Welcome toProblem Solving

Through7 QC TOOLS

7 QC Tools

1. Pareto Diagram

2. Cause & Effect Diagram

3. Graphs

4. Check Sheet / Check List

5. Scatter Diagram

6. Histograms

7. Control Charts

TOOLS

“The term “7 tools for QC” is named after the 7 tools of the famous warrior, Benkei. Benkei owned 7 weapons, which he used to win all his battles. Similarly, from my own experience, you will find that you will be able to solve 95% of the problems around you if you wisely use the 7 tools of QC.” - ISHIKAWA KAORU, Professor Emeritus, University of Tokyo

COURSE OBJECTIVE

• Impart a practical understanding in using Seven QC Tools

• Enable participants to deploy efficient and effective problem solving methods in BMM

COURSE CONTENTS

Chapter 1 : Problem Solving Process

Chapter 2 : 7 QC Tools : Check Sheets

Chapter 3 : 7 QC Tools : Pareto Chart

Chapter 4 : 7 QC Tools : Histograms

Chapter 5 : 7 QC Tools : Cause and Effects Diagrams

Chapter 6 : 7 QC Tools : Scatter Diagrams

Chapter 7 : 7 QC Tools : Graphs

Chapter 8 : 7 QC Tools : Control Charts

The details Pareto Diagram

The Pareto Diagram is a bar graph with a cumulative curve connecting the different points. To draw this diagram, the problems need to be first categorized according to phenomenon or causes such as defects and corrections, before data is collected and arranged in order of the number of defects or the number of corrections. This order is then expressed with the bar graph.

Cause and Effect Diagram

The cause and effect analysis which was first developed by Professor Kaoru Ishikawa of the University of Tokyo in the 1940s, is also known as the ‘Fishbone Diagram’ or the ‘Ishikawa Diagram’

This tool is a picture of lines and symbols designed to represent the relationship between the effects as problems and the causes influencing them.

Graphs

Graphs refer to the results of statistical analysis of data (numbers) which are shown in diagrammatic form to communicate information.

There are numerous types of graphs :Bar GraphBelt GraphLine Graph

Radar GraphPie Graph

Check Sheet

Check Sheets are sheets that are designed in advance to collect the necessary data easily and systematically, which allow the efficient checking of all items for inspection and verification.

No. Symptom Causes Countermeasure When Who Status

1 Xx xx xx xx xx Xx

2 Xx Xx Xx Xx Xx Xx

3 xx Xx Xx Xx Xx xx

Scatter Diagrams

The scatter diagram is a diagram where the relationship between two characteristic values are plotted on a graph paper and analyzed as to whether a correlation exists between the 2 sets of data.This analysis of correlation will enable you to take the necessary steps to control and improve the required process.

Histogram

A histogram is a type of bar graph which displays a range of data that has been grouped into certain classes. It is a useful tool to study the dispersion of data and analyze certain quality characteristics of the product or service to which the data in the histogram refers.

Control Charts

The control chart is a chart to examine whether a process is in a stable condition, or to ensure that the process in maintained in a stable condition.

The chart collects in time series the movement of data and indicates any abnormality and normality in the control limit lines. The objective of control chart is to control the process through ‘accurate judgment, investigating the real cause, taking prompt measure by showing the appropriate indicators.

CHAPTER 1

PROBLEM SOLVING PROCESS

Q U A L I T Y

Q U A L I T Y

WHAT IS A PROBLEM ?

• Difficult matter requiring a solution

• Something hard to understand or accomplish

• Whatever stop us doing things better or more effective

• An opportunity for improvement

Q U A L I T Y

DEFINITION OF “ PROBLEM SOLVING”

• A process to analyze problems, to determine and eliminate root causes.

