Green Shear Strength Research Articles

MOLD PROPERTIES OF INDONESIA NATURE SAND AS GREEN SAND


 The mould properties of Juwono sand, were investigated. The samples were subjected to various physical and mechanical test. These include permeability, green compression strength, and chemical composition by XRF/ XRD analysis. Green shear strength, grain shape, water content, and clay content were also carried out on the samples. Juwono sand casting containing 32.76% clay and category in grade 212/75 of fine sub grades were found to posses adequate permeability, good strength and refractoriness suitable for casting of both ferrous and non ferrous alloys.

Study on Partial Replacement of Silica Sand With Alternatives and Its Effect on Sand Mould and Casting Properties

In the current scenario the demand for reduction of silica sand usage in making sand moulds in the metal casting industry is increasing day by day. The non-silica alternatives will help the foundries to not only get in line with new regulations but also protect the foundry workers and minimizing the compliance costs. The non-silica alternatives such as clay, bio-waste, bagasse-ash and nano-SiO2 in different proportions are added to silica sand to prepare moulding sand. The effect of these alternatives on mould sand properties such as permeability, green shear strength and green compression strength are studied. The aluminium alloy 6061 castings were fabricated in the sand mould prepared using these non- silica alternatives. Effect of these materials on the grain size, surface roughness and mechanical properties of aluminium alloy 6061 castings were studied. Out of all, the silica sand/15%bagasse-ash combination was found more suitable for producing aluminium alloy 6061 castings with high yield strength, ultimate tensile strength and low surface roughness values. The ranking of combinations based low surface roughness and high strength values of aluminium alloy 6061 castings is, bagasse-ash > bio-waste > nano-SiO2 > clay.

Experimental Investigation of the Influence of Sand and Binder Composition on the Mold Properties of Alkyd Type No-Bake Chemically Bonded Sand-Casting System

In comparison to green sand moulds, chemically bonded resin sand moulds have better dimensional accuracy, surface quality, and sand mould qualities. To survive sand drops when pouring molten metal, the mould cavity formed using a chemically bonded sand mould technique must have appropriate permeability, strength, and hardness. The desire for better permeability, strength, and mould hardness is based on a thorough investigation and analysis of the affecting parameters, such as resin percentage, hardener, and catalyst. The influence of binder content on the moulding qualities of silica sand bound with Alkyd oil urethane binder was investigated. Using a sieve shaker, the experimental materials were sieved and manually blended with the binders. AFS standard test specimens (50 mm diameter by 50 mm height) were prepared using a sand rammer, and four key moulding parameters were determined using a universal sand strength machine, permeability meter, and mould hardness tester: green compression strength (GCS), green shear strength (GSS), permeability, and mould hardness. For the minimal experiments, Box-Behnken experimental matrices were used, and the statistical significance of influencing factors and their interactions will be identified to manage the process. To statistically validate the model, an analysis of variance (ANOVA) test was performed using Minitab. Mold hardness, strength, and permeability will each have their own mathematical equation, which was stated as a nonlinear function of input factors based on experimental input-output data. To optimize the process parameters, a response optimizer (using Minitab) has been used. The results revealed that increasing the resin concentration from 1% to 2% enhances permeability and GSS while decreasing GCS and mould hardness. Hardener was increased from 18 to 20%, which resulted in a drop in permeability and GSS but an increase in GCS and mould hardness. Similarly, increasing the catalyst concentration from 2% to 10% reduces permeability and mould hardness while increasing GCS and GSS.

Green strength properties of waterjet abrasive waste as potential composition in green mould by Taguchi and ANOVA approach

The sand casting process still continues today due to the cost-effectiveness of materials and processes. There is a wide variety of castings related to composition and size, but silica sand is widely available from coastal line mining and has a negative impact on the environment. Moreover, waste from waterjet cutting of non-ferrous and ferrous metals is practically unhazardous and may potentially be used in sand casting mould. The aim of this paper is to optimize the proportion of coal dust, water and bentonite added to the silica sand mixture and the waterjet cutting abrasive waste as a new way of handling waste with the potential to be used in sand casting manufacturing. The method used was L9 orthogonal array optimization and the composition was qualitatively measured using a green compression strength test and a green shear strength test. Factors were evaluated using the analysis of variance (ANOVA) to find the the critical factors while confirmation test was conducted for the optimal material proportion. The study concluded that the ideal ratio for silica sand mixture with waterjet abrasive waste is bentonite-12%, coal dust-5%, and water-7% for green compression strength while bentonite-12%, coal dust-6%, water-7% for green shear strength. With proper selection, the incorporation of waterjet abrasive waste into the green sand mixture is promising to potentially be used in green sand mould casting without undermine the quality of mould.

