ASME ASME Geometric Dimensioning and Tolerancing 1 — Questions and Answers
Question 1: Which ASME standard governs Geometric Dimensioning and Tolerancing (GD&T) in the United States?
- ASME Y14.2
- ASME Y14.5 (Correct answer)
- ASME Y14.8
- ASME B46.1
Correct answer: ASME Y14.5
ASME Y14.5 is the standard for Geometric Dimensioning and Tolerancing used in US engineering drawings.
Question 2: In GD&T, what does the feature control frame symbol ⊕ represent?
- Straightness
- Flatness
- Position (Correct answer)
- Circularity
Correct answer: Position
The bullseye symbol (⊕) in a feature control frame represents the position geometric characteristic.
Question 3: What is the purpose of a datum reference frame in ASME Y14.5 GD&T?
- To define material condition modifiers
- To establish a coordinate system from which measurements are made (Correct answer)
- To specify the surface finish of a part
- To indicate the assembly sequence
Correct answer: To establish a coordinate system from which measurements are made
A datum reference frame establishes the three mutually perpendicular planes from which part features are located and measured.
Question 4: Under ASME Y14.5, what does the modifier ⓜ (circle M) mean when applied to a position tolerance?
- Maximum Material Condition (Correct answer)
- Minimum Material Condition
- Regardless of Feature Size
- Projected Tolerance Zone
Correct answer: Maximum Material Condition
The ⓜ modifier specifies Maximum Material Condition (MMC), meaning the feature has the most material — smallest hole or largest pin.
Question 5: Which GD&T characteristic controls the form of a surface to be within two parallel planes?
- Straightness
- Parallelism
- Flatness (Correct answer)
- Perpendicularity
Correct answer: Flatness
Flatness controls the form of a surface by requiring all surface points to lie within two parallel planes separated by the tolerance value.
Question 6: In GD&T, 'Rule #1' (the Envelope Principle) states that:
- All tolerances are independent of feature size
- A perfect-form envelope at MMC must not be violated (Correct answer)
- Datum features must be flat and cylindrical
- All GD&T requires datum references
Correct answer: A perfect-form envelope at MMC must not be violated
Rule #1 requires that a feature of size must not violate a perfect-form envelope at its Maximum Material Condition boundary.
ASME ASME Geometric Dimensioning and Tolerancing 1
Which ASME standard governs Geometric Dimensioning and Tolerancing (GD&T) in the United States?