CONCENTRICITY

LOCATION

Controls the median points of a cylindrical feature to a datum axis

⚠ DATUM REQUIREDASME Y14.5-2009 §7.6 (removed in 2018)

Concentricity controls all median points of a cylindrical or spherical feature relative to a datum axis. Every cross-sectional midpoint must fall within a cylindrical tolerance zone centered on the datum axis. Note: concentricity was removed from ASME Y14.5-2018 — use position or runout instead.

WHEN TO USE IT

Concentricity was historically used for rotating parts where mass balance was critical. Per ASME Y14.5-2018, it has been removed in favor of position (for location) or circular/total runout (for functional surface control). Only use concentricity if working to an older standard like Y14.5-2009.

COMMON MISTAKES

Using concentricity on drawings governed by ASME Y14.5-2018 — it was removed from the 2018 standard

Using concentricity when runout would better serve the functional requirement

Omitting the datum reference — concentricity always requires a datum axis

Confusing concentricity with circular runout — runout is easier to inspect and preferred

IS YOUR CALLOUT CORRECT?

Check these before releasing your drawing.

Is the drawing governed by ASME Y14.5-2009 or earlier?

Concentricity was removed in the 2018 standard. Use position or runout for 2018-compliant drawings.

Does the FCF include a datum axis reference?

Concentricity always requires a datum axis reference.

Would circular runout or total runout better serve the functional requirement?

Runout is generally preferred — it is easier to measure and captures the same functional intent.

RELATED SYMBOLS

OTHER LOCATION CONTROLS

⊕Position ⌯Symmetry

Redprint checks concentricity automatically

Redprint flags concentricity callouts on drawings referencing ASME Y14.5-2018, since concentricity was removed from that standard.

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