Factorial optimization and predictive modelling of properties of Ukpor clay bonded synthetic moulding sand prepared using River Niger silica sand

Moulding sand-related process parameters and properties were analyzed and optimized using design-expert software. The moulding sand mix was prepared using seven different particle sizes of the silica sand and weight percentages of clay and moisture contents, respectively. Three moulding sand parameters (Grain Size, % Clay, and Moisture contents) were designated as the inputs factors while moulding sand properties, viz, green compression strength (GCS), dry compression strength (DCS), green shear strength (GSS), dry shear strength (DSS), mouldability and green permeability were set as the outputs/response variables in the experimental design matrix. The models developed were successfully used to predict an optimal level of the constituents of the synthetic moulding sand and the moulding properties at 385.704 μm, average grain size, 75.985% silica sand, 19.610% clay, and 4.405% moisture contents. The results obtained showed the potential of both dry and green sandcasting for some cast iron and non-ferrous alloys components.

Evaluation of Mechanical Properties, Economic and Environmental Benefits of Partially Replacing Silica Sand with Biomass Ash for Aluminium Casting

Green sand molding for metal casting makes up around 70% of the total castings produced worldwide. Silica sand mining and its transportation to foundries harm the ecosystem, rendering this metal casting process environmentally unsustainable. This research paper introduces a novel method of partially replacing the silica sand with biomass ash - a waste product of combustion in various processes such as domestic and commercial cooking. Suitable experiments were conducted to measure the effects of mixing progressively higher proportions of biomass ash (from 9% to 30%) in conventional green sand mold. The molds then underwent tests for the evaluation of technological properties such as green compression strength, green shear strength, permeability and compaction. After suitable pattern making, the molds were tested for casting using LM 24 Aluminium Alloy. The obtained Aluminium Alloy castsings underwent micro hardness tests and micro structure study. The results obtained for biomass ash molding sand were compared with the corresponding tests results for conventional sand mold casting and the results were satisfactory.

Application of Molasses as a Binder in Sand Mold Operation

The application of molasses as a binder in sand mold operation was investigated. Standard Sand Mold mixture (5 cm diameter x 5 cm height) were made with 1-5% molasses and Chalawa sand the balance. The molding Properties such as ; Green Compressive Strength(GCS), Green Shear Strength(GSS), Dry Compressive Strength(DCS), Dry Shear Strength(DSS), Green Shatter Index, Green Permeability, Flowability, and Compactibility of sand molasses mixture were obtained. 2% Molasses-sand mixture was selected for molding the prototype cast based on the highest values of the Green Compressive Strength, Green Permeability, and excellent Flowability (96.4%) observed in the experiments. The result shows that molasses alone could not be used as a binder. This is further supported by the low values of Green Shatter Index (31.3%) and Compactibility (25%) reported.

Effects of Additives on Some Selected Properties of Base Sand

In this study, effects of sawdust, coal dust and iron filling additives at varied proportions on some selected properties of moulding sand were investigated. Consequently, cylindrical specimens with different percentages of additives were prepared based on standard procedures. The prepared specimens were subjected to basic moulding sand testing including moisture content, bulk density, porosity, permeability, green compression strength and green shear strength using standard methods and equipment. From the obtained test results, all the experimental additives were found to improve the selected moulding properties of the base (silica) sand. Moulding sand specimen with sawdust additive revealed a relatively better compaction as compared to moulding sand specimens with coal dust and iron filling additives respectively. The moisture absorbing strength of the moulds was also found to increase with increasing percentage of sawdust. Addition of coal dust to the moulding sand was found to improve sand porosity and permeability which results in less casting defects, and due to improved moisture absorbing strength of sawdust, moulding sand specimens that contained sawdust were equally found to exhibit good compaction with maximum green compressive strength of 108.99 kPa. Also, the combination of 25% sawdust, coal dust and iron filling in the moulding sand was found to produce mould with optimum green shear strength value of 54.49 kPa.

