quality cpm 1
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Importance of quality:
Customers will buy and keep on buying. If we produce it efficiently, we will
earn a profit.
This definition gives 4 aspects – 3 are independent and the 4th one is
dependent.
• Productivity
• Cost
• Quality
Of these 3 determinants of profitability, the most significant factor in
determining the long range success or failure of an organization is Quality.
Some of the benefits of good quality of the product and the services
1. Competitive edge2. Reduce cost due to returns, rework or scrap
3. Productivity and Profits
3rd is the outcome of the first two.
4. Generates satisfied customers : Benefits of a satisfied customer is - we
have continued patronage and word-of-mouth advertisement
Not only it earns profit, it also gives good will to the company.
Cost of quality
The cost of ensuring that the job is done right + the cost of not doing the job
right
Cost of conformance + cost of non-conformance.
(prevention & appraisal) + (internal & external defects)
Four Cost Categories Related to quality
Prevention Cost: Cost of planning and executing a project so it is error-freeor within an acceptable error range.
Appraisal Cost: Cost of evaluating processes and their outputs to ensure
quality
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Internal Failure Cost: Cost incurred to correct an identified defect before the
customer receives the product.
Identify the defect – do inspection
Not only we should find the defect, we also need to correct it.
Whatever the cost that we are saying that these are the internal cost is the
cost counted before the customer receives the product.
When the customer starts using it and if he finds there is some problem with
the product
External failure cost is basically the cost when the product has been shipped
to the customer.
External Failure Cost – Cost that relates to all errors not detected and
corrected before delivery to the customer.
This has multiple effects – not only the product is coming back to the
company for rework or whatever it is but it is basically spoiling the image
and good will of the company.
So internal and external failure costs need to be carefully ascertained apart
from the prevention and appraisal costs.
This basically shows that the normal cost of quality distribution when the
quality system is not in place; this means – a company which is not having
any quality process, or quality concept or quality system in place, the 4
components that I mentioned – prevention, appraisal, internal and external
failure cost – this slide basically shows all these aspects
Very little in appraisal, little bit more on prevention – total of appraisal and
prevention cost that is the cost of conformance – the spending is very less –as a result, the internal failure cost and external failure cost are very high.
This says that the company good-will, the company product good will or
company itself good will is not good.
Another figure that we will see is “The Optimum Cost of Quality Distribution
when Quality System is in Place.”
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The appraisal cost and prevention cost is increased. The company is
focusing more on prevention and more on appraisal. The result of these two
basically is the reduction in internal and external failure cost.
Once the internal and external failure costs have been reduced, then the
company focuses on the 3 issues mentioned earlier - productivity, cost and
quality.
Once your scrap, rework etc is reduced, certainly your productivity is
improved, quality is improved and cost is reduced. Once the productivity is
there, quality is there, the profit that the company is going to earn is going
to be much higher than the company which is not having the quality system
in place.
With the background of understanding of cost quality and productivity, let usdiscuss about the evolution of quality.
Evolution of quality
During the early days of manufacturing, an operative’s work was inspected
and a decision made whether to accept or reject it. The focus was just to
accept or reject the products based on the specification. No effort was made
on defect prevention.
This means, total productivity or the total output was based only on
inspection. Inspection is basically an audit tool. It is not building quality into
the product. It is just auditing good or bad.
The product is produced, the inspector inspects and then the inspector says
whether the product is good or bad. Bad product is sent back to
manufacturing for rework or scrap and the good product is delivered to the
customer.
There was no effort in identifying the causes that created the bad producttherefore it was mentioned that there was no effort in defect prevention.
In 1922 statistical theory began to be applied effectively to quality control
In 1924 Shewhart made the first attempt of a modern control chart. However, there
was little use of these techniques in manufacturing companies until the late 1940’s.
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1950 – quality management practices developed rapidly in Japanese plants, and
became a major theme in Japanese management philosophy.
By 1960, quality control and management had become a national preoccupation.
1969, Feigenbaum used the term “total quality” for the first time.
1970, Ishikawa used the term “company wide quality control”
1980, Total Quality Management (TQMI came into existence.
As we move into the 21st century, TQM has developed in many countries into holistic
frameworks, aimed at helping organizations achieve excellent performance,
particularly in customer and business results.
Primary
Concern
View of Quality Emphasis Methods
Inspection Detection A problem to
be solved
Product
uniformity
Gauging and
measuringStatistical
Quality Control
Control A problem to
be solved
Product
uniformity with
fewer
inspections
Statistical tools
Quality
Assurance
Coordainating Proactively
solve problem
Production
chain designed
to prevent
failures
Programs and
systems
Strategic
Quality
Management
Strategic
Impact
Competitive
opportunity
Market and
consumer
needs
Strategic
planning and
goal setting.
