Runout versus Ovality 3

[bugs11]

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]

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]

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

 

[GregLocock]

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


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[tbuelna]

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]

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


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[tbuelna]

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: