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How to Use FMEA to Reduce the Size of Your Quality - QS Consult

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How to Use FMEA to Reduce
the Size of Your Quality Toolbox
H
Method allows
adaptation
to quality and
environmental
systems.
THERE’S A LOT OF TRUTH IN THE SAYING, “IF THE
only tool you have is a hammer, it’s amazing how everything looks like a nail.” But
there is another side to this—you can end up with a whole lot of tools. This may not
be a problem for the quality specialist, but it can become a major burden for the people
in operations. They tend to have other, more pressing things to do than study new techniques all the time.
Recently there has been much interest in environmental management systems (EMS) and in
the link between EMS and quality management systems. The integration of both systems, very
often in conjunction with safety, into one general management care system is becoming
increasingly popular. As each area develops its own specific tools, quality professionals run the
risk of ending up with more tools than we can
handle. So why not look for a method that
Figure 1. FMEA Flow
allows the same techniques to be used for
similar problems?
The potential for FMEA:
An analysis of quality risks
Effect
Severity: 1-10
Causes
Occurrence: 1-10
вћЁ
Controls
Detection: 1-10
вћЁ
Expanding process FMEA
to evaluate environmental risks
Failure mode
вћЁ
Developed in the aerospace industry and
rapidly adopted by the automotive industry,
failure mode effects analysis (FMEA) has
proven to be a useful and powerful tool in
assessing potential failures and preventing
them from occurring. As very clearly
explained in the FMEA manual of the QS9000 standard,1 design FMEA for studying
potential failures in new or changed designs
can be differentiated from process FMEA for
assessing potential failures in new or changed
processes.
FMEA is a group-oriented, structured, and
stepwise approach to quantifying the effects of
possible failures, thus allowing a company to
set priorities for action. Figure 1 shows the
process in a schematic way, and the information in the figure is explained in more detail in
the QS-9000 manual.2
вћЁ
by
Willy W.
Vandenbrande
OW BIG SHOULD YOUR TOOLBOX BE?
RPN П­ Severity П«
Occurrence П« Detection
1-1,000
When introducing a new process, the classical process FMEA can easily be adapted to a
study of the potential environmental risks. By
/
Quality Progress November 1998
97
Figure 2. Scoring Guidelines for Severity
Severity of Impact
Ranking
Will hardly be noticeable. Very low to negligible impact on the environment.
1-2
Noncompliance with company policy. Low to very low impact on the environment.
3-4
Noncompliance with legal and regulatory requirements and possible damage to
the reputation of the company. Moderate damage to the environment.
5-6
The health of people living in the surrounding area could be threatened. Serious
damage to the reputation of the company. Serious damage to the environment.
7-8
Endangers the lives of people living in the surrounding area. The further existence
of the company is endangered. Very serious damage to the environment.
9-10
using a new table for scoring severity, the environmental priority number can be calculated in the same way as the risk priority
number. The scoring table (Figure 2) is specifically designed to
assess the severity of the environmental impact related to a failure mode/cause combination. Occurrence and detection are
scored in exactly the same way as in the FMEA process.
Note that we are looking for potential failures that can
have an effect on the environment, regardless of product quality. If a process FMEA is performed, this environmental extra
could be included. Figure 3 gives a simple example of the
method.
One step further: Risk analysis in EMS
The ISO 14001 standard on EMS states in section 4.3.1,
Environmental Aspects:
The organization shall establish and maintain (a) procedure(s) to identify the environmental aspects of its activities, products or services that it can control and over which
it can be expected to have an influence, in order to determine those which have or can have significant impacts on
the environment. The organization shall ensure that the
aspects related to these significant impacts are considered
in setting its environmental objectives. The organization
shall keep this information up-to-date.3
Figure 4, based on Marilyn R. Block’s
Implementing ISO 14001, 4 gives a few
examples to illustrate the difference between
aspect and impact. The ISO 14004 standard
indicates there are positive and negative
environmental impacts.5 Evaluating the negative environmental impacts means performing an analysis of the environmental risks
related to an activity, a process, or a product.
Evaluating the environmental impact of
activities is interesting, but being able to prioritize actions to reduce negative impacts is
even more important. This appears to be a
problem that can be tackled with an FMEAtype approach.
Potential negative environmental impacts analysis
In potential negative environmental impacts analysis
(PNEIA), the first step is to evaluate the various environmental aspects and impacts of a complete plant. SADACI NV in
Gent, Belgium, is a producer of ferroalloys and related products such as ferromanganese, ferromolybdenum, and molybdenum oxides. The plant was willing to test the PNEIA technique on one of its processes. The technique is illustrated
using the following example. Note that the scores in the figures are for illustration purposes only and have no relation to
the real situation.
