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1985, while working with IBM, General Motors, and Ford Motor Company, it
was discovered that a significant need existed in industry. The requirement was
a need for a disciplined, low cost approach to the successful installation of
new equipment. In a number of cases when new equipment, lines, and plants were
“started up” it took months or sometimes years (and in a few cases, never) for
the installed systems to reach a projected or acceptable level of performance
related to operational cost, reliability, maintainability, internal and/or
customer quality and delivery requirements. Clearly, what was needed was a
method that could be utilized to avoid these conditions, while at the same time
minimizing the additional time or cost required for the design and installation
process.
Developing a discipline and methodology
to accomplish these goals, in the late 1980s a number of projects were
successfully piloted. First, in a series of automotive plants and then
followed by a number of installations in the aluminum, steel and food
industries. Since the discipline is heavily focused utilizing statistics
and statistically-based sciences, the term was coined “Statistical Start-UpTM. To date the
methodology has been applied and utilized both inside and outside the United States on such equipment as aluminum cold mills, rice mills,
tin plating lines, coating lines, metal slitters, and various other production
lines.
Historically, companies have
tended to design and purchase equipment with a minimum of requirements, mostly
around functional testing for the expected performance
characteristics for the production process. Additionally, while some of the
required product quality characteristics might be mentioned in purchase
agreements, only acceptance testing would be conducted. Oftentimes, the
results of such a minimal design and planning process would lead to serious and
catastrophic results.
Functional testing, refers to that portion of the engineering and
installation process where the equipment is installed, “turned on,” and tested
to determine if it is operating properly as designed and specified (e.g.,
speeds, feeds, gauging, etc.).
The term acceptance
testing refers to a level of analysis beyond functional testing that speaks
to whether the machine or line is performing at a minimally acceptable level.
Basically, acceptance testing as a disciplined analysis is utilized to;
1.
Compare the product as manufactured
to the required characteristics as previously specified; and
2.
Compare the operational or
performance characteristics as observed to the conditions specified by the
contractual requirements, and/or the parameters upon which the equipment was
originally justified.
Much of the acceptance testing that’s done
relates directly to the performance of the equipment, and often has nothing to do
with the product. However, an appropriate assessment of acceptance testing
involves a number of conditions.
The first category of
conditions that are normally subjected to acceptance testing is what is
referred to as Product Quality
Characteristics. These
characteristics, which usually have been defined with
a target or nominal value with an upper and/or lower specification, describe
the attributes associated with the product. Examples of these attributes would
include thickness, length, width, I.D., O.D., coating weight, viscosity, taste,
surface quality, and color. Usually, these quality characteristics are defined
by the customer(s) for the product.
The identity of those
quality characteristics that are related to the finished product, are often referred
to as End-of-Line (EOL) quality characteristics. Quality
characteristics that the customer has indicated, or that we have identified as
being very important to form, fit, function, use, or safety
considerations are often termed critical or high risk elements as is
sometimes used in the automotive industry. Usually, most companies
installing new equipment or lines will minimally assess the critical EOL quality
characteristics as
defined by the customer(s) for the product. When we observe products/units that
fail to meet one or more specification(s), we refer to the unacceptable product
or unit as nonconforming.
The second category of conditions that are usually assessed in
acceptance testing are product defects, or non-conformities. Defects
are those product conditions by which their presence in terms of frequency,
severity, or both, render the product unacceptable, or defective. Common
examples of defects include scratches, gouges, blemishes, voids, slivers,
cracks, contaminants, dents, and blisters. Again, most companies installing new
equipment or lines will minimally assess a defined number of products or units
to assess whether these defects are present, and at what level.
The third category
of conditions that are generally assessed in acceptance testing are Equipment
Performance Requirements. This category includes the equipment performance
measures or Key Performance Indicators (KPI), which determine the
productivity and therefore, the associated cost of a production process. Luftig
& Warren International uses a comprehensive model that describes the system
in relation to Total Asset Utilization (TAU), and includes elements that
describe and quantify these performance metrics. The elements that are employed
include Availability, Efficiency, Duty Cycle, and Yield, or Recovery.
The calculations for each of these components are fairly complex, however
it should be pointed out that the Availability is broken down into a number of
sub-components, including Reliability and Maintainability. Most
professionals working in this field recognize that common measures related to
these two sub-components are respectively, Mean Time Between Failure (MTBF)
and Mean Time To Repair (MTTR). Many companies installing new equipment
will generally try to assess the condition of the newly installed equipment or
line in terms of these two conditions, as well as efficiency and duty cycle(s).
