Question

In a true centrifugal casting process with the axis of rotation in horizontal direction, an acceleration of 70g, where "g" is the acceleration due to gravity is required for sound casting. The mould speed in RPM for casting of gray CI pipes of 10m long with outside and inside diameters as 2.5m and 2m respectively is

• A. 333
• B. 236
• C. 5.56
• D. 3.93

Answer 1

The correct option is B 236

True centrifugal casting:

$\text{Acceleration a = 70g}$

$\text{Outer dia}{D}_1\text{=2.5m}$

$\text{Inner dia}{D}_2\text{=2m}$

$\therefore \overline{D}=\frac{2.5+2}{2}=2.25m{a}_c=\frac{\overline{D}}{2}{\left(\frac{2\pi N}{60}\right)}^2\Rightarrow 70g=\frac{2.25}{2}{\left(\frac{2\pi N}{60}\right)}^2\therefore N=236rpm$