We have seen the evolution of quality and the historical perspective. If you see, the
table has been divided into 4 parts.
First as I mentioned, initially, in earlier days of manufacturing, the focus was on the
inspection. There was no effort put in to maintain the quality of the product
regarding the prevention of the defects.
2nd row is statistical quality control, third row is quality assurance and the 4th row is
strategic quality management.
For all these perspectives are identified
1. What are the primary concerns?
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2. What view do they take of quality?
3. What is the emphasis on?
4. What method is used for achieving quality?
If we see the inspection –
During the early phase of manufacturing, in the inspection stage, the primaryconcern was detection – detection of scrap, detection of the defective product or
detection of the defect. Although there is no effort on the prevention aspect, as I
earlier mentioned. The view of quality during that period was that a problem is to
be solved. The emphasis was on product uniformity. Every product that is going
into the hand of customer need to be uniform in all the aspects which means it
should be perfect. Methods used are gauges and different measuring instruments
and based on the gauges, calipers and measuring instruments they used to check
whether the product has been made as per the specification or not. Focus was on
the specification – not on the quality into the design of the product
Statistical quality control – although it had started 1920-24, shewahart made the
first attempt to implement the modern quality control chart but up to 1940 there
was nothing there in the history aspect that people are not utilizing the modern
quality control charts in the manufacturing although during the second world war
these techniques were utilized for the maintain or finding the defects as well as to
go for the corrective actions. That is why you see that the primary concern was
control – means to inspect it and find out the reason for why the product is getting
failed or why we are producing defective products.
So, primary concern has to change from detection to control. View of quality was
the same – A problem to be solved, emphasis was – product uniformity with fewerinspections. The focus was that there should be consistency in the quality of the
product as well as the inspection should be as low as possible and the tools that
they used in maintaining the quality of the product are the statistical tools.
Third stage was the quality assurance and the primary concern was coordination.
Earlier, in the inspection and in the statistical quality control, the focus was totally
on the manufacturing side. What is happening before manufacturing and what is
happening once the product has gone into the hands of customer. That focus is
gone. So, in quality assurance stages, they try to integrate the different aspects of
manufacturing, not only the manufacturing, but manufacturing engineering,purchasing, quality in design section and field installation and commissioning of the
product. So they try to coordinate all the activities of the product life cycle and
what was the view of the quality – proactively solve the problem. Emphasis was on
production chain designed to prevent failures. A production chain is basically any
manufacturing activity in the production cycle that starts from the design. Once
they are not able to put the right quality into the design, you cannot put any effort
to bring the quality into the product. So earlier, people were saying that once it is
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in manufacturing stage, they do the inspection and check the specification – if they
meet the expected standards then ok otherwise no. so they try to integrate the
production chain that is designed to prevent failure. Methods were programs and
systems. People were made aware of what are the benefits of quality what are the
different features of quality by using tools, techniques and the awareness programs.
Finally, the present stage, that is, the strategic quality management stage – primary
concern is the strategic impact. It is not only that we are talking about the good
quality or the bad quality of the product, but what is the long term strategic impact
of the product on the company – not only on the profit but also the good will of the
company. View of the quality in the strategic quality management stage is the
competitive opportunity. So there is a lot of competition going on and just to
survive in the competitive market, focus was on competitive opportunity and the
emphasis is on market and consumer needs. Tailor made solutions are now a days
coming up. People were basically driven by the customer earlier – whatever
products were available, the customers used to take it depending on their
requirement; but now, the demand is basically driven from the customer. Methods
– they use the strategic planning and goal setting.
So, this is an overview of the historical perspective in the evolution of quality
starting from the inspection to the strategic quality management in different
concerns from primary concerns to the methods.
Dimensions of quality
Whatever we are saying about the dimension of quality or about the quality – lets
see what we think of quality? – there are various ways we can think of quality asGarvin has mentioned – he has given 8 dimensions of quality – that different people
see quality in different way. Garwin has mentioned that performance is one of the
aspects or one of the quality characteristics that a person can see only depending
on the customer - he may be thinking of the quality, he may be thinking of the
aesthetics – different points are there – some people think of the specification, some
people focus that the product should perform well.
So the first dimension that garvin has given is performance and the question that
we can ask is the product that we are getting or the product that we are
manufacturing – is it doing the intended job or the required job?
2. Second dimension is the reliability. Sometimes, Not only we talk about the
performance of the product, but we also talk about the reliability. How often the
product fails.
