organisms on which they typically grew. The ecology is based on organism interaction with the sediment–water interface quite unlike that of modern vertically tiered metazoan communities that have developed since the start of the Cambrian Period.

Disruptive Innovation

1. IntroductionThere exist sustaining innovations that improve product performance according to existing criteria. In addition, there exist disruptive innovations that can replace existing products, first improving product performance in a different set of criteria despite lower performance in the original criteria, and subsequently causing improvements according to existing product performance criteria (Christensen, 1997).Christensen and Raynor (2003) assumed two types of customers with regard to disruptive innovation: entirely new nonconsumers in markets outside of existing markets, and overshot customers in existing markets.1 New-market disruptive innovations provide new value to nonconsumers through innovations for new markets that subsequently cause disruptive innovations in existing markets. Low-end disruptive innovations provide products and services that grant value in line with low-end overshot customers, but subsequently target customers from the high end (Christensen & Raynor, 2003). Keywords for disruptive innovation are cost, traditional performance, and ancillary performance change (Utterback & Acee, 2005).2 While new-market disruptive innovations may lag in traditional performance, they acquire new markets with innovations in superior ancillary performance and permeate from new markets to existing markets. On the other hand, low-end disruptive innovations exhibit poor traditional performance; nevertheless, innovations with lower costs enable them to withdraw customers from existing markets. 3 New-market disruptive innovations can also be used to replace products on the low end of existing markets; thus, conceptually, there is continuity between new-market and low-end disruptive innovations (Christensen & Raynor, 2003).Existing companies can respond to a sustaining innovation even when the innovation is radical; however, with disruptive innovation, existing companies often fail to form a response. This is because existing companies are bound by their existing value network in which they have developed a customer base and business relationships (Christensen & Rosenbloom, 1995). As understood through the value network, when a value network cannot respond to nonconsumers that demand new value, new-market disruptive innovations occur; when low-end customers are taken from a primary value network with existing products and services, the result is low-end disruptive innovation (Christensen & Raynor, 2003).Can we then assume that there are only two customer types, nonconsumers and overshot customers, with regard to customers who influence the value of a disruptive innovation?4 In Japan's large-scale casting industry, the full mold casting (FMC) method used by Kimura Chuzosho Co., Ltd. became a disruptive innovation that acquired customers with specific requirements unmet by existing wood pattern-based sand mold casting. These customers were neither nonconsumers nor overshot customers.2. Process Innovation of FMCAs the name implies, a wood pattern is a pattern made from wood. Sand mold casting in the casting industry has extensively used these wood patterns. The wood patterns are filled with molding sand, and a mold is formed by solidifying the molding sand. The space created by the removal of the wood pattern is filled with melted metal, and a casting is formed. At present, medium- and small-scale castings are often made by using patterns of metal or plastic, while molds are often formed with metal. However, even today, large-scale castings are made by using sand mold casting with wood patterns.In contrast, FMC also uses molding sand, though it uses patterns made from foam polystyrene instead of wood patterns. In FMC, the pattern fills the interior of the mold, and subsequently melted metal replaces the pattern inside the mold, thereby forming a casting.The process of wood pattern-based sand mold casting is as follows. 1) A wood pattern is formed (this pattern is a model of the finished product). …

High cycle fatigue behavior of different regions in a low-pressure sand-cast GW103K magnesium alloy component

Abstract

The Effect of EMS on the Microstructure of LPSO Mg-Zn-Y Cast Alloy

In this study, long period stacking ordered structure (LPSO) type magnesium alloys have been developed. They consist of LPSO phase and α-Mg phase and have excellent mechanical properties at both ambient and elevated temperatures. In the present study, the influence of electromagnetic stir (EMS) on the structure of LPSO type Mg96Zn2Y2 (at. %) billets of φ200 mm in diameter was investigated in order to establish the large-scale casting technology of LPSO type Mg alloy. EMS refined the grain size of α-Mg up to approximately 1/3.5, and reduced the size difference between the surface and the center of the billets. By applying EMS, it was found possible to provide large-scale casting billets with fine and homogeneous microstructure.

Foundry Technique Designing of the Large Scale Thin-Section Casting

The FDM numerical simulation software View Cast system was employed to the counter-pressure casting of aluminum alloy large-scale thin-section casting. By analyzing the mold filling and solidification, the distribution of liquid fraction, temperature field were studied. The potential shrinkage defects were predicted to be formed at the top of the casting. A solution towards reducing such defects has been presented. The feeding capacity of the riser was improved. Analysis on the shrinkage proved that the improved riser is an effective method for reduction of defects.