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1、1 1“Making today better than yesterday” Introduction to FMEA 2 Carmel Global Summit Meeting, Sep 2013 3 What Is Lean? Producing quality product with minimal resources (Materials, Utilities, Labour, Machine and Time) to fulfill customer demand but there is a control to detect the failure mode itself
2、(see the next slide). 35 Process Control Example In an injection molding process, injection pressure of over 6895 pieze (kilo-pascals) leads to a small dimension. At a later stage, this makes assembly difficult. A process control on the cause (injection pressure) might be a high pressure alarm on th
3、e hydraulic circuit. A process control on the failure mode (small dimension) might be a dimensional inspection of each part. 36 FMEA - Step 10 10. For each process control, estimate the detection. 37 FMEA - Step 10: Detection Guidelines 38 FMEA - Step 11 11.For each cause of failure, calculate the R
4、isk Priority Number. 39 Risk Priority Number (RPN) The RPN number is calculated from the teams estimates of Severity, Occurrence and Detection. RPN = S x O x D If you are using a 1 - 10 scale for Severity, Occurrence and Detection, the worst RPN = 1000 (10 x 10 x 10), while the best would be RPN = 1
5、 (1 x 1 x 1). Use RPN numbers to prioritize failure modes and/or causes of failures in order to work on the highest priority issues. 40 FMEA Tips about Step 11 11. For each cause of failure, calculate the Risk Priority Number. Tips about Step 11: Any failure mode with a severity of 9 or 10 must be i
6、dentified as high priority regardless of the RPN. Addressing the highest RPNs is more important than setting an actual target (all RPNs 150, for example). Teams are all different, so different teams will obtain different RPNs. Use the high RPNs to identify critical issues (failure modes, causes of f
7、ailures, key process inputs). 41 FMEA - Step 12 12. For high priority causes of failure and/or failure modes, develop recommended actions. 42 FMEA Tips about Step 12 12.For high priority causes of failure and/or failure modes, develop recommended actions. Tips about Step 12: Recommended actions shou
8、ld be low cost and effective. Use ideas from all team members to improve the existing or planned project. Try to think of low cost actions that will reduce the occurrence. Reducing the occurrence is the most cost effective way to reduce risk. 43 FMEA - Step 13 13. For each recommended action, assign
9、 responsibility and completion dates. 44 FMEA - Step 14 14. For each recommended action, implement the action and note its effect. Process Function Requirements Potential Failure Mode Potential Effect(s) of Failure Severity Potential Cause(s)/ Mechanism(s) of Failure Occurrence Current Process Contr
10、ols Detection RPN Recommended Action(s) Responsibility & Target Completion Date Actions Taken Spot weld nut to pedestal Nut presentNut not present Cannot assemble seat belt restraint to pedestal 5 Welder cycles without nut present 8 100% Visual Inspection by operator after cycle 4 160 Design, test &
11、 install a nut presence sensing circuit. Welder will not cycle w/o weld nut a Mark, 4/15/96 c Circuit installed on 4/12/96. 10,000 welds- no problem. Circuit added to welder design e Operator fails to load nut into welder 2 100% Visual Inspection by operator after cycle 4 40 See Note aSee above, not
12、e c See above, note e Nut is loaded but falls out before weld cycle 1 100% Visual Inspection by operator after cycle 4 20 See Note aSee above, note c See above, note e Action Results 45 FMEA Tips about Step 14 14. For each recommended action, implement the action and note its effect. Tips about Step
13、 14: It is essential that the team not only verify that the recommended action was implemented, but that they also determine how effective it was. Was it implemented? Yes or No. How effective was it? Get data. 46 FMEA - Step 15 15. For each implemented action, re-estimate the severity, occurrence an
14、d detection rankings and recalculate the RPN. 47 FMEA Tips about Step 15 15. For each implemented action, re-estimate the severity, occurrence and detection rankings and recalculate the RPN. Tips about Step 15: Never recalculate an RPN without implementing an improvement! Guessing is not allowed! Us
15、ually, it is difficult to reduce the severity of a failure mode. However, sometimes a failure mode can be eliminated. The most effective RPN reduction is reducing the likelihood of occurrence. Poka-Yoke can reduce the detection ranking and reduce cost! The least effective RPN reduction is increasing
16、 inspection (reducing the detection ranking). 48 FMEA “Tips” Make it a “team effort.” Analyze new processes to avoid problems before they happen. Analyze existing processes to find and fix problems. Analyze existing processes to discover the high priority (“key”) process input variables. Work down the columns, not across. Keep it moving! Avoid paralysis by analysis. 49 Next Steps Form a team Select a product/process for develop the FMEA Preparation : Process flow / control plan Drawings Customer
