Sand Cores Research Articles

A Simple Process to Prepare High‐Efficiency Durable Oil–Water Filter (Adv. Mater. Interfaces 17/2021)

High-Efficiency Oil–Water Filter In article number 2100594, Jiawei Hu, Yi Chen, and co-workers prepare a high-efficiency oil–water filter by coating sodium alginate hydrogel layer in the surface of porous sand core. This filter exhibits excellent separation ability toward oil–water mixed liquor and oil–water emulsion. Moreover, it has excellent chemical stability, easy cleanliness, and strong durability. All these characteristics make this filter a potential candidate for large-scale applications in wastewater treatment.

Parametric appraisal of strength & hardness of resin compacted sand castings using hybrid Taguchi-WASPAS-Material Generation Algorithm

When compared to green sand moulds, resin bound sand moulds and cores have higher mechanical characteristics and create more dimensionally exact castings, and are thus increasingly preferred for near net form metal components. The effect of binder %, sand particle size and curing time on the mechanical characteristics of no-bake resin bonded mould core was studied in this study using lab testing. Their mechanical characteristics were discovered to rise with the addition of binder amount and curing time, along with dropping with increasing grain fineness number. Microscopic study of cross-linked resin bridges between sand grains also supports this. To get the best blend of mould characteristics, the results were optimized using the WASPAS technique and the Material Generation Algorithm. Tests were used to successfully validate the model and its findings. This study lays the groundwork for optimizing the moulding parameters of resin reinforced sand mould cores in order to achieve the best quality.

Parametric appraisal of collapsibility and core shrinkage of phenol binded unbaked casting moulds using Taguchi-Sunflower optimization algorithm

When compared to green sand moulds, resin bound sand moulds and cores have higher mechanical characteristics and create more dimensionally exact castings, and are thus increasingly preferred for near net form metal components. The effect of catalyst %, sand particle size and no. of strokes for compression on collapsibility and core shrinkage of no-bake resin bonded mould core was studied in this study using lab testing. Their collapsibility were discovered to decrease and core shrinkage increase with the addition of catalyst amount and bigger grain size. Microscopic study of cross-linked resin bridges between sand grains also supports this. To get the best blend of mould characteristics, the results were optimized using the Taguchi technique and Sunflower optimization algorithm. Tests were used to successfully validate the model and its findings. It was reported that the Sunflower optimization algorithm made more precise prediction than Taguchi method in maximization of collapsibility and minimization of core shrinkage. This study lays the groundwork for optimizing the moulding parameters of resin reinforced sand mould cores in order to achieve the best quality.

The first casting mould for a ‘Syrian Bottle’ from Lipnik, Bulgaria

Abstract The following article presents the first mould ever discovered for casting a so-called “Syrian Bottle”, a distinctive vessel type that originated in Mesopotamia around the mid 3rd millennium BC and soon after spread to Anatolia, the Aegean and Southeast Europe, as imports and local derivatives. A few examples were made from precious metals and lead, the most notable one being a golden globular bottle, part of “Priam’s” Treasure A” from Early Bronze Age Troy. The mould from Lipnik seems to have been intended for the production of small metal bottles of ‘Syrian’ shape, and supportive agents like a green sand core applied for the production of such a complex item. The mould, however, was obviously never used. A review of associated manufacturing details like pegholes, riser and vent show that although these features were particularly prominent in the 2nd millennium BC, moulds from earlier (Anatolian) contexts do possess such characteristics as well. This currently unique, locally produced example is therefore dated to the latest 3rd or earliest second millennium BC, coinciding with ever-growing interaction between distant cultural entities stretching from Mesopotamia to Southeast Europe and beyond, and allowing for the exchange of ideas, fashions and technologies.