Q U A L I T Y

PROBLEM SOLVING MODEL

• Problem Identification

• Causal Identification

• Causal Analysis

• Solution Implementation

• Standardization

• Status Monitoring

Q U A L I T Y

POOR PROBLEM SOLVER• Don’t believe that they can solve problems

• Are impatient and give up quickly

• Are careless readers and may begin working before they know what the problem is

• Jump to conclusions and expect to go immediately from what is given to the answer

• Carelessly organise their work or do not organise at all

• Seldom check their work

• Have only one method of working, usually trying to recall a formula and quitting if they can’t

Q U A L I T Y

GOOD PROBLEM SOLVER• Believe they can solve just about any problems if they work at it long enough

• Work for long time on a problem before they give up

• Read problem carefully, often several times, to be certain of what is asked

• Break problems into small steps, solve the steps one by one, and look for relationships as they work

• Organise their work carefully so they can stop at any point and trace their steps

• Check their steps along the way and check their final answer

• Use mental models or drawings to visualise the problems, and try to remember simpler problems that are related

Q U A L I T Y

PROBLEM SOLVING APPROACH

• Traditional • Scientific• Supernatural

• Intuition

Q U A L I T Y

SCIENTIFIC PROBLEM SOLVING APPROACH

• A disciplined process ( e.g PDCA)

• Extensive data collection

• Utilize suitable statistical tools to perform data analysis and monitoring ( e.g 7 QC Tools)

• Conclude facts based on analysed results

• Periodically review results

Q U A L I T Y

PDCA APPROACH

Definition of problem

Analysis of problem

Identification of causes

Planning countermeasure

Implementation

Confirming effectiveness

Standardizations

WHAT

HOW

WHYPLAN

DO

CHECK

ACT

Q U A L I T Y

PDCA Vs QC 7 TOOLS

CHAPTER 2

CHECKSHEET

Q U A L I T Y

Q U A L I T Y

Description• Structure form for collecting and analyzing data. It can be used to confirm and record that steps of a process was done

Purpose• Check sheets are used to systematically collect data. The data collected may be used to plotting histograms, pareto charts, etc.

• Can be used as an inspection checksheet, to ensure that all related items are checked.

Q U A L I T Y

TWO BASIC TYPE OF CHECKSHEET

• Data collecting checksheet

- Process distribution

- Defective items

- Defect location

- Defect cause

• Confirmation checksheet

- Inspection

Q U A L I T Y

PROCESS DISTRIBUTION CHECKSHEET

• Used for continuous data e.g weight, length, time, energy etc.

• Used when individual data are not of major importance.

• Used when need to establish the distribution and relationship to the specifications.

Data Collecting Checksheet – (1)

Q U A L I T Y

SAMPLE CHECKSHEET FOR PROCESS DISTRIBUTION

Q U A L I T Y

PROCESS DISTRIBUTION

CHECKSHEET ANALYSIS

• Distribution resemble bell shape, single-peaked, symmetrical ?

• Centre of the distribution at nominal value ?

• The spread of the data wider than the specification limits ?

Q U A L I T Y

CONFIRMATION CHECKSHEET

• Used to confirm that the requirements are fulfilled.

• Used to enable all necessary items are checked without omission.

Q U A L I T Y

EXAMPLE OF CONFIRMATION CHECKSHEET

Q U A L I T Y

DISADVANTAGE OF CHECKSHEET

• Cannot reveal any changes overtime.

• Possibility of checks not entered by data collector.

• Need to analyse several sheets arranged in chronological order to determine the trend.

• Misinterpreting the data due to different influencing conditions are present.

CHAPTER 3

PARETO CHART

Q U A L I T Y

Q U A L I T Y

DESCRIPTION

• Pareto chart is a bar graph with a cumulative curve

• The length of the bars represent frequency of occurrence or cost.

• The pareto chart visually shows which are the most significant problems, cause or situations.

Q U A L I T Y

HISTORY

• Vilfredo Pareto, a 19th century economist observed that 80% of wealth was owned by only 20% of the populations.

• 1950 Dr. J.M.Juran discovered that if quality problems were arranged in order of frequency of occurrence, relatively few causes accounted for the bulk of the problems.

Q U A L I T Y

PARETO CHART APPLICATION

• Identify the major problem or concern for improvements.

• Can be applied for improvement in all areas.

• Shows whether the actions taken are effective.

Q U A L I T Y

CONSTRUCTION OF PARETO CHART

Step 1 Determine the problem to be studiedStep 2 Identify the data to be used, frequency cost, etcStep 3 Identify the categories

Step 4 Decide the period for data collection ( If comparing the results or different Pareto chart, the time period should be the same)Step 5 Collect the data and total the frequency of occurrences in each category

Q U A L I T Y

Step 6• Arrange the categories in descending order, calculate the percentage and cumulative percentage for each category.

