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

Elsmar Forum Sponsor

Bill Levinson

Industrial Statistician and Trainer
#32
Figure 3.3-1 of the AIAG/VDA manual (2019), page 91, has a parameter diagram for a press in sintered bearing. There is a list of process noise factors from work elements: Manpower, Machine, Material, and Environment. (We can potentially add Method and Measurement where applicable.) It also lists the product requirements, and impacted or changed product characteristic (e.g. due to the noise factors). It has other information as well but I think the key is identification of the potential noise factors, which could become failure causes in the failure analysis.

I can't upload the AIAG figure as it is copyrighted but here is one ( (c) Bill Levinson) I made myself for a webinar on FMEA. It relies on a case study from Shigeo Shingo's Zero Quality Control. Shingo did not do an FMEA, but he described error proofing controls for an issue in which the worker could forget to check the torque. From the notes on a previous slide: "Shingo, Shigeo. 1986. Zero Quality Control: Source Inspection and the Poka-Yoke System. Productivity Press Example 78, p. 224. The worker is supposed to check the bolt torque with the torque wrench, and failure to do so depended on worker vigilance. As soon as we see "worker vigilance" (administrative control) in a Shigeo Shingo case study, we know that errors and omissions are going to happen because administrative controls that rely on worker vigilance are rarely if ever capable of making mistakes impossible."

My figure does not have all or even most of the elements of the AIAG parameter diagram (and it is not intended to be one) but it does include the work elements that could conceivably become failure causes.
 

Attachments

Last edited:

Jimmy123

Involved In Discussions
#33
Figure 3.3-1 of the AIAG/VDA manual (2019), page 91, has a parameter diagram for a press in sintered bearing. There is a list of process noise factors from work elements: Manpower, Machine, Material, and Environment. (We can potentially add Method and Measurement where applicable.) It also lists the product requirements, and impacted or changed product characteristic (e.g. due to the noise factors). It has other information as well but I think the key is identification of the potential noise factors, which could become failure causes in the failure analysis.

I can't upload the AIAG figure as it is copyrighted but here is one ( (c) Bill Levinson) I made myself for a webinar on FMEA. It relies on a case study from Shigeo Shingo's Zero Quality Control. Shingo did not do an FMEA, but he described error proofing controls for an issue in which the worker could forget to check the torque. From the notes on a previous slide: "Shingo, Shigeo. 1986. Zero Quality Control: Source Inspection and the Poka-Yoke System. Productivity Press Example 78, p. 224. The worker is supposed to check the bolt torque with the torque wrench, and failure to do so depended on worker vigilance. As soon as we see "worker vigilance" (administrative control) in a Shigeo Shingo case study, we know that errors and omissions are going to happen because administrative controls that rely on worker vigilance are rarely if ever capable of making mistakes impossible."

My figure does not have all or even most of the elements of the AIAG parameter diagram (and it is not intended to be one) but it does include the work elements that could conceivably become failure causes.
Your example describes step 2 structure analysis, but not step 3 function analysis where the P-Diagram comes into the game. Develop your example. What are the noises for variation of the output? Think about strength and stress noise
like Miners picture. The Intention of the P-Diagram is to think about reasons of variation of the output result inside a tolerance range, not reasons for potential failures outside of the tolerance range. In such a case we can use the Ishikawa diagram. The Intension of different tools are different. Don‘t mix it up, please!
 

Bill Levinson

Industrial Statistician and Trainer
#34
Your example describes step 2 structure analysis, but not step 3 function analysis where the P-Diagram comes into the game. Develop your example. What are the noises for variation of the output? Think about strength and stress noise
like Miners picture. The Intention of the P-Diagram is to think about reasons of variation of the output result inside a tolerance range, not reasons for potential failures outside of the tolerance range. In such a case we can use the Ishikawa diagram. The Intension of different tools are different. Don‘t mix it up, please!
My example is based on the issue of the worker forgetting a step, as opposed to strength and stress noise. (You are right, by the way, that the parameter diagram goes with function analysis but the structure analysis includes identification of the work elements.) The AIAG failure analysis example, incidentally, asks whether the worker can use the wrong part, load a part incorrectly, or use the wrong material. This would indeed be a potential failure outside the tolerance range, and an assignable cause in the bargain; one probably preventable by error proofing.

Design might involve more attention to the issues you ranged. An example might involve a cyclic stress that might cause a perfectly good part to eventually fail. In PFMEA, we must however consider anything that might generate scrap or rework.
 
