chapter 6, management of process quality

Chapter 6Chapter 6

Management Management of Process of Process

QualityQuality

Product Inspection Vs Process Product Inspection Vs Process ControlControl

A Brief History of Quality A Brief History of Quality ControlControl

Concept of Quality have Concept of Quality have traced as far back as traced as far back as 3000 B.C. in Babylonia3000 B.C. in Babylonia

Among the references to Among the references to quality from code of quality from code of Hammurabi, ruler of Hammurabi, ruler of Babylonia is the Babylonia is the following excerpt:following excerpt:

“ “ The mason who builds a The mason who builds a house which falls down house which falls down and kills the inmate shall and kills the inmate shall be put to death”be put to death”

A Brief History of Quality A Brief History of Quality ControlControl

Following the Industrial Revolution and resulting factory system, quality and process control began to take some characteristics that we know today.

Specialization of labor and quality control took a giant step forward in 1911 with the publication of Fredrick Winslow Taylor’s book Principles of Scientific Management.

Taylor’s philosophy was one of extreme functional specialization and he suggested eight functional bosses for the shop floor, one of who was assigned task for INSPECTION.

Taylor later conceded that extreme functional specialization has its disadvantages, but his notion of process analysis and quality control by inspection of final product still lives on in many firms today.

Difference Between QA, QC and Difference Between QA, QC and TestingTesting

Many people and organizations are confused about the Many people and organizations are confused about the difference between quality assurance (QA), quality control difference between quality assurance (QA), quality control (QC), and testing. They are closely related, but they are (QC), and testing. They are closely related, but they are different concepts. different concepts.

Quality Assurance:Quality Assurance: A set of activities designed to ensure A set of activities designed to ensure that the development and/or maintenance process is that the development and/or maintenance process is adequate to ensure a system will meet its objectives. adequate to ensure a system will meet its objectives.

Quality Control:Quality Control: A set of activities designed to evaluate a A set of activities designed to evaluate a developed work product. developed work product.

Testing:Testing: The process of executing a system with the intent The process of executing a system with the intent of finding defects. (Note that the "process of executing a of finding defects. (Note that the "process of executing a system" includes test planning prior to the execution of the system" includes test planning prior to the execution of the test cases.) test cases.)

What is Product InspectionWhat is Product Inspection??

This is historical or traditional approach This is historical or traditional approach in which product is check for quality in which product is check for quality when it is already completed or when it is already completed or manufactured.manufactured.

In this case a variation or defect is In this case a variation or defect is already occurred and nothing could be already occurred and nothing could be done to correct it.done to correct it.

This also known as feedback quality This also known as feedback quality control system.control system.

Definition of processDefinition of process

A process is a set of causes and A process is a set of causes and conditions and a set of steps comprising conditions and a set of steps comprising an activity that transform inputs into an activity that transform inputs into outputs.outputs.

For example consider the number of For example consider the number of processes involved in airline industry: the processes involved in airline industry: the process of taking and confirming a process of taking and confirming a reservation, baggage handling, loading of reservation, baggage handling, loading of passengers, of meal services etc.passengers, of meal services etc.

Characteristics of processCharacteristics of process

The process is any set of people, equipment, procedures, and The process is any set of people, equipment, procedures, and conditions that work together to produce a result -an output.conditions that work together to produce a result -an output.

The process is expected to add value to the inputs in or to produce The process is expected to add value to the inputs in or to produce an output.an output.

The ratio of output to input is called productivity and the objectives The ratio of output to input is called productivity and the objectives are:are:– To increase the ratio of output to input andTo increase the ratio of output to input and– Reduce the variation in the output of the process.Reduce the variation in the output of the process.

If the If the variationvariation is too small or insignificant to have any effect on the is too small or insignificant to have any effect on the usefulness of the product or service, the output is said to be within usefulness of the product or service, the output is said to be within tolerancetolerance..

Should the output fall outside the desired tolerance, the process can Should the output fall outside the desired tolerance, the process can be improved and returned to tolerance by defining cause of the be improved and returned to tolerance by defining cause of the change (the problem) and taking action to make sure that cause does change (the problem) and taking action to make sure that cause does not recur.not recur.