3. Also sometimes we go for durability in conjunction with performance and
reliability – how long the product lasts that is the life of the product.
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4. Serviceability – how easy it is to repair the product if there are some small
failures
5. Aesthetics – what does the product look like?
6. Features – what does the product do? Sometimes not only the performance,reliability and durability of the product are looked at, there are similar products
available in the market – some products are having few features and some
products are having additional features. Whatever additional we are getting –
that appeals to us.
7. Conformance to standards – whether the product meets the specifications.
Sometimes the customer provides the specifications for the product like that the
product needs to have that much tolerance, this much specification or this much
strength etc. whether the product that the customer ordered or the customer
thought initially - whether the product meets the specification as he has
specified
8. Perceived quality – what is the reputation of a company or its products? – that is
the good will. Sometimes we have in our mind that whatever product we are
buying is having good quality or the company’s image basically goes with the
product.
Q- how much does the product cost?
These are the 8 dimensions that depends on the customer that depends on the
person – whether he is looking for 1 dimension, 2 dimensions or all the 8 dimensions
of the product – that he is equally satisfied with the performance, he is equally
satisfied with reliability, serviceability, durability etc. may be sometimes some
persons go only for 1 or 2 dimensions like performance and perceived quality. He isonly looking that the company should have good quality and the product should
perform well. The person may not bother about how long the product lasts. So
depending on the requirement the person can have the different dimension of
quality.
The Eight Dimensions of Quality1 Performance Will the product do the intended job?2 Reliability How often the product fails?3 Durability How long the product lasts?4 Serviceability How easy is it to repair the product?5 Aesthetics What does the product look like?6 Features What does the product do?7 Conformance to standards Whether the product meet the
specifications8 Perceived Quality What is the reputation of a company or its
products?
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And coming to the definition of quality, there are 5 different definitions of quality.
The quality can be defined in 5 different ways.
Definitions of Quality1. Transcendent definition excellence
2. Product-based definition Quantities of product attributes3. User-based definition Fitness for intended use4. Value-based definition Quality vs. price5. Manufacturing-based definition Conformance to specifications
The first definition is the transcendent definition:
1. Transcendent : Excellence in all aspects (in all the dimensions)
The second definition is the product based definition: quantities of product
attributes. The product may be having 1 attribute, 2 attribute, 3 attributedepending on the customer requirement. If the customer is looking for more
attributes, then other definitions may be there.
Third type of definition is basically user-based definition. That is, fitness for use,
fitness for the requirement; whatever I am intending for – whether that product is
fit for use
Fourth is value-based definition. Sometimes, we go for the product, we not only
check for the quality, but also we go for the price. If the price is low, we try to make
the trade-off between the price and quality. Sometimes, we have good features,good quality, good performance but cost are high. In such cases we go for some
other product. Because price is the primary concern, we have to think for another
product. So people can go for the value based definition.
Fifth is the manufacturing based definition: earlier people used to have that is
conformance to specification. Whether the product being manufactured meets the
specifications provided by the designer?
So, these are the 5 different ways that we can define quality. There is no unique
definition. It is an individual perspective – how he looks at quality.
This is a tradition definition that “Quality means fitness for use.” This is given by
Joseph Juran.
Customer –Driven Quality
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“ the totality of features and characteristics of a product or services that bear on its
ability to satisfy stated or implied needs of the customers. (ASQC)”
Customer –Driven Quality as per American Society for Quality control
“ the totality of features and characteristics of a product or services that bear on its
ability to satisfy stated or implied needs of the customers.”
This means – meeting or exceeding customer expectations.
There are different companies that focus on just meeting the customer
expectations. Customer is satisfied, but when you give some additional features,
something extra which the customer was not expecting customer feels delighted in
buying and using the product. There is a difference between meeting and
exceeding customer expectations.
So, when a customer buys a product and he is satisfied with the produce, he is a
satisfied customer. But once you give the product additional features, additional
things that the customer was not expecting that means customer delight.
Customer feels delighted in buying and using the product.
3 aspects of quality:
I earlier mentioned, during quality evolution stages focus was on the inspection in
the manufacturing based definition, I mentioned that the focus is on meeting or
conforming to the specifications.
The 3 aspects of quality in this link I say that all the quality aspects are basically
linked with the quality of conformance, quality of design and quality of
performance.
Quality of design is basically consumer’s perspective.
Quality of Design
Quality of Design: Consumer’s Perspective
The product must be designed to meet the requirement fo the customer.
