Quality management

Quality ManagementQuality ManagementQuality ManagementQuality Management

QualityQuality

• PMI’s quality philosophy summarized by– Definition of quality

– No gold-plating

– Prevention over inspection

• PMI’s quality philosophy summarized by– Definition of quality

– No gold-plating

– Prevention over inspection

PMI Quality DefinitionPMI Quality Definition

• QUALITY IS CONFORMANCE TO REQUIREMENTS AND FITNESS OF USE

• QUALITY IS CONFORMANCE TO REQUIREMENTS AND FITNESS OF USE

No Gold-platingNo Gold-plating

• Don’t give the customer extras• Adds no-value to the project because

– it is beyond the scope – Could cost more– May be based on impressions not

requests

• Don’t give the customer extras• Adds no-value to the project because

– it is beyond the scope – Could cost more– May be based on impressions not

requests

Prevention over inspectionPrevention over inspection

– Quality must be planned NOT inspected– Quality must be planned NOT inspected

Six SigmaSix Sigma

Originally developed by Motorola, Originally developed by Motorola, Six Sigma refers to an extremely Six Sigma refers to an extremely high measure of process capabilityhigh measure of process capability

A Six Sigma capable process will A Six Sigma capable process will return no more than 3.4 defects per return no more than 3.4 defects per million operations (DPMO)million operations (DPMO)

Highly structured approach to Highly structured approach to process improvementprocess improvement

Six sigmaSix sigma

Six SigmaSix Sigma

1.1. Define critical outputs Define critical outputs and identify gaps for and identify gaps for improvementimprovement

2.2. Measure the work and Measure the work and collect process datacollect process data

3.3. Analyze the dataAnalyze the data

4.4. Improve the processImprove the process

5.5. Control the new process to Control the new process to make sure new performance make sure new performance is maintainedis maintained

DMAIC ApproachDMAIC Approach

Tools Of TQMTools Of TQM Check SheetsCheck Sheets

Scatter Diagrams Scatter Diagrams

Cause-and-Effect DiagramCause-and-Effect Diagram

Pareto ChartsPareto Charts

Flow ChartsFlow Charts

HistogramsHistograms

Statistical Process Control (SPC)Statistical Process Control (SPC)

/

/

/ / /// /

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// ////

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Hour

Defect 1 2 3 4 5 6 7 8

A

B

C

/

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Seven Tools for TQMSeven Tools for TQM

(a)(a) Check Sheet: An organized method of Check Sheet: An organized method of recording datarecording data

Figure 6.5Figure 6.5


(b)(b) Scatter Diagram: A graph of the value Scatter Diagram: A graph of the value of one variable vs. another variableof one variable vs. another variable

AbsenteeismAbsenteeism

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(c)(c) Cause and Effect Diagram: A tool that Cause and Effect Diagram: A tool that identifies process elements (causes) that identifies process elements (causes) that might effect an outcomemight effect an outcome


CauseCause

MaterialsMaterials MethodsMethods

ManpowerManpower MachineryMachinery

EffectEffect


(d)(d) Pareto Charts: A graph to identify and plot Pareto Charts: A graph to identify and plot problems or defects in descending order of problems or defects in descending order of frequencyfrequency


Fre

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req

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Pe

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AA BB CC DD EE

Pareto ChartPareto Chart


(e)(e) Flow Charts (Process Diagrams): A chart Flow Charts (Process Diagrams): A chart that describes the steps in a processthat describes the steps in a process


Operator takes phoneorder.

Orders waitto be pickedup.

Supervisorinspectsorders.

Order isfulfilled.

Order waitsfor sales rep.

Is ordercomplete?

Yes

No

Orders aremoved tosupervisor’sin-box.

Orderswait forsupervisor.

Flow ChartsFlow Charts


(f)(f) Histogram: A distribution showing the Histogram: A distribution showing the frequency of occurrence of a variablefrequency of occurrence of a variable


DistributionDistribution

Repair time (minutes)Repair time (minutes)

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(g)(g) Statistical Process Control Chart: A chart with Statistical Process Control Chart: A chart with time on the horizontal axis to plot values of a time on the horizontal axis to plot values of a statisticstatistic


Upper control limitUpper control limit

Target valueTarget value

Lower control limitLower control limit

TimeTime

Variability is inherent in every processNatural or common causesSpecial or assignable causes

Provides a statistical signal when assignable causes are present

Detect and eliminate assignable causes of variation

Variability is inherent in every processNatural or common causesSpecial or assignable causes

Provides a statistical signal when assignable causes are present

Detect and eliminate assignable causes of variation

Statistical Process Control (SPC)Statistical Process Control (SPC)

