Taylor tool-life exponents: In the relation V * T^n = C, the usual range of exponent n for high-speed steel (HSS) tools is stated as 0.25 to 0.40. Is this statement correct?

Introduction / Context:
Taylor’s tool life equation, V * T^n = C, is a fundamental empirical relation in machining. The exponent n depends strongly on the tool–work combination. Knowing realistic ranges for n helps in estimating how speed changes will affect tool life.

Given Data / Assumptions:

• Tool material under consideration: HSS.
• Proposed range for n: 0.25 to 0.40.
• General steel machining under normal conditions.

Concept / Approach:
For HSS, n is typically small because HSS is sensitive to temperature; modest increases in speed drastically reduce tool life. Commonly cited ranges are around n ≈ 0.08 to 0.20 for HSS depending on work material and environment. Higher exponents in the 0.25 to 0.40 range are more characteristic of carbides and some ceramics or coated tools where hot hardness is superior.

Step-by-Step Solution:

Verification / Alternative check:
Shop references and textbooks list example values: HSS often n ≈ 0.1; uncoated carbide n ≈ 0.2–0.25; coated or cermet tools can be higher, corroborating the reasoning.

Why Other Options Are Wrong:
Agreeing would misattribute carbide-like behavior to HSS, overestimating HSS tolerance to speed increases.

Common Pitfalls:
Using a single n value universally; n varies with coolant use, work material, and wear criterion (e.g., flank wear land). Always treat ranges as indicative, not absolute.

Final Answer:
Disagree