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Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
Process fmea
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Process fmea

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Process FMEA course slides

Process FMEA course slides

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  • 1. Failure Mode and Effects Analysis Lawrence Hallett!
  • 2. Purpose How to conduct an FMEA.
  • 3. Origin Failure mode and effect analysis (FMEA) was one of the first systematic techniques for failure analysis. It was developed by reliability engineers in the 1950s to study problems that might arise from malfunctions of military systems
  • 4. Definition of FMEA A Failure Mode and Effect Analysis uses a disciplined technique to identify and help eliminate product and process potential failure modes. o By ID of potential failures o Assessing the risks caused by failure modes and Identify corrective actions o Prioritizing corrective actions o Carry out corrective actions
  • 5. Most COMMON Types of FMEA's Design (Potential) Failure Modes and Effects Analysis-DFMEA • Focus is on potential design- related failures and their causes. ! Process (Potential) Failures Modes and Effects Analysis-PFMEA • Focuses is on potential process failures and their causes.
  • 6. PFMEA's ! ● Focus is on potential process –related failures and their causes. ▪Main drive is to understand the process through the identification of as many potential failures as possible. o e.g. Incorrect material used ● PFMEA typically assumes that the design is sound. ● Development of Recommended Actions is targeted at eliminating the Root Cause of the potential failures.
  • 7. PFMEA's benefits •Identifies Process Functions and Req’s! •Identifies potential failure modes! •Assesses effect of failure! •Identifies causes of failures! •Identifies process controls! •Identifies confirmed Critical Characteristics! •Provides an objective base for action
  • 8. PFMEA's outputs
  • 9. PFMEA's - who prepares it •A team effort - including! •Manufacturing/production! •Engineering! •Design ! •Quality! •Test! ! •However it is a moving feast
  • 10. Related Documents
  • 11. PFMEA Three Parts: ● Process Flow Diagram (PFD) ● Process Failure Mode and Effects Analysis (PFMEA) ● Process Control Plan (PCP)
  • 12. Product Definition: Key Product Characteristics, DFMEA Process Definition: Process Flow Diagram (PFD), Failure Mode Analysis: PFMEA Control Strategy: Control Plan, Error proofing Customer Requirements: Manufacturing: Work Instructions & Process Monitoring Information Flow SOR, Vehicle Tech Specs, System Technical Specs Product and Process Characteristics
  • 13. DFMEA/PFMEA Information Interrelationships DFMEA Design FMEA Process Flow Diagram PFMEA Process FMEA Boundary (Block) Diagram, P- Diagram, Etc. Design Verification Plan & Report (DVP&R) Process Control Plan
  • 14. Process Function/Requirements
  • 15. Process Flow Diagrams ● The Process Flow Diagram provides a logical (visual) depiction of the process that is being analyzed.
  • 16. 12 ● The SAE/AIAG PFMEA guidelines describe two methods of defining process functions. 
 Either or both may be used. ● Process Functions may be described in terms of: ▪ The product features/characteristics that are created or ▪ The process actions that are performed ● Process functions should be identified in detail as necessary to provide information for the PFMEA to develop effective Process Controls Process Function / Requirement
  • 17. 13 ● Consider a simple operation to drill a hole in a metal part ● The product characteristics & requirements are: ▪ Hole size: 4.00 mm +/- 0.13 ▪ Hole Location:
 X = 28.0 mm +/- 0.2 Y = 15.0 mm +/- 0.2 ▪ Perpendicular to surface, no burrs, etc. ● The process operation must create these product characteristics and meet the requirements Process Function / Requirement X Y 4.00
  • 18. ● To drill the correct hole size in the specified location, the process must: ▪ Position and hold the part ▪ Align the part fixturing
 with the drill position ▪ Assure the correct drill
 bit size is used ▪ Set and control drill speed ▪ Anticipate tool wear and
 schedule preventive maintenance ● If the Function/Requirement is defined in the PFMEA as “Drill Hole” could any of these be missed? Process Function / Requirement