Suitability of Molasses as a Core Binder Used in Non-Ferrous Sand Casting

The suitability of blackstrap molasses as a core binder used in non-ferrous sand casting has been investigated. Various core mixture samples were made with molasses varying from 1-5%, soybean oil 1-3%, and Chalawa Sand the balance. The foundry physical properties of the samples; Permeability, Green Compressive Strength, Dry Compressive Strength, Green Shear Strength, Dry Shear Strengths were determined via standard procedure. The sample of 2% molasses, 1% soybean oil, and the balance Chalawa Sand was chosen as the best core mixture based on the highest and optimum Baked Compressive Strength, Baked Shear Strength, and Permeability. Using the optimum mixture, a proto-type aluminium-silicon casting was made. The result revealed that the core has good collapsibility, and the surface finish of the internal cavity of the cast bushing is good.The research work has provided economically cheaper and environmentally friendly organic core binder from locally available raw material for industries as against poisonous and expensive resinous core binders.

Estimation and optimization of shear strength for compacted iron powders by means of soft computing paradigms

The artificial neural network methodology presented in this paper was trained to predict the green shear strength of compacted samples made from iron powder. Iron powders of three different morphologies admixed with three types of lubricants in different amounts were considered. Green compacts were pressed uniaxially in a square floating die. The more or less cubic slugs were sheared to fracture perpendicularly and parallel to the direction of compaction. From the maximum loads at the start of decohesion the green shear strengths were calculated. Compaction parameters together with corresponding shear strength records were used as sets of data for the training process. The performance of the network was verified by putting aside one set of data and testing the network against it. Comparison of the predicted and experimental data confirmed the accuracy of the model.

Effect of Varying Corn Cob and Rice Husk Ashes on Properties of Moulding Sand

The use of rice husk and corn cob ashes as aggregates for foundry moulding sand has been studied. 5-12.5 weight percent of rice husk and corn cob ashes were added to the sand mixture and the sand properties determined. A mixture of equal proportion of rice husk and corn cob ashes was also used. In each case, four weight percent water and clay were added to the sand mixture. Some of the properties of the sand tested are: permeability, green compression strength, dry compression strength, green shear strength, dry shear strength, moisture content and permeability. The results showed that the green compression strength, green shear strength, moisture content and permeability decrease with increase in the additives (rice husk ash, corn cob ash, and (50% rice husk and 50% corn cob ashes). While dry compression strength and dry shear strength increase with increase in weight percent of the additives.

Moulding properties of a Nigerian silica–clay mixture for foundry use

The moulding properties of Igbokoda silica sand, bonded with Ijero–Ekiti clay, were investigated. American Foundrymen Society (AFS) standard cylindrical samples dimensioning Ø50 mm × 50 mm in height were prepared from various sand–clay ratios with 5% tempering water, by applying three ramming blows of 6.666 g each from a height of 50 mm as required for foundry sands. The samples were subjected to various physical and mechanical tests. These include permeability, green compression strength, and dry compression strength tests. Green shear strength, dry shear strength, field mould strength, shattered index and refractoriness tests were also carried out on the samples. Samples containing 23–32% clay were found to possess adequate permeability, good strength and refractoriness suitable for casting of both ferrous and non-ferrous alloys.