The severity of the impact of these aspects is scored using the
severity table shown in Figure 2. Once all impacts have been
determined and scored, an evaluation of individual processes
can begin. In this example, two aspects, the generation of
molybdenum oxide dust and the generation of sulfur dioxide
gas, are observed. The PNEIA study for these aspects and one
related impact on the hammer mill used to break molybdenum
oxide after roasting are examined. Figure 5 shows a portion of
this study and illustrates the method. All further references to
column numbers relate to this figure.
We start off by filling in the header of the PNEIA form. In
column one, the specific element at which we are looking is
Figure 3. Process FMEA—Environmental Risks
Process/activity/product: Gear cutting
* EPN П­ Environmental Priority No.
98
/
Quality Progress November 1998
Hose damaged
by lift truck
5
Noticed by driver
and operator
2
60
Special
protection
Production
12/97
OK
6 2 2 24
Degraded hose
material
3
Preventive
maintenance
check
(2 monthly)
4
72
New hose
material and
preventive
replacement
every 2 years
Maintenance
12/97
OK
6 1 4 24
Fitting comes
loose
4
Preventive
maintenance
check
(2 monthly)
4
96
Better fittings; Maintenance
check of fittings (12/97) and
weekly in operator production
maintenance
(immediately)
OK
6 2 2 24
Action(s)
taken
Severity
6
Recommended Responsiblity
action(s)
and due date
Occurrence
Detection
*EPN
Present
detection
systems
*EPN
Water pollution
by cooling fluid
Results
Cause of
failure mode
Detection
Hose broken
or loose
Environmental
effect of
the failure
Occurrence
Cooling of
cutting tool
Failure
mode
Severity
Subprocess/
function
FMEA No.1
Page 1 of 1
Prepared by: PM
FMEA date 11/15/97 (Rev.) 1
Responsible: Production Manager
Critical Date: 01/01/98
Team: Production
mentioned. In columns two and three, all
Figure 4. Examples of Environmental Aspects and Impacts (Based on ISO 14001)
aspects and impacts determined for the
plant are listed to make sure no possible
Process
Product
Service
aspect is overlooked. In column four, the
Example
Manufacture
of
acrylonitrile
Styrofoam
Lawn maintenance
severity score for each impact is given. If
monomer
coffee cup
a certain aspect or impact is not present
Aspect
Ammonium sulfate
Not degradable
Application of herbicides
for the element studied, a horizontal line
waste produce.
or recyclable
and pesticides
is drawn through all following columns.
In column five, we note the various
Impact
Possible contamination of
Landfill: loss of
Pollution of the lawn
circumstances or external conditions that
soil or water after disposal
available land
in deep wells
can be present. Generally, the following
typical scenarios would be assessed:
• Normal operating conditions
• Abnormal operating conditions like start-up and shutdown
possibility it has of occurring. We score from 1 to 10 in column
• Emergency situations
seven, and Figure 7 gives a scoring proposal.
For the example two conditions were evaluated: normal operAlthough the aim is to prevent problems from happening,
ation and high-temperature operation related to nonoptimal
detecting a situation quickly and reacting to it can reduce the
functioning of the roasting furnace. This last condition is preconsequences. For every situation described in the previous
sent during about 10% of total operating time. When detected,
paragraph, the detection systems that are present must be
action is taken. But roasting is a slow process, and it takes some
determined. These are then listed in column eight. Don’t fortime before normal operating conditions are restored.
get that different situations can have different detection levels. During start-up there may be more personnel around,
A look at contribution
making the chances of detection and action higher. Note that
detecting a condition even without being able to do someAt this point in the analysis we deviate from FMEA by
thing about it gives a high score for detection. Once again, we
introducing a new factor—the contribution. The aim is to estiscore from 1 to 10 in column nine, following the guidelines
mate to what extent the element contributes to the overall
in Figure 8.
impact. In other words, if only this element were in operation,
For each impact and all possible conditions, an environment
would this influence the severity score for the environmental
priority number (EPN) under severity, contribution, occurrence,
impact? In the worst-case scenario, the element would have the
and detection can be calculated (see column 10). The resulting
same impact as the overall plant. Contribution is scored
figures can be used as such but could also be combined, for
between 0.1 and 1.0 according to the guidelines in Figure 6. In
instance to evaluate the overall impact of a specific condition
this way, the plant severity score is reduced to a severity score
and to compare the impact of various elements.
for the function.
