Seven Quality Control Tools

Presented toDR.MAHR MUHAMMAD SAEED

Presented toDR.MAHR MUHAMMAD SAEED

Presented byMamoona Shahzad

MP/2012-27

Presented byMamoona Shahzad

MP/2012-27

Objective

Present an overview of Seven Quality ToolsPresent an overview of Seven Quality Tools

Address purpose and applicationsAddress purpose and applications

Highlight benefitsHighlight benefits

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7 QC Tools

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What are 7 QC Tools ? What are 7 QC Tools ?

QC tools are the means for Colleting data , analyzing data , identifying root causes and measuring the results.

Numerical DATA processing

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Control ChartPareto Chart

Data CollectingScatter Plot Ishikawa Chart

HistogramStratification

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**

*

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• Pareto Diagram

• Stratification

•Scatter Diagram

•Cause and Effect Diagram

•Histogram

•Check Sheet

•Control Chart

7 QC TOOLS 7 QC TOOLS

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Pareto DiagramPareto Diagram

1. What is Pareto diagram ?

A Pareto diagram is a combination of bar and line graphs of accumulated data, where data associated with a problem:

A defect found

Mechanical failure

Complaint from a customer

These are divided into smaller groups by cause.

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Pareto Diagram Pareto Diagram ( No. of Occurrences)

Pareto Diagram Pareto Diagram ( No. of Occurrences)

Used to prioritize actions.

Used to identify a problem.

Used to identify the cause of a problem.

Used to review the effects of an action to be taken.

Allows clarification of important tasks.

Allows identification of a starting point (which task to start with).

Allows projection of the effects of a measure to be taken

Pareto DiagramPareto Diagram

Result UsageMethod

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Stratification Stratification

1. What is Stratification ?1. What is Stratification ?

Stratification means to “divide the whole into smaller portions according to certain criteria.” In case of quality control, stratification generally means to divide data into several groups according to common factors or tendencies (e.g., type of defect and cause of defect).

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StratificationStratification

Grouping by day, time, place, worker,

or process

X

Y

Z

Number of Units

★★★★★★★

△△△△

○○○

•Used to observe variations among strata.

•Used to identify the relationship between cause

and effect.•Used to identify a purpose

and means to serve the purpose

•Allows observation of variations among

strata.•By performing a

cause analysis using the stratified data, the

following can be accomplished.

1.Identification and control of a problem

2.“Division of data (obtained by using each QC tool) into several

groups”

Method Usage Result

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Scatter Diagram Scatter Diagram

1. What is Scatter Diagram ?1. What is Scatter Diagram ?

A scatter diagram is used to “examine the relationship between the two, paired, interrelated data types, ” such as “height and weight of a person.” A scatter diagram provides a means to find whether or not these two data types are interrelated. It is also utilized to determine how closely they are related to identify a problem point that should be controlled or improved.

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Scatter DiagramScatter Diagram

Ab

rasi

on

(m

icro

n)

ｙAxis

x Axis

Number of Rotations

Ab

rasi

on

(m

icro

n)

ｙAxis

x Axis

Number of Rotations

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Method Usage Result

Scatter DiagramScatter Diagram

•Used to identify a relationship between two matters.•Establish countermeasures based on their cause and effect relation.

Scatter DiagramScatter DiagramｙAxis

x Axis

Abra

sion

Number of Rotations

Scatter DiagramScatter DiagramｙAxis

x Axis

Abra

sion

Number of Rotations

•Can identify cause and effect relation.•Can understand the relationship between two results.

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Cause & Effect Diagram Cause & Effect Diagram

1. What is Cause & effect Diagram ?1. What is Cause & effect Diagram ?

A cause and effect diagram is “a fish-bone diagram that presents a systematic representation of the relationship between the effect and affecting factors.

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Cause & Effect Diagram Cause & Effect Diagram

2. When is it used and what results will be obtained?2. When is it used and what results will be obtained?

A cause and effect diagram is mainly used to study the cause of a certain matter. As mentioned above, the use of a cause and effect diagram allows clarification of causal relation for efficient problem solving. It is also effective in assessing measures developed and can be applied to other fields according to your needs.

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Can obtain a clear overall picture of causal relation. (A change in the cause triggers a variation in the result.)Can clarify the cause and effect relationship.

Can list up all causes to identify important causes.

Can determine the direction of action

Method Usage Result

Cause & Effect DiagramCause & Effect Diagram

Used when clarifying a cause and effect relationship.[Used during a phase to analyze causes.]

Used to develop countermeasures.

Material Method

ManMachine

Cause (4M’s) Result (Controlled State)

Effec

tCause and Effect Cause and Effect DiagramDiagram

Material Method

ManMachine

Cause (4M’s) Result (Controlled State)

Effec

tCause and Effect Cause and Effect DiagramDiagram

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Cause & Effect DiagramCause & Effect Diagram

Mechanism of Copying Machine

Quality of Copying Paper

User Surrounding Environment

Smudges on the copied surface

Internal devices not working smoothly

Malfunction of the roller

Printing too lightly

Too thin

Folded

Running out of stock

Dampened

Keyboard handling error

Error in selecting a scale of reduction

Error in placement of paper (setting its face up)

Error in selecting shading

Deterioration of performance due to high temperatures

Nicotine-stained

Dirt on the glass surface

Dust

Man

y C

opyi

ng E

rror

s!

