Maximizing material removal rate (MRR) at the same tool life In turning/milling practice, if the allowable tool life must remain unchanged, which single change most effectively increases the volume of material removed per minute?

Introduction / Context:
Material removal rate (MRR) is a key productivity metric in machining. However, productivity must be balanced against tool life. This question examines which parameter change most effectively boosts MRR while holding the allowed tool life constant, a classic optimization trade-off in manufacturing engineering.

Given Data / Assumptions:

• Tool life must remain the same (constant allowable life).
• Classical Taylor tool life relation applies: V * T^n = C.
• MRR in turning is approximated by MRR = f * d * Vw (units consistent), where f is feed, d is depth of cut, and Vw is work surface speed.
• Within safe power, rigidity, and surface finish limits.

Concept / Approach:
Cutting speed V has a strong influence on tool life through the Taylor exponent n (often 0.1–0.3 for HSS/carbide). Feed and depth also affect life, but typically with smaller exponents in extended models. For a fixed life, increasing V is restricted; increasing feed (and, secondarily, depth) raises MRR markedly with less penalty to life compared with speed increases.

Step-by-Step Solution:
Start from Taylor: V * T^n = C ⇒ at constant T, V is essentially fixed by C and n.Express MRR: MRR ∝ f * d * Vw. If Vw (related to V) cannot increase much at constant T, target f and d.Feed directly multiplies MRR and is usually the first lever before depth for chip-load efficiency and stable cutting.Therefore, increasing feed rate maximizes MRR under the same tool life constraint.

Verification / Alternative check:
In practical shop economics, the “maximum production rate” or “minimum cost” settings derive from balanced f–d–V; charts show that modest speed with higher feed often yields high MRR at acceptable tool life.

Why Other Options Are Wrong:
(a) Increasing cutting speed sharply reduces tool life at constant f, d; not allowed under the constraint. (b) Decreasing speed reduces MRR. (c) Increasing depth of cut helps MRR but is usually the second lever after feed and may hit power/rigidity limits sooner. (e) Nose radius affects finish and tool strength more than MRR directly.

Common Pitfalls:
Assuming speed is the only path to higher MRR; ignoring machine power, chatter, and surface roughness limits when raising feed.

Final Answer:
Increasing the feed rate