Lab Foundry

ContentsTITLE:.................................................................................................................................2OBJECTIVE:.......................................................................................................................2INTRODUCTION:..............................................................................................................2APPARATUS:.....................................................................................................................4Procedure.............................................................................................................................5Result...................................................................................................................................7Discussion............................................................................................................................9RECOMMENDATION.....................................................................................................11CONCLUSION..................................................................................................................11REFERENCE....................................................................................................................11GROUP DISTRIBUTION.................................................................................................12

1

TITLE:Sand Testing Preparation – GFN

OBJECTIVE:This experiment measures the sand grain size and calculates the Grain Fineness

Number (GFN).

INTRODUCTION:

A system has been developed to rapidly express the average grain size of a given andsample. The Grain Fineness Number (GFN) is the quantitative indication of the grain size distribution of the sand sample by carrying out a sand sieve analysis. GFN is important because it provides the foundry a way to verify that its sand is within specification for the castings being produced and helps avoid conditions that could lead to potential casting problems. Sand that is too fine (higher GFN) or too coarse (lower GFN) can affect the quality of castings produced. Sand that is too fine can create low permeability and result in casting gas defects. Sand with high permeability (too coarse) can create problems with metal penetration, rough surface finish, burn-in and burn-on. The grain fineness of sand is measured using a test called Sieve Analysis.

A sieve analysis is a practice or procedure used to assess the particle size distribution of a granular material. Sand sieve analysis is a method for determining the grain size distribution of particles typically between 1.0mm and 0.062mm. It is a relative accurate method for determining depositional hydrology and for refining sedimentary environments. With experience, most geologists can visually measure grain size withinaccuracy of the Wentworth grade scale at least down to silt grade. Silt and clay can bedifferentiated by whether they are crunchy or plastic between one’s teeth. Clay stones and siltstones are not amenable to size analysis from an optical microscope. Their particle size can be measured individually by electron microscope analysis. Boulder, cobbles, and gravel are best measured manually with a tape measure or ruler. Sands are most generally measured by sieving.

Both graphic and statistical methods of data presentation have been developed for the interpretation of sieve data. The percentage of the samples in each class can be shown graphically in bar charts or histogram. Another method of graphic display is thecumulative curve or cumulative arithmetic curve. Cumulative curves are extremely usefulbecause many sample curves can be plotted on the same graph and differences in sorting are at once apparent. The closer a curve approaches the vertical the better sorted it is, as a major percentage of sediment occurs in one class. Significant percentages of coarse and fine end-members show up as horizontal limbs at the ends of the curve.

2

Figure 3.1: Example of Graphical Interpretation of Sieve Data

The four statistical measurements for sieved samples consist of a measure of centraltendency (including median, mode, and mean); a measure of the degree of scatter orsorting; kurtosis, the degree of peakedness; and skewness, the lop-sidedness of the curve. Various formulae have been defined for these parameters.

Figure 3.2: Skewness Analysis

Within geology accurate sieve analyses are required for petrophysical studies which relate sand texture to porosity and permeability. The distribution of sediment for water wells also requires a detailed knowledge of the sediment of aquifers. Sieve analysis data can be used as an interpretive tool to determine the depositional environment of ancient sediments. The philosophy behind this approach is that modern environments mold the distribution of sediment and these differences can be quantitatively distinguished. Thus, by comparing the sieve analysis data from modern depositional environments with samples from the geologic past the depositional environment for these ancient samples can be determined.

3

APPARATUS:

4

Sieves

Sieve panSieve shaker

MaterialsSilica Sand.

Equipment

1 set of 9 sieves (53,75,106,150,212,300,425,600,850) plus the sieve pan, Sieve Shaker, Digital Scale Balance

Hand Tools

Brush

Procedure

a) The screens on the sieves are cleaned carefully by turning the sieve face down and the rim is striking evenly on the table.

5

Container

b) The sand sample 100 grams is weighted to an accuracy of 0.01 grams.

c) The stacks of sieves are placed on the Sieve Shaker Octagon 2000 machine.

6

d) The silica sand is put on the sieve.e) The sieves are shaken continuously for a period of 15 minutes.f) After the shaking operation, the sieves are taken apart and left over sand of each

sieveis carefully weighed. The weight is recorded.