However, some companies—-surprisingly—still don’t measure all of these elements
to verify that they received what they paid for.
It’s the fourth category
that historically does not get a lot of attention in acceptance testing for new
equipment, and this relates to the analysis of Product Performance
Characteristics. This category includes criteria or requirements associated
with how the product performs in use—typically at the customer’s location or
while in the hands of the ultimate consumer. Examples of these types of
measures include such conditions as formability, mobility, line speeds,
in-process rejection rates, and stamping die wear rates; again, at the
customer’s site. Experience indicates that many companies simply haven’t tried
to include these characteristics into their acceptance tests for new equipment
for production lines. Part of the explanation for this is that it requires a
company to understand the interrelationship between their customer’s
performance requirements and their product’s quality characteristics. Companies
who haven’t partnered or had early involvement with their customers in the
design phase, or who haven’t implemented a Quality Function Deployment (QFD)
process, wouldn’t have this data base, and would, as a result, have difficulty
building it into their acceptance testing process. As early involvement efforts
and cost reduction requirements become more and more important in the future, the ability to perform this analysis will
become much more important to obtain new and retain existing business.
If acceptance testing is the
only testing that is executed, the results can be catastrophic. In other
words, there’s nothing wrong with acceptance testing, unless it’s all
the testing that is going to be done. It is equally important to
understand the limitations of acceptance testing. In other words, what
inferences can be made about the process?
Assume a new plating line
has started up and the goal was to start-up the line so that all functional
tests were satisfied, and to pass acceptance tests according to Specifications
Checklist.
(Refer to the Specifications
Checklist to review the product and equipment requirements).
Next, suppose that 10 coils
were produced and inspected during the first 80 hours of production. Imagine
that the acceptance tests yielded the results shown in Figure 1. The
results indicate that all categories have passed inspection. However, now
observe Figure 2. The figure shows the results of acceptance testing
conducted three months later. Although the figures show different
results, the line is exactly the same as it was when the acceptance testing was
conducted the first time. The fact is that all of the acceptance test results
are representative of what one would expect to see from a sample of 10 coils
and 80 hours of scheduled production. One can’t make any inferences about
future states or conditions based on the results of an acceptance test. Regardless
of how good the results are, comparing the observed single-point-in-time data
to requirements or expectations simply can’t indicate how the process will
perform after, say, 3 days, much less 3 months. What is needed at this
point is a testing process referred to as statistical qualification.
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SPECIFICATIONS CHECKLIST
- Product Quality Characteristic: Average
Thickness per Coil
Target = 0.1025
Upper Specification Limit (USL) =
0.1050
Lower Specification Limit (LSL) =
0.1000
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Category
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Requirements
Specifications
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Observed Outcomes*
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Decision/Conclusion
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Product
Quality
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0.1025+/-0.0025
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4.73 Defective
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UNACCEPTABLE
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No More Than 2
Voids per Coil
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Product
Performance
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2% Units per
Coil Maximum
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9.86% of All
Coils >2% Defective Rate
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UNACCEPTABLE
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MTBF ³ 2 Hours
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MTBF =
1.75 Hours
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UNACCEPTABLE
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*Cumulative results after
initial production period.
is
an assessment of whether future production units or equipment performance
conditions are likely to meet the internal or external customer requirements
and expectations, based on the observations gathered from an initial set of
actual conditions. A statistical qualification allows one to predict what is
going to happen, not just what has happened.
It should also be mentioned
that it is possible to conduct a short-term qualification study called a
potential study analysis. The term “potential” is used because the study is
conducted in the short term, like an acceptance test, where stability,
or statistical control has not been documented. In this case the results
can’t be used to predict into the future, but the test provides more
information than just comparing the results to the requirements. Since it can
usually be done with the same data one gets from conducting the acceptance
test, it doesn’t require much more time and effort, so it’s a good idea to use
the technique. The time limitation still exists; however, so long term
qualification tests are still required.
Most companies do not
conduct this type of test for three reasons. The first is that it may take a
bit more time and effort. If the acceptance tests are passed, sometimes company
personnel think they have nothing to worry about, and the extra effort just
isn’t required. That’s where the nasty surprises come from.