#37
For some clarification, if I may, the idea of "NOISE" does, in fact, come from Dr. Taguchi and his Two-Step Optimization approach. However, the P-Diagram comes not from Taguchi, but from the field of Robust Engineering. The P-Diagram was introduced by Madhav S. Phadke in his 1989 book, "Quality Engineering Using Robust Design." Phadke was with AT&T Bell Labs. I think of further interest here is the approach Ford Motor Co. introduced, REDPr (known as "Red Pepper") which was short for the Robust Engineering Design Process. REDPr used the P-Diagram as a foundation to introduce the noise-factors as the basis for a quite thorough analysis of the these factors and not just THAT they were related to the Error States (failures) but HOW they were related and if you actually had adequate test coverage to VERIFY your design was robust to these factors (Robustness Checklist or RCL). The P-Diagram is only the beginning if you want to make it really contribute to an increased Value-Add analysis and not play off as just another pretty picture.

That said, I have studied and applied the P-Diagrams for many years within Product Design Engineering. I have been waiting for someone to come up with a meaningful way to use them on the PFMEA side. Alas, I haven't figured it out nor have I seen anyone else's solution that indicates it can bring value to the PFMEA yet...
 
Last edited by a moderator:

Miner

Forum Moderator
Staff member
Admin
#38
Sure it can.

  • Piece to Piece variation - lack of capability is a risk
  • Changes over life - while tooling wear may be obvious, there are other forms of wear on the machinery that are not as obvious
  • Internal Environment - some processes impact other processes downstream, or can impact a characteristic done upstream
  • External environment - storage and processing conditions may have a huge impact on quality
Many of these items can easily be overlooked when doing the typical PFMEA. The P-diagram forces you to consider them.
1589393900159.png
 
#39
Sure it can.

  • Piece to Piece variation - lack of capability is a risk
  • Changes over life - while tooling wear may be obvious, there are other forms of wear on the machinery that are not as obvious
  • Internal Environment - some processes impact other processes downstream, or can impact a characteristic done upstream
  • External environment - storage and processing conditions may have a huge impact on quality
Many of these items can easily be overlooked when doing the typical PFMEA. The P-diagram forces you to consider them.
View attachment 26814
Miner,
I agree that these are certainly causes that must be addressed. They are within what I would consider to be a standard PFMEA which bring these to bear through consideration of the Ishikawa "M's". I would consider your examples to be "within" the sphere of control. The NOISE FACTORS are, by definition, intended to be impossible or extremely difficult to control and they require special consideration to figure out how we should address our design (or process in this case) to ensure our robustness to them. So, in the end, does the P-Diagram really add value here or is it just another way to show the Ishikawa "M's" under a new name? Or, as my mentor used to challenge me with, "is it better?....or just different?"
 

Jimmy123

Involved In Discussions
#40
Miner,
I agree that these are certainly causes that must be addressed. They are within what I would consider to be a standard PFMEA which bring these to bear through consideration of the Ishikawa "M's". I would consider your examples to be "within" the sphere of control. The NOISE FACTORS are, by definition, intended to be impossible or extremely difficult to control and they require special consideration to figure out how we should address our design (or process in this case) to ensure our robustness to them. So, in the end, does the P-Diagram really add value here or is it just another way to show the Ishikawa "M's" under a new name? Or, as my mentor used to challenge me with, "is it better?....or just different?"
You are right. The AIAG/VDA booklet show a P-Diagram where the Noise factors are the 5M of Ishikawa. This scope is wrong in my opinion and double work without any value add. The scope from Miner is slightly different and can add value, if it is used in the right way. I agree, that no process engineer in our company have used or tried to use that.
 
