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Gas permeability of moulds and cores is an important factor to consider in the casting process. In foundries, gas permeability is measured by using instruments which give dimensionless numbers. Thi...

A high shake-out temperature after casting is beneficial from a production point of view due to the need of a shorter cooling line in the foundry. However, a higher shake-out temperature might also...

Investigations were carried out to use Granulated Blast furnace (GBF) slag as mould material for either full or partial replacement of existing silica sand in foundry industry. Nishiyama process was adopted for evaluating the same. A series of sand tests were carried out on sand and slag individually and also combinations of these two. Three types of moulds were made with sand, slag individually and combination of these two. Both laboratory and industrial castings of ferrous and non ferrous materials were performed. Results of mould permeability, compression and shear strength of GBF slag reveal that is a suitable candidate for either partial or full replacement of molding sand. During casting of both laboratory and industrial, neither fuse, dripping nor collapse of the mould walls was observed; this is true for both ferrous and non ferrous castings. Castings with good surface finish, no surface defects and porosity were made by slag moulds.

Greensand is a widely-used material to produce sand moulds in high production, mainly for iron casting applications. Several authors have studied the high temperature behavior of greensand regarding to the vapour condensation and transfer zones, and the effect of different production parameters on the thermal conductivity. This work focuses on the effect of the mixture composition on the heat absorption (cooling) capacity of the greensand. During the experimental work, various greensand mixtures with changing bentonite + water and coal dust contents were prepared and tested by a novel application of Fourier thermal analysis. The method provides new thermophysical knowledge about moulding sand, through applying real casting conditions by the immersion of spherical sand samples into liquid iron. The findings of the work direclty contribute to the area of thermal sciences and also brings novel understandings to foundry technology in general.

For the possible energy savings and extension of the volume capacity, the monolithic lining of a channel induction furnace was optimised in the following manner. Orthogonal array method is utilised to systematically design the lining concepts, and the finite element simulations including the temperature dependent properties of monoliths are carried out to determine the temperatures and stresses during the preheating and holding. In terms of the main effect analysis materials for the monolithic lining are recommended. Moreover, a thickness–thickness–temperature isothermal map is provided to show the acceptable thickness range of working and insulating linings. Nevertheless, for the final decision the deliberate consideration for the cost effectiveness of a certain lining concept is also necessary.

Several binary and ternary alloys from the Al–Ti–B system were tested for their capacities to grain refine aluminium foundry alloys. The growth restriction factor estimations evidence that the Al–3Ti alloy contributes to the grain refinement of AlSi7Mg0·3 alloy via only growth restriction, providing a twofold reduction in grain size. There is a marked improvement in the grain refining efficiency when Al–Ti–B ternary alloys are employed. While the efficiency increases with increasing B concentration, the mild improvement over a wide range of grain refiner compositions implies that the AlSi7Mg0·3 alloy is not very sensitive to the composition of the ternary Al–Ti–B grain refiners. Al–3B alloy provides the smallest grains at an addition rate of 200 ppm B, producing an average grain size of 298±36 μm in the commercial AlSi7Mg0·3 alloy. The grain refinement efficiency is doubled when the Al–3B grain refiner was added to the Ti free counterpart with average grain size of 145±10 μm.

In this study, we describe the effect of the main alloying elements Ni, Cu and Mg on the mechanical properties of near eutectic and hypoeutectic Al–Si foundry alloys at 250°C after a long term exposure to test temperature. Systematic compositional variations illustrate the significant hardening effect of secondary precipitates such as Al2Cu and Mg2Si. It is also shown that the strength is increased by the addition of Ni, albeit only to a certain level, depending on the fraction of eutectic phase in the alloy. The alloys are considered as coarse two-phase systems, where a hardening effect is caused by load transfer to the harder phase, which requires a certain contiguity of the latter. This paper discusses the individual influences of Ni, Cu and Mg on the high temperature strength and describes a potentially adverse effect of the combinations Cu/Ni and Cu/Mg.

The improvement of foundry coatings to enhance performance is important. This paper investigates the effect of using sol–gel component as an additive to foundry coatings applied on chemically bonded sand cores. Three parameters at three levels each were investigated using Taguchi experimental parameter design. The effects of the sol–gel component on viscosity, density, °Baume, core coverage and permeability are shown. Numerical simulations were used to predict defect areas. The thermal profiles of the core materials during casting were determined, and the surface quality of the castings was evaluated. The results show that the surface quality of castings obtained by adding the sol–gel component to the coatings for cold box cores has no significant difference from castings produced with coatings without sol–gel component. On the other hand, the addition of the sol–gel component in coatings for furan cores showed significant improvement on the surface quality of the castings compared to that obtained withou...

