Apex Metrology - cmm and metrology equipment uk

Apex Metrology - cmm and metrology equipment uk


Program Validation

Changes to Coordinate Measuring Machine (CMM) requirements.

Recently certain aerospace suppliers have upgraded their approval criteria. They now require suppliers using Coordinate Measuring Machines to ensure that CMM programs have been validated by independent third parties.

The motivation for this may be to ensure;
•    The correct Design authority and procedures have been followed.
•    Each datum has been applied appropriately.
•    The tolerances have been interpreted correctly.
•    The features have been probed / scanned to proprietary programming guidelines.
•    That no features have been missed out from the results output.
•    The program output is clearly readable by operators.
•    The probe styli have been referenced correctly.
•    The program instructions show adequate calibration, set up, and running guidance.

These measures will significantly reduce risk of errors causing lost production, and potentially much more costly failures in service.

1. Make valid; substantiate; confirm.
2. Giving legal force to; legalize.
3. Elected officials give official sanction, confirmation, or approval to, procedures, documents.

When a CMM is used to over check components it may appear that the machine is accurate enough for the job if its specification exceeds the requirements of the drawing.

However, the CMM accuracy is based on Linear and Volumetric length checks, the accuracy of actual measurement influenced by other parameters eg.  the length of probe tip stylus used, the number of points taken on the feature, the form of the feature, the surface texture of a scan, and its geometric relationship to corresponding features.

There also needs to be a check of the repeatability of the measurement; as on subsequent batch measurements production variations in the sizes of features may cause mis-probing. This is especially so when larger positional tolerances allow small individual features to ‘float around’.

Apex Metrology Ltd provides :
•    Independent resource for program validation.
•    No risk of being in a competitive situation – Apex Metrology Ltd don’t machine any part !
•    Fully qualified Engineers who can assist with program creation & sign off.
•    Experienced CMM Program validation Engineers.
•    Offline programming resource including Mcosmos, PCDMIS, MODUS, DMIS.
•    Online programming 1500x2000 CMM running Mcosmos, PCDMIS, MODUS, DMIS.
•    CMM prove-out resource should your CMM be fully utilised for production.
•    A fully documented validation program that can be used as part of your customer supplier quality pack. The procedure is accepted by the aerospace industry.
•    CMM prove-out resource should your CMM be fully utilised for production.

Validation will also assist in reducing non-conformances and customer returns as they are addressed at a much earlier stage in the manufacturing process.
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