3. Seven QC tools are fundamental
instruments to improve the quality of the
product. They are used to analyse the
production process, identify the major
problems, control fluctuations of product
quality, and provide solutions to avoid
future defects.
INTRODUCTION
AEW
5. Check Sheet is a tool to simplify data collection. They make it
easy to compile data in such a form that they may be used
readily and analyzed automatically.
A. Production process distribution checks
B. Defective item checks
C. Defect location checks
D. Defective cause checks
E. Check-up confirmation checks
WHAT ?
TOOL 1 – CHECK SHEET AEW
6. A. PRODUCTION PROCESS DISTRIBUTION CHECK SHEET.
STEP 1: Define what is to be investigated & What information is
needed.?
STEP 2: Define on the basis of the results, what action will you
take?
STEP 3: Since production process is to be analyzed, list clearly on
the check sheet information on workers, machines, equipment,
materials, shifts, times, dates, products & others.
STEP 4: Issue the check sheet in the shop floor for data collection.
All that the operator has to do is to make entry marks in the check
sheet.
HOW TO USE ?
CHECK SHEET AEW
7. TOOL 2 – HISTOGRAM
A bar chart that displays the variation within the process. Also
called a frequency distribution because the frequency of occurrence
of any given value is represented by the height of the bars.
Allows one to quickly visualize what’s going on within a large amount of
data.
Provides clues to causes of problems.
Maybe be used to show the relationship between the engineering
tolerance and the capabilities of the process.
WHAT ?
WHY ?
AEW
8. Capability studies are being performed.
Analyzing the quality of incoming material.
Understanding population at a glance
Collect measurements(variable data)from a process or key
characteristic.
Thirty or more measurements are preferred.
Construct check sheet to record the data.
Find the range by subtracting the smallest measurements from
the largest.
Using this guide determine the proper number of class intervals.
WHEN ?
HOW ?
HISTOGRAM AEW
9. Observations No. of classes(K)
25 to 50 5 to 8
51 to 100 6 to 11
101 to 250 9 to 13
251 and over 11 to 15
h=R/k (R = Range)
Construct a frequency table by properly making class boundaries. Tally the
number of observations found in each class.
HISTOGRAM AEW
11. It is a tool that indicates which problem
should be solved first (prioritization) in
eliminating defects and improving the operation.
Pareto Diagrams indicate which factors are most
prevalent and therefore deserve concentrated efforts for
improvements. They can be used to confirm and
measure the impact of improvement.
WHAT ?
TOOL 3 – PARETO DIAGRAM AEW
12. .”
1. To improve the efficiency of office work.
2. To improve machine breakdown prevention and preventive
maintenance planning.
3. To improve safety in the factory.
4. To reduce defectives from a certain process, etc.
WHERE TO USE?
PARETO DIAGRAM AEW
13. 1. Ascertain the classifications to be used in he graph. Ex: Types of
defectives, defects, etc.
2. Decide on the time period to be covered on the graph. Ex: one day,
one week, two weeks, one month, three months, etc.
3. Total the frequency of occurrence of each category for the period.
4. Rank the characteristics according to the totals from step 3.
5. Draw in bars, beginning on the far left with the most frequent
defective item.
6. Plot a line showing the cumulative total reached with the addition of
each category.
.
HOW TO MAKE A PARETO DIAGRAM ?
PARETO DIAGRAM AEW
15. It is a diagram, which illustrates the relationship between
causes of dispersion (Work methods, Materials, Equipment,
Measurement, etc) with effects (percentage of defectives).
This diagram provides a means for teams to focus on the creation of a
list of process input variables that could affect key process output variables.
This technique is useful to trigger ideas and promote a balanced approach in
group brainstorming sessions in which individuals list the perceived sources
(causes) of a problem (effect).
WHAT ?
TOOL 4 – CAUSE & EFFECT DIAGRAM AEW
16. Identifies various causes affecting a process.
Helps groups in reaching a common understanding of a problem.
Helps reduce incidence of subjective decision making.
Looking for all potential causes of problem.
WHY ?
WHEN ?
A graphic tool used to represent the relationship between
an effect and the cause that influence it.
CAUSE & EFFECT DIAGRAM AEW
17. 1. Define the problem or effect clearly.