Example : Cause of Machine Breakdown

Frequency Occur Frequency % Cumulative %

Component failure 20 (20/47) x 100 = 42.6 42.6

Program Hang 14 29.8 72.4

Elec. Contact 4 8.5 80.9

Elec. Component 3 6.4 87.3

Jammed 3 6.4 93.7

Operation 2 4.2 97.9

Others 1 2.1 100

47 100

Q U A L I T Y

Step 7• On a piece of graph, draw the vertical axis and horizontal axis.

5

10

15

Q U A L I T Y

Step 8• Place the categories in the horizontal axis in the descending order, the category having maximum count on the left and so on. ( keep all the horizontal scale same width for all categories )

Q U A L I T Y

5

15

20

A B C D E F G

Cause of Machine Breakdown

A - Component failure

B - Program Hang

C - Elec. Contact

D - Elec. Component

E - Jammed

F - Operation

G - Others

10

Q U A L I T Y

Step 9Draw the right vertical scale for cumulative percentage, set the maximum value (100%) on the scale corresponding to the left vertical axis.

Plot the cumulative percentage line on the chart

Step 10Give title to all the axis and chart

Q U A L I T Y

A B C D E F G

Cause of Machine Breakdown

A - Component failure

B - Program Hang

C - Elec. Contact

D - Elec. Component

E - Jammed

F - Operation

G - Others

50

100 CUM.PERCENTAGE %

5

15

20

A B C D E F G

10

FREQUENCY

Q U A L I T Y

SPECIAL NOTES : Choose the categories carefully, ensure that the categories represent the problem under study.

Eg : To study the high defective rate problem, the categories should be the type of defect.

Make sure the terms used are consistent between data collected and the Pareto chart

The vertical may represent the followings :- Number of defects, reworks or complaint from customer

Cost

Time lost or waiting

Cases of accident

Q U A L I T Y

SPECIAL NOTES (CONT.) :

The horizontal axis may represent the followings :- Type of defects

Cause of defects

Different materials

Different locations, people, machine

The trick : “ study the data before start plotting the pareto chart “

Use Pareto chart to compare before and after improvement, make sure the data collection processes are the same.

Q U A L I T Y

EXERCISE 3a

CHAPTER 4

HISTOGRAM

Q U A L I T Y

Q U A L I T Y

Description

• Histogram is a bar graph that shows the distribution of a set of data

• The shape of the histogram will tell the consistency of one product or process behavior

Q U A L I T Y

Application

• To show the variability of a process, product, material, vendor, etc

• To show the central tendency ( mode and mean ) of a set of measurements.

• To illustrate whether product specifications are met.

• To understand the characteristics of the populations from which the sample are taken.

Q U A L I T Y

CHARACTERISTICS

• Data are displayed as a series of rectangles of equal width and varying heights.

• Width represents and interval within the range of data.

• Height represents the number of data values within a given interval.

• Pattern of varying heights shows the distributions of data values.

• Pattern provide information on the process behavior.

Q U A L I T Y

SAMPLE OF HISTOGRAM

0

10

20

30

40

50

60

1stQtr

Frequency

Class

Interval

Q U A L I T Y

EXERCISE

Data 1 : 3, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 9

Mean = Range = Std Dev =

Data 2 : 3, 5.5, 5.6, 5.7, 5.7, 5.7, 6, 6,6, 6,6.3, 6.3,6.3,6.4, 6.5, 9

Mean = Range = Std Dev =

CHAPTER 5

CAUSE AND EFFECT DIAGRAMS

Q U A L I T Y

Q U A L I T Y

DESCRIPTION

• Tool in allowing a team to identify, explore and graphically display, in increasing details, all of the possible causes related to a problem or condition to discover its root cause(s)

Q U A L I T Y

HISTORY

• Developed by Dr. Kaoru Ishikawa in 1943

• Also known as fishbone diagrams or Ishikawa diagrams

Q U A L I T Y

APPLICATION

• Enables a team to focus on the content of the problem, not on the history of the problem or differing personal interests of team members.

• Creates a snapshots of the collective knowledge and consensus of a team around a problem. This builds support for the resulting solutions.

• Focuses the team on causes, not symptoms.

