Program : Bachelor of Mechanical Engineering (Hons) Manufacturing

(EM221)

Bachelor of Engineering (Hons) Mechanical (EM220)

Course : Manufacturing Processes Laboratory

Course Code : MEM564

Laboratory Name : FOUNDRY

Lecturer Name : Mohd Ridhwan Redza

Title of Experiment : Sand Testing Preparation (Green Sand)

Group : EMD5M13

No.

Student Name Student ID Number Signature

1. USMAN BIN TAIB 2013233774

2. NURUL FARHANA BINTI OMAR 2013677274

3. SHAHEERA DIANA BINTI MOHD SHAROM 2013633416

4. WAN MUHAMMAD FAIZ BIN WAN AZLAN 2014256308

5. WAN MUHAMAD AQIL BIN WAN MOHD NORSANI

2013652164

Date of Practical Session Staff Certification (Signature)

Date of Report Submission Staff Certification (Signature)

KUMPULAN

30

FACULTY OF MECHANICAL ENGINEERING,

UNIVERSITI TECHNOLOGI MARA (UITM)

LABORATORY REPORT

Contents

Objectives..............................................................................................................................................3

Introduction...........................................................................................................................................3

Apparatus..............................................................................................................................................6

Industrial Apparatus..............................................................................................................................9

Procedure..............................................................................................................................................9

Results and Data Analysis....................................................................................................................10

Discussion............................................................................................................................................12

Conclusion...........................................................................................................................................13

Recommendations...............................................................................................................................14

References...........................................................................................................................................15

Objectives

1. To measure the properties of molding sand, green compression strength and permeability

of green sand.

2. To study about molding process.

Introduction

A basic understanding of the materials that constitute a green sand system and the

required equipment to prepare the material are extremely important to assure castings

quality. Green compression strength and permeability are important mechanical properties to

be considered in moulding preparation. Green sand is made up from silica sand, bentonite,

coal dust and water with ratio of 4 : 2 : 2 : 1.

There are four types of test for sand strength which is compression, shear, tensile,

and over-hang bar test. Based on these four test, compression test is most widely used and

very convenient for routine testing of all types of national bonded and synthetic moulding

sand. Green compression strength is define as stress required to rupture the sand specimen

under compressive loading. The sand specimen is then taken out of the specimen tube and

immediately put on the strength testing machine to determine the force required to cause the

compression failure. The green sand is generally range of 0.03 to 0.16 MPa.

Permeability is defined as property of sand which permits the steam and other gases

to pass through the sand mould. Permeability of moulding sand is controlled by several

factors such as sand particle size and shape, water content of the moulding mixture and clay

content of the moulding mixture. Coarse grained sands are more permeable than finer ones.

Figure 1 and 2 shows the effect on permeability based on grain size and water content.

Figure 1 : Effect of grain size permeability Figure 2 : Water content on permeability

Permeability is determined by measuring the quantity of air that passes through a

standard compression with rate in cc/min. Standard permeability is determined by measuring

the time necessary for 2000 cm3 of air to pass through the standard specimen while it is

confined in the specimen tube with three blows of standard rammer and under a pressure of

10 gm /cm2. If the time is determined the permeability number can be calculated from the

formula :

P= V .Hρ . A .T

where,

V : volume of air = 2000 cm3

H : height of sand specimen = 2 inches

P : pressure = 10 gm /cm2

A : cross sectional area of the sand specimen = 1¿2

T : time, sec, for 2000cm3 air to pass through specimen

The formula reduces to AFS Permeability :

P=3000.7T (sec )

The formula reduce to AFS Permeability for Ridscale-Dieter

P= 30557air pressure∈cm of water ×time∈(sec)

=30557p×t

for old machine working with Hg

Apparatus

Materials:

1) Green sand : Made of silica sand, bentonite, coal dust and water.

Equipment:

1

2

2) Permeability Machine : Measures the permeability of the compressed sand in

the specimen tube. A flow or air is passed through the

specimen to check its permeability. The permeability or

rate of the air that will pass through the specimen is in

cc/min.

3) Sand Rammer : To ram and compress the sand to reproduce ramming

conditions.

