Transcript
Page 1: Quality control circle presentation

Prepared by

M.Ganesh Murugan9715447621

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The QC circle was formally organized in

Japan in 1962 by Japanese Union of

Scientists and Engineers (JUSE) and the man who initiated the idea is Dr.Kaoru

Ishikawa

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The organization gets the total man Humanize the work i.e. Quality of work life is

stressed and improved Brings out extra-ordinary qualities from ordinary

people To display the human capabilities fully and

eventually draw out infinite possibilities Prepares the employer and employees to meet

the challenges of the changing time and conditions

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Ensure harmony Effective team work Job satisfaction Problem solving capacity Communication Self development Leadership development Safety awareness and housekeeping Productivity Team building Participation Self-discipline

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Not just for only quality problems Not a forum for grievances Not a spring-board for demands Not a tool for management to unload problems Not problem-focussed, but performance-

oriented Not for changing the existing organisational

structure or chain of command Not a “cure all” or “sure cure” technique Not a panacea for all ills

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One of the prime objectives of QC is to improve the quality of work life and environment

The survival and prosperity of any enterprise depends on the bottom line of the balance sheet i.E. Net profit/economic viability and stability. A higher

level of quality will result in satisfied customer, repeat business, which in turn will improve the profitability, job security and overall harmony of enterprise.

Hence, the emphasis on “quality”

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Everybody participates and contributes in the process of decision-making

Problems are chosen, not given Decision by consensus, not by majority Performance-oriented, not problem-oriented Bottom-up approach Management-blessed, not management-directed Members are responsible from the identification

of a problem to implementation of the solution i.E. For total performance

Aims at the quality of work life Does not replace or substitute any of the

systems or structure

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Problem identification emanates from The members of the circle Management Staff or technical experts

Several problems are identified and the selection of the problem is the prerogative of the circle

Problem analysis and discuss alternatives Data from specialist, if necessary

Arrive at best solution Circle members discuss various alternatives also

before reaching the best solution

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Management presentation The circle makes its recommendations directly to its

in-charge using a powerful communication Review of recommendations and approval by

management Thoroughly in consultation and coordination with

peripheral departments and approves or disapproves Implementation

Approved recommendations are implemented. Recommendations that are not approved are

Communicated to the circle members. It is imperative to explain the reasons to the members of the circle for not approving their recommendations. Communication should be effective in either case

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From the familiarity of the members as well as leaders with the operation in which they are involved

In day-to-day work From the proposals or suggestions by clients From the suggestions by the HOD’s From the suggestions or proposals by any

employee in the organisation From the objectives set out in the company’s

annual plan/targetHowever, it is the prerogative of the circle to select

the problem although the suggestions can emanate from various sources

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Positive attitude Frank discussions and brainstorming with

everyone participating in a cooperative manner

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QC should exercise a systematic approach Confirms the existence of the problem Understands the nature of the problem Identifies the symptoms Finds out the causes Prepares a systematic programs for study Checks those programs with the other members Delegates assignment to members Seeks advice and assistance if required from outside

agencies

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Finds out the various possibilities Uses the relevant techniques that are learnt for

problem-solving Prepares a report of its proposal once it arrives at a

solution Evaluates the relevance and practicability of the

solution Recommends the solution Implements the solution

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1.Meeting A QC meeting must be the focal point of all activities The meeting time should be such that it is convenient

and acceptable for all members 2.Subject (themes)

The subject chosen should be in consonance with the policies of management

A subject which is familiar and of common concern to all the members of the circle should be handled first

Only work related problem should be chosen A problem whose solution is within the capability of

the members of QC should be selected The subject should be so chosen for the impact of its

solution As a rule, a problem should be selected which can be

solved within reasonable period of time

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3.Managing the activities Give opportunities for simple and brief presentation for

those members who are not used to speaking Before others Familiarize all the members with the environment

gradually Utilize every opportunity of praise Suggest better ways of doing things after appreciating

their efforts What is salt to food is humor to effective discussion

without tension. A sense of humor is a necessary ingredient but strict discipline should prevail

Circle members should display their respective role by earmarking their responsibility