Mechanism of Copying Machine

Quality of Copying Paper

User Surrounding Environment

Smudges on the copied surface

Internal devices not working smoothly

Malfunction of the roller

Printing too lightly

Too thin

Folded

Running out of stock

Dampened

Keyboard handling error

Error in selecting a scale of reduction

Error in placement of paper (setting its face up)

Error in selecting shading

Deterioration of performance due to high temperatures

Nicotine-stained

Dirt on the glass surface

Dust

Man

y C

opyi

ng E

rror

s!

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Histogram Histogram

1. What is Histogram ?1. What is Histogram ?

Histograms are used to chart the frequency of occurrence.

How often does something happen?

Frequency distribution diagrams

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HistogramHistogram

2. When is it used and what results will be obtained?2. When is it used and what results will be obtained?

A histogram is mainly used to analyze a process by examining the location of the mean value in the graph or degree of variations, to find a problem point that needs to be improved.

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Method Usage Result

HistogramHistogram

HistogramHistogramStandard

Range

Range of Variations

X Axis (Values Actually

Measured)

HistogramHistogramStandard

Range

Range of Variations

X Axis (Values Actually

Measured)

•Used to assess the actual conditions.•Used to analyze a process to identify a problem point that needs to be improved by finding the location of the mean value or degree of variations in the graph.•Used to examine that the target quality is maintained throughout the process.

•Can identify the location of the mean (central) value or degree of variations.•Can find out the scope of a defect by inserting standard values.•Can identify the condition of distribution (e.g., whether there is an isolated, extreme value).

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Flowchart

Flowcharts are pictorial representations Flowcharts are pictorial representations of a processes. By braking the of a processes. By braking the processes down into its constituent processes down into its constituent steps, flowcharts can be useful in steps, flowcharts can be useful in identifying where errors are likely to identifying where errors are likely to be found in the system.be found in the system.

Flow Chart

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Check SheetCheck Sheet

1. What is Check sheet ?1. What is Check sheet ?

A check sheet is “a sheet designed in advance to allow easy collection and aggregation of data.” By just entering check marks on a check sheet, data can be collected to extract necessary information, or a thorough inspection can be performed in an efficient manner, eliminating a possibility of skipping any of the required inspection items.

A check sheet is also effective in performing stratification (categorization).

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Check SheetCheck Sheet

2. When is it used and what results will be obtained?2. When is it used and what results will be obtained?

It is frequently used in daily business operations, often not specifically for QC purposes.

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Ensures collection of required data.

Allows a thorough inspection of all

check items.

Can understand tendencies and

variations.

Can record required data.

Method Usage Result

Check SheetCheck Sheet

Check SheetCheck SheetDay

Process

Process 1

Process 2

Process 3

Check SheetCheck SheetDay

Process

Process 1

Process 2

Process 3

Used to collect data.

Used when performing a thorough inspection.

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Check SheetCheck Sheet

A check sheet used to identify defects

Date

Defect

Vertical Scratch

Scratch

Dent

TotalDate

Defect

Vertical Scratch

Scratch

Dent

Total

Run Chart

Records the output results of a process over Records the output results of a process over time.time.

What is happening in the process as time What is happening in the process as time goes by.goes by.

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Control Chart Control Chart

1. What is Control Chart ?1. What is Control Chart ?

A control chart is used to examine a process to see if it is stable or to maintain the stability of a process.

This method is often used to analyze a process. To do so, a chart is created from data collected for a certain period of time, and dots plotted on the chart are examined to see how they are distributed or if they are within the established control limit. After some actions are taken to control and standardize various factors, this method is also used to examine if a process is stabilized by these actions, and if so, to keep the process in a stable state.

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Control ChartControl Chart

2. When is it used and what results will be obtained?2. When is it used and what results will be obtained?

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Method Usage Result

Control Chart

Control ChartControl Chart

x-R Control Chart

Control ChartControl Chart

x-R Control Chart

Used to observe a change caused by

elapse of time.

Can identify a change caused by elapse of time.

Can judge the process if it is in its normal state or there are some anomalies by examining the dots plotted on the chart.

Control Chart for Managerial Purposes: Extends the line indicating the control limit used for analytical purposes to plot data obtained daily to keep a process in a good state.

Control Chart for Analytical Purposes: Examines a process if it is in a controlled state by collecting data for a certain period of time. If the process is not controlled, a survey is

performed to identify its cause and develop countermeasures.

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Control Chart

x- Control Chart

Group Number

Examples of Values Represented by Dots

Values above the control limit represented by seven consecutive dots

A decline represented by seven consecutive dots

x- Control Chart

Group Number

Examples of Values Represented by Dots

Values above the control limit represented by seven consecutive dots

A decline represented by seven consecutive dots

Management’s RoleManagement’s Role

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Summary 1-2 The tools listed above are ideally utilized in The tools listed above are ideally utilized in

a particular methodology, which typically a particular methodology, which typically involves either reducing the process involves either reducing the process variability or identifying specific problems in variability or identifying specific problems in the processes. However, other methodologies the processes. However, other methodologies may need to be developed to allow for may need to be developed to allow for sufficient customization to a certain specific sufficient customization to a certain specific process. In any case, the tools should be process. In any case, the tools should be utilized to ensure that all attempts at process utilized to ensure that all attempts at process improvement include.improvement include.

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Summary 2-2

Furthermore, it is important to more Furthermore, it is important to more that the mere use of quality control that the mere use of quality control tools does not necessarily constitutes a tools does not necessarily constitutes a quality program. Thus, to achieve quality program. Thus, to achieve lasting improvements in quality, it is lasting improvements in quality, it is essential to establish a system that will essential to establish a system that will continuously promote quality in all continuously promote quality in all aspects of its operation.aspects of its operation.

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