4) Universal Strength Testing Machine : To measure the strength of the green sand

when compresse

3

4

Hand Tools:

5) Vernier Caliper : To measure the height of the sand specimen

6) Specimen Tube : To place the sand, in order to achieve its cylindrical shape, its

standard test sample shape and before ramming under the sand rammer.

5

6

Industrial Apparatus

In the industry, the apparatus used varies than what is used in the faculty laboratory.

1) In this is experiment, the sand in rammed using a simple sand rammer. The

sand that is rammed is only for the shape of the specimen tube. In the industrial

use however, air sand rammers are used, such as the Kawasaki KPT-2 Industrial

Air Rammer. Air sand rammers can provide powerful blows to ram various

shapes of flasks and molds. This way a much larger production can be achieved

compared to the simple sand rammer in the faculty laboratory.

2) The universal sand strength testing machine is the faculty laboratory are not

electronic, therefore zero and parallax error can occur if the values are not read

properly. In industrial applications, the universal sand strength testing machines

are electronic, such as supplied by Simpson Analytics Electronic Universal Sand

Strength Model 42104. This eliminates zero and parallax error and a more

precise reading of results.

3) As for the permeability machine in the faculty laboratory, it is also not electronic,

and errors can occur when taking the readings. In industries, it is much more

advanced as it is electronic like the Simpson Analytics Absolute Permeability

Tester Model 42501. This way, the results obtained are much more accurate.

Procedure

1. The green sand was prepared by mixing it again with water to increase its water quantity in

the sand and placed it into a container.

2. The green sand was scooped onto electronic scale and the weight of the sand was recorded.

3. The casing was cleaned thoroughly to ensure there was no unwanted sand in it.

4. It was transferred into the casing with its bottom covered using a funnel.

5. The casing and the green sand was placed onto ramming device and rammed for 3 times to

compact the sand.

6. The cover was removed and the casing was placed into permeability machine and tested for

its permeability and the reading were recorded

7. The green sand was removed from its casing and the length of the specimen is measured

using Vernier calliper.

8. If the length was higher or lower than the limit which is 50.675 to 50.925 mm, steps 2 to 6

were repeated.

9. If the length is acceptable, the specimen was transferred into sand universal sand strength

testing machine. The strength of the specimen was recorded.

Results and Data Analysis

Sand Weight (g) Permeability (cc/min) Height of sand (mm)145.03 64 48.86148.07 62 50.3148.63 65 50.9149.16 68 51.34

149.3 65 51155.41 70 53.6

48.86 50.3 50.9 51.34 51 53.6138140142144146148150152154156158

Sand Weight (g) vs Height of sand (mm)

Height of sand (mm)

Sand

Wei

ght(

G)

Calculation:

P= (V. H)/ (p. A. T)

The theoretical properties of permeability for green sand are;

V: volume of air = 2000 cm³

H: height of sand specimen = 2 inches = 5.08cm

P: pressure = 10 gm/cm²

A: cross sectional area of the sand specimen =1in² = 6.4516 cm²

T: time, min, for 2000 cm³ air to pass through specimen = 1min

P= VxHPxAxT

P= 2000 x5.0810 x6.4516 x1

P=157.48 cc /min

Percentage Error of Permeability

Experimental Value,

Pexp (cc/min)

Theoretical Value,

Ptheory (cc/min)

Percentage

Error (%)

65 157.48 58.72

Percentage of error = Experimentalvalue – TheoreticalvalueTheoreticalvalue x 100

= 65– 157.48

157.48 x 100

= 58.72 %

Discussion

The experiment was executed to analyze the green compression strength and the

permeability of molding sand. Both of these properties are very important to determine the

optimum moisture content to produce a good green sand casting mold. Permeability is the

rate of air flow through the specimen. By getting the permeability value, we can determine

the type of molten metal that is most suitable to be used for the green cast molding. If the

permeability number between 0-50 cc/min, it is considered too low and the range between

150-300 cc/min considered too high. Permeability within the ranges of too low and too high

can lead to defects in the cast when poured into the mold later on. The optimum range for

the permeability for the green sand is 80-150 cc/min. The green compression strength on the

other hand, is referring to the stress required to rupture green sand specimen under

compression loading. The strength is obtained by using universal sand strength testing

machine. The ideal strength of green sand is generally in the range between 0.03 to 0.16

MPa.