A Simple Process to Prepare High‐Efficiency Durable Oil–Water Filter

AbstractA simple process is designed to conveniently prepare a high‐efficiency oil–water filter to satisfy the need to separate oil from large amounts of oily wastewater. In this strategy, a porous sand core (SC) is selected as the substrate, and a hydrophilic sodium alginate gel layer is introduced to uniformly cover the outer and inner surfaces of the SC by briefly and successively soaking the SC into sodium alginate solution and CaCl2 solutions. Significant underwater ultra‐oleophobicity is achieved by combining a hydrophilic gel coating with a rough surface microstructure. This modified filter exhibits excellent oil–water separation ability. The SCs with various pore sizes exhibit a separation efficiency of nearly 100% when filtering various oil–water mixtures and oil‐in‐water emulsions, and a water flux of approximately 200–5000 L m–2 h–1 depending on the pore size of the SC and the operating pressure. Moreover, the filter reveals excellent chemical stability, excellent mechanical strength, ease of cleaning, and strong durability, thereby making it a potential candidate for large‐scale applications in wastewater treatment.

Rapid casting technology based on selective laser sintering

Selective laser sintering (SLS), as a kind of additive manufacturing technology, which uses a laser beam to scan and heat powder material layer by layer to form parts (models), is widely used in the field of casting, mainly for preparing casting coated sand cores, investment casting patterns, etc. The SLS technique facilitates rapid casting and shortens the casting production periods by eliminating mold preparation. In this study, we reached conclusions for the basic principles and characteristics of SLS methods, and focused on the research status, key technology and development trend of SLS in the fields of forming coated sand-casting molds and investment casting patterns.

The effect of sand quality on the bending strength and thermal distortion of chemically bonded sand cores

The quality of chemically bonded sand cores used during the manufacturing process of cast components is highly dependent on the properties of the sand, which constitutes the refractory base media of the core. One of the main advantages of the application of different types of sands as molding aggregates that after casting, they can be reclaimed and can be used again during core shooting. The properties of the sand, however, could be remarkably changed during the casting and reclamation processes. This study aims to investigate the effects of the properties of the base sand on the mechanical strength and thermal distortion properties of samples made from new and thermally reclaimed silica sand. For this purpose, particle size analysis, specific surface area, and loss on ignition measurements, as well as differential thermal analysis coupled with thermogravimetry, were executed on the base sands, and the sand grains were analyzed with scanning electron microscopy and X-ray diffraction. Test pieces were made with hot box and cold box technology for bending and hot distortion tests. It was found that by the utilization of reclaimed sand, cores with higher average bending strength and lower thermal deformation can be produced. These differences can be traced back to the more advantageous granulometric properties, lower impurity content, and lower thermal expansion of thermally reclaimed sand.

Development of Salt Core Use Alternative in Aluminum Alloy Casting Parts

For creating complex geometric shapes in the cast part, salt was used to produce core instead of sand which is thermo-chemical or chemical process using resin as a binder.In salt core casting, the efficiency will be increased by reducing the core gas-induced errors in the part. The harmful effect on the environment will be reduced with the absence of odor and smoke from the core gas.Using water in salt core breaking instead of mechanical impact and vibration during sand core breaking will bring benefits such as eliminating the noise source and using less energy. By eliminating the dust generated during sand core breaking, its harmful effects on the environment will be reduced. Since the salt core can be dissolved in water and removed from the piece without any residue, there will be no problem of sand remaining in the sand core from time to time.

A Study of The Properties of Forming Mixtures Containing Polystyrene Wastes

Expanded polystyrene is widely used as a material for packaging, in modern construction as a heat and sound insulation layer, in thermal insulation systems for buildings, as well as tanks and pipelines. It is additionally used in foundry engineering for the production of models which are gasified during the production of castings from ferrous and non-ferrous alloys under the contact with liquid metal. The use of expanded polystyrene products is associated with waste generation, both in production and in consumption. About 40–50 kg/person of polystyrene waste is generated per year. The peculiarity of polymeric wastes is their resistance to aggressive environments. They do not rot and the destruction processes in natural conditions proceed rather slowly, with the formation of harmful substances that poison the environment. Therefore, the problem of the processing of waste from polymeric materials is of great importance, not only from the standpoint of environmental protection, but also due to the fact that in conditions of a shortage of polymer raw materials, this waste becomes a powerful raw material resource. This article describes the prospects for recycling expanded polystyrene wastes in foundry engineering. In this work, the properties of molding and core sands containing a combined binder, consisting of a solution of expanded polystyrene wastes in turpentine and clay were investigated, and their main characteristics (weight during stretching and crumbling) were determined. Molding and core mixtures, which contain only a binder in the form of a solution of expanded polystyrene in turpentine, have a crude strength of not more than 0.01 MPa. The introduction of a mixture of clay in the amount of 2–3% allows a crude strength of the mixture of up to 0.05 MPa to be obtained. After drying, the investigated mixtures containing a solution of expanded polystyrene wastes and clay have a tensile strength of up to 2.1 MPa. Mixtures into which a solution of polystyrene wastes and clay was introduced have an insignificant gas capacity and satisfactory gas permeability.