2. Generate the potential cause of problem through brain storming.
1. Encourage wild ideas
2. ‘Quantity’ rather than ‘Quality’ of ideas
3. Suspend judgment on ‘Good’ or ‘Bad’
4. Ride on another’s idea
3. Construct the cause and effect diagram by:
1. Place problem statement in a box on right hand side.
2. Draw the major cause category boxes on the left hand side.
Commonly used categories are man, machine, method, material and
measurement.
HOW ?
CAUSE & EFFECT DIAGRAM AEW
18. Nurses
Many patients
Long waiting
time after
completion of
ultrasonic scan
MethodsEnvironment
People
Reception
work
Medical charts
hard to tell apart
Many charts to input
Shortage of
numbers
Inexperience
Patients
Two or more booked
in at same time
Record
findings
Charts all
returned together
Handling
Data input
takes time
Calculation
of bill
Charts from all
departments
come together
Test
Rooms
Far away
Busy
Computer
terminal
slow
Recepti
on
CAUSE & EFFECT DIAGRAM AEW
19. It is a diagram, which shows strength of the relationship
between two variables, which may be linear, quadratic, or some
other mathematical relationship.
Ex: Relationship between moisture content in threads and elongation, the
relationship between an ingredient and product hardness, the relationship
between the cutting speed and variations in length of parts, etc. After the
establishment of the relationship, appropriate action can be initiated.
To test for possible causes and effect relationships. Though it
cannot prove that one variable causes the other, the diagram does make it
clear whether a relationship exists and shows the strength of that
relationship.
WHAT ?
WHY ?
TOOL 5 – SCATTER DIAGRAM AEW
20. Collect 50 to 100 paired samples of data believed to be related.
Construct a data sheet.
Draw the horizontal and vertical axis of the diagram.
Label the axes.
“Cause”is usually plotted on the horizontal axis and the “effect”
variable on the vertical axis.
Plot the data on the diagram. If values repeat, circle that point.
HOW ?
There is a need to display what happens to one variable when
another one changes in order to test that the two variables are
related.
WHEN ?
SCATTER DIAGRAM AEW
21. D. Possible negative correlation E. Strong Negative correlation
A. Randomly scattered points -
No correlation
B. Possible Positive correlation C. Strong positive correlation
n=15 r=0.06 n=18 r=0.54 n=14 r=0.96
n=22 r=- 0.5 n=18 r=-0.92
SCATTER DIAGRAM-INTERPRETATION AEW
22. TOOL 6 – STRATIFICATION
Stratification is a statistical technique of breaking
down values and numbers into meaningful categories
or classification.
To focus on corrective action or identify true causes.
WHAT ?
WHY ?
AEW
23. Regroup original data as per the source of data (eg.
Machine wise, shift-wise, model-wise, supplier-wise)
If required collect data afresh after making the source
from which they come.
Recreate histogram, Pareto charts and graphs on
classified data
WHEN ?
To identify the cause of problem if they come from a
particular source.
To analyze root cause in conjunction with other
techniques like Pareto diagram histogram and graphs.
HOW ?
STRATIFICATION AEW
25. TOOL 7 – GRAPHS & CONTROL CHARTS
GRAPHS
It is a tool for organization, summarization and statistical
display to aid in the analysis of data. To derive the maximum
benefits, their purpose should always be known and their use
periodically evaluated.
Types of Graphs
1. Line Graphs
2. Bar Graphs
3. Circle Graphs(Pie-graph)
WHAT ?
AEW
28. CONTROL CHART
They are a type of graph. Data are compared to compute
Control Limits, which are also called as Process Limits. These
limits are computed based on actual/past data. Running a process in
a predictable fashion is the goal of the control charts. Timely action
on out of control points is the key to the success of this technique.
Any control chart consists of three lines as follows:
1. Upper Control Limit (UCL)
2. Mean
3. Lower Control Limit (LCL)
There are different types of control charts depending on the nature
of data used – Variable & Attribute Data – X-Bar Chart, p-Chart, c-
chart.
WHAT ?
GRAPHS & CONTROL CHARTS AEW
29. A control chart correctly used can achieve the following
simultaneously:
1. Reducing Variation
2. Increasing Productivity
3. Reducing cost by eliminating inspection.
GRAPHS & CONTROL CHARTS AEW