  • 19. Process Flow Diagram (PFD) ● Process Flow Diagram is the foundation ▪ The process must be defined step by step, including interfaces ▪ The PFD provides the structure to document what product characteristics and requirements (OUTPUTS) are affected by a given operation and how these characteristics and sources of variation are controlled (INPUTS) ▪ PFD is a graphical representation of every possible path a part can take through the anticipated manufacturing process ▪ A well defined PFD establishes the foundation for the PFMEA ● Helps in developing equipment specifications. ▪ How will the process control non-conforming material? ▪ How and when will inspections be performed, what is required? ▪ How and when will parts be re-introduced into the process?
  • 20. PFD Example
  • 21. PFD Feeds PFMEA
 Identify the Function(s) ● Function is a description of what the Process does to meet the requirements ➢Related to process specification and product characteristics ➢Comes from the PFD operation description column ● Functions can be described as: ➢Do this operation… ➢To this part or material… ➢With this tooling or equipment…
  • 22. Potential Failure Mode
  • 23. Potential Failure Modes Often missed
  • 24. Potential Effect of Failure
  • 25. Example Failure Modes Effect of Failure Case assembled but not to the correct height Fails height check causing rework(3) if not detected Connector corrosion leading to intermittence premature part failure(8)
  • 26. Potential Effects of Failure
  • 27. Potential Effects of Failure
  • 28. Severity Ranking
  • 29. Severity
  • 30. Potential Cause of Failure
  • 31. Cause of Failure
  • 32. How to identify Cause of Failure
  • 33. Developing Causes Always assume a direct correlation between cause and failure i.e if the cause occurs then the failure mode occurs
  • 34. Assumptions
  • 35. Assumptions
  • 36. Occurrence
  • 37. How to identify Occurrence
  • 38. Occurrence Evaluation Criteria Probability of Likely Failure Rates Over Design Life Ranking Failure SUGGESTED OCCURRENCE EVALUATION CRITERIA Very High: Persistent failures High: Frequent failures Moderate: Occasional failures Low: Relatively few failures Remote: Failure is unlikely ≥ 100 per thousand vehicles/items 50 per thousand vehicles/items 20 per thousand vehicles/items 10 per thousand vehicles/items 5 per thousand vehicles/items 2 per thousand vehicles/items 1 per thousand vehicles/items 0.5 per thousand vehicles/items 0.1 per thousand vehicles/items ≤ 0.01 per thousand vehicles/items 10 9 8 7 6 5 4 3 2 1
  • 39. Current controls
  • 40. Current Controls 2 types of controls Prevention Prevent the Cause/mechanism or failure mode/effect from occurring or reduce their rate of occurrence ! Detection Detect the cause/mechanism and lead to corrective action
  • 41. How to identify process controls
  • 42. Current Controls
  • 43. Detection ranking
  • 44. Detection Rankings
  • 45. Risk Priority Number
  • 46. Analysis Of Risk ▪ RPN / RISK PRIORITY NUMBER ▪ What Is Risk? ▪ Probability of danger ▪ Severity/Occurrence/Cause
  • 47. Evaluation by RPN Only ▪ Case 1 o S=5 O=5 D=2 RPN = 50 ▪ Case 2 o S=3 O=3 D=6 RPN = 54 ▪ Case 3 o S=2 O=10, D=10 = 200 ▪ Case 4 o S=9 O=2 D=3 = 54 WHICH ONE IS WORSE?
  • 48. Example ▪ Extreme Safety/Regulatory Risk o =9 & 10 Severity ▪ High Risk to Customer Satisfaction o Sev. > or = to 5 and Occ > or = 4 ▪ Consider Detection only as a measure of Test Capability.
  • 49. Actions taken
  • 50. Actions
  • 51. Re-rating RPN After Actions Have Occurred
  • 52. Re-rating RPN After Actions Have Occurred ▪ Severity typically stays the same. ▪ Occurrence is the primary item to reduce / focus on. ▪ Detection is reduced only as a last resort. ▪ Do not plan to REDUCE RPN with detection actions!!! o 100% inspection is only 80% effective! o Reducing RPN with detection does not eliminate failure mode, or reduce probability of causes o Detection of 10 is not bad if occurrence is 1
  • 53. Outputs
  • 54. ● PCP will be based on the previous activities in PFD and PFMEA. ● Review the PFMEA information developed & supplied and use to identify: ▪ Specific controls that may be needed due to the information added ▪ Identify which controls are Product or Process o Note any Special Characteristics o Identify evaluation methods, frequency and Control Methods o Note Reaction Plans (particularly related to NC parts) Process Control Plan
  • 55. Process Control Plan Example Part/ Process Number Process Name /
 Operation Description Machine, Device, Jig, Tools for Mfg. Characteristics Special Char. Class. Methods Reaction
 Plan No. Product Process Product / Process Specification /
 Tolerance Evaluation Measurement
 Technique Sample Control MethodSize Frequency 300 Initiate weld sequence /
 