Result

A B C D E F

NO SIEVE NO

OPENING (MIC)

SAND MASS(g)

SAMPLE(%)

AFS MULTIPLIER

AFS PRODUCT(C X E)

1 20 850 0.22 0.225 10 2.22 30 600 1.73 1.769 20 34.63 40 425 38.77 39.634 30 1163.14 50 300 16.17 16.53 40 646.8

7

5 70 212 5.51 5.633 50 275.56 100 150 11.52 11.777 70 806.47 140 106 14.77 15.099 100 14778 200 75 6.21 6.348 145 900.459 270 53 2.43 2.484 200 48610 PAN 0.52 0.532 300 156TOTAL ACCUMULATED SAND MASS (g)

97.85 100% 5948.05

ORIGINAL MASS OF SAMPLE BEFORE SIEVING (g)

100

8

1 2 3 4 5 6 7 8 9 1005

1015202530354045

SIEVE NO vs PERCENTAGE OF MASS RETAINED

Series1

PERCENTAGE OF MASS RETAINED

SIEV

E N

O

Discussion

Based on the result obtained, we can see that the total mass of the sand after the

experiment is less than the initial total mass of the sand. This is because of human factor

while doing this experiment. First of all, when we want to brush the sand off the sieves,

there are no precautions taken to make sure every grain of sand falls into the dish. After

9

1 2 3 4 5 6 7 8 9 100

20

40

60

80

100

120

SIEVE NO vs CUMULATIVE PERCENTAGE OF MASS LEFT IN SIEVE

Series1

CUMULATIVE PERCENTAGE OF MASS LEFT IN SIEVE

SIEV

E N

O

this experiment is done, we can see that on the table are a few grains of sands. There

are some to stick on the sieves.

According to the result, the most number of mass would be on sieve number 3. This

shows that most of the sand we use is coarse. While weighing the sand, an error has

occurred that is the factor of air. The weighing station is really sensitive that when we

pass our hand over it, it will give a slight change in the reading. Therefore, we need to be

really careful so that there is no interference during the weighing step. While pouring the

sand into the weighing station, our hand might make the air around it unstable and

cause the reading to have an error.

Besides that, an error might occur if the sieves have not been cleaned thoroughly. The

sands cannot pass through if there are a few grains left sticking in the sieve.

Explain briefly what is GFNGFN or ‘Grain Fineness Number’ is a system developed by AFS for rapidly expressing

the average grain size of given sand. It approximates the number of meshes per inch of

that sieve that would just pass the sample if its grains of uniform size. It is approximately

proportional to the surface area per unit of weight of sand, exclusive of 10 clay. For the

different value of GFN will be used for different applications (e.g. 40:l arge casting, 70:

small casting, 100: non-ferrous alloy cast, 150: aluminium alloy casting). GFN as known

as the grain fineness number is quantitative indication of the grain size and grain size

distribution.

Based on the GFN value, and the distribution obtained, suggests the suitability of the sand for casting.The quality of castings produced depends largely upon the properties of the sand

utilized. To ensure good castings, the sand must satisfy specifications:1.Refractoriness.2.Bond strength.3.Permeability.4. Collapsibility

5. Grain fineness and size

6. Grain shape and roundness

10

The sand which is suitable for casting should has good strength to avoid the mould from broken during the process. It also has high refractoriness to withstand the high temperature of the molten metal. The sand also must have good permeability. The sand must be porous so that the gases generated are allowed to escape. Size of the sand and its shape it’s depend on the materials and casting process. The small size provides better surface finish but the large grain size is more permeable. The sand should have good thermal conductivity, so that the heat from casting is quickly transferred.

RECOMMENDATIONa) Clean all the sieves that we will use before do the experiment. The screen on the

sieves must be clean in order to remove all grain sands.

11

b) Careful when clean the sieve screen without contact with the fingers.

c) Clean the sieve screen gently to make sure the sieve screen not tear.

d) Sieve Shaker that placed the sieve must be locked tidily to prevent it from moving

away when shaking process.

e) Before weighing the silica sand, clean the top area on digital scale to get

accurate readings and prevent it from error happen.

f) Use the soft brush to gently wipe the screen.

CONCLUSIONFrom the experiment the objective is achieve to determine the sand grain size of

silica sand sample and calculate the value of Grain Fineness Number (GFN). The GFN

that we get from silica sand are suitable for casting process. The higher the GFN

number obtained the smaller the grain size thus, the molding have low permeability.

Opposite that the smaller of grains size provides a better surface finish on the product

that we will produce.

REFERENCE1. Serope Kalpakjian, Steven R. Schmid, Manufacturing Technology and

Fundamental, 5th Edition, Prentice Hall, 2004.2. Serope Kalpakjian, Steven R. Schmid, Manufacturing Processes for Engineering

Materials, 4th Edition, Illinois Institute Of Technology, Prentice Hall, 2003.3. http://www.sfsa.org/sfsa/glossary/deftrmgg.html

GROUP DISTRIBUTION

12

1. TitleMohamad Norhafizie bin

Mohd Yasin2. Objective(s)

3. Introduction (background and theory)

Mohamad Syahir bin Azhari

4. ApparatusMohamad Norhafizie bin

Mohd Yasin

5. Experimental Procedure Ibra Adeni bin Ahmad Jelani

6. Results & Data Analysis Fathasya Nurul Aishah bt Izany

7. Discussion of Results Mohamad Asyraf Hafizuddin bin Abdul Latiff

8. Conclusion

Mohamad Norhafizie bin Mohd Yasin

9. Recommendation

10. References

13