Download Quality Management

Exercise – process capability
• For an overhead projector, the thickness
of component is specified to be between
30 and 40 millimeters. Thirty samples of
components yield a grand mean ( x ) of
34 millimeters with a standard deviation
(̂ ) of 3,5. Calculate process capability
index. If the process is not capable, what
proportion of a product will not conform?
Exercise – Xmean, and Range
chart
Obs1 Obs2
day1
6
6
day2
8
6
day3
day4
7
6
6
7
Obs3
5
6
Obs4
7
7
6
5
6
4
Exercise – X and MR chart
• The following table shows
the daily trips. The trucks
generally take 6,5 hours
to make the daily trip. The
owner want to know
whether there is any
other reason of the
increasing delivery time,
or it just depend on the
traffic.
• Use X chart and MR chart
to determine.
Travel Time
MR
6,2
-
6,1
0,1
6,5
0,4
7,2
0,7
6,8
0,4
7,7
0,9
1,7
1,5
1,3
1,1
0,9
0,7
0,5
0,3
0,1
-0,1 1
1,5
2
2,5
3
3,5
4
4,5
5
Example – Median chart
• The table below contains observations of a
process. Use median chart and determine,
whether the process is in control.
Obs 1
Obs 2
Obs 3
Obs 4
Obs 5
1,1
1,2
1,4
1,5
1,6
1
1,02
1,5
1,6
1,6
1,2
1,4
1,4
1,4
1,5
1,3
1,3
1,3
1,5
1,6
1,7
1,6
1,5
1,4
1,3
1,2
1,1
1
1
2
3
4
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
1
1,5
2
2,5
3
3,5
4
Example – s and X mean chart
• Determine using s chart whether the process is
in control, we have 4 samples with n=3.
Obs1
Obs2
Obs3
Sample
2,0000
1,9995
2,0002
1
1,9998
2,0003
2,0002
2
1,9997
2,0000
2,0004
3
2,0003
1,9998
1,9997
4
2,0004
2,0001
2,0000
2,00020
2,00015
2,00010
2,00005
2,00000
1,99995
1,99990
1,99985
1
1,5
2
2,5
1,5
2
2,5
3
3,5
4
4,5
5
0,0008
0,0007
0,0006
0,0005
0,0004
0,0003
0,0002
0,0001
0
1
3
3,5
4
4,5
5