End-of-life indicators for cutting tools in production machining In practical shop practice, a tool is considered to have reached the end of its useful life when which of the following symptoms appear during cutting?

Introduction / Context:
Tool life is a central concept in machining economics and quality control. In turning, milling, drilling, and grinding, a cutting edge gradually deteriorates until it can no longer maintain required accuracy, finish, or productivity. Recognizing the practical end-of-life indicators helps prevent scrap, spindle overloads, and unsafe conditions.

Given Data / Assumptions:

• Conventional metal cutting with either high speed steel or cemented carbide tools.
• Machine tools operating at steady feeds, speeds, and depths of cut.
• End-of-life is determined by process performance, not solely by microscopic wear measurements.

Concept / Approach:
As wear increases (flank wear, crater wear, notch wear), cutting mechanics deteriorate. Friction rises along the tool–chip and tool–work interfaces, increasing power draw and temperature. The worn edge rubs instead of shearing cleanly, degrading surface finish. These symptoms appear together near the end of useful life, prompting tool indexing or replacement.

Step-by-Step Solution:
Identify practical indicators: surface finish, power/force spikes, and visible smoke or discoloration from overheating.Relate each to wear: higher friction from dull edges → higher forces → more heat → oxidation/smoke and poor finish.Conclude that the simultaneous presence of these symptoms defines end-of-life in shop practice.

Verification / Alternative check:
Maintenance logs often show power trends rising shortly before scheduled tool changes. Surface profilometer readings degrade as flank wear approaches its limit (e.g., a specified wear land width). Operators also note audible changes (squeal) and visible sparking/smoke at failure.

Why Other Options Are Wrong:

• Poor surface finish alone (A) can arise from chatter or setup error; it is only one indicator.
• Force/power spikes alone (B) can also result from chip packing or coolant loss.
• Overheating/fuming (C) is a late symptom but not the only one.
• Only dimensional drift (E) ignores the coupled thermal and frictional effects typical at end-of-life.

Common Pitfalls:
Waiting for catastrophic edge failure; attributing rising power solely to material variability; ignoring coolant flow and chip evacuation, which can accelerate wear symptoms.

Final Answer:
all of the above