Taylor’s tool life equation VT^n = C: The exponent n primarily depends on which factor in practical machining?
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Awork material
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Btool material
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Cworking conditions (coolant, rigidity, etc.)
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Dtype of chip produced
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Edepth of cut only
Answer
Correct Answer: tool material
Explanation
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:
Recognize n as slope in log V–log T plots.Note that wear behavior changes with tool materials (hot hardness, chemical stability).Conclude n primarily depends on tool material class.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