Experimental Study and Analysis of Compressive Strength in No-Bake Sand

Journal of Materials & Metallurgical Engineering ISSN: 2231-3818 (Online), ISSN: 2321-4236 (Print) Volume 8, Issue 2 www.stmjournals.com

Experimental Study and Analysis of Compressive Strength in No-Bake Sand Venkat Akhilesh1, Reni Jose2, Benrajesh P.3, * 1,2,3

Department of Mechanical and Automobile, Faculty of Engineering, Christ, Bangalore, Karnataka, India

Abstract No-bake molds are expendable sand molds, similar to typical sand molds, except they also contain a quick-setting liquid resin and catalyst. In no-bake molding process, the molding sand is poured into the flask and held until the resin solidifies, which occurs at room temperature. It is called as a cold-setting process, as there is no heat involved in it. As a result of this molding process, mold produced will have a better surface finish than any other type of sand molds. No-bake sand with high productivity, reduce energy consumption, improve dimensional accuracy, and less curing time escalates its priority of usage in automobile sand casting industries. This study analyses the change in the compressive strength of no-bake sand by varying resin percentage and the loss of ignition (LOI) in each iteration. Four samples (A, B, C, D) are prepared, by various resin percentage. The Graphs are inferred from the results and it was recommended to an automobile sand casting concern.

Keywords: Characterization of no-bake sand, compressive strength, loss of ignition (LOI), nobake sand, resin percentages

*Author for Correspondence E-mail: ben.rajesh@christuniversity.in

INTRODUCTION Foundries today are multifaceted organizations that include molding, core making, melting, cleaning, maintenance, pattern making, quality and engineering departments. Sands are preferred as molding substance in any foundry industry. It has a wide spectrum of utilities such as inert nature to ferrous/nonferrous materials, high temperature immunity, chemical resistant, widely available resources, corrosion resistant and high degree of permeability, less cost of usage [1]. It is available from many resources like earth crust, deep sea bed, volcanic lava sediments, rocks or synthetic made sand. The composition of foundry sand [1,3] is silica with high contribution of 98%, followed with few binders (Clay) of inferior percentages.

No-bake sand would not require any heat for curing its mixture. It uses few chemical binders for curing. After mixing, it can be utilized in cope and drag along with refractive coating on surfaces. It completes its settling time within 10 seconds. In the past, less effort had been carried out to identify [13] the effect of phenolic resins on tensile, transverse and compression strength of the no-bake sand.

The art of developing the bio degradable resin bonded mold was discussed in the article [5]. It tries to compare two kinds of resin bonded casting and identifies the best one with the following attributes: tensile, transverse and compressive strength respectively. The former one is phenolic ester resin which was mixed with the sand in the ratio of foundry sand (78%); phenolic resin (1.5% to 2%) with the ester (20%). The casting obtained by the phenolic and ester resin mold reflects the tensile strength of 7.9 kg/cm2, transverse strength of 6.7 kg/cm2 and compressive strength of 17.8 kg/cm2. The latter one is furan and sulfonic acid mixture prepared by 100 parts of sand with 20 to 30 parts of aqueous acid and 1–2 parts of compounded furan resin. The casting obtained by the furan sulphonic acid mold had the tensile strength of 5.16 kg/cm2, transverse strength of 4.33 kg/cm2 and compressive strength of 18.36 kg/cm2. Based on the results, the casting of the phenolic ester resin was selected for developing bio degradable mold.

BASIC DEFINITIONS Loss on Ignitions It is defined as the process of removal of volatile substances in a compound until its

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Experimental Study and Analysis of Compressive Strength in No-Bake Sand

Venkat et al.

mass ceases to change by adding heat through temperature-controlled furnaces. Example, volatile substances are hydrates and labile hydroxyl compounds.

•

Compressive Strength The Compressive strength is defined as the capacity of a material to withstand loads tending to reduce area.

The percentage of resin content in no-bake sand is varied from 1.1% to 1.5 % for a constant loss of ignition. The finished specimens are kept at different time intervals from 1 hour to 24 hour respectively.

Resins Resins are melting points of gums obtained from either natural or synthetic source. Two common types are Urea formaldehyde and Phenol formaldehyde.

Additives Additives are molding components to improve surface finish, dry strength, refractoriness and cushioning properties. Some of the additives are coal powder, pitch, creosote and fuel oil.

EXPERIMENTAL SET UP

Then the prepared samples are kept in the oven for one hour for curing.

COMPRESSIVE STRENGTH ANALYSIS

Tabular Columns Table 1 shows the value of compression strength for a dried core based on the parameters such as time curing intervals, addition of resin percentages et al for a loss on ignitions (LOI) of 1.15%.

Table 2 shows the value of compression strength for a dried core based on the parameters such as time curing intervals, addition of resin percentages et al. for a LOI of 1.21%.

A Muffle furnace (Figure1) with the limit of 1800 degree Celsius, Analytical balance with least count of 0.1 milligram, Universal strength testing machine with specifications of compression strength from 15 Kg/cm2 to 60 Kg/Cm2, Sand rammer with specimen tube to prepare specimen of 50 mm height by 50 mm diameter, Sand mullers with two mullers and a Crib made up of mild steel plates are used.