Q U A L I T Y

TYPES

• Dispersion Analysis

• Process Classification

• Cause Enumeration

Q U A L I T Y

TYPE 1 – DISPERSION ANALYSIS

Step 1

Write down the effect to be investigated and draw the “backbone” arrow to it. In the example shown below the effect is “Incorrect deliveries”

This is a three step process

Incorrect

deliveries

“ Causes” “ Effect”

Q U A L I T Y

Step 2

Identify all the board areas of enquiry in which the causes of the effect being investigated may lie. For incorrect deliveries the diagram may then become:

Incorrect

deliveries

Communication Skills

Transport Procedures

Q U A L I T Y

Step 3

This step requires the greatest amount of work and imagination because it requires you ( or you and your team) to write in all the detailed possible causes in each of the board areas of enquiry. Each cause identified should be fully explored for further more specific cause which, in turn, contribute to them.

Q U A L I T Y

Incorrect

deliveries

Communication Skills

Transport Procedures

Picking Slips

Legibility

Picking Slips

Lack of knowledge

Telephone

Order

Lack of information

ambiguity

Knowledge

literacy

procedure product

documentation

Incorrect dept Incorrect person

Incorrect

Address

Customer

database

Not up-to-date

In correct program

carriers

efficiency

methods

manual

automated

correctness reliability

consistency

Q U A L I T Y

TYPE 2 – PROCESS CLASSIFICATION

Materials Testing and Marketing

Visual Inspection Packing

Mixing Product

Machine down during test

Marketing Plate

Lot Labeling

Drop units

Weighing

Loose Units

Labeling

In box

Merge Lots

Picking up loose units

Stage too close

Waiting conformation units

Change shift

Q U A L I T Y

TYPE 3 – CAUSE ENUMERATION

• All the possible causes are simply listed ( Brainstorming session )

• Once all the causes are listed, they are placed in the major categories in the cause and effect diagrams

• The advantage of this type of diagram is that all identified causes are listed

• The disadvantage is that it is sometime difficult to relate all the causes listed to the categories

Q U A L I T Y

BRAINSTORMING

• A technique for tapping creative thinking during the construction of cause and effect diagram

• Maximize the brainpower of a team

• Use to generate ideas/issues

• Use to clarify ideas/issues

DESCRIPTION

Q U A L I T Y

KEY STEPS IN BRAINSTORMING SESSION

• Identify a facilitator

• Clarify purpose of the session

• Review rules of brainstorming

• Generate ideas taking turns

• Display ideas

• Review ideas for clarification

Q U A L I T Y

ROLES OF FACILITATOR

• Guide brainstorming session

• Ask questions to excite thinking

• Align when session goes off target

Q U A L I T Y

TWO PHASES

- Only ideas are generated and no clarification or analysis carried out

• Generation

- Ideas generated are clarified if necessary for all to understand and followed by evaluation of the ideas

• Clarification

Q U A L I T Y

PHASES 1 – IDEAS GENERATION

• Let all members speak freely

• Keep to the rule

• See problem from different angle

• Note all viewpoints

Q U A L I T Y

BRAINSTORMING RULES

• No criticism

• The more ideas, the better

• The wilder the ideas, the better

• Hitch-hike on other ideas; if possible

Q U A L I T Y

PRECAUTIONS OF

• A strong but not dominating facilitator

• Keep each session to no more than 2 to 3 hour; preferably

• Take relieve breaks after major sections

BRAINSTORMING

Q U A L I T Y

NOTE FOR CAUSE AND EFFECT

• Do not confuse cause, effect and countermeasure

• Use the wisdom and knowledge of the team

• Should not be only problem related, use it for improvement

• Use as a visual control

• Be innovative when using Cause and effect diagrams

Q U A L I T Y

READING THE CAUSE AND EFFECT DIAGRAMS

• Pursue the causes actively- the most probable may not be the most obvious

• Ascertain cause before checking countermeasure

• Understand the casual relationship to enable work progress

• Badly arrange cause and effect diagram will reduce effectiveness

Q U A L I T Y

USING A CAUSE AND EFFECT DIAGRAMS

• Make use of team knowledge through brainstorming sessions

• Successful countermeasure to be mad into standards

• Train all to use diagrams

• Continuously use Cause and effect diagram for each new problem or opportunity

Q U A L I T Y

CAUSE AND EFFECT DIAGRAMS :

GUIDELINES

C5;23.DOC