【正文】 DetectionFMEA Examples
Plating ExampleAn aerospace plating pany was shipping product to itscustomers with nickel plating that was too thin. Parts were failingcorrosion testing at the customer.
Shipping ExampleThe shipping department of an electronics pany is unable toship an assembly without its clam shell protective packaging. Thiscauses occasional late shipments to the customer.
In the following examples, a single line from the FMEA is used as anillustration for each of the above examples. 圖形技術(shù)分析:Graphical MethodsProcess Variation
Noise variation from discrete inputs
Different operators, machines, setups
Different days, shifts
Different batches, mixtures, raw materials
Noise variation from continuous inputs
Ambient temperature, humidity, pressure
Wear, drift, erosion, chemical depletion) ,..., , ( 2 1 k Process x x x f y =) ,..., , ( 2 1 k Noise n n n f +Intentional Unwanted The equation just means that any output isdetermined by the intentional process settingsand the unwanted noise variation.Common Classification of Noise Variables
Positional (within part variation) Variation within a single production unit
Thickness variation across a plated part Variation across a unit containing many parts
Variation across a semiconductor wafer with many die Variation by position in a batch process
Cavitytocavity variations in an injection molding operation
Cyclical (parttopart variation) Variation between consecutive production units Batchtobatch average differences – consecutive batches
Temporal (timetotime variation) Shifttoshift, DaytoDay, Setuptosetup Variation not accounted for by Positional or Cyclical2 2 2 2Temporal Cyclical Positional Noise σ σ σ ++=Graphical Analysis – Example
Injection molding is used to make a type of socket, four pieces at a time, onepiece per slot. Measurements of the sockets consist of thickness values inexcess of millimeters. The gauges measure in hundredths of amillimeter. The specification is 11 177。R 使用方法說明:1，校準(zhǔn)量具或確認(rèn)最近校準(zhǔn)仍然有效2，收集10個(gè)代表工藝偏差全部范圍的樣本3，從每日使用這種測量方法的員工中選出檢驗(yàn)員4，運(yùn)用 ClacMake Patterned Data 準(zhǔn)備量具研究數(shù)據(jù)表5，讓員工測量所有無標(biāo)識(shí)，隨機(jī)次序的樣本6，分別讓另外其他員工測量所有無標(biāo)識(shí)，隨機(jī)次序的樣本7，重復(fù)第五步及第六步循環(huán)三次。標(biāo)準(zhǔn)化分?jǐn)?shù)如果員工時(shí)常與標(biāo)準(zhǔn)不一致，則需要改變測量系統(tǒng)（或局部標(biāo)準(zhǔn)）工藝能力分析:為何測量工藝能力?使我們根據(jù)數(shù)據(jù)分配資源！ （這可不常見?。┤毕萋实靡粤炕_認(rèn)可以改進(jìn)機(jī)會(huì)分析工藝能力可使組織預(yù)測其所有產(chǎn)品和服務(wù)的真實(shí)質(zhì)量水平確認(rèn)工藝發(fā)生問題的本質(zhì)居中程度或分散度*6mman, machine ,method, measurement, mother nature (environment)(6M:人員，機(jī)器，測量方法，原材料，環(huán)境)《6 Sigma項(xiàng)目運(yùn)作實(shí)例》《測量階段》如何進(jìn)行項(xiàng)目描述如何進(jìn)行項(xiàng)目描述: 1，目標(biāo)陳述2，Metric 圖3，月節(jié)省額如何繪制工藝流程圖:召集小組:流程圖繪制是集體努力的結(jié)果小組包括：流程負(fù)責(zé)人：項(xiàng)目結(jié)果的負(fù)責(zé)人工程部門工藝，產(chǎn)品，設(shè)計(jì)及設(shè)備生產(chǎn)部門操作員，各班次主管，培訓(xùn)員，操作班長，維修技師流程圖所需信息腦力風(fēng)暴觀察/經(jīng)歷操作手冊工程標(biāo)準(zhǔn)，工作指示六大方面（人，機(jī)，方法，測量，材料，環(huán)境）6，完成目標(biāo)陳述。