 Perform TIG weld of frame parts. Robotic Arm controller.
 TIG welders. Weld beads per design specification. Tube welds meet pull test with failure in parent material.
 Pull test using test fixture 20-1.
 
 1 pc. 
 
 Per shift.
 
 Hydraulic pull test instruction TI21-01 Process monitoring form PMF-20-01 Quarantine material since last good pull test. Good welds, no visible defects. yes Weld appearance meets visual standard. Operator evaluation to Visual Std TB20-VS1 100% Each piece. Visual inspection OWI #20-01. Remove part and send to repair. Weld voltage
 yes 24 Volts AC
 +/- 2.0 volts Machine Control 100% Each weld cycle. Closed-loop machine control. Scrap part & Re-start welder. Weld voltage yes 24 Volts AC
 +/- 2.0 volts Visual Once each Shift start or change- over or maint. event. Set-up OWI #20-02 & Form PMF-20-02 Periodic maintenance per PM- WI #20. Scrap current part. 
 Shut down.
 Notify maintenance . Inert gas flow rate yes 5 cubic feet / min.
 +/- 0.5 cfm Visual twice Per shift.
 Operator cleans gas cup twice per shift PM-WI-20. Process monitoring form PMF-20-01 Notify maintenance . Inert gas flow rate yes 5 cubic feet / min.
 +/- 0.5 cfm Visual of verification of Flow Meter Once each Shift start or change- over or maint. event Set-up OWI #20-02 & Form PMF-20-02. Equipment Calibration Procedure #368 Quarantine material since last good pull test.
 Notify maintenance . Form 818-1 (Rev 12Apr02) CONTROL PLAN Control Plan No: Part Number/Latest Change Level Key Contact/Phone Date (Orig.) Date (Rev.) Customer Part Number Core Team Customer Engineering Approval/Date (If Req'd.) Part Name/Description Supplier/Plant Approval/Date Customer Quality Approval/Date (If Req'd.) Supplier/Plant Supplier Code Other Approval/Date (If Req'd.) Other Approval/Date (If Req'd.) Prototype Pre-Launch Production
  • 56. Process Control Plan Example Initiate weld sequence / Confirm Wire feed rate Initiate weld sequence / Confirm Weld voltage Initiate weld sequence /
 Perform TIG weld of frame parts. Initiate weld sequence / Confirm Inert Gas flow rate Scrap part & Re-start welder Closed-loop machine control. Each weld cycle. 100%Machine Control 300 mm / minute
 +/- 10 mm / min. yesWeld wire feed rate Scrap part & Re-start welder Closed-loop machine control. Each weld cycle. 100%Machine Control 24 Volts AC
 +/- 2.0 volts yesWeld voltage
 Notify maintena nce. Operator cleans gas cup twice per shift PM-WI-2500. Process monitoring form PMF-20-10 Per shift.
twiceVisual5 cubic feet / min.
 +/- 0.5 cfm yesInert gas flow rate Remove part and send to repair. Visual inspection OWI #20-010. Each piece. 100%Operator evaluation to Visual Std TB20-VS1. Weld appearance meets visual standard. yesGood welds, no visible defects. Scrap current part.
 Shut down.
 Notify maintenance. Set-up OWI #20-020 & Form PM-20-020 Predictive maintenance
 pinch roller replace @ 180 days. Shift start or change- over or maint. event 100%Operator setup check and verification 300 mm / minute
 +/- 10 mm / min. yesWeld wire feed rate Quarantine material since last good pull test. Notify maintenan ce. Set-up OWI #20-02 & Form PM-00-02. Equipment Calibration Procedure #368 Shift start or change- over or maint. event Once each Visual verification of Flow Meter 5 cubic feet / min.
 +/- 0.5 cfm yesInert gas flow rate Scrap current part. 
 Shut down.
 Notify maintenanc e. Set-up OWI #20-02 & Form PM-20-02 Periodic maintenance per PM-WI #20. Shift start or change- over or maint. event Once each Visual24 Volts AC
 +/- 2.0 volts yesWeld voltage
 Quarantine material since last good pull test. Hydraulic pull test instruction TI41-01 Process monitoring form PM-20-010 Per shift.
 
 1 pc. 
 
 Pull test using test fixture 20-1.
 
 Tube welds meet pull test with failure in parent material.
 Weld beads per design specification. Robotic Arm TIG welders and controllers. 300. .!Robotic Arm TIG welders !Initiate weld sequence / Close and latch curtain 300 FrequencySize Reaction
 PlanControl Method Sample Evaluation Measurement
 Technique Product / Process Specification /
 Tolerance ProcessProductNo. Methods Special Char. Class. Characteristics Machine, Device, Jig, Tools for Mfg. Process Name /
 Operation Description Part/ Process Number

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