The product must be designed right first time and every time and while designing
all aspects of customer expectations must be incorporated into the product.
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This definition basically changes the focus. Earlier people were concerned only
about the manufacturing; now people think that instead of looking at the
downstream, i.e., the manufacturing and the subsequent stages, we should look
upstream. When we look upstream, the focus should be on the design. When
marketing persons go for the market survey and contact the customers, they try to
capture what the customers want. They try to capture the voice of the customer. They do it by means of a survey, warenttil cost, customer meeting – when they
meet the customer, customer tells them what they want. These marketing people
then understand what the customer is actually requiring and give the entire detail
to the product design section or to the designer. When the designer designs the
product he takes the customer needs into consideration. For example, customer
needs a product with high strength. As I designer, I recommend the material to be
used that provides the desired strength. Then, when my design goes to the
manufacturing, manufacturing people may say that the material you are
specifying, we don’t have any machine to machining that particular material.
Machining of that material is not possible. May be the possibility is there, whatever
material the designer is suggesting, the purchasing dept. may think that they
cannot buy the material, the material is not available. This is a great mistake ( a
blunder), I must say, the designer usually do – instead of designing all aspects of
manufacturing, they should involve the people from the subsequent downstream
section like purchasing, manufacturing engineering, manufacturing inspection – all
the stages when the product is in the design stage.
So, when the product is in the design stage, whatever they are designing, may be at
that time, purchasing dept. or purchasing function or purchasing manager may say
that this product or the material that we are suggesting will not be available in the
market. May be, the manufacturing person may say that the tolerance that you areproviding, our existing machines can not deliver that same tolerances. So, the
focus is basically that we cannot put right quality back into the product in the
subsequent stages. We should design the quality right into the product that is why
it is mentioned here that the product must be designed to meet the requirements of
the customer. The product must be designed right first time and every time. So,
first time and every time. Every time basically indicates the consistency of our
delivery. While designing all aspects of customer expectations must be
incorporated into the design. All aspects of customer expectations mean the 8
dimension of the product. May be, the customer is looking for performance,
reliability and durability. Whatever the aspects the customer has specified, all theexpectations or all the aspects the customer is expecting must be incorporated into
the product.
Quality of Design
Quality of Design: Consumer’s Perspective
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The factors need to consider while designing the product are:
1. Type of product
2. Cost
3. Profit policy of the company
4. Demand5. Availability of the parts
So, when a designer designs the product, he needs to focus what type of product
he is designing, he should also have the aspect of the cost, i.e., what is the cost the
customer is willing to pay; he also need to know what is the profit policy of the
company; what is the demand? Whether it is one-of-a-type or continuous-demand
type of product? Whether whatever he is designing and whatever parts or
components he is recommending whether those components or parts are available
in the market or not? It is not only restricted to the parts, as I have earliermentioned the material the designer is suggesting whether that type of material is
available in the near by market or available in the country? Also apart from all
these 5 aspects, the designer must also consider the process capabilities of the
manufacturing machines. That sometimes what happens – suppose the designer
gives the tolerance of ±.003 – means up to 3 places after the decimal. When that
product or component goes into manufacturing, they think that the machines
available in the manufacturing area are not capable of producing parts or
components of that thickness or tolerance, i.e. up to 3 decimal places. So, there is
a to and fro movement of the product and the component – when the available
equipment are not capable of producing the desired specifications, the product is
bound to get rejected because it is not meeting customer’s requirements. The
designer must consider all these factors while designing the product.
The next aspect of quality is the quality of conformance. Quality of conformance is
basically the manufacturer’s Perspective. Earlier aspect that I talked about – the
quality of design that is the consumer’s perspective.
quality of conformance
Quality of conformance: Manufacturer’s Perspective.
The product must be manufactured exactly as designed.
The activities involved at this stage include:
1. Defect finding
2. Defect prevention
3. Defect analysis and
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4. Rectification.
In the manufacture’s perspective, we look what the designer has given to the
manufacturing section and whatever the bill of material and whatever the
specification that has been designed at the product design stage finally comes to
the manufacturing section. The product at this stage must be manufactured exactlyas designed. The activities involved at this stage include: defect finding, defect
prevention, defect analysis and rectification. As per the manufacturer’s
perspective, the focus should be – whatever specification is provided at the design
stage, the manufacturing people should provide exactly the same. So, if not,
because of any reason, the tolerance is not meeting the specification, the first step
in the analysis should be the defect finding. After careful finding of defect, why this
is not happening. Once you know the different types of defects, then the control
phenomena starts – how to prevent these defects. Then we need to find out the
reasons and where are the control mechanisms and then we try to prevent all these
defects. This is possible only when we go for the defect analysis. Once we find thedefect, we analyze the defect then only we can prevent it. Not only our process is
to prevent the defect but also rectification in the process. So that the process
performs all the steps necessary to produce the product in the right way first time
and every time.