The Key Elements of Process Quality By Baldrige National Quality Awards

The key elements of process management are: R&D, design, management of process quality for all work units and suppliers, systematic quality improvement, and quality assessment.

Here it is defined as:– Design and introduction of quality products and

services– Process management: product and service

production and delivery process– Process management: business processes and

support services.– Supplier quality– Quality assessment

Management of Process Quality: The Baldrige Criteria

It is apparent that Baldrige Definition of Management of Process Quality is directly related to how well the processes are managed.

All of the processes in the organization are directly or indirectly related to quality as the customer defines it.

Now the control component (QA) has moved form measuring output (the traditional control system) to controlling the continuous improvement of the processes.

The TQM Based Model of Process Control

INPUTPeopleMaterialEnergyEquipmentMethodsMoney

PROCESSES OUTPUTProduct

orServices

CUSTOMERExternal

AndInternal

Continuous Improvement

ControlQuality

Assurance

Continuous Improvement

Moving form Inspection to Process ControlMoving form Inspection to Process Control

The idea behind process control is to prevent the The idea behind process control is to prevent the variation or defect from happening. variation or defect from happening.

What is needed is the feedforward system that is What is needed is the feedforward system that is opposed to product inspection (feedback system)opposed to product inspection (feedback system)

However, process control still requires measurement However, process control still requires measurement that is determined by inspection, but the activity of that is determined by inspection, but the activity of inspection is now transformed into a diagnostic role.inspection is now transformed into a diagnostic role.

The objective is not to merely discover defects but The objective is not to merely discover defects but rather to identify and remove the cause(s) of defects rather to identify and remove the cause(s) of defects or variation.or variation.

Statistical Process (Quality) ControlStatistical Process (Quality) Control

One of the best technical tools for improving One of the best technical tools for improving product and service quality is statistical product and service quality is statistical Process Control.Process Control.

It involves the use of statistical techniques, It involves the use of statistical techniques, such as control charts, to analyze a work such as control charts, to analyze a work process or its output.process or its output.

The data can be used to identify variations The data can be used to identify variations and to take countermeasures to improve the and to take countermeasures to improve the capability of the process.capability of the process.

Basic Approach to Statistical Basic Approach to Statistical Process ControlProcess Control

Statistical process control were initially developed in Statistical process control were initially developed in the United States in the 1930s and 1940s by W.A. the United States in the 1930s and 1940s by W.A. Shewhart, W.E. Deming and J.M. Juran and others.Shewhart, W.E. Deming and J.M. Juran and others.

The basic approach contains the following steps:The basic approach contains the following steps:1.1. Awareness that a problem exists.Awareness that a problem exists.

2.2. Determine the specific problem to be solved.Determine the specific problem to be solved.

3.3. Diagnose the causes of the problem.Diagnose the causes of the problem.

4.4. Determine and implement remedies to solve the Determine and implement remedies to solve the problem.problem.

5.5. Implement controls to hold the gains achieved by Implement controls to hold the gains achieved by solving the problem.solving the problem.

7 QC Tools7 QC Tools

One of the technical tools for improving product and One of the technical tools for improving product and service quality is Statistical Process Control (SPC)service quality is Statistical Process Control (SPC)

There are 7 basic techniques. Since first four There are 7 basic techniques. Since first four techniques are not really statistical, the word techniques are not really statistical, the word statistical is somewhat of a statistical is somewhat of a misnomer.misnomer.

This technical tool not only controls the process but This technical tool not only controls the process but has the capability to improve it as well.has the capability to improve it as well.

Basic Approach to Statistical Basic Approach to Statistical Quality Control: 7 QC ToolsQuality Control: 7 QC Tools

1.1. Pareto DiagramPareto Diagram

2.2. Process Flow ChartProcess Flow Chart

3.3. Cause-and-Effect DiagramCause-and-Effect Diagram

4.4. Check SheetCheck Sheet

5.5. HistogramsHistograms

6.6. Control ChartControl Chart

7.7. Scatter DiagramScatter Diagram

Pareto DiagramPareto Diagram

In 1879, the famous Italian economist Alfred In 1879, the famous Italian economist Alfred Pareto, noticed that 80% of Italy’s wealth was Pareto, noticed that 80% of Italy’s wealth was controlled by 20% of the population. This concept controlled by 20% of the population. This concept is known as is known as Pareto’s lawPareto’s law or or Pareto’s rulePareto’s rule or or Principle of imbalance Principle of imbalance or simply or simply 80/20 rule80/20 rule..

