04_basic qc tools
DESCRIPTION
Basic QC Tools chapter 4TRANSCRIPT
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1BASIC QUALITY CONTROL TOOLS
Prepared by:
MUSLI BIN [email protected]
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)
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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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3
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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).
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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.
0
50
100
150
200
250
300
Dash boardscratch
End panelbumper
clearance small
End panel andgrill panel not
level
Fuel lid cannotopen
RR room lampgapping
0102030405060708090100
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
0
50
100
150
200
250
300
Dash board scratch End panel bumperclearance small
End panel and grillpanel not level
Fuel lid cannot open RR room lampgapping
0
10
20
30
40
50
60
70
80
90
100
Types of Defects
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STEPS TO CONSTRUCT A PARETO CHART
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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)
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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
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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
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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
0
12
34
56
78
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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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T
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(
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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
30
52015
360
30
20
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