FISCHER FISCHERSCOPE X-RAY XDLM 231, Operator'S Manual

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Measurement device monitoring for the Fischerscope X-RAY Long-term monitoring
124 FISCHERSCOPE
®
X-RAY
The protocol shows the video image of the reference sample that
the camera of the Fischerscope XRAY has recorded. The
measurement area is identified by an orange-colored ring, the
measurement spots where the instrument made individual
measurements during the pre-run are identified by yellow crosses.
Even though the reference area is small compared to the
dimensions of the sample, the distribution of the coatings within the
reference area can be non-uniform. Because during the check
measurement any measurement spot may be selected within the
reference area, a potential inhomogeneity of the coating
thicknesses must already be taken into account during the pre-run.
If the lower and upper limits are too far apart in reference to the
confidence interval, then the reference sample is not suitable due
to a non-uniform coating thickness within the reference area or
because the sample cannot be positioned and measured in a
reproducible fashion. It is then recommended to use a different
specimen as a reference sample.
15.10 Long-term monitoring
After the pre-run, the user is to make at regular intervals new
measurements at the reference sample, or the calibration standard,
respectively, that were used for the pre-run. For practical purposes,
the time intervals should be specified according to the difficulty of
the measurement application (see above). Each new group
provides a point for
x. (spoken as x_bar) in the control chart and a
point for s (thus, the respective quality control charts are also called
x_bar / s-charts). As has already been shown above, the control
limits can also be calculated automatically by the WinFTM software
even without knowledge of the equations. One control chart each is
required for each reference sample and for each feature. This,
however, is already being taken into account by the software.
Upper and lower violations of the control limits suggest to correct
the measurement application by taking the corrective measures
recommended by us. Then a second group is measured in order to
evaluate the success of the corrective measures. If the values
continue to be outside the control limits, a new calibration may
provide help (however, with the disadvantages and limitations that
were mentioned above).
A stability test should be performed if frequent corrections become
necessary because there is suspicion that the stability of the
instrument is not ensured and maintenance or repair including
replacement of components may be necessary. In such cases, the
user should entrust his problem and help to the support and service
personnel of FISCHER.