Use simple techniques effectively and thoroughly

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A problem must be selected and solved only if the members can assure themselves that it will not reoccur

People must be sufficiently motivated even to the point of becoming greedy in getting the most out of activities

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4.Education of QC members QC members must make it a habit to study Read text books as many times as possible and make

the best use of them Develop the habit of getting as much data as possible

from as many sources as possible and utilize them to the maximum extent

Knowledge is not sufficient, but the application of knowledge is more important

What is digestion to food is contemplation to knowledge. Hence applying the knowledge that is acquired in solving the problem is key to the success of circle

Apply the techniques in such a simple manner that everyone can understand

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5.Key factors for the success of QC activities Make a master plan and divide into elements Study, discuss and solve the problem with the co-

operation of all the members so that their commitment is assured for the implementation

Constantly review the progress and the status of the solution

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6.How is a QC program organized? A qc program is an integrated system made up of

several components – The members The leader The facilitator The executive committee

The facilitator takes direction from the executive committee and co-ordinates the activities of the circle meeting and the leader conducts the meeting in such a way that the

members of the circle participate

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7.How to ensure longevity of QC activities?

The following essential ingredients are imperative 7.1.To be problem conscious

The leader, who is normally the group head/shift head should understand the role and function of

Leading the sub-ordinates. They should continuously and constantly learn about the technique.

Support from top and middle management is essential to make qc self-motivating

Peripheral departments also must give their blessings for the continued effort of QC activities. Participation by everyone should not only be encouraged but ensured

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7.2.To enhance people’s awareness in 3 areas Quality (quality of entire working life) Problem Improvement

People must be quality conscious in order to promote QC activities. Once people become problem conscious, improvement is bound to

follow

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7.3.Ensuring voluntary participation People get real satisfaction when they are totally

committed to think and act on their own For the overall prosperity. If one understands why

the activities should be carried out voluntarily, the commitment is bound to follow

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7.4.To find pleasure and sense of satisfaction in the QC activities

There are ten kinds of happiness in QC activities Happiness of developing self-confidence Happiness of being recognized for one’s activities Happiness of displaying one’s ability and capability Happiness of acquiring the ability to identify one’s

capability Happiness to develop and enrich one’s potential ability Happiness to be able to recognize one’s potential ability Happiness to understand and co-operate with the

members of the circle Happiness to have friends and affectionate sub-

ordinates

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Happiness to belong to a company where the QC activities are encouraged and promoted

Happiness of gaining indirect material reward through the prosperity and growth of the company

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7.5.Training Training and re-training from the top management to

the circle member is an indispensable and inevitable

part of ensuring longevity of circles

The members must also be taught value engineering,

job instruction, job method, job relations, creativity

development and leadership qualities

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7.6.How often the circle meetings are held? As a rule of the thumb, circle meetings are held once

in a week

However, some companies have introduced

variations It is desirable to reduce the duration and increase the

frequency of the meeting.

Format enclosed

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Form

at

en

close

d

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The QC circle is program is an integrated system consisting of the following Steering committee

Divisional review committee

Coordinators and facilitators

Circle leader

Circle members

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Steering committee This committee comprises of the executive director,

general managers and a member secretary

(nominated by management). This committee sets

goals and objectives for the QCC activities and

establishes operational guidelines

It meets as often as necessary but at least once a

quarter to review the progress. The secretary is

responsible for the overall coordination of QC circle

activity in the company

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Divisional review committee This committee comprises of the divisional head,

departmental heads, coordinators and

facilitators(member secretary). It provides active

support to the circles

The committee meets as often as necessary but at

least once a month to review the progress

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Coordinators Organizes training programs for members as and

when new circles are formed

Convenes the steering committee meeting regularly

once in two to three months and maintains the

minutes thereof.

Organizes top management presentations regularly

once in two to three months

Centrally registers circles as and when formed and

also maintains records of number of members,

frequency of management representations, etc.