Quality of conformance in continuation – some of the times the difficulties
encountered at the manufacturing stage must be conveyed to the designers for
modification in design, if any. The two way communication between designer and
manufacturing may help to improve the quality of the product
Refer to the earlier example: designer specifies a tolerance level of ±0.003 and the
manufacturing unit communicates that the existing machines are not capable of
that kind or precision. So the designer tries to find an alternative.
Quality of Performance
The product must function as per the expectations of the customer.
The 2 way communication between designers and customer is the key to have a
quality product.
Three aspects of quality diagram goes here 2-way comm.. bet cust-design and
design-manuf
So, once we have all these 3 aspects, the quality of design, quality of conformance
and the quality of performance – in all these 3 cases, we need 100% perfection.
Our design should be 100% right, our conformance to the specification should be
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100% right and the quality of performance should be 100% right. That means we
should get 10/10, 10/10 & 10/10 in all the 3 aspects of quality.
Then only we say that yes, our product meets the customer’s expectations.
The other definition for quality: earlier we discussed 2 definitions of quality: thefitness for use, quality – what the customer wants or exceeding the customer
requirement
There is another definition of quality which is the modern definition
Quality is inversely proportional to Variability.
This variability means variation – higher the variation, poorer the quality. This
variation will be either from the processes or the product. As far as the processes
are concerned, you need to control the processes. Every process, every machine,
every person – they have inherent variation. This inherent variation basically is theevil that is creating the problem. ISO-9000 is answer to this. It is a total
documented approach. It focuses on that whatever you do you document it and
whatever you have documented, you do it. You follow this and follow it
consistently. Now, the question arises – whatever you are documenting whether
you are documenting right or wrong. If you have documented the wrong
procedures then you are following the wrong procedures consistently. So, that
should not be the approach. Before documenting we need to standardize the
processes, we need to standardize the methods. We should document only the
right methods and the right procedures. Once the procedures have been
standardized, the total documentation should be there and whatever is
documented, we need to practice it.
The focus in ISO-9000 is basically is that irrespective of the person, irrespective of
the system, whosoever does the job, follows the documentation and the quality of
the product is exactly the same as was done before.
This concept of quality that it is inversely proportional to the variation is very well
addressed through the ISO-9000. ISO-9000 focuses on the Quality System
approach as well as on the consistency of the processes.
If we see the traditional and the modern view point of quality (diagram). In thisdiagram, you see that this is the LSL and this is the USL. The traditional approach
was that the customer has given 2 boundaries or 2 conditions that the product we
are manufacturing – it should be between the LSL and USL. Now , suppose the
product that we are manufacturing is near the LSL. Suppose you buy this
product and start using it. In six months time, because of wear and tear, the
dimensions, characteristics of the product goes beyond the LSL. Or, the other way,
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if you purchase the product, that is near to the USL, because of wear & tear and
usage, these characteristics of the product may go beyond the USL.
When the product goes beyond the limits, either LSL or USL, you need to do some
maintenance or rework on this particular characteristic of the product so that it
comes into the specified range mentioned by LSL-USL.
That is the traditional way to looking at the quality. Whenever we put effort to bring
the quality back between the LSL and USL means you are putting extra effort – may
be in terms of money may be in terms of human effort.
So, the modern view point, if you look at the 2nd curve, most of the products are just
near the target. Suppose you buy the product that is towards the left hand side of
this distribution or towards the left tail of the distribution. If you buy this product, it
will take entire life of the product to go beyond the specification limits. When you
use the product, because of wear and tear, when it goes beyond the SLs, entire
lifetime of the product is over. This is basically the difference between the
traditional view point and the modern view point. The traditional view point looks at
the goal point philosophy – even if it is closer to the LSL say pass or fail. But, the
modern view point says that you produce at the target and there is a little variation
around the target. So, this is the concept and this concept clearly supports the
modern definition that is quality is inversely proportional to variation. So, lower the
variation, the better is the quality. And quality improvement is basically a
continuous process. If you keep on reducing the variance, our quality will keep on
increasing. The same concept, the variability concept will continue in the next
lecture and we will build up the situation from the variability concept. We will talk
about different quality control tools and techniques. We will talk about the basic 7quality control tools and then we will talk about all the statistical control charts
ranging from variable to attribute type of charts.
X -- -- X –
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