Grain Fineness Number Research Articles

Chemical reclamation of waste green foundry sand and its application in core production

The disposal of Waste Foundry Sand (WFS) poses a significant challenge for the foundry industry today, primarily due to its composition of metal oxides (Al2O3, Fe2O3, MgO, CaO, and Na2O) and sand. These metal oxides, categorized as loosely and strongly bound clays, are considered impurities in core production. This study proposes a chemical reclamation technique for WFS using fresh acid solutions or acidic industrial effluent. Experiments were conducted to remove the loosely and strongly bound clays from the WFS, optimizing parameters such as acid concentration, sand to acid loading, temperature, stirring speed, and reaction time to achieve optimal performance. The quality of the reclaimed sand was evaluated using various foundry standard tests, including determination of clay contents, compressive strength, Grain Fineness Number (GFN), Loss on Ignition (LOI), Acid Demand Value (ADV), and scanning electron microscopy. The reclaimed sand exhibited a loosely bound clay content of 1.5 %, oolitic content of 5.5 %, a grain fineness number of 55, a loss on ignition of 1.92 %, and an acid demand value of 1.5 ml/100 g of sand. Field trials demonstrated that the reclaimed sand can be effectively used for core production at an economical rate.

Preliminary Study on the Potential of Krueng Mane River Sand for Metal Casting Use

Sand casting is a metal casting process to make a component by pouring molten metal into the sand mold. The casting process, the sand is the fundamental material used for mold making. The sand used is generally silica sand, river sand, mountain sand, and beach sand. The sand for molding must have requirements such as having formability, suitable permeability, good distribution of sand grain size, resistance to high temperatures, suitable binder composition, and sand must be cheap. This study investigated to determine the potential of Krueng Mane river sand in Aceh Indonesia for its possible use for metal casting. The important properties studied are moisture content, total clay content, grain fineness number, and grain shape. Tests are carried out following the standards and procedures defined by the American Foundrymen’s Society (AFS). Results obtained revealed that the river sand has average moisture content of 7.78 %, clay content of 3.20%, and grain fineness number (GFN) of 46. Krueng Mane river sand will be suitable for casting of casting of light steel, heavy grey steel, medium grey iron, and non-ferrous metals, with the addition of binding agent in suitable proportion.

Gas Porosity Defect – What It Means and How to Respond

The foundries are facing problem-related to the selection of the parameter’s value for minimum rejection and maximum productivity. The furan no-bake binders system guaranteed dimensional stability and a comparative good surface finish of the casting. Based on past data in the industry, it is found that gas porosity defect is one of the highest. The phenomenon of the formation of the bubble in the fissures of the mould-metal interface, and later on trapping during the solidification leads to gas porosity. The current research work is focused on the minimization of the defect by the selection of the optimum range of input variables. Based on rigorous literature survey and industrial expert’s opinion, it is found that the parameters like grain fineness number (GFN) of the sand, loss on ignition (LoI) of the used sand, the sand temperature at the mixing time, potential of hydrogen (pH) are important parameters for gas porosity defect in the casting.Design-Expert software and particularly response surface methodology (RSM) and sequential approach using the face-centered central composite design is used for the experiments. The results show that a quadratic model with the removal of some insignificant term is a comparatively best fit for gas porosity defects. After analysis, various favorable levels of different parameters are obtained. The research work is based on realistic problems of the foundries and based on the experimental work. Thus, the provided solution is very much useful for foundries to reduce the rejection, particularly for furan no-bake with furfuryl alcohol as resin and sulphonic acid as catalyst. The research problem addressed in the paper is a genuine problem of the foundries and the sole work is based on experimental evidence.

Mechanical and thermal methods for reclamation of waste foundry sand

Binder material (e.g. bentonite, polymeric resins) is used for producing molds and cores in foundries. It deactivates upon exposure to the high temperature (~1400°C) of molten metal. As a result, these binders form either loosely or strongly bound deposits on the surface of sand grains, leaving them unsuitable for further use. Disposal of Waste Foundry Sand (WFS) remains to be one of the significant challenges faced by foundry industry nowadays. In order to remove these deposits from WFS, we have studied and compared two types of methods namely, mechanical and thermal reclamation. The WFS samples after being reclaimed either mechanically or thermally or by combination of both, are compared using various tests. These tests include determination of loosely bound and strongly bound clay content, compressive strength, Grain Fineness Number (GFN), Loss on Ignition (LOI), Acid Demand Value (ADV), Particle size distribution and optical microscopy. We have used the aforementioned tests to characterize the quality of foundry sand and the suitability of reclaimed sand for use in mold and core production in foundries. The results showed that neither of these treatments is sufficient to completely remove the deposits from sand grains. However, solely mechanically reclaimed sand is suitable for the mold production after maintaining 8% active clay and 10% loosely bound clay in the reclaimed sand, respectively.