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Co-ordinates and evolves a consensus for norms to

asses the performance of different quality circles and

of different divisions

Co-ordinates and ensures availability of common

facilities to all quality circles

Prepares a budget for the functioning of quality

circles and submits the same to the steering

committee for adoption

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Facilitators Is responsible for the successful operation of the

quality circles in his area. He has to be a guide,

counselor, teacher and a catalyst

Ensures necessary facilities for quality circles to

operate effectively lends assistance and support to

the leader whenever required and also helps in the

training of members

Is invited to the meetings of the departmental or

steering committees wherein he gives a resume of

the activities of quality circles in his jurisdiction

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Circle leader/deputy leader Makes the necessary facilities available, with the help

of facilitators and others, for enabling quality circles

to perform without constraints

Assigns tasks to different member from time to time

to maintain a high degree of individual involvement

and participation

Trains the members in various problem-solving

techniques and other facets of quality circle

operations, and gives them necessary guidance

whenever required, with the help of the facilitator

and others, if necessary

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Maintains a high degree of cohesiveness of his team.

He does not act as a boss in quality circle activities

but as a friend and partner so that conflicts are

avoided and group cohesiveness is maintained all the

time

Ensures that every circle member is involved in circle

activity and a high level of enthusiasm and

involvement is maintained

Plans the agenda of meetings carefully and conduct

meetings regularly and effectively

Ensures discipline and decorum during the meetings

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Chalks out action plans for a progressive solution of

problems through data collection, interaction and

sets time bound programs for implementation of the

circle’s recommendations

Encourages and evolves consensus decision-making

processes so that win-lose situations are obviated

Ensures that record-notes of meetings and progress

of problems are maintained in two separate registers

regularly and effectively

Interfaces with other levels of management, the

facilitator and different functional agencies to ensure

the effective working of his quality circle

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Takes necessary steps continuously in conjunction

with other members, facilitators, executives and the

department head to ensure that his quality circle

maintains a high degree of morale and enthusiasm

continuously and thereby catalyses the quality circle

movement in the organization to grow steadily and

healthily

Organizes presentations to departmental head and

top management at least once in two to three months

Feeds the information relating to the highlights of his

circle activities to the agency concerned for

publication in appropriate newsletters and journals

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Circle members Participate actively in the discussions during the

meeting and all other activities of the circle. They

willingly execute specific assignments that may be

given to them as decided in the circle meetings.

Thus they actively assist leader/deputy leader in

effectively and efficiently conducting the circle

activities

Contribute towards building of a cohesive group

through which they try to achieve the highest

standards of performance

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Take part in management presentation

Through their personal conduct and enthusiasm, help

in propagating the quality circles concept in other

areas where circles are yet to be launched

Assimilate the inputs given to them during training

and develop in themselves the capability for

systematically identifying analyzing and resolving

problems and also attain leadership qualities

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Check sheet

Stratification

Pareto chart

Cause and effect diagram

Histogram

Scatter diagram

Graph and control chart

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A scientific approach of solving problems and

making workplace improvements

Helps individuals/teams of diagnose, solve and

prevent problems

Can be used to solve 90% of workplace

problems

Simple yet powerful histogram

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Check sheet is a systematic method of

collecting, recording and presenting the relevant

data in a simple manner Helps individuals/teams

of diagnose, solve and prevent problems

Rationale and Benefits To make data gathering simple, systematic, easy and

effective

To arrange and present data in such a way that it can

be understood and used easily

Enables “management by facts” as opposed to

“management by opinion”

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Process performance check sheet

Defect item check sheet

Defect location check sheet

Defect cause check sheet

Task conformation check sheet

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Establish what information is needed

Establish “operational definition” for the data to

be collected

Determine 5W and 2H of check sheet

Construct the check sheet

Test the check sheet

Use the check sheet

Use the information (remember three rules of

QC)

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Why is the data needed?

What type of check sheet should be used?

Where should the data should be collected

from? (Plant/machine/place)

Who has to collect the data?

(Operator/ supervisor/manager)

When will the data be collected?

(Every hour/ at the time of receipt)

How should the data should be measured?

(Instrument/clock)

How much data is essential?