b5黑帶的第一個(gè)項(xiàng)目必須滿足培訓(xùn)目標(biāo)《6 Sigma項(xiàng)目運(yùn)作實(shí)例》《定義階段》我們在定義階段做什么我們在定義階段需要做什么？1，完成項(xiàng)目陳述。b1減少缺陷的70%b目的2，完成項(xiàng)目預(yù)測節(jié)省金額。7，組成項(xiàng)目小組，列出小組成員。確定工藝范圍:范圍至觀重要越窄越好！大量工藝步驟可能表明項(xiàng)目定義不佳或問題源于幾個(gè)項(xiàng)目問題藏于問題中若問題可以由粗略分析解決，管理層會(huì)去做繪制可執(zhí)行的工藝圖你能確認(rèn)缺陷來源嗎？我們能有意識(shí)地改變輸入指標(biāo)變量嗎？有意識(shí)的改變輸入指標(biāo)變量能直接影響輸出結(jié)果嗎？工藝能力研究連續(xù)數(shù)據(jù) 離散數(shù)據(jù) ：短期還是長期？： （通常是長期）： ：Ⅰ ZU,ZL ：Ⅱ CP Ⅰ PPMⅢ CPK Ⅱ Sigma水平ZLTⅣ Sigma水平ZST Ⅲ PPK： ：Ⅰ Sigma水平ZLT Ⅰ Sigma水平ZSTⅡ PPK Ⅱ CPK也盡量打亂員工次序8，用 Minitab 作下列兩個(gè)分析StatQuality ToolsGage Ramp。 6.
Four times a day the supervisor would go to the press and gather up theparts produced by five consecutive cycles of the press. Since each cycleproduced four parts, he would have 20 parts to measure every two hours.The supervisor kept track of the cycle and the cavity from which each partcame and wrote his twentymeasurements in an array likethis: The supervisor collected samples four times a day for five days (20 samplestotal, 20 parts per sample). Calculate the process capability and use a MultiVarichart to help determine sources of variation.A BCDES1 18 19 20 19 21S2 13 16 14 13 13S3 10 11 13 10 13S4 11 12 13 13 13Exercise: Determine Capability Using Minitab, analyze the Thick datain for process capability
Remember, the specifications are: 11 177。 knowledge
For the future:
FMEA helps evaluate the risk of process changes
FMEA identifies areas for other studies –multivari, ANOVA, DOE6s Process FMEA Terminology
FMEA: A systematic analysis of a process used to identify potentialfailures and to prevent their occurrence
Potential Failure mode: The manner in which the process couldpotentially fail to meet the process requirements.
Potential Failure Effect: The results of the failure mode on thecustomer. Severity: An assessment of the seriousness of a failure mode.Severity applies to the effects only.
Cause: How the failure could occur, described in terms of somethingthat can be corrected or controlled.
Occurrence: The likelihood that a specific failure mode is projectedto occur. Detection: The effectiveness of current process controls to identifythe failure mode (or the failure effect) prior to occurring, prior torelease to production, or prior to shipment to the customer.
RPN Risk Priority Number: The product of Severity, Occurrenceamp。量具研究偏差并不一定代表真實(shí)的工藝偏差當(dāng)量具樣本中的偏差代表真實(shí)工藝偏差時(shí)，P/TV等于P/SV定量型量具 Ramp。檢查員分?jǐn)?shù)如果大多數(shù)員工都是100%，則培訓(xùn)作用極為有限篩選有效分?jǐn)?shù)如果員工本身前后一致但是相互間不一致，則重新培訓(xùn)可幫助減少錯(cuò)誤。：對各種詳細(xì)列出的因子再列出其輸入變量。6你是如何得知這些的？ 《6 Sigma項(xiàng)目運(yùn)作實(shí)例》《定義階段》如何繪制宏觀圖如何繪制宏觀圖? 繪制宏觀圖的順序：供應(yīng)商輸入工序輸出客戶《6 Sigma項(xiàng)目運(yùn)作實(shí)例》《定義階段》項(xiàng)目的目標(biāo)陳述要點(diǎn) 項(xiàng)目的目標(biāo)陳述要點(diǎn): 1,目標(biāo)陳述2，計(jì)算方法3，全年節(jié)省額確定Team Members成員:1，小組成員要包括技術(shù)人員2，包括維修人員（如果需要）3，包括操作者4，小組人員不超過5人(特殊情況除外)。5，描述項(xiàng)目的主線。c可交付使用的2對與生產(chǎn)來說：a2 Pa