Casting simulation results are only useful to a foundry if they reflect reality, which requires accurate material datasets for the alloys being simulated. Material datasets include property data such as density, specific heat and thermal conductivity as functions of temperature, as well as latent heat of solidification and a solid fraction–temperature relation. Unfortunately, there are a significant number of commonly used metal alloys for which no reliable material data are available. The present study focuses on five such corrosion resistant alloys: superaustenitic stainless steel CN3MN, duplex stainless steels CD3MN and CD4MCuN and nickel based alloys CW6MC and N3M. Initial alloy material datasets are generated using thermodynamic simulation software. Comparisons of temperatures measured in full scale sand castings made from these alloys with temperatures predicted in computer simulations revealed that these initial datasets are inadequate. Therefore, an iterative method is developed to adjust the datasets (in particular the solid fraction–temperature relation and latent heat) in order to match measured and predicted temperatures and cooling rates. Uncertainties in the simulation are effectively eliminated through parametric studies. Although more tedious, the present iterative method to determine the solid fraction–temperature relation and latent heat is believed to be more accurate than traditional cooling curve analysis using small experimental castings.

Cu provides a grain refining effect for aluminium alloys that starts to deteriorate at ∼6 wt-%Cu. There is no improvement in grain size over that already obtained with 4–5 wt-%Cu when AlCu4 and AlCu5 alloys are inoculated with 0·02 wt-%B. Al–Cu alloys with >6 wt-%Cu, on the other hand, enjoy a remarkable grain refinement upon the addition of 0·02 wt-%B. AlB3 is an excellent grain refiner also for those foundry alloys that contain less Cu but additionally Si, such as A208 and A319. A common feature of these alloys is a liquidus temperature below 640°C, estimated to be the temperature at which AlB2 particles start to precipitate out of the melt. Heterogeneous nucleation of α(Al) on freshly formed AlB2 particles follows and produces very small equiaxed grains.

Hydrogen has high solubility in molten aluminium during solidification, causing porosity, low tensile strength, low elongation and poor surface finish. Porosity is enhanced by inclusions and particles suspended in the melt. The popularity of the reduced pressure test (RPT) stems from its simplicity. It is basically a comparative and semiquantitative test. The reduced pressure encourages pore formation and lower density than if obtained under atmospheric conditions of solidification. The RPT samples of 6063 aluminium alloy were solidified under different vacuum conditions and correlated to its specific gravity. Visual examination of the samples shows that the standard RPT is less sensitive to hydrogen concentration when used with the 6063 alloy than in the case of aluminium foundry alloys. The results reveal that the use of a reduced pressure of 28″Hg (−95 kPa) instead of the suggested standard vacuum of 25″Hg (−84·5 kPa) gives a better visual assessment of the gas content in the melt.

The combined effect of the main alloying elements on the mechanical properties and fluidity of the secondary foundry alloy AlSi9Cu3 has been investigated. Systematic compositional variations within the alloy's tolerance limit illustrate the broad spectrum of attainable properties. The yield strength in the as cast condition can be adjusted from 100 to 200 MPa, while the elongation to fracture can be simultaneously varied between 0·35% and almost 4%. Additionally, variation in fluidity by more than 100% can be achieved. The microstructure–property relationship is interpreted in the light of thermodynamic calculations that reveal a significant mutual interaction of the alloying elements.

Spent filters employed in twin roll casting of wrought Al alloys were thoroughly analysed to identify the type of inclusions responsible for a variety of quality problems in Al sheet and foil. The inclusions are predominantly of the TiB(2), Al(2)O(3) and MgAl(2)O(4) variety. The former are invariably in the form of clusters and occupy a volume fraction relatively larger than that of oxides. The oxides entrapped inside the spent filter are mainly films with a lacy morphology and are accounted for by poor foundry practices. The angular oxide particles, 10 to 20 mm in size, are believed to be inherited from the electrolytic cells where primary Al is produced and from eroded refractory linings. There are occasionally dispersed carbide and halide salt particles retained inside the spent filter. Their volume fractions, however, are too small to generate Bragg reflections in the XRD analysis.