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Check sheet should broadly have three types of

information

Title of the check sheet

Source information Name of the project/ problem theme

Location of data collection

Date and/or time

Name of the person recording data

Content information Column with defect/event name

Column to record frequency

Column to record total

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Test the check sheet with at least three

different collectors

Check if the operational definition is really

“operational”

Reconfirm that the columns are relevant and

required

Check if the check sheet is easy to record and

use

Make changes based on the feedback

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Explain the check sheet to the data collector

Ensure that the data collector understands the

reason for which the data is being collected

Collect data

Standardize its use to assure consistency

Tally mark = 5

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Pay particular attention to irregular data and

irregular conditions

Use data from the check sheet for further

analysis

- Pareto chart, histogram, scatter diagram

Ensure that all the data that is recorded is put

to use OR is likely to be put in future

Regularly audit the use and the usefulness of

check sheet

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Goals are too vague

No agreed operational definition

Data is not collected on time

Too much time and effort being spent on

recording in the check sheet

Check sheet is too complex

Different people are using different check sheet

for the same issue

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Project Name:        

Name of Data Recorder:        

Location:        

Data Collection Dates:                                                               

Defect Types/Event Occurrence

Dates

TOTALSunday Monday Tuesday Wednesday Thursday Friday Saturday

Defect 1                

Defect 2                

Defect 3                

Defect 4                

Defect 5                

Defect 6                

Defect 7                

Defect 8                

Defect 9                

Defect 10                

TOTAL                

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check-sheet-histogram.xls

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A technique used to divide the data into sub-categories or classification to provide useful insight into the problem

Root word is “strata” which means Group

Division

Sub-class

Levels

Layers

Stratification is an act of dividing the data based on groups, division, sub-class, causes etc.

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Data comes from different sources. e.g:

different machines, instruments, cities,

operators etc.

Data sometimes masks real information.

Stratification helps in getting meaningful

information from data.

Divide the data and conquer the information

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List all conditions

Collect and stratify data

Interpret the data

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List all conditions that may seem to be cause of the

problem

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Collect additional data based on classification, if

necessary

Stratify data based on the classification

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Calculate average of each classification or plot

appropriate graph

Look for significant differences or abnormalities

in data

Generate a list of possible causes

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Un – stratified data

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Stratified dataTime 23/2 24/2 25/2

9:00-10:00 15 14 16

10:00-11:00 1 2 0

11:00-12:00 2 0 1

12:00-1:00 1 0 1

1:00-1:30 lunch

1:30-2:30 10 11 12

2:30-3:30 3 1 0

3:30-4:30 0 2 1

4:30-5:30 1 0 1

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Pareto chart is a diagram that shows the order

of the largest number of occurrences by item or

by classes, and the cumulative sum total

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Vilfredo Pareto (1848-1923), an

Italian economist discovered in

1897 that 80% of a nation’s wealth

was owned by 20% of the

population

Dr. Joseph.M.Juran applied this

principle to quality management

and called it the pareto principle

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Pareto principle: 80% of the problems come from

20% of the causes

Distinguishes between vital few and trivial many

Displays relative importance of causes of

problem

Helps the team to focus on those causes that will

have the greatest impact when solved

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20%

80%

InputsCausesEffort

OutputsEffectsResults

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Select the problem Collect data Sort data & calculate cumulative frequency Draw the axes Construct the bars Draw the cumulative percentage line Title and label the chart Identify vital few from the trivial many and plan

further action

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Select the problem for investigation

Decide what data will be necessary and how to

classify them

Determine the method of collecting data and

period of data collection

Design a separate check sheet if necessary

E.g: causes for service complaints of computer

system

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136=100%

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It is undesirable that “others” represent high

percentage (should be < 10%)

If the cause of a problem can be solved easily,

implement it even if it belongs to trivial many

Wherever possible, compare monetary data

with frequency data

Draw the Pareto chart before and after

improvement

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A diagram which represents meaningful

relationship between an effect and its causes

A diagram which shows the relation between a

quality characteristic and the cause factor

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Enables a team to identify, explore and

graphically display all the possible causes

related to a problem

A cause and effect diagram is good for seeing

the whole “causal” relationship

Enables identification of root causes and not

symptoms

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Dr. Kaoru Ishikawa developed

the first cause and effect

diagram in 1943 while

consulting for Kawasaki steel

works

Dr.Joseph.M.Juran named it as

Ishikawa diagram

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Medium Sized Bone

Effect (characteristi

c)

Effect (characteristi

c)

Big Bone

Small Bone

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Dispersion Analysis Type.

