Runout and Concentricity 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 Runout and Concentricity flashcards as text
A turbine rotor requires tightly controlled vibration during operation. Which GD&T control best addresses dynamic balance concerns related to surface geometry?
Answer: Total runout on the rotating cylindrical surfaces
Total runout on cylindrical surfaces controls all geometric deviations that contribute to mass imbalance and vibration in rotating equipment.
Which statement correctly compares the verification complexity of concentricity versus coaxial position?
Answer: Coaxial position is easier because it can be verified using a functional gauge or CMM axis measurement
Coaxial position (axis-to-axis) can be verified with a functional gauge or CMM axis fit, while concentricity requires finding median points which is mathematically complex.
A circular runout symbol (single arrow circle) is placed on a drawing. What is the standard symbol used?
Answer: A circle with a single diagonal arrow
The circular runout symbol in GD&T is a circle with a single diagonal arrow, distinguishing it from total runout which uses a double arrow.
For a part with both runout and position callouts on the same surface, which takes precedence?
Answer: Both must be independently satisfied; neither overrides the other
When both runout and position are called out on the same feature, each must be independently verified and satisfied.
A design engineer specifies runout instead of cylindricity on a bearing journal. What is a key advantage of this decision?
Answer: Runout relates the surface to a datum axis relevant to function, while cylindricity does not reference a datum
Runout ties surface quality to the functional datum axis (how the part actually rotates), while cylindricity only controls the surface form without a datum reference.
What effect does surface roughness have on runout measurement?
Answer: High surface roughness can artificially increase the FIM reading beyond actual geometric error
A rough surface can cause the dial indicator tip to bounce or skip, inflating the FIM reading beyond the true geometric runout error.
A drawing notes circular runout of 0.04 on a surface WITHOUT a diameter symbol (⌀). What does this imply?
Answer: The tolerance applies to individual cross-sections measured perpendicular to the datum axis
Circular runout without a diameter symbol applies at individual cross-sections perpendicular to the datum axis, which is the standard interpretation of circular runout.