Based on EPN, corrective action plans can be developed and
In addition to scoring contribution, the likelihood that the
the EPN can be reevaluated after introduction of the corrective
external condition will occur is now scored. This score is related
action. This is documented in columns 11, 12, and 13. In the
to the amount of time that the condition itself is present or the
Figure 5. PNEIA Form: Environmental FMEA
Generation of
sulfur dioxide
gas
Soil
contamination
Bad smell
7
Condition/
situation
6
Normal
operation
0.5
10
Elevated
temperature
1
8
Normal
operation
0.1
10
Elevated
temperature
1
8
3
8
Present detection/
intervention
systems
Regular furnace
temperature check
by the operators
Regular furnace
temperature check
by the operators
9
10
11
12
13
Results
10
300
7
336
10
30
7
168
Recommended
action(s)
Responsibility
and due date
Action(s)
taken
Severity
6
*EPN
Hammer mill Generation of
molybdenum
oxide dust
5
Detection
Subprocess/ Environmental Environmental
function
aspect
impact
4
Occurrence
3
Controls
2
Severity
1
PNEIA No.1
Page 1 of 1
Prepared by: WV
PNEIA date 10/13/97 (Rev.) 1
Responsible: WV
Critical Date: 11/15/97
Team: Sadaci
Occurrence
Detection
*EPN
Process/activity/product: Roasting
* EPN П­ Environmental Priority No.
/
Quality Progress November 1998
99
simple example shown in Figure 5, the following conclusions could be drawn:
• The generation of dust is a serious problem, even in normal operation.
• The elevated temperature condition has a
very negative influence on environmental
impact.
These conclusions can lead to appropriate
action to lower EPN values, such as looking
for methods to avoid or reduce the elevated
temperature condition.
Figure 6. Scoring Guidelines for Contribution
Contribution to Impact
Ranking
Remote. The contribution to the impact is hardly noticeable.
0.1-0.2
Low. There is a slight contribution to the overall impact.
0.3-0.4
Moderate. The element has a reasonable contribution to the total impact.
0.5-0.6
High. The impact of the element on the environment is almost
as high as the total impact of the plant.
0.7-0.8
Very high. The impact of the element is as high as that of the plant.
0.9-1.0
PNEIA can be updated
A PNEIA document is a living document
that can be updated when changes are introduced in a system. It is also a good source of
information for future developments on similar systems.
By slightly adapting the FMEA method
and the scoring guidelines, the tool can be
expanded to environmental risk analysis. In
this way a factory uses the same principles
for handling various problems without reducing the quality of the analysis.
It is a simple method to quantify the
potential risks and find out objectively what
the most critical environmental aspects and
impacts of various processes are. It can help
readers of this article prioritize actions to be
taken to reduce the negative environmental
impacts of their companies.
Figure 7. Scoring Guidelines for Occurrence of Condition
Occurrence of Condition
Remote. Highly unlikely condition
will ever occur
Estimated Chance
less than
1 in 1,000,000
Ranking
1-2
Low. The condition occurs in isolated
cases, but chances are low.
1 in 20,000 to
1 in 2,000
3-4
Moderate. The condition has a reasonable
chance to occur (could be startup
and shutdown).
1 in 80 to
1 in 2,000
5-6
High. The condition occurs very regularly
and/or during a reasonable amount of time.
1 in 8 to 1 in 80
7-8
Very high. The condition will inevitably occur
during long periods (typical for normal
operating conditions).
П® 1 in 2
9-10
Acknowledgment
The author thanks SADACI NV for its cooperation during the writing of this article.
Figure 8. Scoring Guidelines for Detection
Detection of Aspect
The current controls will almost certainly immediately detect the aspect,
and reaction can be instantaneous.
References
1. Potential Failure Mode and Effects Analysis
(FMEA) Reference Manual, second edition
Chances are high that the aspect will be detected shortly after occurrence,
(Chrysler Corporation, Ford Motor Company,
and a quick reaction is possible.
General Motors Company, 1995).
2. Ibid.
There is a moderate chance the aspect will be detected in a reasonable
3. International Standard, ISO 14001,
time frame, and/or it will take some time to react.
Environmental Management Systems—
It is unlikely the aspect will be detected, or it will take a fairly long time
Specification with Guidance for Use (Geneva,
before action can be taken and results are seen.
Switzerland: International Organization for
The aspect will not be detected in any reasonable time frame, or there
Standardization, 1996).
is no reaction possible (normal operating conditions).
4. Marilyn R. Block, Implementing ISO 14001
(Milwaukee, WI: ASQ Quality Press, 1997).
5. International Standard, ISO 14004,
Environmental Management Systems—General
Guidelines on Principles, Systems and Supporting Techniques
(Geneva, Switzerland: International Organization for Standardization,
What did you think about this article?
1996).
Quality Progress needs your
Excellent
feedback. On the postage-paid
Willy W. Vandenbrande is a consultant in quality management and
reader service card inserted
Good
president of Quality Solutions Consult, Brugge, Belgium. He earned a
toward the back of this magamaster’s degree in total quality management from the University of
Fair
zine, please circle the number
Limburg in Belgium. He is a member of the American Society for
that corresponds with your
Poor
Quality.
opinion of the preceding article.
100
/
Quality Progress November 1998
Ranking
1-2
3-4
5-6
7-8
9-10
Circle #373
Circle #374
Circle #375
Circle #376
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