Q311
A single point thread cutting tool should ideally have
A.
Zero rake angle
AnswerB.
Positive rake angle
C.
Negative rake angle
D.
Point angle
Answer: Option A
Solution
Answer: Option A
Solution:
The correct option is "Zero rake angle" (Option A).Reason: In thread cutting, accuracy of the thread form is critical. A zero rake angle preserves the true geometry of the thread profile and avoids distortion during cutting.
Why not positive rake? Although it reduces cutting forces in general machining, it changes the effective cutting geometry in threading and can distort the thread form.
Why not negative rake? It increases cutting forces and is unnecessary for precision thread cutting, potentially harming surface finish and tool life.
About point angle: The point (included) angle defines thread geometry (e.g., 60° for metric/UN), but it is a different parameter and not the ideal rake requirement.
Conclusion: For single point thread cutting tools, use zero rake angle to maintain accurate thread profile and dimensional correctness.