A Comparative Analysis on Organic and Inorganic Core Binders for a Gravity Diecasting Al Alloy Component

The last two decades have seen a growing trend toward the use of inorganic binders in core making for the metalcasting field. Despite the health and environmental benefits of the inorganic binders, wider commercial use requires ongoing technical improvements to address some potential inherent limitations of this technology. Considering that inorganic cores can suffer from storage stability, this study sets out to check whether inorganic core binders are fit to replace organic ones in producing a gravity diecasting Al alloy component. First, the humidity resistance of both organic and inorganic sand cores, within a typical time-frame storage in the foundry, was evaluated by moisture absorption tests. Then, 3D optical measurements were performed to assess the relative dimensional changes of inorganic cores. Last, the influence of the core system was analyzed through microstructural and mechanical investigations on castings manufactured by using organic and inorganic binders. The experimental findings have shown that the moisture absorption during storage in the foundry warehouse, which lasted up to 14 days, was not enough to jeopardize the functionality of the cores. Furthermore, the tensile and microstructural outcomes revealed that inorganic cores could comply with both high component design requirements and even more stringent environmental regulations of foundries.

Dehydroxylation of Perlite and Vermiculite: Impact on Improving the Knock-Out Properties of Moulding and Core Sand with an Inorganic Binder.

The article presents the results of research aimed at examining the type of swelling material introduced into moulding or core sand to improve their knock-out properties. Tests on Slovak perlite ore (three grain sizes), Hungarian perlite ore and ground vermiculite (South Africa) were carried out. For this purpose, thermal and structural analyses (FTIR—Fourier Transform Infrared Spectroscopy), a chemical composition test (XRF-X-Ray Fluorescence), phase analysis (XRD—X-Ray Diffraction), and scanning electron microscopy (SEM—Scanning Electron Microscope) as well as final strength tests of moulding sands with the addition of perlite ore and vermiculite were carried out. The results of thermal studies were related to IR (Infrared Spectroscopy) spectra and XRD diffractograms. It has been shown that the water content in the pearlite ore is almost three times lower than in vermiculite, but the process of its removal is different. Moreover, the chemical composition of the perlite ore, in particular the alkali content and its grain size, may influence its structure. The phenomena of expansion (perlite) and peeling (vermiculite) have a positive effect on the reduction of the final sand strength and eliminate technological inconveniences (poor knocking out) that significantly limit the wide use of moulding sands with inorganic binders.

Research on the Release of Dangerous Compounds from the BTEX and PAHs Groups in Industrial Casting Conditions

The assessment of the harmfulness of moulding and core sands is mainly based on investigations of compositions of gases emitted by liquid casting alloys during the mould pouring. The results of investigations of moulding sands obtained under industrial conditions are presented in this paper. A unique research stand was designed and built for this aim. It allowed us to determine emissions of gases at individual stages of casting a mass up to 50 kg. This approach enables simulation of foundry conditions. Moulding sands bound by organic binders (phenol-formaldehyde; furan), inorganic binders and green sand, were subjected to investigations. The composition of gases that evolved during the individual stages, pouring, cooling and knocking out, was tested each time, and the contents of Polycyclic Aromatic Hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylenes (BETX) were analysed. Investigations indicated that the emission of gases from sands with inorganic binders is negligible when compared with the emission of gases from sands with organic binders. The emission of gases from green sand is placed in the middle of the scale. As an example: the sand with furan resin emitted 84 mg of BTEX (in recalculation for 1 kg of sand) while from sands with inorganic binders there was a maximum of 2.2 mg (for 1 kg of sand). In the case of sands with inorganic binders, MI and MC sands indicated comparable and very low emissions of gases from the PAHs group, at the level of 0.018 mg and 0.019 mg for 1 kg of sand, respectively. The higher emission of PAHs from MG sand is the result of its different way of hardening (a binder was of an organic character) than of sands MI and MC.

