【正文】 %可接受的P/T30%測(cè)量系統(tǒng)的測(cè)量方法P/TV:精確度與總偏差之比代表量具偏差占據(jù)總偏差的部分此部分通常用百分率來(lái)表示最好情形10% 量具可接受條件30%測(cè)量系統(tǒng)的指標(biāo)分辨指數(shù) :分辨指數(shù)是測(cè)量系統(tǒng)從工藝數(shù)據(jù)中可辨認(rèn)的不同讀數(shù)的數(shù)量分辨指數(shù)是一個(gè)分辨率指標(biāo)分辨指數(shù)是重復(fù)性和復(fù)制性的函數(shù)最好情形：4 ，可接受的：34P/T 和 P/TV 的用處:P/T （% 公差）最常用于測(cè)量系統(tǒng)的精確度評(píng)估將量具的精確度與公差要求進(jìn)行對(duì)比如果量具用來(lái)對(duì)生產(chǎn)樣品進(jìn)行分類(lèi) P/T 還可以P/SV（%Ramp。R）6 Sigma 首選測(cè)量量具與量具研究偏差相比其性能如何最適合進(jìn)行工藝改進(jìn)的評(píng)估使用時(shí)應(yīng)小心。量具研究偏差并不一定代表真實(shí)的工藝偏差P/TV（%Ramp。R）6 Sigma 首選測(cè)量量具與工藝偏差相比其性能如何使用時(shí)應(yīng)小心。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。R 使用方法說(shuō)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(cè)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(cè)量所有無(wú)標(biāo)識(shí)，隨機(jī)次序的樣本6，分別讓另外其他員工測(cè)量所有無(wú)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。也盡量打亂員工次序8，用 Minitab 作下列兩個(gè)分析StatQuality ToolsGage Ramp。R Study(Crossed)StatQuality ToolsGage Run Chart9，對(duì)測(cè)量系統(tǒng)能力研究結(jié)果進(jìn)行分析10，確定適當(dāng)?shù)暮罄m(xù)措施定量型量具 Ramp。R Minitab 實(shí)例:一個(gè)黑帶想對(duì)冶金工藝使用的溫度表進(jìn)行量具研究，他嚴(yán)格按前面一頁(yè)的方法進(jìn)行實(shí)驗(yàn)，并將數(shù)據(jù)輸進(jìn)了Ramp。 中。運(yùn)用Minitab分析數(shù)據(jù)并評(píng)估量具能力StatQuality ToolsGage Ramp。R Study(Crossed)...Minitab 量具Ramp。R研究選項(xiàng)輸入該工藝公差和偏差，如果你想要Minitab幫你計(jì)算P/T 和 P/TV的話(huà)。Minitab 默認(rèn)計(jì)算P/SV量具Ramp。R結(jié)果ANOVA表P值是變化源在統(tǒng)計(jì)上對(duì)總偏差影響是否不顯著的概率在這個(gè)例子中，部件和員工均為顯著的偏差源另外，你能用Minitab的計(jì)算器計(jì)算總的平方和嗎？這個(gè)值代表什么意思？ 《6 Sigma項(xiàng)目運(yùn)作實(shí)例》《分析階段》失效模式及后果分析失效模式及后果分析: Failure Modes and Effects Analysis (FMEA)Background:
Failure Modes and Effects Analysis (FMEA) First developed in the 1950’s Appropriated by NASA in the 1960’s for the space program Ford Motor Company was the first North American pany to widelyimplement the use of FMEAs
Types of FMEA System – Toplevel, early stage analysis of plex systems Design – Systems, subsystems, parts amp。 ponents early in designstage Process – Focuses on process flow, sequence, equipment, tooling,gauges, inputs, outputs, set points, etcWho? When?
Who constructs the FMEA?
The Black Belt is the team leader.
The process owner inherits the finished FMEA.
Use the process mapping, Camp。E matrix team.
May need to add a rep from quality, a supplier, reliability
When should the FMEA be constructed?
After the process map amp。 the Camp。E matrix
Before or after the control plan, depending on the maturityof the processWhy?Warm up exercise:
You have 60 seconds to document: What would you want to know about a “defect”?
For the process:
FMEA improves the reliability of the process
An FMEA identifies problems before they occur
FMEA serves as a record of improvement amp。 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。 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。 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 sup