【正文】 P/T ration:% total of tolerance): Less than 10% Outstanding 10% to 20% Capable 20% to 30% Marginally Capable Greater than 30% NOT CAPABLE For the P/P ratio and the P/T ratio, either or both approaches can be taken depending on the intended use of the measurement system and the desires of the customer. Generally, If the measurement system is only going to be use to inspect if the product meets the specs, then we should use the %Ramp。 PVRRTVm ????Analysis Techniques: Variable Gage Analysis 1. The ANOVA Method: A weakness with the AverageRange method of using the range to determine gage Ramp。R) is pared to the process output tolerance to estimate the precision to tolerance ratio (P/T ratio). This is important to determine if the measurement system can discriminate between good and bad output. The basic interest of studying the measurement process is to determine if the measurement system is capable of measuring a process output characteristic with its own unique variability. This is know as the Percent Ramp。R Gage Ramp。 Reproducibility。 TS16949 ? Base on QS9000 amp。 Linearity Stability(Alias: Drift): Stability is the total variation in the measurements obtained with a measurement system on the same master or parts when measuring a single characteristic over an extended time period. A stable measurement process is in statistical control with respect to location. Stability Introduction: Where does the variation of measurement system e from? ? The Five Characterizations of Measurement System: 1. Location Variation: Bias。R Reproducibility is the variation in the average of the measurements made by different appraisers using the same gage when measuring the identical characteristics of the same part. It is betweensystem variation, monly referred to as Variation. Reproducibility Introduction: Where does the variation of measurement system e from? ? The Five Characterizations of Measurement System: 2. Width Variation: Repeatability。R Study: The Average and Range Method The ANOVA Method The mon step for conducting Gage Ramp。amp。R statistics are then calculated as follows: 2222 ropo SSSS m s ???Measurement Error: Part: tnSnSPMSPV rop 22)( ??? Operator: pnSnSOMSOV rop 22)( ???Interaction: nSOPMSIV r2)( ?? Reproducibility: 22 IVOVAV ??Repeatability: M S EEV ? Measurement Error: 22amp。 values less than indicate poor agreement. Repeat above step, we can got following kappa measures for the appraisers: Table 4 Analysis Techniques: Attribute Gage Study Σ aΣ ef NΣ ef Ka p p a A B C A B C Table 4 Using the same steps to calculated the kappa measure to determine the agreement of each appraiser to the reference decision: Table 5 Total summary on Table 6: Analysis Techniques: Attribute Gage Study A B C K app a Table 5 S ourc e A p p ra i s e r A A p p ra i s e r B A p p ra i s e r CT ot a l Ins p e c t e d 50 50 50 M a t c he d 44 46 43M i x e d 6 4 795%U CI % % %Ca l c ul a t e d S c ore 88% 92% 86%95%L CI % 81% % T ot a l Ins p e c t e d 50 i n A g re e m e nt 4295%U CI % Ca l c ul a t e d S c ore 84%95%L CI %%S c ore vs A t t ri but eA n n e B e n C a t h y7 58 59 5A p p r a i s e rPercentW i t h i n A p p r a i s e rA n n e B e n C a t h y7 58 59 5A p p r a i s e rPercentA p p r a i s e r v s S t a n d a r dA s s e s s m e n t A g r e e m e n tD a t e o f s t u d y :R e p o r t e d b y :N a m e o f p r o d u c t :M i s c :[ , ] 9 5 . 0 % C IP e r c e n tAnalysis Techniques: Attribute Gage Study Analysis Techniques: Attribute Gage Study The AIAG MSA reference manual edition 3 provides acceptability criteria for each appraisers results: Definition: False Alarm – The number of times of which the operator (s) identify a good sample as a bad one. Miss – The number of times of which the operators identify a bad sample as a good one. D eci si on M easu r em ent S y st e m E f f ect i venes s Mi ss R at e Fal se A l arm R at e A cce pt abl e f or appr ai ser ≥ 90% ≤ 2% ≤ 5% M ar gi nal l y accept abl e f or t he app r ai ser m a y need i m pr o v e m ent ≥ 80% ≤ 5% ≤ 10% U nac cept abl e f or t he appr ai ser needs i m pr o v e m ent s 80% 5% 10% Number of correct decisions Total opportunities for a decision Effectiveness = Analysis Techniques: Attribute Gage Study Number of False Alarm Total opportunities for a decision False Alarm Rate = Number of False Alarm Total opportunities for a decision Miss Rate = So summarizing all the information of the example with this table: Table 7 F als e A l ar m R at eA 88% 4% 8%B 92% 6% 2%C 86% 8% 14%E f f e c t i ve n e s s M i s s R at eAnalysis Techniques: Attribute Gage Study Conclusion: The measurement system was acceptable with appraiser B, marginal with appraiser A, and unacceptable for C. So we shall determine if there is a misunderstanding with appraiser C that requires further training and then need to redo MSA. The final decision criteria should be based on the impact to the remaining process and final customer. Generally, the measurement system is acceptable if all 3 factors are acceptable or marginal. Minitab also can perform attribute gage analysis, but it didn’t declare the acceptability criteria, so it is not recognized by QS9000 standard. An