Subsequently, people in various disciplines and Subsequently, people in various disciplines and professions noticed that this same 80/20 applied, in professions noticed that this same 80/20 applied, in a broad way, to a wide range of phenomena.a broad way, to a wide range of phenomena.

Dr. Joseph Juran also recognized this concept as Dr. Joseph Juran also recognized this concept as universal that could be applied to many fields. He universal that could be applied to many fields. He coined the term coined the term vital fewvital few and and useful manyuseful many..

Dr. Juran and Dr. Kaoru Ishikawa popularize the Dr. Juran and Dr. Kaoru Ishikawa popularize the use of this chart in the field of Quality Assurance.use of this chart in the field of Quality Assurance.

Alfred Pareto

(1848-1923)


When and why Pareto Chart is used in the Statistical When and why Pareto Chart is used in the Statistical Quality Control?Quality Control?

Pareto chart are used to show those vital few characteristics of Pareto chart are used to show those vital few characteristics of a process that need attention to direct the resources to take a process that need attention to direct the resources to take necessary action.necessary action.

Examples of vital few are:Examples of vital few are: A A few customersfew customers account for account for majority salesmajority sales A A few processes few processes account for account for bulk of scrap or rework costbulk of scrap or rework cost.. A A few nonconformities few nonconformities account for account for the majority of customer the majority of customer

complaints.complaints. A A few product few product account account for the majority of the profitfor the majority of the profit A A few items few items account for account for the bulk of inventorythe bulk of inventory..

Construction of Pareto Construction of Pareto ChartChart

Construction of Pareto Chart is simple. Construction of Pareto Chart is simple. There are five steps:There are five steps:

1.1. Determine the method of classifying data: by Determine the method of classifying data: by problem, cause, non-conformity, and so forth.problem, cause, non-conformity, and so forth.

1.1. Decide if Money (Rs), frequency, or both are to Decide if Money (Rs), frequency, or both are to be used to rank the characteristics.be used to rank the characteristics.

1.1. Collect data for an appropriate time interval or Collect data for an appropriate time interval or use historical data.use historical data.

1.1. Summarize the data and rank order categories Summarize the data and rank order categories from largest to smallest.from largest to smallest.

1.1. Construct the diagram and find vital few.Construct the diagram and find vital few.

Process Flow DiagramProcess Flow Diagram


A flow chart is a pictorial representation A flow chart is a pictorial representation showing all the steps and processes involve in showing all the steps and processes involve in the operation.the operation.

The diagram makes it easy to visualize the The diagram makes it easy to visualize the entire system, identify potential trouble spots, entire system, identify potential trouble spots, and locate control activities.and locate control activities.

It answers the question, “Who is the next It answers the question, “Who is the next customer?”customer?”

Improvements can be accomplished by Improvements can be accomplished by changing, reducing, combining, or eliminating changing, reducing, combining, or eliminating steps.steps.


What are the benefits of using Flow Chart in What are the benefits of using Flow Chart in improving quality?improving quality?

Following items can be analyzed to improve Following items can be analyzed to improve system in the organization: system in the organization:

– Time-per-event (reducing cycle time) Time-per-event (reducing cycle time) – Process repeats (preventing rework) Process repeats (preventing rework) – Duplication of effort (identifying and eliminating Duplication of effort (identifying and eliminating

duplicated tasks) duplicated tasks) – Unnecessary tasks (eliminating tasks that are in Unnecessary tasks (eliminating tasks that are in

the process for no apparent reason) the process for no apparent reason) – Value-added versus non-value-added tasksValue-added versus non-value-added tasks

Cause-and-Effect DiagramCause-and-Effect Diagram

A cause-and-effect (C&E) A cause-and-effect (C&E) diagram is designed to diagram is designed to represent a meaningful represent a meaningful relationship between effect and relationship between effect and its causes.its causes.