Natural VariationsNatural Variations

Also called common causesAlso called common causes

Affect virtually all production processesAffect virtually all production processes

Expected amount of variationExpected amount of variation

Output measures follow a probability distributionOutput measures follow a probability distribution

For any distribution there is a measure of central For any distribution there is a measure of central

tendency and dispersiontendency and dispersion

If the distribution of outputs falls within acceptable If the distribution of outputs falls within acceptable

limits, the process is said to be “in control”limits, the process is said to be “in control”

Assignable VariationsAssignable Variations

Also called special causes of variationAlso called special causes of variation

Generally there is some change in the processGenerally there is some change in the process

Variations that can be traced to a specific reasonVariations that can be traced to a specific reason

The objective is to discover when assignable causes The objective is to discover when assignable causes

are presentare present

Eliminate the bad causesEliminate the bad causes

Incorporate the good causesIncorporate the good causes

SamplesSamples

To measure the process, we take To measure the process, we take samples and analyze the sample samples and analyze the sample statistics following these stepsstatistics following these steps

(a)(a) Samples of the Samples of the product, say five product, say five boxes of cereal boxes of cereal taken off the filling taken off the filling machine line, vary machine line, vary from each other in from each other in weightweight Fre

qu

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Fre

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WeightWeight

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Each of these Each of these represents one represents one sample of five sample of five

boxes of cerealboxes of cereal

Figure S6.1Figure S6.1

SamplesSamples

(b)(b) After enough After enough samples are samples are taken from a taken from a stable process, stable process, they form a they form a pattern called a pattern called a distributiondistribution

The solid line The solid line represents the represents the

distributiondistribution

Fre

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Fre

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WeightWeightFigure S6.1Figure S6.1

SamplesSamples

(c)(c) There are many types of distributions, including There are many types of distributions, including the normal (bell-shaped) distribution, but the normal (bell-shaped) distribution, but distributions do differ in terms of central distributions do differ in terms of central tendency (mean), standard deviation or tendency (mean), standard deviation or variance, and shapevariance, and shape

WeightWeight

Central tendencyCentral tendency

WeightWeight

VariationVariation

WeightWeight

ShapeShape

Fre

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ency

Fre

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SamplesSamples

(d)(d) If only natural If only natural causes of causes of variation are variation are present, the present, the output of a output of a process forms a process forms a distribution that distribution that is stable over is stable over time and is time and is predictablepredictable

WeightWeightTimeTimeF

req

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SamplesSamples

(e)(e) If assignable If assignable causes are causes are present, the present, the process output is process output is not stable over not stable over time and is not time and is not predicablepredicable

WeightWeightTimeTimeF

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Control ChartsControl Charts

Constructed from historical data, the Constructed from historical data, the purpose of control charts is to help purpose of control charts is to help distinguish between natural variations and distinguish between natural variations and variations due to assignable causesvariations due to assignable causes

Types of DataTypes of Data

Characteristics that can

take any real value

May be in whole or in

fractional numbers

Continuous random

variables

VariablesVariables AttributesAttributes

Defect-related Defect-related

characteristics characteristics

Classify products as Classify products as

either good or bad or either good or bad or

count defectscount defects

Categorical or discrete Categorical or discrete

random variablesrandom variables

Control Charts for VariablesControl Charts for Variables

For variables that have continuous For variables that have continuous dimensionsdimensions Weight, speed, length, strength, etc.Weight, speed, length, strength, etc.

x-charts are to control the central x-charts are to control the central tendency of the processtendency of the process

R-charts are to control the dispersion of R-charts are to control the dispersion of the processthe process

These two charts must be used togetherThese two charts must be used together

Control ChartControl Chart

Patterns in Control ChartsPatterns in Control Charts

Normal behavior. Normal behavior. Process is “in control.”Process is “in control.”


TargetTarget




TargetTarget



One plot out above (or One plot out above (or below). Investigate for below). Investigate for cause. Process is “out cause. Process is “out of control.”of control.”



TargetTarget



Trends in either Trends in either direction, 5 plots. direction, 5 plots. Investigate for cause of Investigate for cause of progressive change.progressive change.



TargetTarget



Two plots very near Two plots very near lower (or upper) lower (or upper) control. Investigate for control. Investigate for cause.cause.



TargetTarget



Run of 5 above (or Run of 5 above (or below) central line. below) central line. Investigate for cause. Investigate for cause. Figure S6.7Figure S6.7


TargetTarget



Erratic behavior. Erratic behavior. Investigate.Investigate.


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