spc統(tǒng)計制程管制-wenkub
2024-10-24 22 本頁面
【正文】 落在規(guī)格上,下限外的斜線面積即為產(chǎn)品的不良率.,Standard Deviation from mean,目前在品管里常注重制程的分散寬度,故有定義制程能力為下式者:,群體標(biāo)準(zhǔn)差每不易直接求得一般以樣本資料推定之,其推定方法有下列三式,:,(1)直接由樣本特性值計算時,(2)由次數(shù)分配表計算時,(3) 管制圖計算時,一般均采用公式(3),制程能力的數(shù)量表示法,1分散寬度以 表示之.,制程能力= (或 ),d2,Cpk 計算時用公式(1),兩種錯誤之經(jīng)濟平衡點,Break even point, BEP,通常,在管制圖使中會有兩種錯(ERROR). 第一種即是當(dāng)制程仍屬管制狀態(tài),但卻因隨機性原因點落於管制界限外時,為了尋找不存在之問題而導(dǎo)致成本增加. 第二種即是當(dāng)制程已失去管制,但數(shù)據(jù)點由於隨機問題仍落於管制界限內(nèi),因而誤判制程處於管制狀態(tài),因而造成更大之損失.,The Accuracy of an instrument can be improved by recalibrating to reduce its error, but recalibrating generally does not improve the instrument’s Precision.(Repeatability also sometimes known as “Precision”),Accuracyamp。,3.Cp=1.33時, 穩(wěn)態(tài)控制下不合格品率為0.0063%=63PPM,在圖例上表示為中心沒有偏移 (實際中心值與規(guī)格中心重合),μ,DPPM,DR=DRL+DRR DR(Defect Rate):總不良 DRL (Defect Rate Left) :左不良 DRR (Defect Rate Right) :右不良,Table 1 Quality levels and Corresponding Number of Defects,Six Sigma 有多小?,Table2.The Number of Defective(Parts per Million)for Specified OffCentering of the Process and Quality Levels,中心偏離時dppm的計算,offcenter(σ),面積,z,常態(tài)曲線下之面積,e=2.718.,0,Z=(x 181。 4.選用合格的作業(yè)員。 8.找出最好的作業(yè)方法.,Item,No.,Quality,Level,Specification,Format,LSL,USL,DRL,(Dppm),DRR,(Dppm),DR,(Dppm),1,1 Sigma,181。1.5 Sigma,42.804,42.727,42.880,66807.23,66807.23,133614.46,3,2 Sigma,181。2.5 Sigma,42.804,42.676,42.931,6209.68,6209.68,12419.36,5,3 Sigma,181。3.5 Sigma,42.804,42.625,42.982,232.67,232.67,465.35,7,4 Sigma,181。4.5Sigma,42.804,42.574,43.033,3.40,3.40,6.80,9,5 Sigma,181。5.5 Sigma,42.804,42.523,43.084,0.019036,0.019036,0.04,11,6 Sigma,181。),Spec,LSL,Spec,USL,Tolerance,OffCenter,(Sigma),1,4,42.804,0.204,42.599,43.008,0.408,0.00,2,4,42.780,0.204,42.576,42.984,0.408,0.46,3,4.46,42.780,0.228,42.552,43.008,0.455,0.46,Ca,Cp,CpK,Grade,DRL,(Dppm),DRR,(Dppm),DR,(Dppm),0.00,1.33,1.33,A,31.69,31.69,63.37,0.12,1.33,1.18,B,4.05,202.05,206.10,0.10,1.49,1.33,A,0.43,32.03,32.46,Prepared by :VQM /Xu Gang,Approved by: Howard Lin,Verification,Item,Remark: Green means it can be changed or modified , Yellow means,it can not be changed or modified .,C.Choose Quality Level and Define Specification,D.Process Capability Verification,2,3,1,,Return d2,X Bar R,A2,D4,CPK Guidance,CPK formula for 90% confidence interval,Use this cal
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