精益生产第四讲

1、.Lean Manufacturing/Operations7 Quality ToolsCG. RobinsonPsychologySystem ThinkingTheory of KnowledgeCHANGEData CollectionRun ChartsHistogramsControl ChartsCause & EffectParetoScatter DiagramsRadar / Glyph ChartsVariationUnderstanding VariationDisplay & UnderstandInvestigate Sources .Lean Manufactur

2、ing/OperationsCG. RobinsonRecap Previous lectureData collection2. Run Charts 3. Histograms4. Control Chartsspecial cause variationcommon cause variationCp & Cpk5. Tampering.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonDateTotal DeliveriesSuMTWThFSSuMTWThFSSuM10

3、/110/210/310/410/510/610/710/810/910/1010/1110/1210/1310/1410/1510/16319305284252301526499290319258276309462508327274TWTh10/1710/1810/19384145343972574938414137577543441020304050607080903411433158113042018321Number Late XrMean x 46.9UCL x 76.69LCL x 17.11spread.Lean Manufacturing/OperationsMeasuresP

4、rocess CapabilityThe voice of the processA process must be stable before it is considered capableA process capability index is a technique for summarising the capability and location of a process that is in statistical controlNever compute a process capability index for a process that is not in stat

5、istical controlUse graphs like control charts and histograms to support any statistical indices reportedCG. Robinson.Lean Manufacturing/OperationsMeasuresProcess CapabilityFurther DataCG. RobinsonThe tolerance of late deliveries the business can stand is between 44 and 64. (the specification)So the

6、upper spec limit is 64 and the lower spec limit is 44.Lean Manufacturing/OperationsMeasuresProcess Capability=ENGINEERING SPECIFICATIONUSLLSLET=R_=1.128STANDARD DEVIATION DATA3Sd6Sd.SdSdSd3Sd6Sdxx36=CAPABILITY INDECES (Cp)6SdETCp.PROCESS APABILITY INDEX (Cpk)=.X_-USLDA3SdCpk upper=-.X_LSLDB3SdCpk lo

7、werCpk WARNING, ONLY CONTINUE IF PROCESS IS STABLE AND PREDICTABLE CG. Robinson.Lean Manufacturing/OperationsMeasuresProcess Capability=ENGINEERING SPECIFICATIONUSLLSLET=R_=1.128STANDARD DEVIATION DATA3Sd6Sd.SdSdSd3Sd6Sdxx36=CAPABILITY INDECES (Cp)6SdETCp.PROCESS CAPABILITY INDEX (Cpk)=.X_-USLDA3SdC

8、pk upper=-.X_LSLDB3SdCpk lowerCpk WARNING, ONLY CONTINUE IF PROCESS IS STABLE AND PREDICTABLE 11.2644420206446.917.146.9442.9.098Quote the lower value of the twoCG. Robinson-9.929.759.4.33675.09769.929.729.7.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCpwidth of

9、the processwidth of engineering toleranceCG. Robinson.Short Run SPC Using Deviation From AimIn short run SPC, were making a few parts of different sizes, so we cant really use the actual measurements. Instead of evaluating the variation of each measurement, we use the variation of parts from a targe

10、t value. So, if the first group of parts has a target value of 74mm, we measure each part and determine the variation from the target. If the next group of parts has a target value of 60mm, we measure those and determine their variation. Ideally, the variation from the target value will remain stabl

11、e even though the parts vary in size. Lean Manufacturing/OperationsControl or Process Behaviour Charts.Bar LengthMTWThF10/210/310/410/510/6-.10-.2-.1+.500,8DateSizer.- 0.2- 0.4- 0.6- 0,8Part A 2,60 +/- .08Deviation2,52,62,42,53,1MTWThF10/210/310/410/510/6-.3-.2-.2-.3+.0,8r

12、,10,1,4- 0.2- 0.4- 0.6- 0,8MTWThF10/210/310/410/510/61,51,91,31,31,700,8r,4,2,6,4- 0.2- 0.4- 0.6- 0,8Part B 3,40 +/- .08Part C 1,50 +/- .083.13,23,23.13.5+,4-,2-,2+,20Lean Manufacturing/OperationsControl or Process Behaviour ChartsShort Run SPC Using Deviation From Aim.Part A = 2,60 +/- .08

13、Bar LengthPart B = 3,40 +/- .08Part C = 1,50 +/- .08MTWThF10/210/310/410/510/600,8DateSizer- 0.2- 0.4- 0.6- 0,8Deviation-.10-.2-.1+.506162,52,62,42,53,1PartAAAAA-.3-.2-.2-.3+.122023.13,23,23.13.51,51,91,31,31,73601+,4-,2-,2+,2041BCBCBCBCBCLean Manufacturing/OperationsControl or Process Beha

14、viour ChartsShort Run SPC Using Deviation From Aim.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonLean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonVideo “A Japanese Control Chart.Which control chartUse X-MR chartIs it Variables

