DEK高级培训资料.pdf - 第210页
T OLERANCE CAP ABLE Process Capability (Cp) Issue 2: July 2007 CAP ABLE The patt ern ’s width di vided into the T oleranc e goes MORE than 1.33 INCAP ABLE The patt ern width di vid ed int o the T oler ance goes LESS than…
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
Cp = 1
TOLERANCE
Process Capability (Cp)
Issue 2: July 2007
Cp = 2
Cp = 1.33