How best to ask for CMM data ?

[motomartin]

We have an expensive large bearing set manufactured and CMM'd by our sub-contractor.
The Data he is sending us is largely rubbish - consisting of 2 unreferenced columns of txt data -( X,Y) and an un-datumed DXF file with offset profiles and no other information.

What can i reasonably ask him to supply that is useful?

We have solidworks cad.

Thanks

 

[Kapitan]

I would request a proper drawing of the part being measured, showing the coordinate system the CMM operated in, with respect to the part. You must know where the origin is, what plane it is on and what datums were used, so that the coordinate system can be defined in the SW model, before the CMM measurement points are imported into that model.

The dxf file should have more information than (X,Y), the CAD system will need a (Z) value. What does 'offset profiles' mean, is it any thing do with the probe spherical radius ?

If the CMM was driven by a program to goto pre-determined points then the two files can be compared to each other to give a file of differences, which can be further analized.

The sub-contractor should supply enough information so that there can be no doubt, and no assumptions have to be made.

 

[CMfgE1]

Agree with Kapitan. If the supplier does not give you useful information I would consider another contractor.
There are hundreds of companies that do this. And frankly they should know what info to give you. Give them a shot to redeem and if they still are not helpful, ship themout and get somebody else.


Good Luck!

Quote: "Its not what you know, its who you know"
Everythings a learning experience-Everything

 

[RRBD]

Your sub is probably accustomed to reading the same data he gives to you. Heres what you do...Make your own conformance report, have a drawing and a couple of columns, one with the print dimension and the other they fill in the actual dimension and require they fill it out and sign it off, it pretty common nowadays

 

[segges]

I am not sure if I agree with CMfgE1 in that companies should know what information to provide you. Frankly, they should know what the print asks for, what they need to produce the part to print and other related specs. Anything beyond that should be clearly stated somwhere else like the RFQ or your own specification sheets, which you should be providing to the vendor. It is entirely possible that the info you are now getting is perfectly usable and valid as long as you both use the same QC process. At the same time, the info you need may be completely useless for the manufacturig process, in which case they have to do an additional operation to get the info to you. But anyway, I think your question was in the first place that what would be reasonable to require from the supplier. The simplest answer is that it is your product, you apparently know what you need, so write it down and specify it in the drawing or the RFQ, from then on it will be responsibility of the supplier to provide it with the finished goods.

 

[metrologyman]

I work for an A2LA acc. Lab. We do a lot of custom inspection for other companies on our CMM & Vision system. We use excell and list each dim. on the print in one colum with tolerance,then the actual measured value. We also make note of out of spec. dimensions. This method is simple and easy to understand.

 

[billy8581]

when i worked at my old company the used various cmm machines and all the measurments taken had some kind of reference to a drawing size tolerance etc I saw many reports with actual features listed with sizes and it was very easy to follow, maybe u could suggest they do something similar