IE 380 – Quality Control and Improvement
Instructor Emre Nadar
Unit 1 Notes
1.
Unit 1 Goals
• Introduce the course, its requirements, expectations, etc.
• Explore what we mean by quality, quality improvement, and quality control.
• Explore situations in which a quality program is likely to work (and those in
which it is likely not to work).
• Discuss the history of quality.
2.
Introduction
2.1
Me
2.2
This Course
We will spend time on trying to define what quality is (many definitions are out
there), discussing why we want to instill it, learning the tools we can use to
quantify quality, and looking at ways in which companies (with varying degrees
of success) have tried to incorporate quality into their workplace. We will see
that adopting quality is as much of a philosophical leap as a practical one. When
efforts fail, it is more often than not due to the unwillingness to make such a
change in philosophy.
In short, the course will cover three main topics:
1. Exploring what we mean by quality.
2. Learning the tools used to implement a quality program.
3. Studying actual implementations to see common successes and failures.
2.3
Syllabus
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3.
Introduction
“The first job we have is to turn out quality merchandise that consumers will buy
and keep on buying. If we produce it efficiently and economically, we will earn a
profit, in which you will share.” – William Cooper Procter
US companies are finally moving toward quality. It is pretty much universally
accepted that Japanese companies had much greater foresight than US companies
as far as the “quality revolution.” Whereas Deming was invited to Japan in 1950, a
survey of US consumers in 1981 showed that nearly fifty percent of them believed
that the quality of American products had gone down in the past five years.
These two events are related: Had the Japanese not upped the quality ante so
to speak, American consumers may not have developed their negative impression
about US goods. But they did. And this, more than anything else, is what began,
and still drives, Quality. Fulfilling the needs and wants of the consumer as reliably
and efficiently as possible.
QUESTION: Why do you think quality concepts were adopted so much earlier
in Japan than in the US?
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3.1
What is Quality?
We will discuss the history of quality later. For now, I want to discuss what it
is exactly that we mean by quality. This is certainly something which we must
know before we can hope to “totally manage” it.
There are many definitions of quality, each with a bunch of different “points.”
We will get to that. For now, I want to know what you think quality means. And
rest assured, there are so many definitions out there that anything you say can
probably be supported by someone’s formal definition.
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• Crosby’s definition: “Quality is conformance to requirements or specifications.”
• Juran’s definition: “Quality is fitness for use.”
• Mitra’s definition: “The quality of a product or service is the fitness of that
product or service for meeting or exceeding its intended use as required by
the customer.”
• Montgomery’s definition: “Quality is inversely proportional to variability.”
• Garvin divides the definition of quality into five categories:
– Transcendent definition.
– Product-based definition.
– User-based definition.
– Manufacturing-based definition.
– Value-based definition.
3.2
Quality Improvement
Ensuring quality should be an integrated process by which a company sets out
to consciously and constantly improve their product for their customer. Most
experts agree that this must be a top-down process – the responsibility, and the
ability, resides with management. Implementation is often difficult since people
on the whole don’t like change.
Typically, Quality Improvement follows this kind of a pattern:
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• How do we “fine tune the process”?
• How do we “improve the process”?
According to Mitra: “Quality improvement is the detection and elimination of
common causes.”
• Common causes:
• Special causes:
According to Montgomery: “Quality improvement is the reduction of variability
in processes and products.”
When is the easiest time to improve quality, when things are good, or when
things are bad?
What is the number one killer of quality program initiatives in companies?
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3.3
Quality Control
Quality control may generally be defined as a system that is used to maintain a
desired level of quality in a product or service. This general area may be divided
into three main subareas:
• Off-line quality control:
Off-line quality control procedures deal with measures to select and choose
controllable product and process parameters in such a way that the deviation
between the product or process output and the standard will be minimized.
Much of this task is accomplished through product and process design.
• Statistical process control:
Statistical process control involves comparing the output of a process or a
service with a standard and taking remedial actions in case of a discrepancy
between the two. It also involves determining whether a process can produce
a product that meets desired specifications or requirements.
