Basic sand tests can measure tensile strength, friability, moisture content, permeability, green compression strength, compact ability, loss on ignition, volatiles content, grain size and distribution and many more. Permeability Test: Permeability is a condition of porosity and thus is related to the passage … 16th Edition, Khana Publishers, Nai Sarak, 153-158. Proceedings of the 41st International Foundry Congress, Liege, 8. Given the importance of this parameter the green compression strength of a moulding mixture can be estimated using the model and the information can be used in predicting the mouldability of the moulding mixture. 8th Reprint, Dhanpat Rai Publications, New Delhi, 51-8-10. Composition of green sand molding mixture for iron foundries typically consists of 100 parts silica sand, 8 parts bentonite clay and other additions like carbon ( 0,3 parts ) or … The green compression strength of a molding sand is measured by making a standard . Empirical values and mathematical model values. Green Compression Green compression has been the most widely used control tool to measure the rate of clay addition to a sand molding system. This means that 94% of changes in green compression strength are caused by clay content. type of additives have a significant effect on green compression. Low green compression strength in green moulds may result in defective and unsound casting [6] . Equation (9) which is a model for predicting the green compression strength of green sand mould based on the influence of clay content only can be used assuming the only influence on green compression is coming from clay content. `The … 2.2.2. This sand has more rigidity, thermal stability, and strength. 72% of the changes in green compression strength values in green sand mould are brought about by the combined influence of clay content % and moisture content %. For a sand mixture to be mouldable it must have a green compression strength value of 1.5 psi (10.34 kPa… Home | About SCIRP | Sitemap | Contact Us. One reason is because it determines the mouldability of a sand mixture. Journal of Minerals and Materials Characterization and Engineering, 11, 1050-1054. One reason is because it determines the mouldability of a sand mixture. Properties of moulding sand. Porosity or Permeability: It is the ability of sand by which it allows the gases to pass through … They also agreed that statistical approaches will bring out clearly the nature of relationships that exists between green compression strength the dependent variable, clay content and moisture content the independent variables [8] -[12] . 4. Equations (9), (11) and (15) are the developed regression models for simple and multiple linear regression relationships existing between green compression strength and the two variables of clay content and moisture content in the green mould. On the strength of this Table 3 was produced. (2012) Foundry Raw Materials for Sand Casting and Testing Procedures. Green compression strength increases with moisture until a point is reached where further increase in moisture leads to decrease in compression strength. Journal of the Institute of the British Foundrymen, 114-118. One reason is because it determines the mouldability of a sand mixture. coefficient of determination for Ys: X1. Sample 3 was recorded to have an average green strength … How to check Compressive Strength The machine consists of an oil reservoir, movable ram, plug-in coupling low & high-pressure gauges to read 0 to 1.600gms/cm and 0 to 13 kg/cm compression strength respectively, loading piston connecting to threaded shaft and wheel, funnel with a special connection, a bottle of oil. Calculation of separate regressions with green compression strength as Ys. http://creativecommons.org/licenses/by/4.0/, Received 10 July 2014; revised 30 August 2014; accepted 14 September 2014. The results also show that in order to achieve maximum green … Empirically generated data in National Metallurgical Development Centre, Jos Sand Testing Laboratory were used for the study. Green compression strength indicates the maximum compression stress the sand mixture is capable of sustaining and is used to control the rate of clay addition to the green sand system. 2.2.5. Dry sand is made by baking or drying the mold made from the green sand in a decent oven. Green compression strength increases with increase in clay content of the green sand mould. Procedure - The green compressive strength of green sand is the maximum compressive stress that a mixture is capable of sustaining when prepared, rammed and broken under standard conditions. Brown, J.R. (1994) Foseco Foundryman’s Handbook. Loss on ignition should decrease. Metals can be cast with 1% water addition to the moulding sand mixture, mould endobj Green sand moulding – Steps , Advantages and Disadvantages GREEN SAND MOULDING. From what it can be seen, the strength of the green sand managed to get is 114.6023kN/m2 or 16.3 Ib/in2. Table 2 gives the calculation of separate regressions with green compression strength as Ys, clay content as X1 and moisture content as X2. Specimen Preparation, Rammer Method and AFS 2251-00-S: Riddling, Molding Sand. Dry compressive strength of a moulding-sand mixture increases as moisture is added, until the sand … Literatures that have being reviewed for this work have also shown that moisture content increase do lead to increase in green compression strength until an optimum point is reached where further increase leads to a decrease in green compression strength [6] [13] [14] . The main variables in the work were clay (binder) which was varied from 1.5% to 7% and moisture (water) which was varied from 2% to 8%. Leonardo Electronic Journal of Practices and Technologies, 19, 85-96. Green compression strength indicates the maximum compression stress the sand mixture is capable of sustaining and is used to control the rate of clay addition to the green sand system. Friability should decrease up to 30% new sand additions. This work is licensed under the Creative Commons Attribution International License (CC BY). 2) The coefficients of correlation, coefficients of determination and coefficient of multiple determinations are great tools for studying the relationship between the variables (independent and dependent variables). �uE�Q �бב�T�7�x¿����h�V�|+˛�[��VZgE�$�C.�i[�Z!����wy-V��������p{���3��|�蠏V�zV�����S����������#o݉��p�k�:��Ej�׫{׳�Xy�%�oV�����.�:��h ~�(�X�X�Ɔ��Ow_�F�����e��ݭ،�>���+N8�����m�qc;�_;v�x�y����(!ӫȪ�C�����R��kg�Ct~|� ��`�k�[2��x��l�glj�c;��k�G4����oW#%6l`,�h�I��.1��/����M�C[g)@'b���Sd5�Ul`����r���h�W����¹��9��SK�6�F6Bʷ�w�8�������cU"���yxi@�W�8�?~n�?�s���C��=�ش9. Copyright © 2014 by authors and Scientific Research Publishing Inc. Jain has made this observation in his work [1] . Which can be solved using the normal equations thus: From this can be developed models with more than two variables and this is illustrated below using a 3 variable model (one dependent and two independent variables, Y, X1, and X2). The various coefficients are interpreted as follows: : this indicates that about 88% of the variation in green compression is caused by variation in clay content this is a major influence and the influence is positive which means that an increase in clay content % will bring about an increase in green compression strength. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 9 0 R 10 0 R] /MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Properties of moulding sand. (2011) Effect of Moisture Content on the Foundry Properties of Yola Natural Sand. Eckey, D.C. and Goldress, J.E. The convex parts of the two press piece (AA) and (M) are inserted in the concavity (P) so that the two ratchets of the both press pieces … It was observed that the … and Ogbodo, J. Lucey, T. (2000) Quantitative Techniques. i.e. (2012) Impact of Swelling Indices of Sokoto Clays on the Moulding Properties of the Clays in Sand Mixtures. Wet tensile properties should increase. Their interactive influence on green compression strength has also been studied through the use of multiple coefficient of determination R2. Table 1 shows the data that was used for this study. Wet and Dry Compression Strength for Green Sand. This mathematical model is derived with the combined influence of clay content and moisture content all taken into account and therefore can be used to predict the green compression strength of the green sand mould. Prior to performing this test, you must complete the following sand tests: AFS 5222-13-S: 2 in. 2.2.1. Coefficient of correlation, coefficients of determination and coefficient of multiple determinations were used to explain the relationship … 10.4236/msa.2014.512089, The Study of Green Compression Strength of a Green Sand Mould Using Statistical Approach, Department of Mechanical Engineering, University of Uyo, Uyo, Nigeria, Email: draondonaphilip@gmail.com, irdimanagement@yahoo.com. The importance of moisture is also observed practically while preparing moulds. He said that as moisture is increased, green compression strength also increases until a point is reached where further increase leads to decrease in green compression. The study has clearly shown that statistical approach is a good tool for studying green compression strength of green sand moulds. Coefficient of correlation, coefficients of determination and coefficient of multiple determinations were used to explain the relationship existing between the two independent variables of clay and moisture content and green compression strength, the dependent variable. Equation (15) is developed based on the influence of both clay content and moisture content variation on green compression strength of green sand moulds as indicated by the coefficient of multiple determination R2. 