The second is that in a
number of cases, which are getting to be smaller in frequency, the company is
small and just doesn’t have staff that is knowledgeable in how to conduct the
qualification studies and finally, the third is political.
In a number of companies,
the staff responsible for installing and functionally
starting up the equipment or lines aren’t the same people who are responsible
for running production, assuring the quality of the output, or for the
reliability or maintainability of the equipment. So if, for example, the
engineering group is responsible for getting the equipment “properly”
installed, operations is responsible for production, the maintenance group is
responsible for TAU and downtime, and the quality group is responsible for
quality and customer complaints, then the engineering group might take the
position that once the line meets its functional and acceptance requirements,
it is up to all those other groups to worry about “the rest.”
Unfortunately, common sense
is no match for a vertically integrated organization with departmental metrics.
If qualification testing is done at all it is usually after engineering has
“handed off” the equipment or line to operations, and then the surprises set in
and by this time, the original start-up team is working on a new project.
Of course, the problem is
that if the qualification procedure is started after production begins,
scheduling and other customer commitments come into the picture and valuable
engineering resources are off the project. Consequently, it takes a long
time to understand and ultimately solve all the problems the line might have. Much
longer, in fact, than if the tests were conducted before full-scale
production was initiated.
Assume that a new piece of
equipment or line was being installed (Refer to Figure 3). Assume further that
all functional and acceptance testing is conducted and everything passes.
All of the test requirements, by the way, would have been specified before the
equipment or line was ordered, minimally; and hopefully before the equipment
was even designed.
Now, one of two conditions
can occur. Suppose the line or process fails one or more of the acceptance
tests. This, by definition, is also a failure on the qualification
requirements, because they’re more stringent. At this point, a Statistical
Start-Up would be initiated on the elements where a gap exists, based on the
acceptance tests. For the elements that passed the acceptance tests, in today’s
competitive environment in most industries, one would almost certainly want to
conduct a qualification analysis. For any of the elements failing the
qualification tests, these would be added to the first list, and subjected to
the Statistical Start-Up procedure. Those that passed would be standardized and
put into place using the Quality Operating System (QOS).
So, basically, at this
point, one could now have a set of product performance characteristics, product
quality characteristics, product defects, and equipment performance
requirements that failed to pass at acceptance and/ or qualification, and it
would be these conditions which would be the focus of the Statistical Start-Up.
Figure 3
OPTIONS IN THE
PROCESS OF ESTABLISHING EQUIPMENT/LINE ACCEPTANCE, QUALIFICATION, AND
OPTIMIZATION
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The statistical startup methodology
uses a large number of advanced strategies and tools in a highly disciplined,
integrated fashion. There is a text that is used to guide personnel through the
process. The major strategies and tools usually required in a standard
statistical startup are shown in Figure 4 and Figure 5 shows how the data might
appear in many industries and companies at the end of the qualification portion
of the Statistical Startup process.
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Figure 4
MAJOR STRATEGIES, PROCESSES,
AND TOOLS COMMONLY UTILIZED IN STATISTICAL START-UP PROJECTS
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Strategies
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Processes
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Tools
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Quality
Improvement Strategy
Problem-Solving
Strategy
Total Asset
Utilization Improvement Strategy
Measurement
Control and Capability Improvement Strategy
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Supplier
Quality Assurance Process
Customer
Quality Assurance Process
Quality
Function Deployment
Daily
Management Process
Policy
Deployment Process
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Statistical
Process Control (SPC) Charts
FMEAs, FMECAs
Design of
Experiments (DOE) Technology
Reliability
Root Cause and Failure Tabulation Matrices
Standardization
Systems (SOPs)
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Note that Figure 5 uses some
statistical symbols and terms. For those readers who are proficient in the quality
sciences, this should indicate that the process, for all relevant
characteristics, is in a state of control and is minimally capable. Normally,
at this point, if the qualification tests are passed and, based on the
objectives, all requirements and expectations are met; the associated variables
would be standardized, and implemented for full-scale production with
continuous improvement activities employed through Kaizen. Or one could
engage in the advanced methods component of a Statistical Start-Up and proceed
to Optimization. However, if one or more of the product or equipment
characteristics are shown to fall short of requirements or expectations in the
qualification tests, full-scale production should not be initiated.
Instead, the optimization component of the Statistical Start-Up process would
be conducted.
