Symbols and Rules Flashcards
7 cards from real GD&T practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Symbols and Rules flashcards as text
Which of the following best describes the 'unilateral' profile tolerance symbol introduced in ASME Y14.5-2009?
Answer: A 'U' in a circle with a value indicating how much of the zone shifts outside the true profile
The unequal (unilateral) profile modifier uses a circled 'U' followed by the amount of the zone that falls outside the true profile, shifting the bilateral default.
What is the key difference between concentricity and coaxiality in modern GD&T practice (ASME Y14.5-2018)?
Answer: Concentricity controls derived median points; coaxiality controls the axis using MMC/LMC modifiers
Concentricity is an RFS control of derived median points (difficult to measure), while coaxiality uses the axis and allows MMC/LMC for easier functional gaging.
A straightness tolerance applied to the surface of a cylinder (not its axis) creates a tolerance zone that is:
Answer: Two parallel lines on the surface in the direction of measurement
Surface straightness controls each line element of the cylinder surface within two parallel planes (lines in 2D), independent for each longitudinal line element.
Which GD&T symbol is used to indicate that a dimension is for reference only and does not govern production or inspection?
Answer: Parentheses around the dimension value
Reference dimensions are enclosed in parentheses to indicate they are informational only and are not to be used for manufacturing or inspection purposes.
The 'statistical tolerance' symbol (ST) in a feature control frame indicates that the tolerance:
Answer: Is valid only when statistical process controls are in use during manufacturing
The ST symbol means the tolerance is valid only if the manufacturing process is controlled using statistical methods (SPC), allowing slightly larger individual tolerances.
In a GD&T position callout for a pattern of holes, the 'simultaneous requirement' means:
Answer: All features in the pattern are located relative to the same datum reference frame in one setup
The simultaneous requirement means that all features sharing the same datum reference frame are treated as a single pattern and inspected in one setup.
Which of the following is the correct GD&T symbol for 'total runout'?
Answer: Two arrows pointing in opposite directions along a surface line
Total runout is represented by two arrows pointing in opposite directions (a double-headed arrow), distinguishing it from circular runout's single-headed arrow.