Why have a feed force in the cutting process?

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Discussion Overview

The discussion revolves around the necessity and implications of feed force in the cutting process, particularly in relation to the geometry of cutting tools and their interaction with materials. It explores theoretical and practical aspects of cutting forces, including the influence of rake angles and tool profiles.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that the cutter's profile affects the force required to feed it into the material, with positive rake angles potentially pulling the cutter in and negative rake angles possibly resisting entry.
  • There is a suggestion that the use of negative rake angles necessitates stronger and more rigid machine tools due to the increased feed force required.
  • One participant questions the existence of a feed force when the rake angle is zero, implying that without motion in the feed direction, the feed force may not be necessary.
  • Another participant emphasizes the complexity of cutting geometry and suggests that the discussion should focus on specific scenarios, such as a parting-off tool in a lathe, to clarify the relationship between rake angle and feed force.
  • It is mentioned that a dull or rounded cutting edge would increase the feed force required, even if the rake angle is zero.

Areas of Agreement / Disagreement

Participants express differing views on the role and necessity of feed force, particularly regarding the influence of rake angles and tool conditions. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

Limitations in the discussion include the lack of specification regarding the cutting geometry and the conditions under which feed forces are analyzed, which may affect the interpretations of the participants.

exln
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You knew there is a cutting force in the orthogonal process, it is exerted by cutting speed, buy why have a feed force?
 

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The profile of the cutter has an effect on the force needed to feed the cutter into the cut.
A tool steel saw with positive rake may hook or pull the cutter into the material.
A carbide cutter with negative rake may be forced back from the material.
The increased use of negative rake requires stronger, more rigid machine tools with more powerful feed.
https://en.wikipedia.org/wiki/Rake_angle

What material are you machining?
What tool material and profile are you using?
 
Baluncore said:
The profile of the cutter has an effect on the force needed to feed the cutter into the cut.
A tool steel saw with positive rake may hook or pull the cutter into the material.
A carbide cutter with negative rake may be forced back from the material.
The increased use of negative rake requires stronger, more rigid machine tools with more powerful feed.
https://en.wikipedia.org/wiki/Rake_angle

What material are you machining?
What tool material and profile are you using?
thank you, but you knew whatever the type of tool, there is no motion in the direction of feed force. If the rake angle equal to zero, is there a feed force?
 
There are too many different possible interpretations of the cutting geometry. The relative motion of the work and the tool in 3D have not been specified.

You need to restrict the discussion to a simple situation, such as a parting-off tool in a lathe. A zero rake angle would then have a low feed force while the edge was perfect. The moment the cutting edge became slightly dull or rounded, it would present a higher feed force, but it would continue to cut.
 

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