# WHere can I locate a CPK calculator

Six Sigma – iSixSigma Forums Old Forums General WHere can I locate a CPK calculator

Viewing 7 posts - 1 through 7 (of 7 total)
• Author
Posts
• #38465

Denzil
Participant

If 1.33 means 6 parts defective for every 100,000 produced. If I have a cpk of 1.0 on my anaylsis, what will my defects per 100,000 produced?
Denzil Oliver

0
#115062

Mikel
Member

Dude, its called a normal table but here’s some help –

Cpk
PPM  if centered
Cpk
PPM if not centered

1
2700
1
1350

1.1
967
1.1
483

1.2
318
1.2
159

1.3
96
1.3
48

1.33
66
1.33
33

1.4
27
1.4
13

1.5
7
1.5
3

1.6
2
1.6
1

1.67
0.5
1.67
0.3

1.7
0.3
1.7
0.2

1.8
0.07
1.8
0.03

1.9
0.01
1.9
0.01

2
0.002
2
0.001

0
#115064

Tim F
Member

Dude II,Of course, you can only use a normal table if the data is normal to begin with! But I expect Stan knew that ;-)Normality is a common assumption, but by no means necessary. With non-normal data (which is not that rare), then you can only make very broad estimates of the defect rate. A process with a calculated Cpk of 1 or 2 could produce (virtually) no defects, or it could produce many more than listed in the previous table.Cpk is a pretty good summary of the capability, but working backwards to predict actual defects is shaky.Tim F

0
#115065

Mikel
Member

Let’s see Tim – the guy doesn’t know about the normal table and his numbers for Cpk are wrong but seem to assume the distribution is centered – and you want to tell him to worry about non-normal data.
How about walking before running? Or did you warn your kids about the dangers of running on icey surfaces when they were crawling?

0
#115083

Denzil
Participant

Thanks for your help, This will be a great tool for us

0
#115102

Aquinas
Member
0
#115113

Kumar
Participant

You can see a Cpk Calculator at  http://www.sigmaguru.com/9cpcalculator.htm

0
Viewing 7 posts - 1 through 7 (of 7 total)

The forum ‘General’ is closed to new topics and replies.