A study is reported in which cryogenic temperatures are applied to intensify the mechanical reclamation of used foundry sand in experimental equipment that reproduces the abrasion, rubbing and crushing found in industrial processing. Results for used silica sands with bentonite and silicate (water-glass plus ethylene glycol) binders carried out at approximately –70°C and ambient temperature are presented. The reclaimed material was characterised by pH value, ADV (acid demand value) and Na2O content, which usefully define ease of reclamation, bending sand strength and compressive sand strength. Mechanical–cryogenic reclamation clearly improved the output for both sand types, utilising the hygroscopic behaviour of moulding sands to intensify the release of sand from the binder. The presence of a 'freezing' agent changes the volume of both binder and sand grains, leading to increased stresses on the surface and inside the grains, combined with higher brittleness of the binder material. Compared with ...

Three treatment processes for the reclamation of green moulding sands coming out from a cast iron foundry located in Northern Italy are considered in this study. A wet mechanical treatment, a dry mechanical treatment and a dry mechanical plus heat treatment are compared to evaluate the efficiency of each process and to point out the best regeneration solution for the recycling of reclaimed sand in foundry operations. The inflow and the outflow samples of each process were characterised by means of particle size analysis and the determination of silica, loss on ignition, acid request, oolitic and some metals contents. A final evaluation of the three processes was performed taking into account the obtained quality of recovered silica sand and the economical aspects; the wet mechanical and the dry mechanical plus thermal treatments are most effective for the recovery of green moulding sands coming out from the considered foundry plant for cold box core production.

The approach to the grain size prediction in AA5754 Al alloy ingots based on artificial neural networks (ANN) has been used in the present study. The ANN has been trained on data that was measured in the real industrial conditions during the process of direct chill Al ingots casting. A very complex relation between the numerous casting parameters and the microstructure of the ingots justifies the application of neural networks, which are known for mapping complex and non-linear systems. A feed forward ANN model with the resilient back-propagation learning algorithm and weight decay regularisation has been developed to relate the grain size to casting rate, meniscus level, casting temperature, water flow for the metal mould cooling and speed of wire for master alloy addition. The results obtained from the ANN are found to be consistent with the theoretical researches and experience from the foundry.

A systematic study of the effect of ultrasonic treatment on the structure of the A356 Al–Si–Mg alloy was carried out. Ultrasonic vibrations were applied to the melt at several temperatures (628 to 608°C) for different periods (0–180 s). The results showed that the ultrasonic treatment is effective in controlling the morphology and size of aluminium grains when applied between 619 to 626°C, and is very effective at 622–625°C, where fine non-dendritic grains are formed. Grain sizes smaller than 60 μm and roundness values of 0˙7 and higher were achieved by 15 s ultrasonic treatment at 623 and 620°C. At higher temperatures, the microstructures are dominantly rosette like and dendritic. At lower temperatures (below 617°C), the samples show inhomogeneous microstructures in terms of grain size and morphology. The current results are useful to set some process parameters for the ultrasonic treatment of liquid Al–Si–Mg foundry alloys prepared for semisolid processing.

In the present work, the regenerative thermal oxidiser (RTO) with preheating and baking system was applied to treating volatile organic compounds (VOCs) discharged from the shell mould casting. As a result, it was found that the tar characterised by more than 523 K of high boiling point was formed by the shell mould casting. The Fourier transform infrared spectrometry analysis showed that the tar was composed of paraffin, zinc stearate and quartz. A part of the tar was deposited on the ceramic honeycombs in the heat exchanger. However, the tar can be almost completely removed by means of baking treatment at 623 K in the RTO. Regarding the decomposition of VOCs, it was found that the concentrations of all VOCs were reduced to less than 1 ppm. Further, 98% of offensive odour was removed by the treatment. Thus, it can be concluded that the RTO is suitable for decreasing VOCs from the shell mould casting in the foundry.

State of technologies in Japan related to composite casting was reviewed based on the three year survey of Composite Casting Process Sub-Committee in Committee on Foundry Technology (24th) of JSPS. Other than making metal matrix composite, cast-in insertion, bonding and joining of cast materials and other technologies combining different materials by casting process were included. Basic theories and the key technologies are explained, and a number of typical examples of products, on production or on experimental bases, were reported. Overseas literatures were also surveyed.

Rheocasting processes produce a globular (non-dendritic) morphology in the primary phase of a metallic alloy. The authors have developed the direct thermal method (DTM) of obtaining this morphology, using only standard foundry equipment. In the DTM the alloy is poured, at low superheat, into a cylindrical thin walled metallic mould, and by careful selection of mould materials and geometry, a near isothermal situation occurs for sufficient time to render the primary phase globular. No active thermal management is required or used. The sensitivity of DTM rheocasting of aluminium alloy to variables such as mould inner and outer diameter, mould material, heat transfer at the system interfaces, and starting temperatures, is assessed in this paper. This is done through both experiment and computer modelling. It is concluded that steel is a superior mould material than copper for the DTM, both for operational reasons and to enable the casting of larger diameter billets.

