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Operator‘s Manual FERITSCOPE
®
FMP30
Glossary
mean value. A negative skewness indicates a distribution whose peak
stretches more towards values that are smaller than the mean value. The
skewness of symmetric distributions is zero (e.g., for normal distribu-
tions). When evaluating the open Application with the FERITSCOPE
®
FMP30, the skewness is calculated according to the information in /
20 /.
SPC
Statistical Process Control.
Statistical Process Control (SPC)
SPC chart
Process control chart (quality control chart, SPC chart)
Specifications
Requirements according to which production is defined within certain
limits for variable and attributive properties, like for instance the lower
and the upper specification limit for the
-ferrite content. Quality control
monitors adherence to these requirements.
Specification limits (LSL and USL)
The lower specification limit LSL is the minimum
-ferrite content allowed
for the measuring object. The upper specification limit USL is the maxi-
mum
-ferrite content allowed for the measuring object. Specification
limits are usually set by engineering requirements to assure proper func-
tioning or serviceability of the product (
fication limits monitoring enabled,
b
appears on the display of the FER-
ITSCOPE
®
FMP30.
Specimen
Stability
As with every process, test methods are also subject to deviations. This
may lead to systematic measurement errors (e.g., drift), independent of
handling. By examining the stability and by regular checks, one can en-
sure stability.
Standard
Standard deviation
Statistical Process Control (SPC)
A quality control method. In high volume productions, only random sam-
ples are taken instead of 100% inspection which would be too costly.
The measurement results of the random samples are extrapolated for the
entire production lot with mathematical-statistical methods, and then