I cannot remember where my mind was that day. I probably intended 4M, but substituted the transactional equivalent 4P instead (Place, Process, People, Policies/Procedures).
Example of a P-Diagram for Process FMEA - Uncontrollable noises
- Thread starter Jimmy123
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Bill Levinson
Industrial Statistician and Trainer
The 4th edition of AIAG's FMEA manual (page 21) describes the P diagram or Parameter Diagram. It requires identification of
(1) Inputs
(2) Outputs
(3) Control factors
(4) Noise factors including production and use
Its application is to design FMEA in which, for example, a catalytic converter receives input signals such as the composition of the exhaust gas as well as different forms of energy, and delivers outputs such as noise, odors, and also regulated and non-regulated emissions. Control factors include, for example, the precious metal loading, while noise factors such as piece to piece variation influence performance. I recommend AIAG's publications very highly.
Also Systems2Win discusses P diagrams and offers an example.
The process FMEA also uses elements of the P diagram as shown by Figure IV.2 on page 72 of the AIAG reference. Each operation has sources of variation (noise factors, although the diagram does not use this term) and deliverables, i.e. outputs. The process FMEA ties in with the control plan, which seems to correspond to the control factors.
I am glad somebody posted this because, while I read the FMEA manual, it was useful to revisit this. My next step will be to see if there is anything new in the AIAG/VDA manual, which is the newest reference.
(1) Inputs
(2) Outputs
(3) Control factors
(4) Noise factors including production and use
Its application is to design FMEA in which, for example, a catalytic converter receives input signals such as the composition of the exhaust gas as well as different forms of energy, and delivers outputs such as noise, odors, and also regulated and non-regulated emissions. Control factors include, for example, the precious metal loading, while noise factors such as piece to piece variation influence performance. I recommend AIAG's publications very highly.
Also Systems2Win discusses P diagrams and offers an example.
The process FMEA also uses elements of the P diagram as shown by Figure IV.2 on page 72 of the AIAG reference. Each operation has sources of variation (noise factors, although the diagram does not use this term) and deliverables, i.e. outputs. The process FMEA ties in with the control plan, which seems to correspond to the control factors.
I am glad somebody posted this because, while I read the FMEA manual, it was useful to revisit this. My next step will be to see if there is anything new in the AIAG/VDA manual, which is the newest reference.
Bill Levinson
Industrial Statistician and Trainer
Page 91 of the AIAG/VDA FMEA handbook (the newest one) features a parameter diagram for a process rather than a design. The process is a press for a sintered bearing. Noise factors include manpower, machine, material, and environment (measurement and method seem to be omitted). Note the tie-in to the cause and effect diagram here, which can help identify potential noise factors.
The takeaway is however that a P diagram can be done for a process as well as a design, and it makes excellent sense to me.
The takeaway is however that a P diagram can be done for a process as well as a design, and it makes excellent sense to me.
Jimmy123
Involved In Discussions
Hello Bill, my concern is exactly the template for the P-Diagram for the PFMEA. I am agree that this model helps to understand the influences to the process result. Why do the AIAG workgroup write under noises the cause Elements 5M?
This element are necessary for the process and not noises. I need an operator for example, this is not a noise!
On the other hand the Design P-Diagram use another systematic or wording, like part to part variation, operating condition, deterioration, loading, etc. . A P- Diagram Focus on the source for variation, noises who can’t control. This wording is also suitable for processes. The FMEA failure causes 5M mostly can controlled. Under machine in FMEA we consider process parameters, which are control factors and not noise factors! The P-Diagram should help to Define Experiments to collect knowledge about the correlation of control factors to the response, compare Taguchi books. I need to see, how this could be work for DoE and FMEA in this way?
Manoj Mathur
Quite Involved in Discussions
Please Guide me. If P Diagram is USEFUL only to make Design FMEA only or is there any role in P-FMEA also.. Please Reply.
Bill Levinson
Industrial Statistician and Trainer
The AIAG VDA manual (2019) adds consideration of potential noise factors for the process, specifically Manpower, Machine, Material, and Environment. These are also depicted as potential failure causes (the word "mechanism" seems to have been replaced but I am still trying to digest the material).
Jimmy123
Involved In Discussions
The Man, Machine, Material couldn’t be noises, because this are resources of the process! Stupid in my opinion and controversy to the P-Diagram for Design.
Bill Levinson
Industrial Statistician and Trainer
Fig. 3.3-1 of the manual depicts Man, Machine, Material, and Environment as "Process Noise Factors" because these resources of the process are potential variation sources. They are of course necessary to the process but they are also potential sources of variation.
toniriazor
Involved In Discussions
For non-native speakers like me I always thought that "noise factor" means some rattling, strange noises obviously and etc. Now I am surprised to see it refers to 4M, piece-to-piece variation and many other causes that can cause process variation.
To me P-Diagram is a tool to identify functions, requirements and potential failure modes on DFMEA. If anyone can give an example for usage of P-Diagram on Process FMEA would be useful for everyone here.
To me P-Diagram is a tool to identify functions, requirements and potential failure modes on DFMEA. If anyone can give an example for usage of P-Diagram on Process FMEA would be useful for everyone here.
Bill Levinson
Industrial Statistician and Trainer
By "noise" they mean variation, as opposed to actual noise (e.g. "Signal to noise ratio" as used by Taguchi). The manual does apply the P diagram only to DFMEA but its counterpart applies to PFMEA, where they consider which factors can add variation to the process.