Process Flow Classification Type.

Cause – Enumeration Type.

Note

Dispersion analysis type and Cause –

Enumeration type differ only in the method of

construction

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State the undesirable effect

Identify the main cause groups

Identify causes and sub-causes

Identify potential root causes

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Draw the back Bone and draw a line

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Such as man, machine, method, material, measurement, tool

ManMan

MethodMethod

MachineMachine

MaterialMaterial

Measurement

Measurement

Environment

Environment

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Brainstorm: Ask “why” questions

ManMan

MethodMethod

MachineMachine

MaterialMaterial

Rod bent

Poor handling

No Inspectio

n High Hardness

Measurement

Measurement

Environment

Environment

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Runs out of ideas, focus attention to place

ManMan

MethodMethod

MachineMachine

MaterialMaterial

Rod bent

Poor handling

No Inspectio

n High Hardness

Measurement

Measurement

Environment

Environment

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State the undesirable effect

Identify the main process flow diagram

Identify the causes and sub – causes at each

stage of the process

Identify the potential root cause(s)

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Draw a vertical line state the undesirable effect

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Draw a vertical line state the undesirable effect

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State the undesirable effect

List all possible causes using brainstorming

Arrange causes and sub – causes showing the

relationship between cause and effect

Identify potential root cause(s)

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Identify all the relevant causes (factors) & the

causes most strongly influencing the effect

(characteristic)

Express the effect (characteristic) “negatively”

The linking question between effect and its

cause is “why?”

Make the same number of causes and effect

diagrams as that of effects

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It is a type of run chart used for studying the

process performance over time in order to

understand and reduce variation

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Dr.Walter.A.Shewart invented the

control chart

He was working in bell labs on a

project to make all telephones alike

Published the book called

“Economic control of quality of

manufactured product” in 1931

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Every process is subject to variation

More the variation in the process, more the loss to

the society

Two types of causes affect variation

Common cause (also known as chronic cause, chance

cause)

The cumulative effect of many small and “individually

uncontrollable” causes of variation in a process. Express the

effect (characteristic) “negatively”

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Special cause (also known as sporadic or assignable

cause)

One of a few causes of variation that result in a large

variation in the process

Action on variation entirely depends on type of

cause identified

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Control chart is used for differentiating between

common causes and special causes of variation

Control charts also helps in determining whether

the

Process is stable

Process is capable

It helps in predicting process performance

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Variable data

Data that can be measured

E.g. Weight, height, length, hardness, diameter, angle

Attribute data

Data that can be counted

E.g. Defects, scratches, dent, spatters, blow, holes,

cracks

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Y - Axes Variable Data

subgroups

Central line

Control limits

Data Points

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Sub groups

Smaller groups of sample data collected over time

Central line

The average of all the sub group averages

Control limits

The outer limits of “Process Variation”

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Collect the data

Calculate sub – group average

Calculate overall average

Calculate the range

Compute average of range

Calculate control limit for X and R

Plot the chart

Interpret the chart

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Collect and stratify data into sub groups

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1 = X1+X2+X3+X4+X5

n

1 = 47+32+44+35+20

5

= 35.6

Where n is the size of the groups

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= 35.6+29.2+22.2+39.2

4

= 35.6

Where K is the size of the sub group

= 1+ 2+ 3+ 4

K

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= Maximum value – Minimum value

= 47 – 20 = 27

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= 1 + 2 + 3 + 4

K = 27 + 18 + 33 + 31

4

Where K is the size of the sub group

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Central line =

Upper control limit : UCL = + A2

Lower control limit : LCL = - A2

A2 is the coefficient whose value depends on

the subgroup size

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Central line =

Upper control limit : UCL = D4

Lower control limit : LCL = D3

D3 and D4 are the coefficient whose value

depends on the subgroup size

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Vertical axis : and R values

Horizontal axis : sub – group number

Draw the central line : and R

Draw the control limits

Plot the and R values and join the points

Write necessary items like name of the process,

product, size of the subgroup, work conditions,

shift, etc.

