Question

A true centrifugal casting operation needs to be performed horizontally to make copper tube sections with outer diameter of 250 mm and inner diameter of 230 mm. The value of acceleration due to gravity, g = 10 $m/s^2$. If a G-factor (ratio of centrifugal force to weight) of 60 is used for casting the tube, the rational speed required is rpm. [Round off to the nearest integer]

• A. 662

Answer 1

The correct option is A 662
$\text{Given data:}$

$D_0=250mm;D_i=230mm;$

$g=10m/s^2;\text{G-factor}=60$

$F_c=mr{\omega }^2$

$F_g=mg$

$\text{G-factor}=\frac{F_c}{F_g}=60$

$\text{G-factor}=\frac{F_c}{F_g}=\frac{mr{\omega }^2}{mg}=\frac{D_0}{2g}{\left(\frac{2\pi N}{60}\right)}^2$

$N=\sqrt{\frac{2\times \text{G-Factor}\times g}{D_0}}\times \left(\frac{60}{2\pi }\right)$

$N=\sqrt{\frac{2\times 60\times 10}{0.25}}\times \left(\frac{60}{2\pi }\right)$

$N=661.93=662rpm$