【文章內(nèi)容簡(jiǎn)介】 ecking dispersion shape, center value, and the nature of dispersement.IDENTIFYING POTENTIAL FAILURESUSE of STATISTICAL TOOLSTYPES/DEFINITIONS4. Control Charts. Serve to detect abnormal variations. Sample data (defining potential failures) are plotted to evaluate situations and trends in a process. Comparisons can be made against required control limits.5. Scatter Diagrams. Corresponding data are plotted and the relation between the data (and impact on prospective failures) can be analyzed.BESIDES THESE ANALYTICAL (STATISTICAL) TOOLS, THERE CAN OFTEN BE MANAGEMENT SITUATIONS WHERE THE DATA NEEDED FOR PROBLEM SOLVING ARE NOT AVAILABLE. NEW PRODUCT DEVELOPMENT IS AN EXAMPLE. ANOTHER MAY BE DEVELOPING A NEW MANUFACTURING METHOD TO IMPROVE PRODUCTIVITY. THESE SITUATIONS REQUIRE COLLABORATION AMONG PEOPLE FROM DIFFERENT DEPARTMENTS. IDENTIFYING POTENTIAL FAILURESPROSPECTIVE QUESTIONSFOLLOWING ARE REPRESENTATIVE QUESTIONS TO CONSIDER IN SOME BASIC AREAS THAT MAY REQUIRE FMEA. THIS IS NOT ALL INCLUSIVE, BUT EXAMPLES TO EVALUATE.A. MATERIAL1. Are there any mistakes in volume?2. Are there any mistakes in grade?3. Are there impurities mixed in?4. Is the inventory level adequate?5. Is there any waste in material?6. Is the handling adequate?7. Is the quality standard adequate?B. OPERATION METHOD1. Are the work standards adequate?2. Is it a safe method?3. Is it a method that ensures a good product?4. Is it an efficient method?5. Are the temperature and humidity adequate?6. Is the lighting adequate?7. Is there adequate contact with the previous and next processes?IDENTIFYING POTENTIAL FAILURESPROSPECTIVE QUESTIONSC. MACHINE1. Does it meet production requirements?2. Does it meet process capabilities?3. Does it meet precision requirements?4. Is the layout adequate?5. Are there enough machines/facilities?6. Is everything in good working order?7. Is operation stopped often because of mechanical trouble?D. MANPOWER (OPERATOR)1. Does s/he follow standards?2. Is his/her work efficiency acceptable?3. Is he/she responsible (accountable)?4. Is he/she qualified?5. Is he/she experienced?6. Is he/she assigned to the right job?7. Does he/she maintain good human relations? EFFECT AND ANALYSIS METHODOLOGIESFailure ModeEffect Severity: 110Causes Occurrence: 110Controls Detection: 110RPN = Severity XOccurrence X Detection11,000EFFECT AND ANALYSIS METHODOLOGIESDEFINING FMEA TERMSRISK PRIORITY NUMBER (RPN)The RISK PRIORITY NUMBER (RPN) is the product of the SEVERITY (S), OCCURRENCE (O), and DETECTION (D) ranking:RPN = (S) x (O) x (D)The RPN is a measure of design risk. The RPN is also used to rank order the concerns in processes (., in Pareto fashion).The RPN will be between “1” and “1,000.” For higher RPNs the team must undertake efforts to reduce this calculated risk through corrective action(s).EFFECT AND ANALYSIS METHODOLOGIESDEFINING FMEA TERMSSEVERITY (S)SEVERITY (S) is an assessment of the seriousness of the effect of the potential failure mode. SEVERITY applies to the effect only. A reduction in SEVERITY ranking index can be effected only through a design change. SEVERITY is estimated on a “1” to “10” scale.EFFECT AND ANALYSIS METHODOLOGIESSEVERITY (S) Evaluation CriteriaEffectCriteria: SEVERITY of EffectRankingHazardouswithoutwarningVery high severity ranking when a potential failure mode affects safe operation and/or involves nonpliance with regulations without warning.10Hazardouswith warningVery high severity ranking when a potential failure mode affects safe operation and/or involves nonpliance with regulations with warning.9Very highProduct/item inoperable, with loss of primary function.8HighProduct/item operable, but at reduced level of performance. Customer dissatisfied.7ModerateProduct/item operable, but may cause rework/repair and/or damage to equipment.6LowProduct/item operable, but may cause slight inconvenience to related operations.5Very LowProduct/item operable, but possesses some defects (aesthetic and otherwise) noticeable to most customers.4MinorProduct/item operable, but may possess some defects noticeable by discriminating customers.3Very MinorProduct/item operable, but is in nonpliance with pany policy.2NoneNo effect.1NOTE: Make sure team members agree on the criteria for ranking severity and apply them consistently.EFFECT AND ANALYSIS METHODOLOGIESDEFINING FMEA TERMSOCCURRENCE (O)OCCURRENCE (O) is the likelihood that a specific cause/mechanism will occur. OCCURRENCE is estimated on a “1” to “10” scale.EFFECT AND ANALYSIS METHODOLOGIESOCCURRENCE (O) Evaluation CriteriaProbability of FailurePossible Failure RatesRankingVery High: Failure is almost inevitable179。1 in 2101 in 39High: Repeated Failures1 in 881 in 207Moderate: Occasional Failures1 in 8061 in 40051 in 2,0004Low: Relatively Few Failures1 in 15,00031 in 150,0002Remote: Failure is Unlikely163。1 in 1,500,0001NOTE: The team should agree on an evaluation criteria and ranking system, which is consistent, even if modified for individual product/process analysis.EFFECT AND ANALYSIS METHODOLOGIESDEFINING FMEA TERMSDETECTION (D)DETECTION (D) is an assessment of the abilityof proposed *type (2) current design controls to detect a potential cause/mechanism (design weakness), or the ability of the proposed type (3) current design controls to detect the subsequent failure mode, before t