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Random variation and no systematic pattern

No action required (if Cpk > 1.67)

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Presence of special cause

Identify root cause and take action

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Presence of special cause

Process has shifted

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Presence of special cause

Process is deteriorating

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Presence of special cause

Periodic Interference in the process

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Presence of special cause

Identify root cause and take action

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Process capability is a measure of inherent

variability of the process when compared with the

customer requirements

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Assess capability of a process to meet customer’s

requirement

Assist in selecting or modifying a process

Assist in selection of machine

To build quality into the product and process

rather than achieving quality by inspection

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Establish process variation

process variation = 6σ

σ = .

d2

d2 is a constant based on sub – group size

Refer slide number 124

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Capability = Customer Requirement Process variation

Cp = USL –LSL

6 σ

Cp > 1.33; Process is more capable than customer requirement

Cp = 1.0; Process is just capable of meeting customer’s requirement

Cp < 1.0; Process is not capable of meeting customer’s requirement

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Cpk = Minimum (USL - ) ; ( - LSL) 3σ 3σ

Cpk = Cp; process is centered with respect to

customer’s requirement

Cpk љ Cp; Process is not centered with respect to

customer’s requirement

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Histogram is a type of bar chart representing

the frequency distribution of the data from a

process

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Displays large amount of data, that are difficult

to interpret in tabular & graphical form

Shows the relative frequency of occurrence of

the various data values

Provides useful information for understanding

the present performance and predict future

performance of the process

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Reveals the centering, variation & shape of the

data

Helps evaluate process capability & the

question “is the process capable of meeting

customers requirements?”

Enables corrective action to keep the process

within specification limits

Excellent planning and forecasting tool

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When the data are numerical

When you want to see the shape of the data’s

distribution, especially when determining

whether the output of a process is distributed

approximately normally

When analyzing whether a process can meet

the customer’s requirements

When analyzing what the output from a

supplier’s process looks like

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When seeing whether a process change has

occurred from one time period to another

When determining whether the outputs of two

or more processes are different

When you wish to communicate the distribution

of data quickly and easily to others

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Decide on the process measure

Gather data

Prepare of frequency table

Calculate range, class intervals, class width and

boundaries

Draw the axes

Draw the bars

Interpret the histogram

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Only one parameter can be used for

constructing the histogram

The data should be variable data, i.e., Measured

on a continuous scale (weight, time,

temperature, dimensions, speed, etc.)

Example : weight of a rice bag

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For accurate analysis of mean, dispersion and

patterns, collect at least 50 to 100 data points

98.7 100.6 100.2 100.6 100.3 100.3 98.6 99.6

100.0 100.3 99.9 99.9 99.9 100.8 100.5 99.5

100.4 99.7 100.2 99.8 100.1 99.7 100.4 99.8

99.6 100.3 99.4 100.4 99.0 99.9 99.5 99.2

101.5 99.3 101.3 99.2 100.9 100.1 101.6 100.2

100.5 101.1 100.0 101.2 100.1 99.4 99.1 100.1

99.2 100.0 99.6 100.0 100.2 101.4 101.0 100.2

101.0 98.8 100.7 100.3 100.8 100.1 100.0 100.9

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Calculate the number of data points, n

Determine the range, R

Determine the number of class intervals, k

Determine the class width, H

Establish the class boundaries

Establish class intervals

Construct the frequency table

Page 149: Quality control circle presentation

Calculate the number of data points, n

Count the number of data points “n” in the sample

n = 64 data points

Page 150: Quality control circle presentation

Calculate the number of data points, n

Determine the range, R

Determine the range “R” in the sample. Range is the

smallest value in the set of data subtracted from the

largest value

R = Xmax – Xmin

R = 101.6 – 98.6 = 3.0

Page 151: Quality control circle presentation

Calculate the number of data points, n

Determine the range, R

Determine the number of class intervals, k

Determine the number of class intervals, “k” needed.

