Relating tool geometry across processes The rake angle of a single-point cutting tool in turning corresponds to which geometric angle on a twist drill used in drilling?

Difficulty: Easy

Correct Answer: helix angle

Explanation:


Introduction / Context:
Cutting geometry concepts repeat across machining processes. In turning, rake angle controls chip flow and cutting forces. In drilling, chip flow is governed by the drill's flute helix. Understanding the correspondence helps transfer intuition between operations.



Given Data / Assumptions:

  • Single-point turning tool with defined rake face.
  • Standard twist drill with helical flutes and cutting lips.
  • Comparative mapping of cutting geometry terms.


Concept / Approach:
Rake angle is the angle that facilitates chip flow off the cutting edge. On a twist drill, the equivalent function is served by the helix angle of the flutes, which determines chip flow direction and effective rake along the cutting lips. Other drill angles (point angle, chisel edge angle, lip clearance) serve different functions.



Step-by-Step Solution:
Identify the function of rake: reduce cutting resistance, guide chip flow.Find the drill feature that controls chip flow similarly → flute helix angle.Conclude helix angle best corresponds to rake angle in turning.



Verification / Alternative check:
Drill design references treat helix as providing positive rake along the lips; altering helix angle changes chip evacuation and cutting forces analogous to changing rake in turning.



Why Other Options Are Wrong:

  • Lip clearance angle affects relief behind the cutting edge, not chip flow direction.
  • Point angle defines included tip angle and penetration characteristics.
  • Chisel edge angle addresses the web at the tip (extruding action, not primary rake).
  • Margin relief angle concerns friction with the hole wall.


Common Pitfalls:
Assuming point angle equals rake; overlooking that effective rake along drill lips is a function of helix and point geometry together.



Final Answer:
helix angle

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