Cylindricity Callout

[Kam40819]

I currently have a part that has a an OD with a total tolerance of .0012. This same part has a cylindricity callout of .005 in the Free state. This is a thin wall part which tends to be out of round while machining it. It is my understanding that the callout for cylindricty needs to be smaller than the total tolerance of the feature.
To be honest I do not believe that the customer truly care if the part is out of round when it is sent to them as long as it is within .005 in the free state which is not a problem. However the callout on their drawing shows cylindricty.
Am I wrong in my thinking that the customers callout is incorrect? I have done a lot of research regarding this and just want to make sure I cover all avenues prior to asking the customer to change a print they have been using for years. Any help is greatly appreciated.

Jay

 

[greenimi]

IMHO, accordin to Y14.5 ASME standard, the cylindricity tolerance must be a refinement of the total size tolerance.

 

[Belanger]

The cylindricity tolerance must be less than the size tolerance, with the exception of "parts subject to free-state variation" (paragraph 5.4.4 of Y14.5). So it looks like they are actually OK in doing that. However, that raises a question about how they expect the diameter to be verified. Is there any note about "AVG" (average)?

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[powerhound]

Other exceptions are if either a note stating "PERFECT FORM AT MMC NOT REQUIRED" is associated with the size dimension OR if a circle I is associated with the size dimension.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[fsincox]

I believe the whole intent of specifying "FREE STATE" is to trump, or note, that rule 1 will not apply to this in the FS, therefore I would say it is OK.
Frank

 

[Kam40819]

Thanks for all of the information it is greatly appreciated and extremely helpful. There is no note to use an average on the diameter of the part. However the OD must be restrained in order to check the ID per a call out. With this given plus the Cylindricity in the Free State I believe in seeing the example Fig. 5-13 in 5.4.4 that the diameter is implied to be averaged in in the Free State.
Maybe I am misunderstanding that information but we have been shipping this part for years it just becomes a problem with certain inspectors who didn't understand the callout. I wanted to be certain I understood it before I go any further and this has helped me realize that the mentality here was incorrect and that the "customer is always right".
Thanks again for the help!