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The paper has investigated the effects of ramming on the mould properties of Yola natural sand. The work considered the variation of the number of rams with green compression strength, dry compression strength, green permeability and bulk density. The results showed that as the number of rams increase, the green compression also increases attaining...
Contexts in source publication
Context 1
... Compression Strength (GCS) Figure 1 shows the effect of number of rams on green compression strength of Yola natural sand. The number of rams was increased from 1-6. ...
Context 2
... packing, as well as formation of more electro-chemical bonds due to exposure to fresh surface charges during ramming, also results in increased green strength properties of the sand (Chakraboty andDhindaw 1982, Richards 1982). This explanation quite fits the curve in figure 1 and agrees with the result of the test. The highest green compression strength of 186.17kPa corresponds to 6 rams. ...
Context 3
... Compression Strength (GCS) Figure 1 shows the effect of number of rams on green compression strength of Yola natural sand. The number of rams was increased from 1-6. ...
Context 4
... packing, as well as formation of more electro-chemical bonds due to exposure to fresh surface charges during ramming, also results in increased green strength properties of the sand (Chakraboty andDhindaw 1982, Richards 1982). This explanation quite fits the curve in figure 1 and agrees with the result of the test. The highest green compression strength of 186.17kPa corresponds to 6 rams. ...
Citations
... Several other researchers also agree with this explanation [7][8][9][10][11][12][13][14][15][16][17][18]. ...
The effect of moisture content of Yola natural sand has been studied. The moisture content was varied from 1 to 9%. The effect of the moisture content on the green compression strength, green permeability and bulk density was investigated. Particle size distribution of the natural sand, the grain fineness number, average grain size, grain shape and the clay content of the natural sand were also studied. 5% moisture gave the optimum green compression strength of 118.6KN/m2. The dry compression strength increased with moisture content, an optimum value of 4000KN/m2 was obtained at 9% moisture. The Yola natural sand had a grain fineness number of 88.05AFS, average grain size of 335.78 microns and a clay content of 26%. A sand mixture containing 5% moisture was prepared and used to produce a test casting with aluminium scraps, the test casting was sound.
... A look at the result in 3.1 agrees with the analysis that the sands are not equally effective this is because the different sands gave different strength values, with sand A giving the highest strength values. Several authors [9,10] have also explained that the strength of core mixtures depend not only on the nature of the binder but also on the nature of the sand. This has to do with the particle size distribution, shape and compactability of the sand. ...
... This suggestion is true and agrees with the application of Kruskal-wallis test in this work. Previous works carried out by several authors [5,6,9,10] have pointed out the same fact that different binders used with the same sand for the production of core mixture for core making will not have the same dry compression strength. In a work carried out at NMDC Jos different organic binders were used in producing core mixtures for core making using the same sand. ...
The use of Kruskal-Wallis test as an analytical tool for the key components of a newly developed core mixture was studied. The study showed that Kruskal-Wallis test can be use to analyze a core mixture using data collected on the properties of the core mixture. In this work the data used was the dry compression strength of cores produced using the core mixture. The key components of the core mixture; the binders and the sands were analyzed. The result showed that the dry compression strength values of the core mixture depend on the type of sand and on the nature of the binder used. This analysis agreed with previous works carried out by several other authors using conventional methods for analysis of core mixtures.
In this research, the analysis of ramming factor, wall thickness, and quantity of additives powder have been considered on the permeability of mould which is used to make flange coupling cast. The data has been collected from the mould sand making industry using L27 orthogonal array. It was revealed from the analysis that the maximum permeability has been obtained from the lowest ramming factor, thin wall thickness, and minimum mixing of additives. The mould permeability number increased significantly to the proper allowability of gas from the mould cavity. The surface finish of the outer wall of the casting had been improved with minimum backpressure formation by increasing permeability number. The confirmation tests were conducted to validate the predicted process parameter on responses.