From the graph of Mass of Green Sand(g) vs Height of Green Sand(mm), it is

observed that the height of green sand increases with respect to the mass. In addition to

that, the permeability of the green sand also increases. This happens because when the

mass increases, the volume will increase. Increasing the volume in the green sand will lead

to the decrease of the tight packing of green sand, thus increasing the permeability.

Based on the experimental results we obtained, the permeability of the green sand is

65 cc/min. The result is below the optimum range value. The value needs to be slightly

higher for a more optimum permeability. Based on the theoretical calculation however, the

permeability value is 157.79 cc/min. The permeability of experimental result is much lower

compared to theoretical value with a percentage error of 58.72%. These discrepancy in

values could be due to the errors that occurred in our experiment. As for the compression

strength, the value of strength is 0.0903 MPa, which in the range of ideal compression

strength.

From the result of green sand strength of 0.0903 MPa, we can then determine the

suitable material that can be used as the molten metal. The ideal molten metal must have

the melting temperature is between 500-1000°C for this strength. As the range of the melting

temperature is considered as low, the suitable material that can be used is non-ferrous metal

as the molten metal. Some examples of non-ferrous metal that can be used are Aluminium,

Zinc and Tin.

Addressing the discrepancy of the values that we obtained in the experimental and

theoretical values, it could be to the errors that could have occurred while performing this

experiment. One of them could be due to how the specimen been produced. In the process

of ramming the sand into the specimen sample tube, the sand rammer should perfectly clean

as if there were any leftover sand on it, it will affect the volume of green sand and also its

height. In addition to this, parallax error could have contributed in our discrepancy in results.

From this experiment, the parallax error could have occurred when taking the height of

specimen by using the vernier caliper. Apart from that, the parallax error also could have

occurred when taking reading on the universal sand strength testing machine. Besides this,

surrounding environment could have also affected the specimen. After the ramming test, the

specimen might have been left too long before conducting the permeability test and the

characteristic of the green sand specimen might have changed.

Conclusion

It is clearly proven in this experiment that the green compression strength and

permeability test is crucial in obtaining the most optimum sand mold before proceeding for

mold preparation and pouring of molten metal. If the sand specimen is not within the

optimum permeability range value of 80-150 cc/min, the cast will exhibit defects, like gas

defects as the air and steam are not able escape when the molten is poured into the mold.

As for the green compression strength, it is too crucial for the value to be in the optimum

range of 0.03-0.16 MPa as for it to be able to withstand compression loading and will not

rupture upon the pouring of molten metal. By knowing the strength of the green sand mold,

we can determine suitable melting point that the green sand mold can withstand and

subsequently what molten metal can be used for the cast. It is essential to prepare the most

suitable mold before proceeding to pour the molten metal suitable based on its strength and

permeability. Errors that have occurred in this experiment must be avoided in the future to

produce and obtain the most accurate results. Parallax error which is the most recurring

error in the experiment must be eliminated by making sure the readings are taken parallel to

eye level and in bright light. The preparation of the specimen also must be done properly

and with care to ensure it does not contaminated by environmental factors.

Recommendations

During conducting this experiment, there are few recommendations to improve the accuracy of this experiment : 

a) Green sand produced must have right composition of silicon sand, bentonite, coal

dust and water for sand casting quality.

b) The sand specimen can be placed in closed area to prevent the loss of moisture that

will cause drying of the sand specimen.

c) The rammed sand specimen must be handled carefully and avoid too much force

during handling in order to get accurate height of the sample.

d) Carefully remove or take out the sand specimen from specimen tube to prevent the

specimen from rupture.

e) Right amount of water must be added to the sand to ensure the sand specimen is not

too wet or too dry for the bonding of the green sand.

f) Sand specimen must be rammed only three times to obtain accurate height for

strength testing.

References

1. American Foundry Society. (2001). Mold And Core Handbook Third Edition.

2. Bureau Of Indian Standards. (1997). Methods Of Physical Tests For Foundry Sands.

3. Pn Rao. Manufacturing Technology