Optimization, which is also referred to as Statistical
Optimization, is the advanced component of the Statistical Start-Up
process. It is defined as the strategy by which product or equipment
characteristics are brought into the highest level of control and capability
available given the nature and condition of the existing process; at the
minimum cost possible. The term ‘existing’ refers to the notion that
the optimization process gets the equipment or line running at its highest
level of capability possible, given the equipment available as it has been
designed and purchased. Only the process referred to as Advanced Quality
Planning, properly executed, can guarantee, so to speak, that all of the
requirements will end up performing in a state of control and capability.
The key is that the
optimization process achieves a point where the system is performing as well
as it can, without making fundamental changes or additions to the equipment and
spending additional capital. Hence Statistical Start-Up may be
defined as a process by which advanced statistical methods are applied in a
strategic fashion to critical product performance, quality, and defect
requirements, as well as critical equipment performance requirements, in an
attempt to achieve full statistical qualification or optimization prior to the
initiation of full-scale production.
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Category
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Requirements/
Specifications
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Observed Outcomes*
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Decision/Conclusion
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Product Quality
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0.1025+/-0.0025
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99.994% In
Specification with
m = 0.1025
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ACCEPTABLE
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No More Than 2
Voids per Coil
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Product
Performance
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2% Units per
Coil Maximum
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99.997% of All
Coils <2% Defective Rate
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ACCEPTABLE
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MTBF ³ 2 Hours
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MTBF In Control
at 2.25 Hours
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ACCEPTABLE
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*Projected cumulative results
after initial production period.
The “hit rate” of success in
utilizing this strategy is on the order of 95% or more for the product and
equipment characteristics pursued, in those cases where the entire Statistical
Start-Up discipline, including the Optimization component was utilized.
Usually, the product and equipment design engineers have fundamentally done a
good job. It’s the last piece of qualification and optimization that has
historically been missing. Even where qualification or acceptance does not pass
testing, the Statistical Start-Up strategy will at least indicate where the
problem(s) is(are), and what one has to do to change
the process to modify the outcome.
For example, Figure 6
illustrates results of what might be expected after qualification and after
optimization from the same process with no additional costs invested. Clearly,
this has implications for cost savings. For example, on one project,
after using the process to achieve qualification on a number of internal characteristics,
on one single product characteristic, the effect realized in the
reduction of internal rejection rates had an annual impact to the company
translating into bottom line savings of approximately 1.6 million dollars.
Given these observations one
would think that more companies would utilize this process. However, as
was mentioned earlier, there were at least three reasons why this is not
so. Perhaps a fourth reason could also be what we might call an
inappropriate decision related to priorities.
Usually,
when talking to management teams about conducting a Statistical Start-Up, the
politically, vertically-driven folks in the room who just see this as more work
get uncomfortable. Inevitably, the question is asked, “How much more time and effort will it take?”
An appropriate response to
this question is to address the word “it”. What’s “it”? If “it” is the
goal of getting a product off the line that kind of looks like what we’re
trying to make, or to be able to make one or two units that meet spec, and then
dump the problem equipment or line on the operations folks, wash our hands and
walk away, then yes, this is going to take extra time and effort.
But if “it” means starting up
the equipment and line in a state of control and maximum level of capability
possible, then, it will always take less time to achieve
that goal during a Statistical Start-Up, than after full-scale production is
initiated—and that’s a fact. Of course, some Start-Ups require additional
calendar time, and the amount of that time is dependent on the size of the
project, but it’s like the old saying, you can pay now, or pay (big) later.
Other benefits, which are
included in the deliverables of a Statistical Start-Up, include SOPs, Reaction
Plans, Audit Requirements, FMEAs, and training guides
all, which are required to continue to operate the line or plant in a state of
control. What this means is that if the company is seeking ISO certification,
QS-9000 certification, or some other type of certification status, virtually no
additional work needs to be conducted to achieve that goal. The output
from this methodology plugs directly into this framework.
Of course, this same
methodology can be applied to existing equipment, which may be performing very
poorly and where management wants a breakthrough improvement in costs, product
quality, or equipment performance. This discipline, in fact, can turn a losing
line or plant into a profitable one. Further, it is not always necessary
to stop the production lines. Often the requirement is partial production
or a slight reduction in output for a short while.
Currently, this methodology
has been successfully applied to more than a billion dollars of equipment,
lines and plants for both domestic firms as well as firm’s abroad.
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