GD&T concept check: which term describes the state in which a finished feature contains the maximum amount of material allowed by its size tolerance (for example, smallest hole or largest shaft)?
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AMaximum material condition
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BMachined material condition
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CMaximum machined indication
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DMachine mark indication
Answer
Correct Answer: Maximum material condition
Explanation
Introduction / Context:Geometric tolerancing often references material condition modifiers to relate permissible geometric error to part size. Understanding these states is key for functional gaging and tolerance stack analysis.
Given Data / Assumptions:
- A feature of size (hole or shaft) has stated limits.
- We consider the condition with most material present.
- Standard GD&T terminology is used.
Concept / Approach:Maximum Material Condition (MMC) is the size at which a feature contains the most material: for a shaft, the largest permissible diameter; for a hole, the smallest permissible diameter. It is commonly marked with the MMC symbol in feature control frames.
Step-by-Step Solution:
For shafts: more material → larger size within tolerance → MMC at upper limit.For holes: more material → smaller size within tolerance → MMC at lower limit.Therefore, the correct term is Maximum Material Condition.Verification / Alternative check:Functional gages often simulate virtual condition boundaries based on MMC; parts that pass such gages will assemble in worst-case scenarios.
Why Other Options Are Wrong:
- Machined material condition / Maximum machined indication / Machine mark indication: Nonstandard or incorrect terminology.
Common Pitfalls:Confusing MMC with Least Material Condition (LMC), which is the opposite (smallest shaft, largest hole).
Final Answer:Maximum material condition