Atlas Copco PowerMACS 4000 User Manual

SPC and Statistics
9836 3521 01 405
Calculation of the process capabilities Cp and Cpk:
 
 
i
i
slsu
LTLUTL
Cam
ssl
LTLX
ssu
XUTL
Cpk
sslsu
LTLUTL
Cp
tableseecmi
c
S
s
or
tableseedmi
d
R
s
k
dd
d
R


*
*
,
*
min
*
):(..1;
):(..1;
864,0
645,1
''
'
4
4
'
2
2
'
5*5
*5




















where
 for a normal distribution su = sl = 3
 d5 = 2.326 for subgroup size = 5
 k = no of subgroups to calculate
Cam is only calculated for subgroup size = 5, and requires range to be collected. Cam is not applicable to
standard deviation.
An error event is generated if the value of Cam, Cp or Cpk is out of limit.
When SPC is wanted for a station, not for its individual bolts, the calculations are made on those variables
that happen to be set up for data collection on that station.
Station, Program, Step and Variable are still defined, so only variables matching those criteria are used.
It is not possible to specify alarm limits or control limits for SPC calculated on a station.The weighing
together of values for the separate bolts are done for each subgroup according to the following rules:

Atlas Copco PowerMACS 4000 Specifications

General

Brand	Atlas Copco
Model	PowerMACS 4000
Category	Power Tool
Language	English