Taylor’s tool life equation VT^n = C: The exponent n primarily depends on which factor in practical machining?

Introduction / Context:
Taylor’s tool life law VT^n = C encapsulates how cutting speed V influences tool life T, with n and C as empirical constants. The exponent n indicates sensitivity of life to speed; a higher n means a small increase in speed shortens tool life dramatically.

Given Data / Assumptions:

• Conventional single-point machining at fixed feed and depth.
• Comparing classes of tool materials: HSS, carbides, ceramics, CBN, PCD.
• Reasonably consistent working conditions.

Concept / Approach:
Empirical data show that n depends mainly on tool material (and the wear mechanisms it resists). Typical values: HSS n ≈ 0.08–0.15, carbide n ≈ 0.2–0.3, ceramic/CBN higher still. While work material and conditions influence C and scatter, the dominant, textbook-cited dependency for n is tool material class.

Step-by-Step Solution:

Verification / Alternative check:
Data tables list distinct n values by tool material; changing workpiece shifts C more visibly than n for a given tool class.

Why Other Options Are Wrong:

• Work material matters but does not chiefly set n across materials.
• Working conditions alter scatter and C; n remains characteristic.
• Chip type is a consequence, not the primary determinant of n.

Common Pitfalls:
Assuming n is universal; in reality, it varies with tool material and specific wear mechanisms (diffusion, abrasion, oxidation).

Final Answer:
tool material