4 0 obj 3) The study has shown the positive strong relationship that exists between green compression strength of the dependent variable and the two independent variables of clay content and moisture content. <>>> He noted that as moisture increases coarse grained sand moulds have higher green compression strength than fine-grained sand moulds. Green compression strength Green compression strength is the ability of sand mould to withstand pressure of molten metal. The aim of adding to the simple two variable models is to improve the fit of the data. Other variables like mixing time, number of rams, sand (grain size and shape) were all kept constant. R2: this shows the combined influence of the two variables of clay content and moisture content %. The model will not be correct if there are other variables involved in determining green compression strength. Coefficient of Multiple Determination, R2, The various coefficients of determination can now be summarized. 1．Compression strength test of green sand mold. Green sand is also known … ABSTRACT Sand casting process involves many parameters such as size of the sand grain, amount of clay, percentage of moisture, green compressive strength, permeability, number of … The degree of mulling, sand to metal ratio, clay content, compactability range and additive type affect green compression strength. (2008) A Text Book of Material Science and Metallurgy. Which can be solved by the normal equations for a three variable model, as follows: The line of best fit gives way to a plane of best fit, b1 is the slope of the plane along the X1 axis, b2 is the slope along the X2 axis and the plane cuts the Y axis at “a”. Green compression strength data with variation in clay and moisture content. From 10 to 15% of the whole amount of molding sand is the facing sand. For a sand mixture to be mouldable it must have a green compression strength value of 1.5 psi (10.34kPa… Statistical approach have indeed proven to be a good method for the study of green compression strength as can be seen above it had provided a step by step analysis of the relationship between green compression strength and the two variables of clay content and moisture content. Numbers on green compression strength can vary all over the map depending on the type of molding In this module, the AFS 5202-09-S: Compression Strength, Green or Dried sand test will be performed. Jain [1] tried to assess the combined effect of grain size variation and moisture content on green compression strength of green sand mould. As a casting is poured, sand adjacent to the hot metal quickly loses its water as steam. Statistical approach of the study of this important property will give in-depth information on how to produce good moulds. Diameter x 2 in. Ihom, A.P., Agunsoye, J, Anbua, E.E. Procedure - The green compressive strength of green sand is the maximum compressive stress that a mixture is capable of sustaining when prepared, rammed and broken under standard conditions. This is because there will be erosion, collapse, and damage of the mould wall and this will result in defects like rat tails, sand inclusions, incomplete molten metal flow, rough surfaces etc. This explains how important this property is in mould production and is always monitored in sand casting [4] -[7] . (1967) Principles of Metal Casting. Green compression strength is very important in the preparation of moulds. Dry compression strength should increase up to 30% new sand … Green compression strength is very important in t he preparation of moulds. It is the property of that allows mould sand to flow to all portions of … This explains why clay that does not have sufficient binding ability in small quantity in moulding mixtures becomes mouldable when the quantity of clay is increased. The individual influence on green compression strength is therefore significant. (1989) The Design of Experiments in the Sand Casting Foundry. Hello, friends in this video I will show you how to measure the compression strength of sand specimen in sand testing. Flowability: This is similar to plasticity. Moulds, Statistical Approach, Study, Sands, Green Compression. and Rosenthal, P.C. 2” x 2” specimen and placing it in a Universal Sand Strength machine, then compressing it to its rupturing point. A minimum 1600gm/cm2green compression strength is … The researcher took time to explain how each of these affects green compression strength. (1979) Utilization of Regression Equations in Optimization of Properties of Clay Bonded Sands. … endobj The sand strength can be of two types (i) Green strength: The strength of sand possessed by it in its green or moist state is called green strength. Multiple Regression Model Development, The basic two variable models (one dependent and one independent variable) is. Table 2. Similar strengths were measured for all samples, with the exception of sample 3. `A mold with adequate green strength will be able to retain its shape and will not distort or collapse. Jain, R.K. (2009) Production Technology. The