The following table can be used as a thumb rule

No. of data points

No. of classes “k”

< 50 5 – 7

50 – 100 6 – 10

100 – 250 7 – 12

> 250 10 - 20

k = 7 cl

asses

Page 152: Quality control circle presentation

Calculate the number of data points, n

Determine the range, R

Determine the number of class intervals, k

Determine the class width, H

Determine the class width “H”. The formula for this is

H = R/k

This should be rounded off to a suitable value

depending upon the data collected

H = 3.0 / 7

H = 0.428 ~ 0.5

Page 153: Quality control circle presentation

Calculate the number of data points, n

Determine the range, R

Determine the number of class intervals, k

Determine the class width, H

Establish the class boundaries

Use the smallest individual measurement in the

sample or round off to the next appropriate lowest

round number. This will be the lower end point for the

first class interval

Do the same for the highest number. This will be the

higher end point for the last class interval

Class Boundaries – 98.5 & 102.0

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Establish class intervals

Add the class width “H” to the lower end point. This

will be the lower end point for the next class interval

Each class interval must be mutually exclusive

Add the class width to the lower class boundary until

the “K” class intervals and/or the range of all the

numbers are obtained

98.50 – 98.99 100.00 – 100.49

99.00 – 99.49 100.50 – 100.99

99.50 – 99.99 101.00 – 101.49

101.50 – 101.99

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Construct the frequency table

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Process Centering

Process Variation (Dispersion)

Histogram Shape

Process Comparison with specification(Process

Capability)

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Process Centering

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Process Centering

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Process Centering

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Process Variation (Dispersion)

Process

too

variable

Process

within

requiremen

ts

What is

the

variation

or spread

of the

data? Is it

too

Variable?

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Histogram Shape

Normal distribution

Skewed distribution

Distribution with isolated island

Bi-modal distribution

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Process Comparison with specification(Process

Capability)

Process

capable and

centered

Maintain

Process

Process

capable but

not centered

Re-set to

centre the

Process

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Process Comparison with specification(Process

Capability)

Process just

capable and

centered

Reduce

variation to

avoid defects

Process just

capable but not

centered

Centre process

and reduce

variations

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Process Comparison with specification(Process

Capability)

Process not

capable but

centered

Reduce process

variation to avoid

defects

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Choose critical process parameters

Gather as much as data as possible

Choose appropriate class intervals, width,

boundaries and scale

Specify targets and specification limits

Take corrective action and verify

Page 168: Quality control circle presentation

Before drawing any conclusions from your

histogram, satisfy yourself that the process was

operating normally during the time period being

studied. If any unusual events affected the

process during the time period of the

histogram, your analysis of the histogram shape

probably cannot be generalized to all time

periods

Analyze the meaning of your histogram’s shape

Page 169: Quality control circle presentation

A chart used to study and identify the possible

relationship between two variables

To identify the possible relationship between

the changes observed in two variables

To establish the

Existence of correlation

Type of correlation

Strength of the relation

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To confirm a hypothesis (assumption) that two

variables are related

Provide both visual and statistical means to test

the strength of a potential relationship

Provide a good follow up to a cause and effect

diagram to find out if there is more than just a

consensus connection between causes and

effects

Page 171: Quality control circle presentation

Cake height and Oven temperature

Weight and Height of a man

Population & Literacy levels in a state

Weight error and Earthing voltage

Nonconformance & Operator experience.

Hardness and carbon content

Inspection mistakes and Illumination levels

Elongation of threads and moisture content

Child’s height and Father’s height

Quality characteristic and the factor affecting it

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Weight and Height of a Person

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Collect paired data

Choose independent and dependent variable

Draw the axes

Plot the points

Label and title the charts

Interpret the chart

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Collect 50 – 100 paired data (X,Y) between

which you want to study the relation, and

construct a data chart

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Always choose ‘X’ axis for the cause and ‘Y’ axis

for the effect, when the two variables consists

of a factor and quality characteristics

Oven temperature = independent

Cake height = dependent

Find the respective maximum and minimum

values of the variables

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M.Ganesh Murugan9715447621