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Page 21

Kinetics of liquid metal flow in gating design of investment casting production

E x p e r i m e n t a l o b s e r va t i o n s a n d r e s u l t s

S. Roy – U. K. Maity – A. K. Pramanick – P. K. Datta

Two different types of experiments were taken for verifying the gating design. First one was done by simulation of pouring liquids like water and kerosene into thin glass molds and then castings were done by pouring liquid brass in hot clay molds. Simulation with water and kerosene A horizontal cylindrical glass tube with core (Fig. 3) was taken for experimentation. Tab. I. Experimental water flow pattern

Tab. II. Experimental kerosene flow pattern

Time

Time

Pictorial Flow Pattern

Schematic Flow Pattern

1.0 s

Pictorial Flow Pattern

Schematic Flow Pattern

0.25 s

1.8 s

1.9 s

6

Calculated Filling Time Experimented Filling Time

5

3.3 s

Filling Time (s)

2.9 s

4.8 s

4 3

5.2 s

2 1

6

0 0.05

6

Calculated Filling Time Experimented Filling Time

Filling Time (s)

6 Calculated Filling Time Experimented Filling Time

5

Filling Time (s)

1 0 0.0

4

4

2 1

3

0 0.0

0.2

2 1

6

3 0.2 2

5

0.4

Calculated Filling Time Experimented Filling Time

0.6

0.8

0 0.0

1.0

results with water and kerosene The calculated and experimental filling time with respect to percentage of volume filled are plotted in Fig. 4 and Fig. 5 for water and kerosene respect0.4 0.6 0.8 1.0 ively. Close proximity of experimental Percentage of Volume times with the proposed mathematical model justify the propositions.

0.2

0.4

0.6

0.8

1.0

Percentage of Volume

Percentage of Volume 4 3

Fig. 4. of experimental and 1 Comparison 2 calculated filling time with re1 spect to percentage of volume 0 0.0 filled 0.2 0.4 0.6 0.8closed 1.0 for water showed 0 0.0 0.2 0.4 0.6 0.8 1.0 Percentage of Volume proximity ofPercentage experimental times of Volume

Fig. 5. Comparison of experimental and calculated filling time with respect to percentage of volume filled for kerosene also demonstrated closeness

(a)

Experiments for actual casting Castings were investigated to compare the calculated and experimental filling time. Dancing doll with Dam sprue A wax pattern of a dancing doll (Fig. 6) was cast using a dam sprue (sprue with a dam). Details of casting produced are mentioned in Tab. III. Calculated and (b)parameters are given in designed gating Tab. IV.

(a)

Fig. 6. (a) Casting, schematic diagram of casting, sche- matic diagram of mold, sprue and gate, sectional view of the dam sprue (left to right onwards)

(a)

1.0

4

Filling Time (s)

Filling Time (s)

3

0.8

Percentage of Volume Experimental

Calculated Filling Time 3 Filling Time Experimented

5

4

2

Filling Time (s)

5

Calculated Filling Time Experimented Filling 0.4 0.6 Time

0.2

(b)

(b)

(a)

(b) (b)

(c) (c)

(d)

(d)

S l é vá re ns t v í . L X V . k v ě te n – č e r v e n 2017 . 5 – 6

151

PŘESNÉ LITÍ

The effect of resistance of gas pressure (ΔPgas) is neglected here, as, annular cavity and fluid both are at room temperature. Calculated inlet (vg) and final velocity (v f) is followed by the effect of surface tension. In this case surface tension factor increases the velocity as, both water and kerosene wet the surface (θ < 90°). The experimental flow pattern at different time has been demonstrated pictorially as well as schematically in Tab. I and Tab. II for water and kerosene respectively.

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