1BASIC QUALITY CONTROL TOOLS

Prepared by:

MUSLI BIN MOHAMMADmmusli@uthm.edu.my

95%Of the problems in a company

can be solved by using the7 QC Tools

- Kaoru Ishikawa -

7 BASIC QC TOOLS

1. Check sheets2. Pareto Diagram3. Cause and

Effects Diagram4. Histogram5. Scatter Diagram6. Control Chart7. Graphs

Katsuya Hosotani, 1993

1. Check sheet2. Pareto Chart3. Cause and

Effects Diagram4. Histogram5. Scatter Diagram6. Control Chart7. Flowchart

Stevenson, 2005

1. CHECK SHEET

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

What ?

For simplifying and systematically collect data Can be used as an inspection check sheet, to

ensure that all related items are checked.

Purpose ?

Clarifying the problems Understanding present situation Investigating past and present situation Confirming effectiveness Standardization and establishing control

When to use ?

(also known as Tally Sheet or Tally Chart)

2Two Basic Types of Check Sheets

Recording/Data Collection Check Sheets- Production process distribution check sheet - Defective item check sheet- Defect location check sheet- Defect cause check sheet

Confirmation Check Sheets- Inspection check sheet

result is counted, measured accordingly and recorded

A list of items to be confirmed is checked and recorded as OK or NOT OK

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42. PARETO DIAGRAM

To identify the major problem or concern for improvement.

Focuses on causes that have greater impact if solved. Displays importance of the problems in a simple,

easily interpreted, visual format. Making before and after comparison of a problem that

has been solved.

Purpose ?

Clarifying the problems Understanding present situation Setting targets Confirming effectiveness Investigating past and present situation Investigate mutual relationships

When to use ?

Visual display of data to show the most significant problem, causes or situations.

What ?

(also known as Pareto Chart)

STEPS TO CONSTRUCT A PARETO CHART

FrequencyEnd panel bumper clearance small 100End panel and grill panel not level 50Dash board scratch 120Fuel lid cannot open 40RR room lamp gapping 30

TOTAL 340

Frequency12010050

Fuel lid cannot open 40RR room lamp gapping 30

TOTAL 340

Dash board scratchEnd panel bumper clearance smallEnd panel and grill panel not level

Step 1: Decide items to study and collect data.Step 2: Tabulate data based on the frequency of occurrences

in each category and calculate totals. Arrange the data in descending order. Place others item last (if applicable).

5Step 3: Calculate the percentage of total and cumulative percentage for each category.

Frequency Percentage (%) Cumulative %120 35.3 35.3100 29.4 64.750 14.7 79.440 11.8 91.230 8.8 100.0340 100

Defects

Fuel lid cannot openRR room lamp gapping

Total

Dash board scratchEnd panel bumper clearance smallEnd panel and grill panel not level

120

340X 100% = 35.3% 29.4 + 35.3= 64.7

STEPS TO CONSTRUCT A PARETO CHART

Step 4: Draw 2 vertical axis.

STEPS TO CONSTRUCT A PARETO CHART

Left side: Mark from 0 to overall totalRight side: Mark from 0 to 100%Draw horizontal axis: Divide according to the number of items classified.

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Dash boardscratch

End panelbumper

clearance small

End panel andgrill panel not

level

Fuel lid cannotopen

RR room lampgapping

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STEPS TO CONSTRUCT A PARETO CHART

Step 5: Draw bars for each classification. Label each item under the horizontal axis.

Step 6: Draw cumulative line. Connect the lines.

Step 7: Give title to all axis and chart. It is better to write the source of data, total samples data collected etc.

TITLE OF THE DIAGRAM

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Dash board scratch End panel bumperclearance small

End panel and grillpanel not level

Fuel lid cannot open RR room lampgapping

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Types of Defects

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STEPS TO CONSTRUCT A PARETO CHART

6Ticket No. Work

1 Tires

2 Lube & oil

3 Tires

4 Battery

5 Lube & oil

6 Lube & oil

7 Lube & oil

8 Brakes

9 Lube & oil

10 Tires

11 Brakes

12 Lube & oil

13 Battery

14 Lube & oil

15 Lube & oil

Ticket No. Work

16 Tires

17 Lube & oil

18 Brakes

19 Tires

20 Brakes

21 Lube & oil

22 Brakes

23 Transmission

24 Brakes

25 Lube & oil

26 Battery

27 Lube & oil

28 Battery

29 Brakes

30 Tires

Make a check sheet and pareto diagram for the following car repair shop data.

Assignment 2.1 3. CAUSE AND EFFECT DIAGRAM(also known as Ishikawa Diagram and Fishbone Diagram)Tool to identify, explore and graphically display, all of the possible causes related to a problem or condition to discover its root cause

What ?

To recognize important causes. To understand all effects and causes. Creates a snapshot of the collective knowledge

and consensus of a team around a problem.

Purpose ?

Clarifying the problems Understanding present situation Investigating causes and effects Setting up the countermeasures

When to use ?

Three Basic Types of Cause and Effect Diagram

Dispersion Analysis

Process Classification (not covered)

Cause Enumeration (not covered)

7Type 1: Dispersion Analysis

Objective is to analyze causes of variability. What is causing the dispersion or variation.

Include as much information as possible on the what, where, whenand how much of the problem. If possible use data to specify problem.

Be flexible in the major cause bones that are used.

For manufacturing process, the normal categories are; (1) Materials (raw materials / components), (2) Machine (equipment/tools), (3) Method (how work is done) and (4) Man (the human element).

