Oblique cutting system: Identify the correct description(s) of geometry and chip flow for oblique (non-orthogonal) cutting.
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AThe cutting edge is inclined at an angle less than 90° with the normal to the tool velocity.
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BFrequently, more than one cutting edge is simultaneously in action.
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CThe chip flows over the tool face at an angle less than 90° to the normal on the cutting edge (i.e., oblique flow).
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Dall of the above
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Enone of the above
Answer
Correct Answer: all of the above
Explanation
Introduction / Context:Metal cutting is broadly categorized into orthogonal and oblique cutting. Oblique cutting is the more general and more common case in real machining, where the cutting edge is not perpendicular to the cutting velocity. Recognizing its geometric features helps predict chip flow, forces, and surface finish characteristics.
Given Data / Assumptions:
- Steady-state machining, no built-up edge considered.
- Tool has a finite inclination (obliquity) angle i.
- Cutting takes place with a single-point tool (but multiple edge segments may engage in oblique geometry).
Concept / Approach:In oblique cutting, the major cutting edge is inclined, producing a chip flow direction that is neither purely upward nor purely normal to the cutting edge. The chip flows sideways across the rake face, giving a three-dimensional chip flow vector. This often results in more favorable chip evacuation and can influence surface finish and tool life.
Step-by-Step Solution:
Note geometry → cutting edge is inclined, not perpendicular to tool velocity.Infer chip flow → oblique to the normal on the cutting edge, typically at a finite chip flow angle.Acknowledge edge participation → depending on nose radius and inclination, more than one edge portion may contribute concurrently.Verification / Alternative check:Draw the 3D velocity diagram: the chip velocity has components both normal to and along the cutting edge, confirming oblique chip flow and the described angles.
Why Other Options Are Wrong:Here, options (a), (b), and (c) collectively describe oblique cutting; dismissing any one would leave the description incomplete. Therefore, “all of the above” is the most accurate choice.
Common Pitfalls:Assuming orthogonal cutting applies to most turning operations; in practice, nose radius and lead/inclination angles make the process oblique. Also, confusing rake angles (back/side) with the inclination that defines oblique geometry.
Final Answer:all of the above