It was developed by Dr. Kaoru It was developed by Dr. Kaoru Ishikawa and is sometimes Ishikawa and is sometimes refer to as an refer to as an Ishikawa Ishikawa diagramdiagram or a or a fishbone fishbone diagramdiagram because of its shape. because of its shape.

Cause-and-Effect DiagramCause-and-Effect Diagram

C&E diagrams are used to investigate C&E diagrams are used to investigate either a “bad” effect or problem and to either a “bad” effect or problem and to correct the causes or a “good” effect and correct the causes or a “good” effect and to learn those causes that are responsible.to learn those causes that are responsible.

It’s a brainstorming or idea generating It’s a brainstorming or idea generating technique and usually done by a project technique and usually done by a project team.team.

The C&E diagrams has nearly unlimited The C&E diagrams has nearly unlimited application in research, manufacturing, application in research, manufacturing, marketing, office operations, services, etc.marketing, office operations, services, etc.

Selection of Causes for C&E DiagramSelection of Causes for C&E Diagram

Causes in a typical diagram are normally arranged into Causes in a typical diagram are normally arranged into categories, the main ones of which are:categories, the main ones of which are:

The 6 M's (Recommended for manufacturing industry)The 6 M's (Recommended for manufacturing industry)– Machine, Method, Materials, Measurement, Man and Mother Machine, Method, Materials, Measurement, Man and Mother

Nature (Environment)Nature (Environment)

The 8 P's (Recommended for administration and service The 8 P's (Recommended for administration and service industry). industry). – Price, Promotion, People, Processes, Place / Plant, Policies, Price, Promotion, People, Processes, Place / Plant, Policies,

Procedures & Product (or Service)Procedures & Product (or Service)

The 4 S's (Recommended for service industry). The 4 S's (Recommended for service industry). – Surroundings, Suppliers, Systems, SkillsSurroundings, Suppliers, Systems, Skills

How to Construct a C&E DiagramHow to Construct a C&E Diagram

Problem or

an Effect

Material Man

MethodMachine

How to Construct a C&E DiagramHow to Construct a C&E Diagram

House Paint

Peeling

Material Work Method

Environment

Machine

No instructions

Paint over dirt

Humidity

Acid rain

Temperature

Air pollution

Too thin

Too thick

WrongType

Dirt

Contaminated

Cheap Solvents

Dirty

Paint Brush

Bad bristle

1

23

4

5

Check SheetsCheck Sheets

The The check sheetcheck sheet also called also called defect concentration defect concentration diagramdiagram is a simple document that is used for is a simple document that is used for collecting data in real-time and at the location where collecting data in real-time and at the location where the data is generated the data is generated

The main purpose of check sheets is to ensure that The main purpose of check sheets is to ensure that the data is collected carefully and accurately by the data is collected carefully and accurately by operating personnel.operating personnel.

Data should be collected in such a way that it should Data should be collected in such a way that it should be quickly and easily used and analyzed.be quickly and easily used and analyzed.

A defining characteristic of a check sheet is that data A defining characteristic of a check sheet is that data is recorded by making marks ("checks") on it. is recorded by making marks ("checks") on it.

Check sheets have no standard format. It is based on Check sheets have no standard format. It is based on the creativity of data collector and it design depends the creativity of data collector and it design depends on the requirement, recording and marking of data.on the requirement, recording and marking of data.


When to use When to use

– When data can be observed and collected When data can be observed and collected repeatedly by the same person or at the repeatedly by the same person or at the same location. same location.

– When collecting data on the frequency or When collecting data on the frequency or patterns of events, problems, defects, patterns of events, problems, defects, defect location, defect causes, etc. defect location, defect causes, etc.

– When collecting data from a production When collecting data from a production process. process.


No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8 Total

11 4

66 7

55 20

22 10

Others 4

Weeks

Deptt

Check Sheet of Reworked Jobs

HistogramsHistograms

A A histogramhistogram is a graphical display of tabulated is a graphical display of tabulated frequencies. frequencies.

A histogram is the graphical version of a table which shows A histogram is the graphical version of a table which shows what proportion of cases fall into each of several or many what proportion of cases fall into each of several or many specified categories. specified categories.