strength of the sand in green or moist state is termed as green strength. Universal strength testing machines, manual green compression strength tester, sand rammer, mixer, measuring cylinders were used during the work as equipment. Green compression strength decreases with coarse grains but increases with increase in fineness of sand grains. Permeability and green compression strength are among the important mechanical properties and considered much in the sand casting mould preparation. Basic sand tests can measure tensile strength, friability, moisture content, permeability, green compression strength, compact ability, loss on ignition, volatiles content, grain size and distribution and many more. The individual correlation between clay content and green compression strength is given by the coefficient of correlation and the value is 0.94 and is a positive relationship. 2.5 Green sand. Both green compression strength and permeability are important to enhance the … A minimum 1600gm/cm2 green compression strength is to be maintained. This clearly confirms the crucial nature of statistical approach in the study of green sand moulds. coefficient of determination for Ys: X2. The correlation is 0.95 which means that 95% of the increase in green compression strength will be caused by increase in moisture content of the moulding mixture if the moisture content is the only variable. and Nyior, G.B. and Bam, A. Specimen preparation with Sand Rammer (VR)2. The compression reading should be read at comparable compactibility ranges. This particular data was generated from green compression strength tests on green moulds using Bacita foundry sand, clay binder and moisture (H2O). Transactions of the American Foundryman Society, 62, 605. Dry sand is made by baking or drying the mold made from the green sand in a decent oven. Literatures reviewed for this work also support the above strong correlation between clay content and green compression strength [13] [14] . A mixture bonded with 8% clay possesses higher green compression strength compared to samples bonded with 4% clay. Modern Casting, 39, 85. Wet and Dry Compression Strength for Green Sand. Copyright © 2006-2013 Scientific Research Publishing Inc. All rights reserved. No wonder it had been supported by many researchers as a useful research tool [8] -[14] . The casting of the dry sand is heavy and large. We also acknowledge your effort for the enormous amount of data bank that now exists in that Laboratory on Nigerian foundry sands. Moisture content has a very strong positive correlation with green compression strength of green sand moulds. 1 0 obj A. Khanna, O.P. The closeness of fit is measured by the coefficient of multiple determination R2 for which the general formula and a useful computational formula is given below. The dry sand must have strength … 2 0 obj endobj The layer of facing sand in a mold usually ranges between 20-30 mm. 2.2.4. The established relationship from the coefficient of multiple determination agrees with what is obtained practically and empirically generated results both clay content and moisture content increase green compression strength of moulding mixture making it mouldable [6] [13] [14] . Ihom, A.P., Suleiman, U.M. Jain in his work also noted that as moisture is increased angular shaped grain sand moulds lose their green compression strength more than round grained sand moulds. Numbers on green compression strength can vary all over the map depending on the type of molding These molding sand properties … The mould with adequate green strength retains its shape and do not collapse even when the pattern is removed from the moulding … In this module, the AFS 5202-09-S: Compression Strength, Green or Dried sand test will be performed. stream Jain [1] in his work said that “the green compression strength of a green sand mould depends on grain size, shape and distribution of sand grains, type and amount of clay or other binder and moisture content”. (2006) Application of Multiple Regression-Model to the Study of Foundry Clay-Bonded Sand Mixtures. x��Zko�F�n��a��Z�ߤ�E��I���hT,�~�D���|Xi���̐�D��-�Z�p�>�=��eū_�7߼z|x�F8�~+^�y�7�7�޹��f{� Materials Sciences and Applications As stated earlier green compression strength of 10.34 kPa and above is required for mouldability of green sand moulds [4] -[6] [14] . (1985) Application of the Statistical Design of Experiments in the Study of Clay-bonded Sand Mixtures, the British Foundryman. The casting of the dry sand … 10th Edition, Pergamon Press PLC, Oxford, 10-68. (2009) The Use of Statistical Approach for Modeling and Studying the Effect of Ramming on the Mould Parameters of Yola Natural Sand. Table 3. Empirically generated data in National Metallurgical Development Centre, Jos Sand Testing Laboratory were used for the study. Modified Green Sand (MGS)was made by mixing with different percentages of additives such as molasses and fly ash to green sand. Table 1. Heine, R.W., Loper Jr., C.R. Dry strength. Green Strength: It depends on: (a) Grain size, (b) Shape and distribution of sand grains, (c) Type and amount of clay or other binder, and (d) Moisture content. 