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Example of a P-Diagram for Process FMEA - Uncontrollable noises

Jimmy123

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#1
Have anyone an example of a P-Diagramm for Process FMEA. Could you give me some examples for not controllable noises?
 

Miner

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Staff member
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#2
By definition all noise is uncontrollable. You might be able to control it for a short period of time, but it is ultimately not feasible or too expensive to control long term.

Noise may be categorized into the following:
  • Piece to piece variation (design tolerances, manufacturing variation, operator variation, process stream variation, tooling/cavity variation, etc.)
  • Changes over life variation (machine/tooling wear, shrinkage/expansion, compression set, etc.)
  • Internal environment variation (manufacturing/storage conditions, system interactions, component clearances)
  • Customer usage variation (application, misuse)
  • External environment variation (application conditions: temperature, humidity, shock & vibe, etc.)
 

Bev D

Heretical Statistician
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Super Moderator
#3
By noise do you mean sounds? or random variation in the data? or perhaps conditions that effect your product that you might think are uncontrollable?
 

Miner

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Admin
#4
By noise do you mean sounds? or random variation in the data? or perhaps conditions that effect your product that you might think are uncontrollable?
I think by referring to a p-diagram the OP intended uncontrollable factors that cause random variation in the output. Noise is a category used in p-diagrams.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#5
Ah now it makes sense. Thanks Miner. I am not familiar with the p-diagram as part of PFMEA
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#6
I looked at the site Miner referenced. The paragraph that addresses 'noise' is quite interesting:

"Noise Factors are things that can influence the design but are not under the direct control of the engineer, such as piece-to-piece variation, normal degradation of materials or equipment over time, intended and unintended customer usage, foreseeable environmental conditions and system interactions. These noise factors, if not protected against, can make the design ineffective; in other words, the design should be robust against the expected noise factors."
With this context I can understand why Miner said the noise factors can't be controlled.


I've always disliked the term 'noise' when used as a descriptor of factors as it is too vague and easy to misinterpret it and it often different meanings in different contexts...meh.
 

Jimmy123

Involved In Discussions
#7
By definition all noise is uncontrollable. You might be able to control it for a short period of time, but it is ultimately not feasible or too expensive to control long term.

Noise may be categorized into the following:
  • Piece to piece variation (design tolerances, manufacturing variation, operator variation, process stream variation, tooling/cavity variation, etc.)
  • Changes over life variation (machine/tooling wear, shrinkage/expansion, compression set, etc.)
  • Internal environment variation (manufacturing/storage conditions, system interactions, component clearances)
  • Customer usage variation (application, misuse)
  • External environment variation (application conditions: temperature, humidity, shock & vibe, etc.)
Thanks, this is what I know from a Ford training, too. Now, the new AIAG Handbook shows a P- Diagram for PFMEA too. But in the example, they show the 4M, what are Process elements and not noise factors in my understanding. Therefore I ask, if someone have tried to use the P-Diagram for a Process. I think this could be done, but only with the same systematic like above. Is PTP Variation, the Variation of machining? It would be great if someone can show an example.
 

Miner

Forum Moderator
Staff member
Admin
#8
The 4P can work as well, but I think it is less focused than the 5 noise categories. In addition 4P applies to the inputs and control factors as well. It is a step in the wrong direction.

Yes, part 2 part variation would include variation due to machining. Few people will be willing to share this as it will be viewed as proprietary information. Have you tried searching for "parameter diagram images"? There are numerous examples online.
 

Jimmy123

Involved In Discussions
#9
The 4P can work as well, but I think it is less focused than the 5 noise categories. In addition 4P applies to the inputs and control factors as well. It is a step in the wrong direction.

Yes, part 2 part variation would include variation due to machining. Few people will be willing to share this as it will be viewed as proprietary information. Have you tried searching for "parameter diagram images"? There are numerous examples online.
I think, we are on the same path:). Yes, I have tried to find one, but not successfully for a process.
 

Jimmy123

Involved In Discussions
#10
The 4P can work as well, but I think it is less focused than the 5 noise categories. In addition 4P applies to the inputs and control factors as well. It is a step in the wrong direction.

Yes, part 2 part variation would include variation due to machining. Few people will be willing to share this as it will be viewed as proprietary information. Have you tried searching for "parameter diagram images"? There are numerous examples online.
Dear Miner, could you please explain me, what 4P stand for?
 
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