Thread starter Similar threads Forum Replies Date
O Example of Turtle Diagram with Risk/Opportunities General Auditing Discussions 1
C IT Internal Audit Turtle Diagram example wanted Internal Auditing 3
B Example Turtle diagram needed Process Maps, Process Mapping and Turtle Diagrams 3
Anerol C Corrective Preventive Action Turtle Diagram example needed Process Maps, Process Mapping and Turtle Diagrams 6
D Test summary report example for design validation wanted - ISO 13485 ISO 13485:2016 - Medical Device Quality Management Systems 1
M Risk managment report of Surgical Mask Example ISO 14971 - Medical Device Risk Management 14
M Example of statement for procedure pack MDR Article 22? Elsmar Cove Forum Suggestions, Complaints, Problems and Bug Reports 0
A 5 x 5 Risk Matrix - Looking for a good example Manufacturing and Related Processes 2
N Post Market Surveillance Package Example Wanted ISO 13485:2016 - Medical Device Quality Management Systems 1
D Calibration Process Flow Map Example Wanted General Measurement Device and Calibration Topics 3
D Redacted 510(k)s - Example wanted Document Control Systems, Procedures, Forms and Templates 14
F Hi friends, can anyone show me an example of a procedure for ISO 13485 6.4.1 Work Environment? ISO 13485:2016 - Medical Device Quality Management Systems 2
DuncanGibbons Looking for example aerospace part CAD files to be used for a case study Career and Occupation Discussions 2
M An example of risk analysis of class I MD ISO 14971 - Medical Device Risk Management 36
D Monitoring and measuring resources - Example of how section ISO 9001 7.1.5 would apply to a manufacture of software ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 4
D Validation of existing equipment - Risk based approach example ISO 13485:2016 - Medical Device Quality Management Systems 3
A ISO/TS 22163 Item 5.2.4 Safety policy - Example wanted Other ISO and International Standards and European Regulations 2
F Internal Audit - Procedure example Internal Auditing 5
I Functional Safety Analysis/Report Example IEC 60601 - Medical Electrical Equipment Safety Standards Series 3
H Man Hour Plan 145.A.30 example needed EASA and JAA Aviation Standards and Requirements 0
R Real Example of a currently marketed Procedure Pack CE Marking (Conformité Européene) / CB Scheme 1
D Example for Accessories of "Annex XVI non-medical devices" and how to classify it now with respect ot EU MDR Other Medical Device Regulations World-Wide 1
MichaelDRoach Oganization's Self Declaration of Conformance to ISO 28000 wording example wanted Supply Chain Security Management Systems 1
A Australia TGA Medical Device Sponsor Agreement - Example or Template Other Medical Device Regulations World-Wide 11
J ISO 13485 8.4 Analysis of Data - Procedure example ISO 13485:2016 - Medical Device Quality Management Systems 1
S Question about a basic additive variance/tolerance example Quality Tools, Improvement and Analysis 2
N ISO 9001: 2015 - Example standards policies, procedures, acknowledgements and checklists ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
M AS9100d (section 7.1.3) example of compliance in machine shop environment. AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 3
supadrai How does the FDA count violations of, for example, misbranding? (Medical Devices) Other US Medical Device Regulations 1
E Labware cleaning validation protocol example Qualification and Validation (including 21 CFR Part 11) 1
D Laboratory Manual ISO/IEC 17025 Example wanted ISO 17025 related Discussions 2
P Template or example Excel list of ISO certificates issued to clients ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
T Example wanted - Template for internal audit IATF 16949 IATF 16949 - Automotive Quality Systems Standard 1
M Example ISO 14971 policy and risk criteria ISO 14971 - Medical Device Risk Management 0
D System Level FMEA example wanted FMEA and Control Plans 2
E Example of 9001:2015 audit report with non-conformances ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
A IATF 16949 Cl. 8.4.1.2 Supplier Selection Process - assessment example IATF 16949 - Automotive Quality Systems Standard 11
D Where I can find an ISO 13485:2016 Audit Schedule example? ISO 13485:2016 - Medical Device Quality Management Systems 4
R Clinical evaluation Meddev (2.7.1 revision 4) - Example or Template EU Medical Device Regulations 4
A IATF 16949 - 9.2.2.1 Internal Audit Programme - looking for example IATF 16949 - Automotive Quality Systems Standard 5
S Looking for an example of a medical device file ISO 13485:2016 - Medical Device Quality Management Systems 1
C PFMEA example with machining (lathe+mill) FMEA and Control Plans 1
L Simple Example for PFMEA / Control Plan Training Training - Internal, External, Online and Distance Learning 1
T Process Matrix for ISO 9001 - SRI requests R.20 44KO Sample/Example ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
D IATF 16949 - 8.5.2.1 Traceability Plan - Does anyone have an example? IATF 16949 - Automotive Quality Systems Standard 4
L I need an example rework procedure/instruction for injected plastic parts Document Control Systems, Procedures, Forms and Templates 2
B Seeking for an example or a template of a Business Plan Service Industry Specific Topics 3
A Technical File Procedure (for Company) - Example wanted EU Medical Device Regulations 1
M Example Medical Device Validation Plan and Report wanted CE Marking (Conformité Européene) / CB Scheme 4
T Example System & Process Audit Check Sheet for IATF 16949 IATF 16949 - Automotive Quality Systems Standard 1
Similar threads


















































Top Bottom