For service processes, the normal categories are; (1) Policies (higher level decision rules), (2) Procedures (steps in task), (3) Plant (equipment / space), and (4) People (the human element).

In both types of processes, Environment (building, logistics and space) and Measurement (calibration / data collection) are also frequently used.

There is no perfect set / number of categories. Make them fit the problem.

Fishbone Diagram

QualityProblem

MachinesMeasurement Man

MethodEnvironment Material

Faulty testing equipment

Incorrect specifications

Improper methods

Poor supervision

Lack of concentration

Inadequate training

Out of adjustment

Tooling problems

Old / worn

Defective from vendor

Not to specificationsMaterial-handling problems

Deficienciesin product design

Ineffective qualitymanagement

Poor process design

Inaccuratetemperature control

Dust and Dirt

8Assignment 2.3

Assuming that a table lamp fails to light when turned on. Prepare a cause and effect diagram to analyze possible causes.

4. HISTOGRAM Plotting the shape of a distribution and comparing it

with specifications To show the variability of a process, product,

material etc To show the central tendency of a set of

measurements To illustrate whether product specifications are met To understand the characteristics of the population

from which the sample are taken

Purpose ?

Clarifying the problems Understanding present situation Setting targets Analyzing causes Stratification Setting up the countermeasures Confirming effectiveness Standardization and establishing control

When to use ?

Determine range of data, no. of class interval, class width, and class boundary.

Select mid class Tabulate frequency for each class Draw the histogram

How to construct histogram ? Decide no of classes too few lose information, too many

also no meaning Usually choose 5 20 classes Let us choose 7 classes class width must be enough to

put in all the data Approximate width find range divide by no of classes =

(4.7-1.6)/7 = 0.443 should have same no of significant places as data, therefore choose the value 0.5

Decide where to start bottom interval start at 1.5 and lower boundary is 1.45. Then add width 1.45 +0.5 = 1.95 continue for the others

Midpoint is (1.5+1.9)/2 = 1.7 Count the no of observations and record in the table Total the frequency to check all data has been counted

9Class interval

Class boundaries

Class midpoint

Frequency

1.5 1.9 1.45 1.95 1.7 2

2.0 2.4 1.95 2.45 2.2 12.5 2.9 2.45 2.95 2.7 43.0 3.4 2.95 3.45 3.2 153.5 3.9 3.45 3.95 3.7 104.0 4.4 3.95 4.45 4.2 54.5 4.9 4.45 4.95 4.7 3

Construct histogram based on the given data.

5. SCATTER DIAGRAM

Finding correlation between paired set data Supplies the data to confirm a hypothesis that

two variables are related

Purpose ?

Investigating causes and effects Stratification Investigate mutual relationships

When to use ?

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6. GRAPH Visual display of data to achieve a deeper and

quicker understanding of data. Easy to remember the information. Easy to determine the trends/patterns. Reveal hidden facts. Attracts attention of people viewing it.

Purpose ?

Clarifying the problems Understanding present situation Planning of activities Setting targets Investigating past and present situation Investigate temporal changes Setting up the countermeasures Confirming effectiveness Standardization and establishing control

When to use ?

LINE GRAPHS

A visual display of the pattern of data. Showing the changes over time.

Number of Vehicles serviced by the technician

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Monday Tuesday Wednesday Thursday Friday Saturday(Days)

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BAR GRAPH

A visual display of the difference in quantity. Showing the quantity of the variable being studied.

PIE CHARTS

A visual display of the proportion of the different classification.

7. FLOWCHART

Understanding processes by showing all the steps in the process.

Examining how various steps in a process are related to each other.

Identify loopholes which are potential sources of trouble.

Purpose ?

Understanding present situation Standardization and establishing control

When to use ?

A picture of a processWhat ?

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Flowchart

Activity

DecisionYes

No

Flowchart

Process Chart Symbols

Operations

Inspection

Transportation

Delay

Storage

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process

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91011

Unload apples from truckMove to inspection stationWeigh, inspect, sortMove to storage

Wait until neededMove to peelerApples peeled and coredSoak in water until needed

Place in conveyorMove to mixing areaWeigh, inspect, sort

TotalPage 1 0f 3 480

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52015

360

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190 ft

20 ft

20 ft

50 ft

100 ft

Date: 9-30-00Analyst: TLR

Location: Graves MountainProcess: Apple Sauce

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8. CONTROL CHART

To check whether a process is under control or not Serves as an alarm for on-going control of a

process Determine when a process needs to be adjusted and

when it is to be left as it is

Purpose ?

Clarifying the problems Understanding present situation Setting targets Investigating past and present situation Investigate temporal changes Confirming effectiveness Standardization and establishing control

When to use ?

Graphical display of quality characteristics that has been measured and computed from the sample; it shows the control limits lines

What ? Types of control chart

7 BASIC QC TOOLS 1. CHECK SHEETTwo Basic Types of Check Sheets2. PARETO DIAGRAMSTEPS TO CONSTRUCT A PARETO CHARTSTEPS TO CONSTRUCT A PARETO CHARTSTEPS TO CONSTRUCT A PARETO CHARTSTEPS TO CONSTRUCT A PARETO CHARTSTEPS TO CONSTRUCT A PARETO CHART3. CAUSE AND EFFECT DIAGRAM(also known as Ishikawa Diagram and Fishbone Diagram) Fishbone Diagram Assignment 2.34. HISTOGRAM5. SCATTER DIAGRAM6. GRAPHLINE GRAPHSBAR GRAPHPIE CHARTS7. FLOWCHARTFlowchart FlowchartProcess Chart Symbols8. CONTROL CHARTTypes of control chart