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

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Discussion Overview

The discussion revolves around calculating the force required for machining a circular tube, specifically focusing on reducing the outer diameter from 32mm to 25mm while considering the wall thickness of 2.3mm. The context includes aspects of machining processes, specifically swaging and reducing, and the associated forces involved.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the relevance of calculating a constant force, suggesting that the force varies at different stages of the machining process depending on the method used.
  • Another participant clarifies that the process being referred to is more accurately described as "reducing" rather than "swaging," and notes that specialized tools are typically used for this purpose.
  • There is mention of the need for specific values to input into machines, but uncertainty remains about the exact pressure or force required for the reduction process.
  • A participant shares anecdotal evidence of having seen a pressure gauge reading of 750psi for a similar process, implying that the force required may be less for the current scenario.
  • Concerns are raised about the complexity of calculating eccentric loads, with a suggestion that relying on an experienced machinist may be more practical.

Areas of Agreement / Disagreement

Participants express differing views on the terminology and methods involved in the process, with no consensus on the exact force required for the machining task. The discussion remains unresolved regarding the specific calculations needed.

Contextual Notes

Participants highlight the variability of forces during the machining process, the dependence on specific tools and methods, and the lack of a straightforward calculation for the required force. There are also references to practical experiences that may not directly translate to the current question.

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

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