The initial working part of the standard, ISO10360-2, is aimed at assessing the “volumetric length measuring” and “probing” uncertainty of a given machine.In order to identify between the two aspects, this part of the standard is further broken down into two elements, namely ISO10360-2 “E” for length and ISO10360-2 “P” for the probing.

ISO10360-2 “E” for length

Where does the volumetric length measuring element “E” apply?

Basically all length dependant features such as: distances, diameters and position tolerances.

How is this part of the test performed?

A set of 5 length gauges are measured 3 times.This task is then repeated at a further 7 positions within the measurement volume which gives a total of 5 x 3 x 7, or 105 separate length results.

Length bar measurement

The results of each gauge artefact location are then plotted against an error budget as defined by the manufacturer. In the case of the “E” term, a typical error statement would be 2+3L/1000 microns.

ISO10360-2 “P” for the probing

The volumetric probing error (P) applies to all form measurements:
  • Free form tolerances
  • Straightness
  • Flatness
  • Roundness
  • Cylindricity

Datum sphere calibration points 


Test procedure for the volumetric probing error (P)

A reference sphere is measured with 25 evenly distributed points.
P = (Rmax-Rmin= Sphere form)=> Form error of the CMM