Mohr–Coulomb characterisation of inorganically-bound core materials

This work aims at modelling the mechanical behaviour of inorganically-bound core materials. In this article, the mechanical material parameters for inorganically-bound core materials for various binder amounts and temperatures are determined. Specifically, the influence of the binder amount on the elastic properties and the Mohr–Coulomb parameters of the sand cores is studied. Furthermore, the hardening process of the cores after the core shooting is analysed regarding its influence on the material parameters. The goal is to characterise inorganically-bound core materials for handling simulations. This material model is implemented into a finite element simulation to predict core failure in industrial handling processes. This finite-element model is validated with a complex water jacket core geometry and different load cases, which are derived from real industrial handling processes.

Characterisation of the decoring behaviour of inorganically bound cast-in sand cores for light metal casting

This article proposes a new method to classify the decoring behaviour of different cast-in sand cores for light metal casting. Sand cores are in use to realise hollow structures in casting parts. More and more inorganically bound sand cores are used due to environmental requirements, which, in contrast to organically bound sand cores, do not disintegrate during the casting process. The inorganically bound cast-in sand cores need to be removed after the casting process by a process called decoring. A test rig derived from the industrial decoring process was built to investigate the decoring behaviour and to measure the effort of decoring. The proposed method is based on single impulses imposed on the test geometry. The goal of this approach is to understand the factors influencing the decoring behaviour of a sand core. Therefore, different sand-binder systems, with varying amounts of binder and different grain size distributions, were decored and examined with the developed test rig. A validation of the experimental results using simulation methods showed a high influence of the residual compression strength of the sand cores to their decoring behaviour. The authors showed that specimens with a higher amount of residual compression strength are more difficult to decore than specimens with a lower amount of residual compression strength. The methods and results presented in this article build the foundation to model a digital twin of the decoring process which is a missing link in the digital process chain in casting technologies.

Wireless Ventilation Measurement in 3D Printed Sand Molds

Additive Manufacturing is enabling the casting of complex geometries directly from digital design data, including 3D-scanned and reverse-engineered structures and even functionally graded lattices. By ink jetting binder into a bed of sand layer-by-layer, dimensionally precise sand molds and cores can be printed to serve as soft tooling for sand casting. However, the related increase in geometry complexity can lead to challenges in ensuring casting quality and yield. One recently explored remedy is to introduce sensors (the Internet of Things) to enable the collection of a diversity of data at difficult-to-access locations in molds in order to measure temperature, pressure, moisture, and core shift. This effort has explored measuring barometric pressure at strategic locations to evaluate the ventilation design of internal cores. Optimized and measurable ventilation can be leveraged to improve the quality of castings by reducing porosity and improving surface finish. By measuring the pressures that accumulate within cores due to binder decomposition, new ventilation designs and strategies—enabled with complex, 3D printed fluidic channels—can be explored. In this work, two castings with different metal temperatures were poured and internal pressures were measured and compared to simulations demonstrating that wireless disposable sensors can be used to measure pressure and that the measured pressure correlated with venting strategies now possible with 3D printed sand cores.

Characterization of the Strength of a Natural Sand and Artificial Sand Core Manufactured with Inorganic Binder

