Question

A cuboidal casting of 30000 cm${}^3$ total volume has to be filled with a parting gating system as shown in the figure.


The highest of mould cavity above and below the runner plane are equal. The total liquid head is maintained constant such that it is equal to the mould height above the runner plane. If the runner has uniform cross-section of 20 mm diameter, the total time for filling (in seconds) the cavity will be ________ .

• A. 66
• B. 59
• C. 44
• D. 75

Answer 1

The correct option is B 59


For cavity (1), the gating system acts as a top gating system.

So, ${\tau }_1=\frac{15000\times {10}^3}{\frac{\pi }{4}\times {20}^2\times \sqrt{2\times 9810\times 300}}$

= 19.68 sec

For cavity (2), the gating system acts as a bottom gating system.
Since the top surface coincides with free surface of molten metal, the time taken will be twice as compared to the time taken in top gating system.

$\therefore {\tau }_2=2{\tau }_1=2\times 19.68=39.36$ sec

$Totaltime,\tau ={\tau }_1+{\tau }_2$

= 19.68 + 39.36 = 59.04 sec