117
MC see main controller
n.c. not connected – the named pin is not connected
NOK not error free
OK error free
Power unit Component for the motor control of the screwdriver
Process ability index (C
p
) C
p
= total specific torque tolerance of the
Connection: 6 Sigma (s).
This index just provides information about the spread angle of
the torque values.
s
tlower_limitupper_limi
C
p
6
Process capability coeffi-
cient (C
pk
)
Is defined as the minimum of:
1.)
s
tlower_limitupper_limi
C
pk
3
or
2.)
s
tlower_limimean_value
C
pk
3
This index provides information about the placing as well as
the spreading of torque values.
The lower acceptable C
pk
- value for a screwdriver is 1.33
(corresponds to a calculation of the C
pk
on limits of 4 Sigma
(s)).
C
p
/ C
pk
Limit values
within limit
values
Error contri-
bution
0.30
s
68.3 > 30%
0.70
2s
95.4 ~ 5%
1.00
3s
99.7 3
1.33
4s
99.994 60 ppm
1.63
4.891s
99.9999 1 ppm
1.66
5s
99.99994 0.6 ppm
2.00
6s
99.9999998
The mean value must not deviate from the target value by
more than 3%!!!
A correct statement about the process capability index is
then no longer possible.
Process capability ex-
amination
Prior to using a processing device for the series production it
is possible to check if the requirements are met with sufficient
safety.
It is the objective of the process capability examination to ver-
ify that
a) the process to be examined is processing with the recog-
nizable are legality. If legality is not recognizable then the
process has no defined capability. Especially then it is not
permissible to allocate a statistically calculated capability
characteristic.
b) the process is able to produce the parts in the indicated
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