# How to calculate the force required for machining a circular tube?

1. Jul 24, 2014

### sagar

Hi everyone,
I need to calculate the force required for machining a circular tube of outer dia 32 and a wall thickness of 2.3, how much ll be the force required for the machining the outer dia to 25?

2. Jul 24, 2014

### Simon Bridge

Welcome to PF;
I suspect you are asking the wrong question - what do you expect the force to tell you?
Basically - there will not be a constant force applied - but different forces in different places at different stages of the machining process - all depending on the specific method used.

If, for instance, you are boring the tube from a cast cylinder, then you will have to apply a torque to turn the bore against the friction of the drill, and you have to apply a force down the axis to press the drill into the metal.
These will depend on the drill properties, and how fast you want to drill the hole out.

3. Jul 24, 2014

### sagar

Thanks for ur response Simon Bridge,
sorry for the wrong question i asked, actually i need to calculate the force required for the swaging of the circular tube, pls refer this video for reference,
i have only this much following data OD 32 and need to swaged to the OD 25 and it as the wall thickness of 2.3 what is the force required for the swaging to take place? hope now u can able to understand my question

Last edited by a moderator: Sep 25, 2014
4. Jul 24, 2014

### Simon Bridge

I think I get it now. You are basically deforming the pipe at one end.

OD 32 = outside diameter 32mm - is that correct?
So you want to go from 32mm to 25mm? And the pipe is 2.3mm thick?

1. that's called "reducing" not swaging (iirc - could be wrong)
2. there are specialized tools to do this
3. you'd normally reduce by the thickness... i.e. go from 32mm to 19.7mm

I do not know off hand how much pressure you'd need to reduce pipe for a particular thickness though.
Whenever I've done it, it has always been a power or hand-tool so no need to worry about it.
A handbook with the tool usually has a table or a use guide or something.

This is why I'm wondering what you expect the force value to tell you.
i.e. do you need some value to input into a machine?

Ref:
... that was a large steel tube, and I saw 750psi on the gauge. You'll need less.

Last edited by a moderator: Sep 25, 2014
5. Jul 29, 2014

### Chronos

Eccentric loads are more trouble to calculate than they are worth. An experienced machinist is a better solution.