नई खबर
"Application of 7 Quality Control (7 QC) Tools for Continuous Improvement of Manufacturing Processes"
"In this blog a review of systematic use of 7 QC tools is presented. The main aim of this blog is to
provide an easy introduction of 7 QC
tools and to improve the quality level of manufacturing processes by applying
it.QC tools are the means for Collecting
data , analyzing data , identifying root causes and measuring the results.
these tools are related to numerical data
processing .
The work shows continuous use of these tools upgrades the personnel
characteristics of the people
involved. It enhances their ability to
think generate ideas, solve problem
and do proper planning. The development of people
improves the internal environment of the
organization, Which plays a major
role in the total Quality Culture."
Keywords:-
QC Tools ,
continuous improvement , manufacturing processes ,Quality control , Root Cause
analysis,PDCA,Efficiency.
Introduction:-
The 7 QC Tools
are simple statistical tools used for problem
solving. These tools were either developed in Japan or introduced to Japan by the
Quality Gurus such as Deming and Juran.
Kaoru Ishikawa
has stated that these 7 tools can be
used to solve 95 percent of all problems.
For solving quality problems seven QC tools used
are Pareto Diagram, Cause & Effect Diagram ,Histogram, Control Charts ,
Scatter Diagrams, Graphs and Check Sheets .
Methodology:-
For solving quality problems
following seven QC tools are required
1. Pareto Diagram
2.
Cause & Effect Diagram
3.
Histogram
4.
Control Charts
5. Scatter Diagrams
6. Graphs
7. Check Sheets
1) Pareto Diagram:-
Pareto
Diagram is a tool that arranges
items in the order of the magnitude of their
contribution, thereby identifying a few items exerting maximum influence. This tool is used in SPC and quality
improvement for prioritizing projects
for improvement, prioritising setting up of
corrective action teams to solve problems,
identifying products on which most
complaints are received, identifying the nature of complaints occurring most often, identifying most frequent
causes for rejections or for other
similar purposes.
Pareto principle also known as the 80/20 rule is used in the field of materials
management for ABC analysis. 20% of the items purchased by a company account for 80% of
the value. These constitute the A items on which maximum attention is paid.
2) Cause & Effect Diagram:-
A Cause-and Effect Diagram is a tool that
shows systematic relationship between a result or a symptom or an effect and
its possible causes. It is an effective tool to systematically generate ideas
about causes for problems and to present these in a structured form. This tool
was devised by Dr. Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram.
3) Histogram:-
Histograms or Frequency Distribution Diagrams are bar charts showing the
distribution pattern of observations grouped in convenient class intervals and
arranged in order of magnitude. Histograms are useful in studying patterns of
distribution and in drawing conclusions about the process based on the pattern.
Variability is inherent in all
manufacturing processes.
These variations may be due to two causes ;
i. Random / Chance causes (un-preventable).
ii.
Assignable causes (preventable).
Control charts was developed by
Dr. Walter A. Shewhart during 1920's while he was with Bell Telephone
Laboratories. These charts separate out assignable causes.
Control chart makes possible the
diagnosis and correction of many production troubles and brings substantial
improvements in the quality of the products and reduction of spoilage and
rework.
It tells us when to leave a
process alone as well as when to take action to correc trouble
.
4) Control Chart:-
Basic Concept:-
a. Data is of two types :-
Variable - measured and expressed quantitatively
Attribute - quanlitative
b. Mean and Range :-
X - Mean is the average of a sub-group
R - Range is
the difference between the minimum and maximum in a sub-group
c.control Charts for Variables:-
Charts
depleting the variations in ⎯X
and R with time are known as ⎯X
and R charts. ⎯X and R
charts are used for variable data when the sample size of the subgroup is 2-5. When the subgroup size is larger, s Charts are used instead of R charts where s
is the standard deviation of the subgroup.
d.control
Charts for Attributes:-
The control charts for attributes are p-chart, np-chart, c-chart and
u-chart. Control charts for defectives are p and np charts. P charts are used
when the sample size is constant and np charts are used when the sample size is
variable. In the case where the number of defects is the data available for
plotting, c and u charts are used. If the sample size is constant, c charts are
used and u charts are used for variable sample sizes.
5)Scatter Diagram:-
When
solving a problem or analysing a
situation one needs to know the relationship between
two variables. A relationship may or
may not exist between two
variables. If a relationship exists, it may be positive or negative, it may be strong or
weak and may be simple or complex. A tool to study the relationship between
two variables is known as Scatter Diagram. It consists of plotting
a series of points representing several observations on a graph in which one variable is on X-axis and the other variable
in on Y-axis. If more than one set of values are identical, requiring more
points at the same spot, a small
circle is drawn around the original
dot to indicate second point with the
same values. The way the points lie scattered in the quadrant gives a good
indication of the
relationship between the two
variables.
6) Graphs
Graphs of various types are used for pictoral representation of data.
Pictoral representation enables the
Sr.No
|
Type of graph
|
purpose
|
1
|
Bar Graph
|
To compare sizes of data
|
2
|
Line Graph
|
To represent changes of data
|
3
|
Gantt chart
|
To plan and schedule
|
4
|
Radar chart
|
To represent changes in data (before and
after)
|
5
|
Band Graph
|
Same as above
|
7) Check
Sheets:-
As measurement and collection of data
forms the basis for any analysis, this activity needs to be planned in such a way that the
information collected is both relevant
and comprehensive.Check sheets are tools for collecting data. They are designed specific to the type of data to be collected. Check sheets aid in systematic collection of data. Some examples of check sheets are daily maintenance
check sheets, attendance records, production log books, etc.
Seven
basic quality tools (7QC tools)
|
|||||
Plan
|
Do
|
Plan , Check
|
Plan ,Act
|
Check
|
|
Problem
Identification
|
Implement
solutions
|
Process analysis
|
Solution
Development
|
Result Evaluation
|
|
Flow chart
|
√
|
√
|
|||
Cause and Effect
diagram
|
√
|
√
|
|||
Check Sheet
|
√
|
√
|
√
|
||
Pareto diagram
|
√
|
√
|
√
|
||
Histogram
|
√
|
√
|
|||
Scatter plot
|
√
|
√
|
√
|
√
|
|
Control chart
|
√
|
√
|
√
|
||
Comments
Post a Comment