Process capability or Process control - Which comes first?

[Helmut Jilling]

hjilling

You can also control your processes with metrics (No SPC) and targets which is the typical way to control Macroprocesse.

The principle I was trying to explain is metrics are the result of process control, not the controling agent.

For example, my speeodmeter measures how fast I am going, but my gas pedal and brake pedal control it. The speedometer has no function which will control it.

Metrics are a result, not the control agent. And, capability index is a metric, not a control agent.

 

[Cordon - 2007]

Please excuse me if I'm out of place here, but wasn't the question answered on the first page?

 

[jrubio]

The principle I was trying to explain is metrics are the result of process control, not the controling agent.

For example, my speeodmeter measures how fast I am going, but my gas pedal and brake pedal control it. The speedometer has no function which will control it.

Metrics are a result, not the control agent. And, capability index is a metric, not a control agent.

Great.

 

[jrubio]

Therefore you can contol your process playing with the imputs...
(No SPC)

 

[roland_lu]

I have missed Jim, for he could have given really clear and unarguable answer to questions like this.

I do not know where it comes from that Ppk is for unstable process, for I did not fall for it.

AIAG PPAP 4th edition has given more clear defination of Cpk, Ppk ( Page 8).

as Tim said early, Cpk used within variation to estimate population variation, it is rough, but quick and easy.

and Ppk uses all the measurements to compute total variation, thus is not practic in a long run, if you do not have good hardware and software.

You have to have stable process in order for the capability index make senses. If not stable, why trying to get meaningless number? Please refer to AIAG SPC 2nd edition, Page 19 to 22.

 

[jrubio]

I have missed Jim, for he could have given really clear and unarguable answer to questions like this.

I do not know where it comes from that Ppk is for unstable process, for I did not fall for it.

AIAG PPAP 4th edition has given more clear defination of Cpk, Ppk ( Page 8).

as Tim said early, Cpk used within variation to estimate population variation, it is rough, but quick and easy.

and Ppk uses all the measurements to compute total variation, thus is not practic in a long run, if you do not have good hardware and software.

You have to have stable process in order for the capability index make senses. If not stable, why trying to get meaningless number? Please refer to AIAG SPC 2nd edition, Page 19 to 22.

I said:

Ppk is the capability when the process is not stable. Please Refer to
PPAP Manual page 7 Third Edition.

When the process becomes stable the index must be Cpk.

Please read page 7

I will translate exactly the sentence, May be I am wrong.

Sorry for My English is getting worse.

"It can be calculated the Cpk index if the process is stable, PPk it should be used for a process Chronic unstable but with a result that meet specification"

Please I am not in the Automobile Arena currently can you copy the sentence here.

 

[jrubio]

I have missed Jim, for he could have given really clear and unarguable answer to questions like this.

I do not know where it comes from that Ppk is for unstable process, for I did not fall for it.

AIAG PPAP 4th edition has given more clear defination of Cpk, Ppk ( Page 8).

as Tim said early, Cpk used within variation to estimate population variation, it is rough, but quick and easy.

and Ppk uses all the measurements to compute total variation, thus is not practic in a long run, if you do not have good hardware and software.

You have to have stable process in order for the capability index make senses. If not stable, why trying to get meaningless number? Please refer to AIAG SPC 2nd edition, Page 19 to 22.

It has sense.

Your process meet spec (Capability >1.67) but this index is changing (not stable)

 

[jrubio]

I have missed Jim, for he could have given really clear and unarguable answer to questions like this.

I do not know where it comes from that Ppk is for unstable process, for I did not fall for it.
AIAG PPAP 4th edition has given more clear defination of Cpk, Ppk ( Page 8).

as Tim said early, Cpk used within variation to estimate population variation, it is rough, but quick and easy.

and Ppk uses all the measurements to compute total variation, thus is not practic in a long run, if you do not have good hardware and software.

You have to have stable process in order for the capability index make senses. If not stable, why trying to get meaningless number? Please refer to AIAG SPC 2nd edition, Page 19 to 22.

So the answer is that AIAG said that (Not me)

 

[roland_lu]

Sorry, I do not have PPAP 3rd edition handy, and 4th edition is in play. But I believe your translation is just fine.

I have a feeling that Cpk and Ppk are among the most abused and confused terms in quality engineering.

Tim F

I guess AIAG realized that, and this new explanation is much better fit, and make sense.

 

[jrubio]

Sorry, I do not have PPAP 3rd edition handy, and 4th edition is in play. But I believe your translation is just fine.



I guess AIAG realized that, and this new explanation is much better fit, and make sense.

Read it, put the same bellow.