• Acceptance sampling plans:
These are plans that determine the number of items to sample and the
acceptance criteria of the lot, based on meeting certain stipulated conditions
(such as the risk of rejecting a good lot or accepting a bad lot).
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3.4
Why Quality?
Quality can lead to many good results:
• Reduction of waste.
• Improved productivity.
• Reduction of cost.
• Improved market share.
• Survivability in the long run.
Costs associated with quality:
• Prevention costs. These are the costs of ensuring quality. They include planning and set-up costs, experimentation, training, SPC, data costs, reporting,
and project costs.
• Appraisal costs. Inspection costs, which include incoming material inspections, testing done during design and manufacture, destructive testing, equipment maintenance, and inventory testing.
• Internal failure costs. These are costs incurred before shipment, which include scrap, rework, retest, downtime, reduced yield, and disposition (deciding what to do with nonconforming pieces) costs.
• External failure costs. These are costs incurred after shipment, which include
complaints, returns, warranty costs, and price adjustments.
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4.
Historical Perspective of Quality
Prior to the industrial revolution, quality was something that was hand-crafted
into products by master craftsmen, the status of whom were closely controlled by
guilds. You learned your craft as an apprentice, and when you were accomplished
enough, you could petition to enter the guild, and be certified. People knew when
they were getting a Stradivarius, or a Michelangelo that they were getting quality,
but how many such masters are out there?
With the advent of the industrial revolution, manufacturing was taken out of
the hands of individuals, and moved into the factory. “Ownership” of a product
lost its meaning; with individuals responsible for a small part of the whole, no one
was really accountable for quality.
At approximately the turn of the century Frederick Taylor embarked on an
effort to standardize and quantify worker productivity, through the use of time
studies and wage incentives. This essentially began industrial management, but
the focus was only on how much was produced, not on the quality. In addition,
the standard becomes either an unattainable goal, which is dispiriting, or a barrier,
above which there is no incentive to improve.
Further quantification of manufacturing occurred in the 1920s, when Walter
Shewhart developed the technique of control charting to monitor the progress
of a process over time. This allowed the detection of deviations or variations
from what was desired, which is the first step to elimination of such occurrences.
Unfortunately, the work standard was still widely held at that time, so control
charting initially had little effect.
If we are not making any organized effort to prevent our process from producing
unacceptable products, how can we maintain our integrity with the customer?
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Not coincidentally, at this same time the science of probability and the techniques of acceptance sampling were evolving. Dodge and Romig at Bell Labs
devised the first scheme for acceptance sampling, eliminating the need for tedious
(and often impossible) 100% inspections. They also devised an acceptable quality
standard. Like all standards, this proved to be a ceiling to improvement.
Things essentially stayed that way until the 1950s. Manufacturing was booming, and better and better sampling techniques were being devised. Progress was
being made!
Meanwhile, in Japan, the ideas of W. Edwards Deming and Joseph M. Juran
were coming to the fore. These two men, along with Genichi Taguchi, were to a
large extent responsible for the quality revolution.
The 1960s saw the gradual involvement of several departments and management personnel in the quality control process. The concept of zero defects, which
centered around achieving productivity through worker involvement, emerged during this time. For critical products – for example, missiles and rockets used in the
space program by the NASA – this concept proved to be very successful.
In the 1980s, US advertising companies placed quality control in the limelight.
Consumers were bombarded with ads relating to product quality, and frequent
comparisons were made with those of the competitor.
Within the industry itself, an awareness of the importance of quality was beginning to evolve at all levels. Top management adopted training programs in
statistical quality control methods for all levels of workers.
As computer use exploded during the 1980s, an abundance of quality control
software programs came on the market. The notion of a total quality system increased the emphasis on vendor quality control, product design assurance, product
quality audit, and other related areas.
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5.
Next Up
Ideas of various quality “gurus.”
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