Prevention of defects in castings using back propagation neural networks

Defects in castings often lead to rejection, which would ultimately result in loss of productivity for a foundry. Expert systems developed by some researchers mostly act as postmortem tools, discussing and analyzing a defect after it has occurred. Though some investigators have attempted to predict a few important defects, a tool that could predict all the possible defects just before the castings are made has not yet been developed. Hence in the present work, an attempt has been made to predict major casting defects like cracks, misruns, scabs, blowholes and air-locks using back-propagation neural networks from the data collected from a steel foundry. The neural network was trained with parameters like green compression strength (GCS), green shear strength (GSS), permeability, moisture percent, composition of the charge and melting conditions as inputs and the presence/absence of defects as outputs. After the training was over, the set of inputs of the casting that is going to be made was fed to the network and the network could predict whether the casting would be sound or defective. If defective, the nature of the defect was also specified by the neural network. The neural network could predict cracks, misruns and air-locks accurately in most of the cases. The neural network could also predict other defects successfully. Investigating the causes followed by altering the moulding parameters and appropriate treatment of the molten metal can prevent the defects that were predicted by the backpropagation neural network.

Controlling green sand mould properties using artificial neural networks and genetic algorithms — A comparison

Optimum formulation of the green sand mixture has remained as a critical problem for the foundryman, for several years. In the present work, experiments were conducted with varying grain fineness number, clay percentage, moisture percentage, mulled time and hardness with an objective to formulate the green sand mixture optimally. The corresponding mould properties namely green compression strength, green shear strength, permeability, dry compression strength and dry shear strength have been measured. In the first investigation, the above data were fed to a back propagation artificial neural network. The inputs to the neural network were mould properties and the outputs were grain fineness number, clay percentage, moisture percentage, mulled time and hardness. (In this paper, outputs of neural networks and genetic algorithms will be termed as ‘mould controlling parameters’ or simply ‘controlling parameters’). After training, the network was asked to predict the set of controlling parameters, which could yield a particular set of desired mould properties. (This particular set of desired mould properties was one of the sets of mould properties obtained from experiments and the same was excluded in the training of neural network). The set of controlling parameters predicted by the neural network was compared with the set of experimental controlling parameters by calculating percentage error. In the second investigation, the same inputs and outputs (used to train the neural network) were fed to a micro genetic algorithm. The objective function was designed such that it predicts the set of controlling parameters, which would realize the same set of desired mould properties. The set of controlling parameters predicted by the genetic algorithm was compared with the set of experimental controlling parameters by calculating percentage error. The comparison revealed that the percentage errors obtained by genetic algorithm were small in most of the cases. It was also found that genetic algorithms could offer few advantages over artificial neural networks in the present task.

Mould-metal movement in a horizontal sand mould

Six types of green sand were prepared with different mulling times and different compositions; with additions of bentonite (C sand), bentonite and seacoal (S + C sand), bentonite, seacoal and reused dust (S + C + D sand). Six batches of green sand and CO2 core sand were used to make standard sand specimens (50 mm in diameter and 50 mm in length). The whole sand mould was made of CO2 core sand and the prepared standard sand specimen was set at the smaller end of the bar cavity. The movement of the metal/sand specimen interface was measured, after molten gray iron was poured into the mould cavity, to produce a horizontal bar casting.For short-mulled green sand containing combustible seacoal, the measured deformation curve indicated that an apparent expansion of the mould-metal interface occurred for a period of time after the sand specimen came into contact with the molten iron. This expansion was in relation to the percentage of moisture absorbed in green sand and the ratio of green compressive strength and green shear strength. The mechanism for the expansion of the mould-metal interface was schematically explained and discussed. The contraction of the mould-metal interface as measured at 300 seconds after filling, was inversely proportional to the tested AFS clay and green shear strength of the sand specimen.

Calcium Silicate Products with Crushed Building and Demolition Waste

The suitability of crushed building and demolition waste as a raw material for the production of calcium silicate products has been determined. Therefore calcium silicate bricks have been produced by replacing the natural sand with crushed building and demolition waste of different sources. The mechanical properties of the bricks made with these wastes are comparable or, in some cases, even better than those of bricks with natural sand. The green shear strength of the bricks is higher. The amount of quartz and reactive SiO2 in the waste materials is high enough for the formation of tobermorite as a cementitious material between the grains. A negative aspect is the appearance of brown stains on the surface of the bricks when the waste materials are slightly contaminated with organic substances. This risk can be reduced when, besides the crushing of the waste, a washing process is also included.