Difficulty: Easy
Correct Answer: Coarse grained
Explanation:
Introduction / Context:
Wheel grit size determines chip accommodation and the aggressiveness of cutting points. For soft, ductile work materials, the tendency to smear and clog the wheel must be countered by appropriate grit selection.
Given Data / Assumptions:
Concept / Approach:
Coarse grains create larger chip spaces, reduce wheel loading, and promote a free-cutting action. This is often paired with a softer grade and more open structure to enhance self-sharpening.
Step-by-Step Solution:
Verification / Alternative check:
Shop practice and grinding handbooks recommend coarse grit/open structure for soft metals to avoid glazing.
Why Other Options Are Wrong:
Fine and dense wheels quickly load on soft materials; medium grit may still be inadequate. Extra-hard grades exacerbate glazing rather than prevent it.
Common Pitfalls:
Attempting to improve finish on soft metals with excessively fine grit; finish often worsens due to wheel loading and heat marks.
Final Answer:
Coarse grained
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