Festo Checkbox Compact CHB-C Series Manual page 98

5. Teaching parts
5.2.2 Observing the scatter of characteristics
C...
5−10
Observe the display when scanning the sample parts. It
shows briefly for each part the maximum value of the scatter
of characteristics for the current feature which differs to the
greatest extent (C−value).
The following factors influence the scatter of characteristics:
the parts geometry
different contours of the part, depending on the rotary
angle around the longitudinal axis (e.g. with springs,
screws)
different positioning on the conveyor device.
If the displayed C−value changes erratically, you have prob
ably placed the conveyed part incorrectly on the conveyor
device. If the C−value changes only minimally, a sufficient
scatter of characteristics in the current orientation has prob
ably been achieved. The optimum situation is when the curve
of the values changes at first considerably and then becomes
increasingly more constant.
Small values indicate narrow manufacturing tolerances and a
steady supply of parts. Very large values indicate that the
taught sample parts differ greatly from each other with re
gard to their properties. If the (good) parts are allowed to
differ greatly from each other, the Teach procedure can never
theless still be continued.
C−value Meaning
< 10 Sample parts are very similar in all features
> 30 Large scatter of at least one feature
An exact description of the arithmetical algorithm of the scatter of
characteristics can be found in the appendix A.3.2
Tab. 5/1: C−value (scatter of characteristics)
Festo P.BE−CB−COMP−en en 0503c