3 0 obj The results in Table 3 have shown that the developed model can be a quick method or tool for the prediction of green compression strength on the shop floor. The Green Compression Strength (GCS) of the moulding sand mixture decreased from 11.11psi (76.59KN/m2) to 4.2 psi (28.98KN/m2) of 1% and 10% water addition respectively. Green compression has been the most widely used control tool to measure the rate of clay addition to a sand molding system. Table below shows empirical values with calculated values using the mathematical model. For a sand mixture to be mouldable it must have a green compression strength value of 1.5 psi (10.34 kPa) and above [5] . The combined effect of clay content and moisture content as well as the influence on green compression strength has been given by the coefficient of multiple determination and interpreted above. The influence is a major influence and it is positive. Table 3 gives the empirical values of green compression strength against mathematical model values and predicted values of green compression strength. How to check Compressive Strength The machine consists of an oil reservoir, movable ram, plug-in coupling low & high-pressure gauges to read 0 to 1.600gms/cm and 0 to 13 kg/cm compression strength … For Regression Ys on X1 (Clay Content %), The regression equation for the relationship of clay content and green compression strength value of the green mould is, The coefficient of correlation for this relationship is, Substituting the values in Table 2 in Equation (10) we have. 2” x 2” specimen and placing it in a Universal Sand Strength machine, then compressing it to its rupturing point. strength more than round grained sand moulds. Each test obtained very specific characteristics of the sand. Zrimsek, A.H. and Vingas, G.J. Specimen Preparation, Rammer Method and AFS 2251-00-S: Riddling, Molding Sand. The sand specimen is taken out of the specimen tube and is immediately (any delay causes the drying of the sample which increases the strength) put on the strength testing … The study of green compression strength of a green sand mould using statistical approach has been successfully carried out and the following conclusions are from the study: 1) Statistical approach has been found to be a good method of studying green compression strength of green sand mould. The Multiple Regression (Ys: X1 and X2), The multiple regression calculations are carried out using the three variable normal Equations (4)-(7) with substitution with values from Table 2 new set of equations are derived as follows, Solving these three equations simultaneously gave, Now substituting the model equation for three variables in Equation (4), this new model equation is obtained. Diameter x 2 in. The authors hereby extend their sincere appreciation to the staff of the Sand Testing Laboratory of NMDC Jos who assisted with the generation of this data. Ihom, A.P. This sand has more rigidity, thermal stability, and strength. Dry sand is the type of green sand, from which moisture is being removed. <> Ihom, A.P., Yaro, S.A. and Aigbodion, V.S. The table showed that green compression strength has been predicted for 8% clay content and 9% moisture content, and 9% clay content and 10% moisture content and the result of the prediction is within a reasonable range as can be seen in the table. For Regression of Ys on X2 (% Moisture Content), The regression equation for the relationship of moisture content with green compression strength value of the green mould is. %PDF-1.5 2nd Edition, Tata Mcgraw-Hill Publishing Company Ltd, New Delhi, 100-150. Moulds with moisture content below optimum do tend to be lacking in green compression strength. The findings of Jain agree with several authors who also confirm the above explanation [2] -[4] . This will save the time used in setting up instrument for tests to determine green compression strength. This mathematical model is derived with the combined influence of clay content and moisture content all taken into account and therefore can be used to predict the green compression strength of the green sand mould. This shows that Tudun-Wada clay has good bonding characteristic at 1% water addition. Vol.05 No.12(2014), Article ID:50679,6 pages The dry sand contains a mixture of 15% to 20% of clay and silica. Each test obtained very specific characteristics of the sand. A look at Table 3 shows that the difference between the empirical values of green compression strength and the calculated green compression strength values is not so much. %���� Dry sand is the type of green sand, from which moisture is being removed. Green compression strength should decrease slightly.
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