DEK高级培训资料.pdf - 第209页
68% 95% 99.7% Normal Distrib ution Curve Issue 2: July 2007 99.7% 3 3 2 2 1 1 0 • Most organisa tions use +/- 3 σ as th e sample size • This is referred to as the ‘ Process Width ’ • W e can no w use this val…
X Y
-0.0055
-0.0055
-0.0024
0.0077
-0.0013
-0.0105
-0.0025
0.0043
-0.0008
-0.0071
-0.0002
0.0064
-0.0028
-0.0068
-0.0019
0.0065
Normal Distribution
Plot the data on
a graph
Issue 2: July 2007
x
x
-0.0070
-0.0112
0.0097
-0.0023
-0.0087
0.0084
-0.0081
0.0075
-0.0102
-0.0077
-0.0013
-0.0019
0.0065
-0.0036
0.0015
0.0053
0.0005
-0.0019
-0.0049
-0.0030
-0.0022
-0.0038
-0.0006
-0.0040
-0.0004
0.0039
a graph
As more data is
added - this shape
starts to appear
68%
95%
99.7%
Normal Distribution Curve
Issue 2: July 2007
99.7%
3 32 21
1
0
• Most organisations use +/- 3 σ as the sample size
• This is referred to as the ‘Process Width’
• We can now use this value to calculate the
accuracy and repeatability of a process
TOLERANCE
CAPABLE
Process Capability (Cp)
Issue 2: July 2007
CAPABLE
The pattern’s width
divided into the Tolerance
goes MORE than 1.33
INCAPABLE
The pattern width divided into
the Tolerance goes LESS than 1.33