Defining and assessing machinability Which set of practical indicators is commonly considered together when evaluating the machinability of an engineering material?

Introduction / Context:
Machinability expresses how easily a material can be machined to the desired finish and accuracy. It is not a single property but a practical assessment derived from several measurable indicators under specified conditions.

Given Data / Assumptions:

• Comparable cutting conditions (tool, speed, feed, depth of cut) across materials.
• Objective measures available: forces, tool wear, chip form, power, and surface finish.

Concept / Approach:
Good machinability means lower cutting forces/power, longer tool life, and favorable chip forms (continuous without BUE). Shear angle trends also indicate ease of shearing. Considering multiple factors gives a robust evaluation rather than relying on a single metric.

Step-by-Step Solution:
Record cutting forces/power → lower values suggest easier cutting.Measure tool life → longer life at given conditions implies better machinability.Observe chip type and shear angle → favorable chip flow and larger shear angle indicate improved machinability.Combine indicators for a comprehensive rating.

Verification / Alternative check:
Machinability rating charts compare materials using normalized baselines (e.g., free-machining steel) considering several indicators.

Why Other Options Are Wrong:
Each single indicator (A, B, C) is valid but incomplete; relying on surface roughness alone (E) ignores tool wear, power, and chip control.

Common Pitfalls:
Comparing machinability across different tools or parameters; ignoring coolant effects; failing to define the measurement method.

Final Answer:
all of these