Investigation of the Foundry Properties of the Locally Available Sands for Metal Casting

Utilization of locally available sands for building moulds for sand casting will reduce the production cost and time as compared to procured sands. In the present study, the foundry properties of the locally available sands namely, mined silica river and beach sands have been investigated to check their suitability for metal casting. Different physical and mechanical tests were conducted on the chosen sand samples. Aluminium alloy was cast in all mould types and its cast properties such as volumetric porosity and surface roughness (SR) i.e. Ra value were determined for comparison. The foundry test results showed that the beach sand was the finest possessing highest grain fineness number (GFN) of 64 and the mined silica sand was the roughest, possessing lowest GFN of 44 among all sand samples. The pH value of all the sands was more than 7 which represents their good bonding ability with the binder. The mould’s permeability and strengths was found to decrease and increase with rise of 5–30% clay content in all cases. The mined silica sand mould demonstrated highest permeability in contrast to other sand moulds. The Al-Si alloy castings obtained from the mined sand mould exhibited minimum porosity with acceptable surface roughness.

Characterization of Southwestern Nigeria River Sand for foundry use

The greater number of castings produced globally are made by using sand casting techniques that utilize sand as major moulding material. This paper characterizes Isasa River sand based on its physical and chemical properties with the aid of Tandem pelletron electrostatic accelerator, trinocular microscope, mechanical sieve shaker, and box furnace, for Foundry application. Results obtained revealed that the River sand has moisture content of 4.30%, clay content of 2.22%, grain fineness number (GFN) of 49, Silica (SiO2) content of 93%, and sintering point of 1400oC. The River sand is a 4-screen sand, having angular grains with medium sphericity. Isasa River sand will be suitable for casting of gray iron and non-ferrous metals, with the addition of binding agent in suitable proportion.

Characterization of Waste and Reclaimed Green Sand Used in Foundry Processing

The aim of this study is to discuss the importance of characterization of green, waste green and reclaimed sand. The transformations and changes which take place in the green sand, are due to the casting process. Green sand which loses its properties during the casting process at a high temperature of molten metal results into waste green sand. Various techniques are applied for characterization of foundry sands. They include Universal Testing machine (UTM) for compressive and shear strengths, texture analyzer for impact test, Thermogravimetric Analysis (TGA) for weight loss kinetics, Inductively Coupled Plasma (ICP-AES) for elemental composition, sieves for Grain Fineness Number (GFN), permeability tester for permeability number of the mold, X-Ray Diffraction (XRD) for crystallinity, Scanning Electron Microscopy (SEM) for morphology and Fourier Transform Infrared spectroscopy (FTIR) for organic functional groups. The waste green sand after being reclaimed in two- stage attrition device, through mechanical attrition, has been later compared with the fresh sand. This study confirms that reclaimed sand can be used either directly for molding or it can be mixed with the appropriate amount of fresh sand.

Feasibility of US Foundry Supply Chain Consumables for Three-Dimensional Sand Printing

The purpose of this study was to assess the performance characteristics of commercially available US foundry consumables for use in three-dimensional sand printers. The silica sands selected were 57 grain fineness number (GFN) and 70 GFN. These sands were a high-purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates. The furan resin system was selected since it is the most widely utilized resin system for 3D printed sand in the USA. The furan resin system was from a domestic US foundry supplier. The printed samples were traditional tensile specimen and rectangle samples for the determination of density. The samples were examined for the following properties: tensile strength, loss on ignition, density, scratch hardness, and permeability. The results of this investigation confirmed that the tested domestic resin system and silica sands matched the original equipment manufacturer performance properties.

Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm2) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.

Linear and non-linear statistical modelling of green sand mould system

In the present work, design of experiments (DOE) technique with response surface methodology was used to develop both linear and non-linear models, to establish the input–output relationships in green sand mould system. Grain fineness number (GFN), amount of clay, amount of water and number of strokes (degree of ramming) were considered as the input variables (parameters), which control the outputs (i.e. mould properties). Full factorial DOE was utilised for the linear model, whereas central composite design and Box-Behnken designs were used to develop the non-linear models. Experiments were conducted to measure the green sand mould properties, such as permeability, green compression strength, mould hardness and bulk density. The adequacy of all the developed models was checked through statistical analysis. Twenty random test cases were considered, to validate the models and compare their performances. A model that is statistically adequate and gives minimum percentage of deviation in prediction was adjudged as the best model for a particular response.