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Chapter 10Chapter 10Chapter 10Chapter 10

Principles of Principles of

Six SigmaSix Sigma

Key IdeaKey Idea

Although we view quality improvement tools and techniques from the perspective of Six Sigma, it is important to understand that they are simply a collection of methods that have been used successfully in all types of quality management and improvement initiatives, from generic TQM efforts, to ISO 9000, and in Baldrige processes.

Six-Sigma MetricsSix-Sigma Metrics

DefectDefect – any mistake or error – any mistake or error that is passed on to a customerthat is passed on to a customer

Defects per unit (DPU)Defects per unit (DPU) = number = number of defects discovered of defects discovered number number of units producedof units produced

Defects per million opportunities Defects per million opportunities (dpmo)(dpmo) = DPU = DPU 1,000,000 1,000,000 opportunities for erroropportunities for error

Six-Sigma QualitySix-Sigma Quality

Ensuring that process variation is half Ensuring that process variation is half the design tolerance (Cp = 2.0) while the design tolerance (Cp = 2.0) while allowing the mean to shift as much as allowing the mean to shift as much as 1.5 standard deviations, resulting in at 1.5 standard deviations, resulting in at most 3.4 dpmo.most 3.4 dpmo.

Key IdeaKey Idea

Although originally developed for manufacturing in the context of tolerance-based specifications, the Six Sigma concept has been operationalized to any process and has come to signify a generic quality level of at most 3.4 defects per million opportunities.

k-Sigma Quality Levelsk-Sigma Quality Levels

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Problem SolvingProblem Solving

ProblemProblem: any deviation between what : any deviation between what “should be” and what “is” that is “should be” and what “is” that is important enough to need correctingimportant enough to need correcting– StructuredStructured– SemistructuredSemistructured– Ill-structuredIll-structured

Problem SolvingProblem Solving: the activity : the activity associated with changing the state of associated with changing the state of what “is” to what “should be”what “is” to what “should be”

Quality Problem TypesQuality Problem Types

1. Conformance problems2. Unstructured performance

problems3. Efficiency problems4. Product design problems5. Process design problems

Key Factors in Six Sigma Key Factors in Six Sigma Project SelectionProject Selection

Financial return, as measured by costs associated with quality and process performance, and impacts on revenues and market share

Impacts on customers and organizational effectiveness

Probability of success Impact on employees Fit to strategy and competitive advantage

Problem Solving ProcessProblem Solving Process

1.1. Redefining and analyzing the Redefining and analyzing the problemproblem

2.2. Generating ideasGenerating ideas

3.3. Evaluating and selecting ideasEvaluating and selecting ideas

4.4. Implementing ideasImplementing ideas

Key IdeaKey Idea

A structured problem-solving process provides all employees with a common language and a set of tools to communicate with each other, particularly as members of cross-functional teams.

DMAIC MethodologyDMAIC Methodology

1.1. DefineDefine

2.2. MeasureMeasure

3.3. AnalyzeAnalyze

4.4. ImproveImprove

5.5. ControlControl

DefineDefine

Describe the problem in Describe the problem in operational termsoperational terms

Drill down to a specific problem Drill down to a specific problem statement (statement (project scopingproject scoping))

Identify customers and CTQs, Identify customers and CTQs, performance metrics, and performance metrics, and cost/revenue implicationscost/revenue implications

MeasureMeasure

Key data collection questionsKey data collection questions– What questions are we trying to What questions are we trying to

answer?answer?– What type of data will we need to What type of data will we need to

answer the question?answer the question?– Where can we find the data?Where can we find the data?– Who can provide the data?Who can provide the data?– How can we collect the data with How can we collect the data with

minimum effort and with minimum minimum effort and with minimum chance of error?chance of error?

AnalyzeAnalyze

Focus on why defects, errors, or Focus on why defects, errors, or excessive variation occurexcessive variation occur

Seek the Seek the root causeroot cause 5-Why technique5-Why technique Experimentation and verificationExperimentation and verification

ImproveImprove

Idea generationIdea generation BrainstormingBrainstorming Evaluation and selectionEvaluation and selection Implementation planningImplementation planning

ControlControl

Maintain improvementsMaintain improvements Standard operating proceduresStandard operating procedures TrainingTraining Checklist or reviewsChecklist or reviews Statistical process control chartsStatistical process control charts

Tools for Six-Sigma and Tools for Six-Sigma and Quality ImprovementQuality Improvement

Elementary statisticsElementary statistics Advanced statisticsAdvanced statistics Product design and reliabilityProduct design and reliability MeasurementMeasurement Process controlProcess control Process improvementProcess improvement Implementation and teamworkImplementation and teamwork

Design for Six SigmaDesign for Six Sigma

Focus on optimizing product and Focus on optimizing product and process performanceprocess performance

FeaturesFeatures– A high-level architectural view of the design– Use of CTQs with well-defined technical requirements– Application of statistical modeling and simulation

approaches– Predicting defects, avoiding defects, and

performance prediction using analysis methods– Examining the full range of product performance

using variation analysis of subsystems and components

Key IdeaKey Idea

All Six Sigma projects have three key characteristics: a problem to be solved, a process in which the problem exists, and one or more measures that quantify the gap to be closed and can be used to monitor progress.

Key Six Sigma Metrics in Key Six Sigma Metrics in ServicesServices

AccuracyAccuracy Cycle timeCycle time CostCost Customer satisfactionCustomer satisfaction

Lean Production and Six Lean Production and Six SigmaSigma The 5S’s: The 5S’s: seiri seiri (sort), (sort), seiton seiton (set in order), (set in order),

seiso seiso (shine), (shine), seiketsu seiketsu (standardize), and (standardize), and shitsuke shitsuke (sustain). (sustain).

Visual controlsVisual controls Efficient layout and standardized workEfficient layout and standardized work Pull productionPull production Single minute exchange of dies (SMED)Single minute exchange of dies (SMED) Total productive maintenanceTotal productive maintenance Source inspectionSource inspection Continuous improvementContinuous improvement