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Reported parameters

What are the reported parameters the MCG tools provides?

The analysis reports various parameters that are displayed on the page 'Data' and on the page 'Analysis'.

The 'Sphere' section

MCG sphere

The parameters of the best fitted sphere are displayed as 'Radius' and 'Centre O' with its three co-ordinates O.x, O.y and O.z.

The radial errors from the best fitted sphere are analysed, the minimum and maximum errors are displayed as well as the span (max-min) and the standard deviation of the radial errors.

The admissible error is computed from the CMM accuracy formula and the MCG arm length used for the test.  The maximum absolute error is also reported to ease the comparison with the machine specification.

The 'Identified geometrical errors' section

Identified geometrical error

 The section displays:

  • Three relative scale errors
  • Three squareness errors
  • Remaining radial errors are analysed as the raw sphere radial errors
  • The minimum and maximum errors, the span (max-min) and the standard deviation of the remaining form errors
  • This form errors analysis that is virtual calculates the machine performance if the six CMM errors were corrected

The 'Pivot' section

MCG pivot

During the analysis of the form errors a pivot offset is best fitted in order to identify whether the centre of the elliptical form errors differs from the sphere centre.  A big offset would indicate that either some data points are incorrect or that the machine has important errors that are not squareness or scale errors.  What is considered as A BIG offset?

The 'Database' section

When a data set has been analysed the results can be archived.  The 'Record in Database' button will copy the results and the set up parameters in the workbook data base.  See the section 'What is archived' for more details.

The 'Gain' section

The geometrical errors are also displayed on the 'Analysis' page as circular plot.  The form errors are multiplied by a gain that can be changed on the 'Data' page.  In order to take effect, the data has to be reanalysed by clicking the 'Calculate' button again.