Capability study with a minimum spec

qcman

Registered Visitor
Hoping for some help on this. How do you do a capability study on something that has a minimum spec only? In this case it is a minimum coating thickness of .236mil I normally use QImacro to run the numbers and while I have yet to learn Minitab I do have that.
 

Ninja

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If it were me, and assuming that a 'less than zero' coating thickness is not possible, I would do a GRR on a spec range of 0.000-0.236mil and see if that closed the discussion.
Then adjust the scale to 0.230-0.236mil, how's that?

Do you have any operator measurements within 0.005 mil of the minimum?
Are you riding the line, or is this a numbers exercise when your mean coating is 0.527mil?

What is the resolution of your measuring equipment?
 

qcman

Registered Visitor
Spec is .236mil min coating so any less is NG. Attached are the numbers (2 place reading) that I am working with. We target .25 as more just wasteful.
 

Attachments

  • coating.xlsx
    8.4 KB · Views: 203

Ninja

Looking for Reality
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Have a look at Miner's blog ... look specifically for one-sided spec...
@Miner covers this far better than I could... I was waiting for him to chime in, but he hasn't so far. He may yet.
 

Miner

Forum Moderator
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Admin
Hoping for some help on this. How do you do a capability study on something that has a minimum spec only? In this case it is a minimum coating thickness of .236mil I normally use QImacro to run the numbers and while I have yet to learn Minitab I do have that.
Do you know how to use Minitab using a bilateral tolerance? If so, just enter the lower spec and leave the upper spec blank.
 

qcman

Registered Visitor
Just started with Minitab but this is what I came up with.
 

Attachments

  • Capability study with a minimum spec
    Cap study.jpg
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