Level of accuracy for Cencentricity

[[jo...]]

What level of accuracy can be expected when measuring a part with a Ø1.00" bore and inner bore diameter of Ø.682"

Engineering is requiring them to be concentric within .0002"

Can the GOM software and ATOS system measure that accurately using only photos and not probe touch points. 

 

Johnny C.

GOM Operator and Inspector 

Stroco Manufacturing 

[[St...]]

Hi Johnny,

if you would have said 0.002’’ my answer would have been yes we are able to inspect it with an ATOS system, although there is a lot of confusion and misinterpretation in terms of what is really meant by concentricity.
Buzz word here is the “elimination of the concentricity and symmetry” in the latest version of the ASME Y14.5 2018 standard. Because these were withdrawn in the standard the GOM Software 2021 also doesn’t support concentricity in respect to ASME in the latest Software version.  
But anyway, we are able to check the desired function by either coaxiality and or position and runout tolerances, or according to ISO standard.

But you didn’t say 0.002’’ you said 0.0002’’ which is an approx. ~ 5µm tolerance zone in my metric world. (I’m sorry but I’m better in calculating in meters). This is a very tight tolerance zone to be inspected and you must do a couple things right to investigate this even with very high accurate CMM machine. (temperature, alignment, quality and strategy of datum system measurement,  …).

So to figure out what the specific limit of your ATOS measurement volume is - I would suggest it would be the best to directly contact your local support team (I guess its Capture 3D in the US?) and to have a detailed look onto the drawing and the specifications of this specific inspection task.
May I ask what kind of application this is? 
Best regards
Stefan

[[Be...]]

Hi,

one additional note: If we are talking about a ~ 5µm tolerance zone there is a rule of thumb in the measurement departments all over the world: The accuracy of your measured data should have the factor of 10 in regards to your dimension (in this case the expected tolerance zone). This means an accuracy of 0.5 µm per point. This is quite hard to achieve even with "normal" cmm  (and the complete process of measurement stability like temperature stabilization etc).

Regards,

Bernd

[[Bo...]]

Sorry I of course do not have your answer only a follow up question which may assist us.

Is their a published method to determine the accuracy of the ATOS system if all of the required information is known?

If yes, would the determined accuracy be per surface point?

Thanks

Bob

[[Be...]]

Hi,

for questions regarding accuracy of measurement machines or sensors you have so much to consider (even if a corresponding datasheet suggests this) . An easy answer in a Forum is not possible from my point of view.

I recommend to contact your local GOM partner to discuss this topic in detail.

Regards,

Bernd

[[jo...]]

Please sign in to view this quote.

Thank you Stefan for the detailed response to my question. Yes it is a very tight tolerance zone and one that will be difficult to prove if awarded the job. I cannot say the part due to classifications and restrictions but it was brought to my attention but the bid/quote team here and they asked if it were possible for us to check accurately. I will follow up with our local rep for our ability to check said tolerance zones on our existing system.

Thank you again.