A systematic approach to analyse the reclamation of used foundry sands is proposed. The development of an energetic model for dry mechanical reclamation of used foundry sands is described. The theoretical basis of the model is the Rittinger hypothesis for crushing minerals, which balances the energy input for reclamation against the energy consumed in creating additional surface area as the average size of the used sand agglomerates is reduced. The Rittinger number is known for pure silica, which has properties close to those of quartz sand grains. It is shown that information from routine grain size analysis, performed by sieving during reclamation, can be used to calculate the Rittinger number for binder materials, assisting in optimisation of the dry reclamation process. Processing at cryogenic temperatures (−80°C) increases dry reclamation efficiency and produces reclaimed sands with better technological parameters, but must be closely controlled to prevent excessive dusting.

As cast and heat treated 400–18 grade ductile cast iron was obtained in different foundry conditions, using various metallic charges, Mg treatment with and without rare earth (RE) additions and various inoculation parameters. Pearlitic influence factor (P x) and antinodularising action factor (K 1) were found to have an important influence on ultimate and tensile yield strength and ductility, as did Mn and P content, the metallurgical quality of the melt, RE addition and inoculation power. The influence of Mn was in turn influenced by the phosphorus and residual element contents. To obtain an as cast ferritic structure 2·0) leads to the appearance of pearlite in the as cast structure, but a ferritic structure is obtained after a short annealing treatment. Lower level of phosphorus (

A method based on geometric reasoning techniques is presented to predict hot spots and use of geometric parameters of a casting to obtain effective interface boundary conditions. The proposed method combines Chvorinov's rule and Heuvers' circle method with the medial axis transformation technique to develop an elegant optimisation technique for the optimal feeding design of castings. The results are validated using a FE based solidification analysis. It has been shown that the method has the ability to constrain heat transfer coefficient values to yield more realistic predictions for foundry practices. The proposed method has a considerable potential to reduce the number of FE simulations that are otherwise needed to achieve an optimal thermal design.

The compaction behaviour of green sand was studied to assess the applicability of the Cooper–Eaton equation under conditions close to those of real foundry operations. The results indicate that the Cooper–Eaton equation describes the behaviour reasonably well, allowing prediction of the pressure required to achieve sand moulds of reasonable density. A corresponding distinct element method numerical simulation was also attempted. The study contributes useful information to the understanding of green sand compaction. It is clear that spherical sand is preferable to improve filling behaviour and that the gap between mould wall and pattern must be sufficiently large to avoid prevent weak sand compaction.

Reuse and reclamation of sodium silicate sands have long been of interest because of their unique characteristics in both bonding mechanism and high temperature strength, which make them ideal for applications in cast steel production. After analysis of the characteristics of the used sands containing sodium silicate binder and the requirement for moulding sands, a suggestion is proposed for a sand reuse scheme. Used sands can be reclaimed as support sands after dry treatment or reconditioning, but for use as face sands wet reclamation is necessary. This assertion has been confirmed experimentally on newly developed reclamation equipment. The results showed consistent sand properties and casting quality when applying reused support sands and reclaimed face sands.

Post-inoculation during the casting of iron is known as one of the techniques most often used in the foundry. The aim of this operation for the cast iron with nodular graphite is the control of str...

The concept of virtual manufacturing has been attracting the attention of foundrymen. With this technology simulation models of real production systems can be built in computer based on data, logics, and layout of the systems respectively. The simulation model can help foundry management to analyze the existing production system and they can modify the layout or process route of the model on computer screen when necessary. Then the data will be fed back to show the effects of the modifications before actual modifications are made.This paper gives a brief introduction of virtual manufacturing technology and introduces a simulation model of the fettling shop of a leading iron foundry for engine castings in China. The bottlenecks of the fettling shop with different input levels and product mix have been found by the simulation analysis and the maximum capacity of the existing shop has been calculated with the model. The virtual fettling shop has helped the foundry management in making decision to modify the ...

Feeder models that incorporate mass transfer from feeder to casting are reviewed, and assumptions made during their development are discussed. A new approach that incorporates a superheat model from the literature is introduced. The new approach is based on the equality of solidification times of feeder and the feeder-casting combination. The superheat model is used to adjust the solidification times of feeder and casting to account for heat transfer. Introduction One of the biggest contributions to foundry engineering was made by Chvorinov, 1 who stated that the solidification time, t , is determined by: n AVt B  (1) where B is the mould constant, V is the casting volume, A is the surface area through which heat is lost, and n is a constant (2 in Chvorinov‟s work). Equation 1 is referred to as Chvorinov‟s Rule. The V/A ratio is known as the modulus (M), and has been used as the basis for a number of approaches to determining the size of feeders for the production of sound castings. Despite its wide acceptance, Chvorinov‟s Rule has certain limitations because of the underlying assumptions used in deriving the equation. As a result of these limitations, the exponent, n, fluctuates between 1 and 2, depending on the shape and size of the casting, and the mould and pouring conditions. One of the reasons for this anomaly is that Chvorinov‟s Rule originally did not take the shape of the casting into consideration. A new geometry-based model was introduced in an earlier publication

Sands are important refractory materials in the foundry industry. The shape of sand particles influences significantly the properties of moulds and cores, especially the strength. Ideally the sand ...

Together with porosity, the problems created by the formation of iron intermetallics in Al-Si alloys pose serious concerns in regard to their use in structural components. The presence of these intermetallics, particularly the brittle β-Al5FeSi phase, tends to reduce the alloy properties and casting quality. In order to optimise the iron intermetallics in Al-6.5% Si-3.5% Cu-Fe alloys, the effects of cooling rate, Sr modification, other melt additions, and heat treatment were studied, with a view to determining the means of their formation and dissolution, in relation to their effect on porosity formation and alloy properties. The iron levels selected for study were 0.5%, 1.0% and 1.5%, covering the range of levels normally observed in foundry alloys. Castings were prepared using a cooling fin sand mould (DAS range: 25–85 μm) for microstructural analysis, and a Stahl permanent mould for tensile testing purposes. Samples of molten metal quenched in cold water provided much smaller DASs. Microstructural char...

The impact properties of 413, 356, 319 and 332 alloys were assessed using instrumented impact testing equipment. The fracture responses of the impact specimens were studied in terms of total absorb...

Dissolution of MgSi particles and homogenisation in aluminium foundry alloys A356 and A357 have been simulated by a simple numerical diffusion model. The model predicts that dissolution and homogenisation are complete after solution treatment times of less than one hour at 540°C for both alloys. Model predictions have been verified by metallography.

Thermal analysis is widely used in foundry to control melt preparation of cast irons. Its great versatility explains that many attempts have been made in the past to use it not only for controlling...

Grain size determination is of great importance to metallurgists and foundry alloy producers since grain size can be related to many fundamental casting and mechanical properties. Conventional techniques for grain size measurement, developed mainly for wrought aluminium alloys, consist of the grinding and fine polishing of a sample, an often difficult to achieve anodizing step, and examination under crossed polarizers. Such techniques give good results, but are long and difficult to accomplish. A more simple technique, which is less time consuming, easier to achieve, and relatively inexpensive has been developed. It gives good results for a wide range of alloy compositions, and is particularly effective on Al-Si foundry alloys. The technique is not influenced by the presence of common grain refining elements and does not depend on the grain size of the sample. The application of this method to commercial alloys such as 319,356 and others is discussed.

Foundry rejections due to “cold shut” defects on the surface of a graphite cast iron casting made by the “H” Process have been greatly reduced by computer simulation aided optimizing gate-system de...

Thermal analysis can provide a cost effective and reliable method to quantify the iron contents of aluminium-silicon alloy melts before the casting process is performed. The formation of the Al5FeS...

In the foundry, green sand moulding is an important process having a major influence on the casting process and product quality. In order to clarify the behaviour of sand particles in air-flow press moulding, the sand moulding process model has been built using the distinct element method (DEM) coupled with air flow analysis. In this model, the individual particle is moved by three forces, namely, contact force, drag force and gravitational force. Numerical simulation is performed to predict the behaviour of the sand particles during the air-flow stage, and laboratory experiments are carried out to examine the calculated results. From the simulation, contact force and drag force of individual particles are obtained as the function of time. It is clarified that effective force acting on the particles is changed from drag force to contact force during the process. This study utilizing DEM, gives useful information such as the effective moulding parameters for the optimisation of the air-flow process.

An attempt has been made to develop a suitable foundry process for production of highly reactive magnesium—lithium alloy castings. This process would permit the manufacture of shaped castings to co...