Atlas Copco PowerMACS 4000, User Manual

Page: 404 / 668

SPC and Statistics
404 9836 3521 01
Calculation of Average of Range or Standard deviation:
R
R
m
i m
and
S
S
m
i m
i
i
 
 


; ..
; ..
1
1
Calculation of Control levels (if enabled):
UCL X A R
LCL X A R
UCL D R
LCL D R
or
UCL X A S
LCL X A S
UCL B S
LCL B S
A D D and A B B see table
X
X
R
R
X
X
S
S
 
 


 
 


2
2
4
3
3
3
4
3
2 4 3 3 4 3
*
*
*
*
*
*
*
*
, , , , :
Check and alarm (if enabled) if following happens with Average or Range or Standard deviation:

one value outside control levels (One out)

points consecutively increasing (Seven up)

7 points consecutively decreasing (Seven down)

7 points consecutively above average (Seven above)

7 points consecutively below average (Seven below)

>90% in mid third (Mid gather)

<40 in mid third (End gather)