Materials used for sand casting are silica sand (98% of Silica), resin {Methylene diphenyl di isocyanate (MTH)}, reducing agents (Coal powder, Pitch), cushioning materials (Wood Flour, Saw dust).

The configuration of mixture is as follows: • Base sand of two kilogram is weighed in digital weighing machine and it is added to the muller.

• Then, it is mixed with resin in the range of 1.1 percent to 1.5 percent of total weight and the samples are identified as A, B, C and D based on the resin content.

• Reducing agents are mixed with the ratio of five percentages by total weight of the silica sand.

• Cushioning materials are added till three percentages to the silica sand weight.

Fig. 1: Muffle Furnace.

Table 1: Sample-A {LOI-1.15%}.

S. Resin No Percentage 1.

1.1

2.

3.

Compression strength for various time cured mixtures (Kg/cm2) 1 Hr 2 Hr 4Hr 8 Hr 24 Hr 0.1

1.06

2.64

6.56

1.2

0.1

1.32

4.38

4.53

9.67

1.3

0.15

1.42

4.73

5.84

11.61

4.

1.4

0.1

2.85

4.63

6.23

12.83

5.

1.5

0.15

3.05

4.84

9.88

13.08

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7.58

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Journal of Materials & Metallurgical Engineering Volume 8, Issue 2 ISSN: 2231-3818 (Online), ISSN: 2321-4236 (Print)

Table 3 shows the value of compression strength for a dried core based on the parameters such as time curing intervals, addition of resin percentages et al. for a LOI of 1.30%.

Figure 1 and Figure 2 shows the sharp trend curve of the compression strength versus curing time of the core; for the LOI as 1.15% and 1.21%, by keeping resin percentage as 1.4% as constant.

Figure 3 and Figure 4 shows the sharp trend curve of the compression strength versus curing time of the core; for the LOI value as 1.30% and 1.35 %, by keeping resin percentage as 1.4% as constant.

Fig. 2: Compression Strength Analysis of Sample-B.

Table 2: Sample-B {LOI-1.21%}.

S. Resin No Percentage 1.

2.

3.

4.

5.

1.1 1.2 1.3 1.4 1.5

Compression strength for various time cured mixtures (Kg/cm2) 1 Hr 2 Hr 4Hr 8 Hr 24 Hr. 0.1 1.06 2.64 6.56 7.58 0.1 1.32 4.38 4.53 9.67 0.15 1.42 4.73 5.84 11.61 0.1 2.85 4.63 6.23 12.83 0.15 3.05 4.84 9.88 13.08

Table.3: Sample-C {LOI-1.30%} S. Resin No Percentage 1.

2.

3.

4.

5.

1.1 1.2 1.3 1.4 1.5

Compression strength for various time cured mixtures (Kg/cm2) 1 Hr. 2 Hr. 4Hr 8 Hr. 24 Hr. 0.15 1.52 2.95 4.12 5.13 0.15 1.37 2.54 4.64 6.97 0.30 1.32 3.10 4.59 9.21 0.30 1.32 3.54 4.65 8.91 0.4 3.71 4.82 7.29 10.14

Fig. 1: Compression Strength Analysis of Sample-A.

Fig. 3: Compression Strength Analysis of Sample-C.

Fig. 4: Compression Strength Analysis of Sample-D.

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Experimental Study and Analysis of Compressive Strength in No-Bake Sand

Venkat et al.

that, Sample-A is the high performer in the baked compressive strength whereas the highest value of the compressive strength (Figure 6) is 12.83 kg/cm2.

CONCLUSIONS

Fig. 5: Compression Strength Analysis-I.

Thus, no-bake resin sand can be an optimal choice in the manufacturing of heavy weighted automobile components with high dimensional accuracy and less energy consumption by casting process. The compression strength of a core is driven by the factors such as Loss on ignition and the time of curing. The sand temperature can increase the rate of curing.

Lower nitrogen and the water percentages can produce the environment friendly furan bonded casting. Sand density must be increased by ramming and then the furan coating can be done as it leads to permanent bonding. If the furan resin is added initially, the sand density will be reduced.

REFERENCES

Fig. 6: Compression Strength Analysis-II. Figures 5 and 6 show the comparison chart of all LOI (1.15, 1.21, 1.30, 1.4} and compression strength (Samples A, B, C, D), for the constant resin percentage of 1.4%.

RESULTS AND DISCUSSION The samples A, B, C and D of no-bake sand, are prepared by varying resin percentages. The sample is then tested in UTM machine and the compressive strength is graphically recorded in the Figure 1, Figure 2, Figure 3 and Figure4 respectively. As the curing time increased, the compressive strength soared high. Maximum baked compressive strength of the sample-A, B, C and D is at the 25th curing hour. The plots obtained from Figure 5 and Figure 6 shows the consolidation of all the sample plots. The data inferred from Figure 5 shows

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Cite this Article Venkat, Akhilesh, Reni Jose et al.

Experimental Study and Analysis of Compressive Strength in No-bake Sand.

Journal of Materials & Metallurgical Engineering. 2018; 8(2): 18–22p.

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