Runout versus Ovality
3

Question

Runout versus Ovality

bugs11 (Automotive)

(OP)

26 Jul 16 17:44

Hello all,
There is a difference of opinion when sitting on the same face of a part that you are checking either runout or ovality. While sitting on face A there is a probe on that same face A monitoring 360° movement. Some say Runout some say Ovality. What is the real answer?

Thank you all in advance for answers.

gearcutter (Industrial) · Answer 1 · 2016-07-26 20:28:00

You need to define how the surface you're measuring relates to the datam you've chosen to use. You also need to define which drawing/measurement standards you're using as different standards use different terminology.
Other terms to consider are perpendicularity, parallelism, out-of-round, concentricity, etc.

BrianE22 (Specifier/Regulator) · Answer 2 · 2016-07-26 21:04:56

I'd say you are measuring runout. Runout can be made up from different specific contributors like ovality.

GregLocock (Automotive) · Answer 3 · 2016-07-26 21:12:19

Roughly speaking if it has two highs and two lows per rev it is ovality, one high and one low it is runout. Roughly.

Cheers

Greg Locock

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tbuelna (Aerospace) · Answer 4 · 2016-07-28 01:33:27

I don't believe the ASME Y14.5 GD&T standard describes an "ovality" characteristic. This condition would usually be toleranced with a cross section profile defined by basic dimensions, and a geometric profile tolerance callout referencing the basic profile.

GregLocock (Automotive) · Answer 5 · 2016-07-28 11:13:58

Hate to break it to you but for some applications the third order variation ie three waves per rev is also called out.

Cheers

Greg Locock

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tbuelna (Aerospace) · Answer 6 · 2016-07-31 01:19:58

GregLocock-

Your post regarding ovality and harmonic analysis of radial profile shapes was helpful. I did some reading on the subject and learned that ovality describes a specific runout profile having 2 undulations (or lobes) per revolution (UPR). The harmonic characteristics of a runout profile, such as ovality, are often evidence of certain problems with the set-up/process used to manufacture a precision cylindrical part. Below is an interesting chart on the subject from this brochure:

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Runout versus Ovality
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