It differs from a bar chart in that it is the It differs from a bar chart in that it is the areaarea of the bar of the bar that denotes the value, not the height, a crucial distinction that denotes the value, not the height, a crucial distinction when the categories are not of uniform width.when the categories are not of uniform width.

Histograms can give sufficient information about a quality Histograms can give sufficient information about a quality problem to provide a basis for decision making without problem to provide a basis for decision making without further analysis.further analysis.

A histogram is like a snapshot of process showing the A histogram is like a snapshot of process showing the variation.variation.

Histograms can determine the process capability, compare Histograms can determine the process capability, compare with specifications, suggest the shape of population, and with specifications, suggest the shape of population, and indicate discrepancies in data such as gaps.indicate discrepancies in data such as gaps.

HistogramsHistograms

When to use histogramsWhen to use histograms

When the data are numerical. When the data are numerical.

When analyzing whether a process can meet the customer’s When analyzing whether a process can meet the customer’s requirements. requirements.

When analyzing what the output from a supplier’s process looks When analyzing what the output from a supplier’s process looks like.like.

When seeing whether a process change has occurred from one When seeing whether a process change has occurred from one time period to another. time period to another.

When determining whether the outputs of two or more processes When determining whether the outputs of two or more processes are different. are different.

When you wish to communicate the distribution of data quickly When you wish to communicate the distribution of data quickly and easily to others and easily to others

Control ChartControl Chart

The The control chartcontrol chart, also known as the , also known as the ''Shewhart chartShewhart chart'' or ' or 'process-behavior process-behavior chartchart'' is a statistical tool intended to help is a statistical tool intended to help assess the nature of variation in a process and assess the nature of variation in a process and to facilitate forecasting and management. to facilitate forecasting and management.

Variations occur in a process due to many Variations occur in a process due to many sources such as equipment, materials, sources such as equipment, materials, environment, and operator.environment, and operator.

A control chart always has a central line for the A control chart always has a central line for the average, an upper line for the upper control average, an upper line for the upper control limit and a lower line for the lower control limit. limit and a lower line for the lower control limit.

Walter Andrew Shewhart

1891-1967


5 10 15

20 25

3.52

3.5

3.48

3.46

3.44

3.42

3.4

3.38

3.36

3.34

3.32

3.3

Su

bg

rou

p a

vera

ge

Subgroup number

Run Chart


5 10 15

20 25

3.52

3.5

3.48

3.46

3.44

3.42

3.4

3.38

3.36

3.34

3.32

3.3

Su

bg

rou

p a

vera

ge

Subgroup number

Upper Control Limit(UCL)

Lower Control Limit(LCL)

A True Control Chart

Practical Example of RunPractical Example of Run

Electronic Run ChartElectronic Run Chart

Elp

ro R

eadin

gs

Every T

wo

Min

utes

Scatter DiagramScatter Diagram

Scatter diagram is the simplest way to Scatter diagram is the simplest way to determine the cause-and-effect determine the cause-and-effect relationship between two variables.relationship between two variables.

Examples of cause-and-effect Examples of cause-and-effect relationships are:relationships are:– Cutting speed and tool lifeCutting speed and tool life– Temperature and lipstick hardnessTemperature and lipstick hardness– Training and errorsTraining and errors– Breakdowns and equipment ageBreakdowns and equipment age– Accidents and years with the organization.Accidents and years with the organization.

Example of Scatter DiagramExample of Scatter Diagram

Data on Automotive Speed vs Gas MileageSample Speed Mileage Sample Speed Mileage

Numbers (mi/hr) (mi/gal) Number (mi/hr) (mi/hr)

1 30 38 9 50 26

2 30 35 10 50 29

3 35 35 11 55 32

4 35 30 12 55 21

5 40 33 13 60 22

6 40 28 14 60 22

7 45 32 15 65 18

8 45 29 16 65 24

Scatter Diagram of Speed and Scatter Diagram of Speed and Gas MileageGas Mileage

30 40 50 60 70 80

40

30

20

10

0

Gas m

ileag

e –

mi/

gal

Speed – mi/h

END OF CHAPTER 6END OF CHAPTER 6

chapter 6, management of process quality

Documents

characteristics of process

services process management

quality control qc

broader definition of

notion of process analysis

quality assurance qa

systematic quality improvement

traditional control