Natural sand and organic binders are commonly used in casting processes, but these ingredients produce environmental problems with dust and harmful TVOC(Total Volatile Organic Carbon) gases. Research on the introduction of artificial sand and inorganic binders to solve these environmental problems is being actively conducted mainly in the casting industry. Artificial sand has superior durability and a spherical shape compared to natural sand, and above all, it does not generate dust. In addition, inorganic binders have the advantage that no harmful gas is generated during casting and the used sand can be recycled. This study confirmed whether inorganic binders can be applied when replacing natural sand with artificial sand. First, eco-friendly inorganic binders that do not produce harmful gas were synthesized. Then characteristic analyses were carried out with artificial sand and natural sand. Physical and chemical properties were compared using X-Ray Fluorescence (XRF), Powder Flow Test (PFT) and particle size distribution analyses. The general strength and absorption (absolute humidity 29.9 g/cm<sup>3</sup>) strength of the sample core was measured using each sand (artificial sand, natural sand) and inorganic binder. Also, X-ray Photoelectron Spectroscope (XPS) analysis confirmed the combination structure. As a result, it was confirmed that artificial sand exhibited mold characteristics with similar strength even with lower inorganic binder content than natural sand.

Durable hydrophobic ceramics of Al2O3–ZrO2 modified by hydrophilic silane with high oil/water separation efficiency

Separating materials of oil/water are widely used to deal with oil leakage and industrial oily wastewater. Herein, hydrophobic–oleophilic porous ceramics of Al2O3–ZrO2 were prepared by combustion synthesis-molding method and modified with 3-amino-propyltriethoxysilane (APTES). The effects of Al2O3–ZrO2 mole ratio, starch content and sintering temperature on permeability of porous ceramics were investigated in detail. When the molar ratio of Al2O3–ZrO2 is 1:0.15 and the amount of starch is 35 wt%, the porous ceramics with average pore diameter of about 42 nm and porosity of about 46% can be obtained after sintering at 1450 °C for 2 h. APTES was adopted to modify the porous ceramic of Al2O3–ZrO2 to construct the hydrophobic surface. The optimum conditions of modification for the Al2O3–ZrO2 ceramic were that the time was 4 h, the temperature was 70 °C and the modifier concentration was 2%. Most notably, the as-prepared hydrophobic ceramic was a rare example that adopted hydrophilic molecule to build hydrophobic material. Due to the favorable permeability and hydrophobicity, the Al2O3–ZrO2 ceramic was designed into sand core to separate oil/water mixture. The ceramic displays high separation efficiency (93%), good reuse performance (10 cycles) and super abrasion resistance (10 times).

Factors Influencing Characteristics of Sand Core for Water Jacket in Automotive Cylinder Blocks Casting

The characteristics of the foundry sand were analyzed for water jacket core required to prevent structural deformation from the heat generated in the cylinder bore during the casting of the cylinder block of an automobile. The sand core tensile strength tester, AFS-GFN, and optical microscope were used to evaluate the its properties. If the SiO2 content is high in the foundry sand, the dimensional defects and veining defects occur due to high temperature expansion. Also, if it is too low, the core breakage, porosities, chemical burn-on defects occur. The particle size index and grain shape influenced the core strength and resin consumption, resulting in fluctuations in defect types. The higher the alkalinity of the dried sand, the lower the core strength. And the more basic, the lower the core strength. At the resin content of 1.6∼1.8%, the increase in core strength after 1 hour curing was approximately at its maximum.

Optimization of Casting Process of Headstock Based on Numerical Simulation

In this paper, the casting process optimization design of a certain type of headstock is carried out by numerical simulation technology of casting process. Designed the pouring plan based on theoretical calculation; based on the numerical simulation results, quantitatively designed the riser size, and rationally arranged the pouring riser system based on the equilibrium solidification theory, which can reduce the shrinkage porosity and shrinkage defects in the casting process and increase the process yield; Finally, a sand core production plan is provided based on the precision machining technology of the moldless casting mold, which provides a new idea for the process plan design of complex spindle box castings.

Research on a Traceability Process of Sand Core Information by Printing QR Code on Sand Core Surface in the Casting Production Process

The quality of the sand core directly affects the quality of the casting during the casting process. The establishment of an information link between the sand core and the casting can realize the traceability of sand core production and process data in the casting production. The technology can be used when casting defects related to the sand core occur and quickly respond to the causes and optimize the manufacturing process of the sand core making process. This article describes the necessity of establishing a traceability process for sand core making information and introduces a traceability process of sand core information in casting production to ensure that each sand core has its own production process information, which is for product quality management and process optimization. It provides information supervision and promotes the development of intelligent casting manufacturing technology and management technology.