PowerPoint Presentation

Quality ControlQuality Control is a process that evaluates output relative to a standard and takes corrective action when output doesnt meet standardsAcceptance Sampling vs Statistical Process Control

InspectionIts an appraisal activity that compares goods or services to a standardIt can occur before production, during production and after productionBasic issues in inspectionHow much to inspect and how oftenAt what points in the process inspection should occurWhether to inspect in a centralized or on-site locationWhether to inspect attributes or variables

Low-Cost High Volume Items such as pencils vs High-Cost Low Volume Items such as an aircraftRaw Materials,Finished Products,Before a Costly Operation,Irreversible Process etc.Attributes(are counted, e.g. no of defective parts in a sample) & Variables(on a continuous scale, e.g.Time needed to complete a task)2CostOptimalAmount of InspectionCost of inspectionCost of passingdefectivesTotal CostVariations and ControlRandom variation: Natural variations in the output of a process, created by countless minor factorsAssignable variation: A variation whose source can be identified Control ChartPurpose: to monitor process output to see if it is randomA time ordered plot representative sample statistics obtained from an on going process (e.g. sample means)Upper and lower control limits define the range of acceptable variation

0123456789101112131415UCLLCLSample numberMeanOut ofcontrolNormal variationdue to chanceAbnormal variationdue to assignable sourcesAbnormal variationdue to assignable sourcesThe Control ProcessDefineMeasureCompareEvaluateCorrectMonitor ResultsTypes of ErrorsType I errorConcluding a process is not in control when it actually is.Type II errorConcluding a process is in control when it is not.

And the conclusion isIf a process is actuallyControl Charts For VariablesMean control chartsUsed to monitor the central tendency of a process.X bar charts

Range control chartsUsed to monitor the process dispersionR charts