Carbide-tipped tools — typical rake selection For general turning at high speeds, carbide-tipped single-point tools most commonly employ which rake angle strategy to strengthen the edge?

Difficulty: Easy

Correct Answer: Negative rake angle

Explanation:


Introduction / Context:
Rake angle influences cutting forces, edge strength, and heat distribution. Carbide-tipped tools, with high hot hardness but limited toughness compared with HSS, often use negative rake geometry for durability at high speeds and heavy cuts.



Given Data / Assumptions:

  • Carbide-tipped or indexable carbide inserts in general steel turning.
  • High cutting speeds and significant cutting temperatures.
  • Machine rigidity sufficient to handle increased forces from negative rake.


Concept / Approach:
Negative rake geometry thickens the wedge angle, increases edge strength, and places the cutting load more in compression, which carbides tolerate well. While positive rake reduces forces, it thins the wedge and can chip at high loads or interrupted cuts.



Step-by-Step Solution:

Consider edge strength of carbides vs. HSS → carbide benefits from a stronger wedge.Negative rake increases wedge angle → better edge strength at speed.Thus, negative rake is commonly adopted for carbide-tipped tools in heavy/high-speed work.


Verification / Alternative check:
ISO insert geometries and chipbreaker designs frequently feature negative basic rake with engineered chip grooves to moderate cutting forces.



Why Other Options Are Wrong:
Positive rake is used for low-power machines and gummy materials but compromises edge strength. Zero rake is sometimes used, but not the typical choice for robustness across conditions. Exotic alternating rake edges are impractical.



Common Pitfalls:
Applying negative rake on a flimsy setup can induce chatter; ensure sufficient rigidity and appropriate feeds/speeds.



Final Answer:

Negative rake angle

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