15、Data?Sub Group Size = 1?Use XR chartCan the data being collected be larger than the subgroup?Equal sized subgroups?Equal sized subgroups?Use c-chart or u-chartUse u-chartUse np-chart or p-chartUse p-chartNo (attributes data)yesyesyesyesyesnonononoLean Manufacturing/OperationsCG. RobinsonLean Manufac

16、turing/OperationsControl or Process Behaviour ChartsCG. RobinsonTypes & where to use them.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonLean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. Robinson“The Deming management Method, Mary Walton

17、, Pages 105 to 107 & 111 to 116 isbn 1-85252-141-4“A Study of the Toyota Production System, Shingeo Shingo, Pages 16 to 17, isbn 0-915299-17-8“The Lean Toolbox, John Bicheno, Pages 174 to 175, Short Run SPC, isbn 0-9513-829-9-3.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour Charts

18、CG. RobinsonLean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonVideo “A Japanese Control ChartTake notes for discussion afterwards.Lean Manufacturing/OperationsMeasuresControl or Process Behaviour ChartsCG. RobinsonLean Manufacturing/OperationsMeasuresControl or Proc

19、ess Behaviour ChartsCG. Robinson.Lean Manufacturing/OperationsControl or Process Behaviour ChartsCG. RobinsonLean Manufacturing/OperationsCG. Robinson.Lean Manufacturing/OperationsCG. RobinsonRecap Previous lectureData collection2. Run Charts 3. Histograms4. Control Chartsspecial cause variationcomm

20、on cause variationCp & Cpk5. Tampering.Lean Manufacturing/Operations7 Quality ToolsCG. RobinsonPsychologySystem ThinkingTheory of KnowledgeCHANGEData CollectionRun ChartsHistogramsControl ChartsCause & EffectParetoScatter DiagramsRadar / Glyph ChartsVariationUnderstanding VariationDisplay & Understa

21、ndInvestigate Sources .Cause & EffectCG. Robinson.Lean Manufacturing/Operations7 Quality ToolsCause & Effect DiagramsPurpose: To generate, identify and sort potential causes of variation within a process CG. Robinson.Lean Manufacturing/OperationsCause & Effect DiagramsUse & Benefits : Very simple to

22、 use Helps sort possible causes of variation Provides a systematic approach to problem solving Documents ideas and theories Gets all the experts involvedCG. Robinson.Lean Manufacturing/OperationsCause & Effect DiagramsConstruction :MaterialsMethodEquipmentPeopleEnvironmentEffectCauseCauseCauseCauseC

23、auseCauseCauseCauseCauseCauseCauseCauseCauseCauseCauseCauseNote: You may use other headings if you wishCause CategoriesA quality characteristic, Preferably numericCG. Robinson.Lean Manufacturing/OperationsCause & Effect DiagramsMethod :Create the team of expertsYou must define the problem clearly (M

24、ost Important)Define the fishbone categoriesBrainstorm each cause category and record all ideasReview all ideas asking why at least 5 times to establish the root cause (example)Rank the ideas into primary (most likely) and secondary (lets keep them for later)Create an action list for data collection

25、, with owners and timescalesCG. Robinson.Lean Manufacturing/OperationsCause & Effect DiagramsFacilitation Rules : Encourage Spontaneous freewheeling responses Do not discuss individuals ideas Create a supportive environment Write everything down Encourage response from the quieter participants Disco

26、urage non-verbal responses to ideasCG. Robinson.Lean Manufacturing/OperationsCause & Effect DiagramsLimitations :Deals only with opinions, therefore theories must be tested The structure (i.e., main branch categories) have a tendency to lead peoples thinking and must be identified beforehandNot effe

27、ctive if there is fear among the groupCause & Effect diagram is only as good as the ideas generated. Therefore following brainstorming guidelines is very important CG. Robinson.ParetoCG. Robinson.Lean Manufacturing/OperationsMeasuresParetoPareto diagrams summarise items by their relative frequency a

28、nd organises them in order of decreasing frequency.PurposeCG. Robinson.Lean Manufacturing/OperationsMeasuresParetoParetos Law (also known as the 80;20 rule)States that 20% of causes gives 80% of the effect, e.g., 20% of customers generate 80% of turnover.This is not a rigid rule but a useful guideCG

29、. Robinson.Lean Manufacturing/OperationsMeasuresParetoBenefitsProvides a graphical method for prioritising issuesHelps to separate the vital few from the trivial manyProvides a means of viewing issues from different perspectivesCan be used to compare the rank order of problemsTo compare the number o

30、f problems before and after improvement effortCG. Robinson.Lean Manufacturing/OperationsMeasuresParetoWhat is the biggest reason for being late for work? Pareto:-Traffic JamLeft house lateCar troubleSnow stormRan errand510Data collected over a three month periodCG. Robinson.Lean Manufacturing/OperationsMeasuresPareto LimitationsLimitationsDoesnt distinguish between special and common causesUses historical data not real timeOften not acted upon ( especially if largest factor is difficul