# How to design a casting machine?

I was wondering, what are the factors to consider or how to find the required technical specifications for the new machine?

For example, if we consider a design of horizontal centrifugal casting machine with orbitary dimensions, Let suppose I do not know the dimensions of the machine. How do I calculate

1. centrifugal force required?
2. Torque of the Motor?
3. Power required to rotate the rotating tube?

To calculate the Centrifugal force, $F_c=mv^2 / r$ or $F_c=M\omega^2r$. where, angular velocity, $\omega=2\pi N/60$.

Hence, in order to calculate the centrifugal force we need to have the Speed ($N$) of the rotating tube. But, how do we know that whether the assumed Speed is enough for the casting process? Using this $F_c$, torque and power can be calculated, $T=F_c*r$ and $P=2\pi NT/60$.

Assuming $N=200\text{ rpm}$, I have carried out some calculations which are as follows, $\omega=2\pi N/60=20.94\text{ rad/s} = 3.33\text{ rps}$.

Let, part to be cast is Aluminium and has $\phi_{out}=20\text{ cm}$, $\phi_{in}=10\text{ cm}$ and $L=50\text{ cm}$. Then, $V=3750\pi\text{ cm}^3$ and $m=31.83\text{ kg}$. Hence, from $F_c=M\omega^2r=173.13\text{ N}$ (considering inner radius of the cast part as the Minimum distance need to achieve which 5 cm).

Dimensions of rotating tube is assumed as $\phi_{out}=30\text{ cm}$ and $\phi_{in}=20\text{ cm}$ and $L=50\text{ cm}$. Torque required $T=173.13\cdot0.15=25.96\text{ Nm}$ (considering radius as the outer radius of the rotating tube that is 15 cm).

Power, $P=543.70\text{ W}$.

Are the steps I have performed are correct? If so, How do I know that assumed $N$ is the suitable value for the present machine or what is the usual Speed of the rotating tube in horizontal casting machine considered?

If not, how do I approach when there are several unknowns or dependencies present in the system, for example centrifugal force depends on angular velocity which in turn depended on speed of the rotating tube.

• A diagram would help? With which axis are you rotating the tube...? – Solar Mike Mar 29 '18 at 9:02
• The axis of the rotating tube is horizontal. I am not able to add diagrams because it is not showing any such options to do but it resembles the diagram of horitzontal centrifugal casting machine. @Solar Mike – Ranjith Mar 29 '18 at 10:53 