Case study: FMEA

Work developed by:

With the mercy of God

Ahmed Aziz Naceur

 What is FMEA?

It is a qualitative analysis technique for the reliability of systems.

industrialists through the analysis of failure risks.

Reliability material products

Maintainability means of production

Availability manufacturing process

Security organizations.

WHEN?

This method can be implemented throughout the system's life cycle:

Design of a new product.

Evolution of an existing product.

Industrialization, manufacturing.

Exploitation and maintenance.

HOW?

It is an inductive, systematic, and predictive analysis method:

Failures of a system.

From their origins and their consequences.

And allowing:

Highlighting critical points.

The definition of appropriate corrective action.

 2. Types of FMEA

DENOMINATIONS TARGETED OBJECTIVES

PRODUCT FMEA Ensuring the reliability of a product in

improving its design.

FMEA PROCESS Ensuring the quality of a product in

improving production operations
of this one.

FMEA MEANS OF Ensure availability and security of

PRODUCTION means of production by improving the
conception, the exploitation or the
(MACHINE FMEA)
maintenance of this one.

3. Principles of FMEA

FMEA is based on:

(1) The concept of decomposing equipment into simple elements, through research.
functions of the equipment.
(2) The notion of effect observed by the end user.
(3) The concept of criticality through:

The frequency of failures.

The gravity of the consequences.

The probability of not discovering the effect.

4.Practical approach FMEA

1.1 Definition of systems
The system to analyze: Air Conditioner

4.2 Operating phase

Normal march

4.3 Definition of Objectives

Objectives to achieve

Obtain the maximum overall yield of production equipment at the best cost.
engine) by mastering the failures.

Possible fields of interventions to propose

Reduce the number of failures.

Reduce downtime after failure.

Benefits for the company

Data structuring on failure risks.

Sharing of participants' experiences and skills, leveraging existing knowledge.

In-depth knowledge of the production tool's operation, assistance in training

of the staff.

Brand image.

Better staff participation.

5. Functional Breakdown
Air conditioner
ELEMENT FUNCTION
must transmit
Evaporator
the energy to allow
a heat exchange
perfectly defined.

Change the physical state of the

The condenser refrigerant fluid in

allowing condensation
superheated steam

To aspire; compress and

The compressor recharge the refrigerant

in the gaseous state..

allows to supply
correctly the evaporator
Regulator: (the capillary)
in refrigerant fluid

6. Failure analysis of systems

PRACTICAL APPROACH:

PHASE 1 : Analysis of failure mechanisms.

Identification of failure modes.

Researching the causes.

Research of effects.

Census of detections.

PHASE 2 : Assessment of criticality.

Evaluation of scoring criteria.

Criticality assessment.

Failure classification.

6.1 Analysis of failure mechanisms: Air conditioner

ESTF - GTE FMEA

 Phase of machine : air conditioner
Operation: Sub-assemblies: compressor - filters -
normal walk fans.
Elements Function Mode of Cause Effect Detection
failure
Compressor it is a device that Compressor compressor the evaporator the BP goes
allows you to compress the too small is under produces more than increase
refrigerant fluid of (loss of sized FF vapors strongly
low pressure to high power of in relation to that him
pression. compressor) the evaporator compressor no
can aspire
broken valve or
not waterproof
the compressor
will be less good
cooled and its sound
Carter will be rather
hot.
Compressor a device The unit Triggering
starts then under outer of of compressor
stops sized air conditioner no
the klixon can no longer working
to be
damaged

Filters Purify the air and avoid a accumulation Dust alter the Visual
accumulation of of dust yield and the
dust qualities
of hygiene
the air stirred by
the air conditioner.

fan Very important role for fan of Break Effects on the Visual
the operation of a the evaporator operation
compressor and turns to from the evaporator
evaporator the reverse or not and compressor
works
more

ESTF-GTE FMEA
 air conditioner Operating phase:

Subsets: Condenser - Fluids normal walk

refrigerants
ELEMENT FUNCTION MODE OF CAUSE EFFECT DETECTION
FAILURE

the location
of the condenser
Cool down and change it Condenser is poorly chosen The condenser Visual
refrigerant fluid phase too small (a no longer ensuring
the vapor state to the liquid state reduction a good The increase
the tubes and the from HP
abnormal from the little winglets of
cooling
Condenser
power of vapors of
condenser
condenser FF.
are clogged
the consumption
electric of
the loss of compressor is
charge more important

the lack of mass flow rate

air flow on of the conveyed FF
the condenser by the
compressor
diminishes

the belt of The compressor

fan- aspirant less than
condenser FF as much as he can
skate or where
broken

the condenser
is clogged

Fluids absorb excess heat FF level Leaks The air conditioner does not

refrigerants breathe air, then blow air and base does not work
new the effects on Visual
the environment
ESTF- Page 1/3
GTE
FMEA
System: air conditioner Phase of Date of
Subsystem: evaporator functioning: the analysis
pipes Normal march
Elements Function Mode of the Cause of Effect of the Detection Criticality Actions
failure the failure F G N C correctives.
defaulter
this
Evaporator Changes the statea the evaporation the fluid the gap of 1 3 2 6 MPS:
of fluid reduction -tor is is no more temperature on Control
abnormal grimy cooled the fluid
from the correct me increase
power nt
of loss of the FF is not 1 3 2 6 MPS:
the evaporate charge more Verification
ur totally
vaporized
Party flow rate lack of Visual with a 1 3 4 12 D
superior of air refrigerant fluid noise of
evaporator insufficient the evaporator
-r climb ant
frost
Pipelines limit the Leaks and Corros- The pipe Visual 1 2 1 2 MR:
losses ion crushing of the return Isolate the
Mauve does not cool down pipelines
like this not and the
installation compress
ion your cut
in
some
minutes.

ESTF- Page 2/3

GTE
FMEA
System: air conditioner Operating phase: Date of
Subsystem: condenser the analysis
Normal march

Elements Function Mode of the Cause of Effect of the Detection Criticality Actions
failure the failure correctives.
default F G N C
e

Condenser cooling and Condenser the place The Visual 1 3 5 15 MR:

change the too small lie of condenser The increase Modification
phase of (a condense not ensuring from HP in the
fluid reduction r is bad plus a good the location
refrigerant abnormal of choose cool down nt
 the state the power the tubes of the
steam at you and the vapors of
the liquid state condenser wings of FF. 1 2 5 10 MPT:
condenseu Control
are their states
soiled

the
consumption
ion
electric
you 1 3 5 15 MPT:
compressor Control the
the is more condenser
condens- important
eur is
soiled The
compressor
aspirant 1 3 4 12 MPH:
less FF Ensure the
the lack that he can air flow
of flow necessary
of air on
the
condense
eur

ESTF-GTE Page 3/3

FMEA
System: air conditioner Phase of Date of
Subsystemregulator operation: the analysis:
Normal walk
Element Function Mode of the Cause of Effect of the Detection Criticality Corrective action.
failure the failure F G N C
failure
e
 Regulator It is a Regulator regulator The the temperature of 1 3 5 15
device that too small bad fluid compressor to be cooled at Change of
allows to selection can aspire the entrance of regulator
relax the é more than the evaporator
fluid vapors that increase
refrigerant of regulator the evaporator
high pressure sick r
at low mechanics lack of
pressure ement
FF in 1 3 5 15
the evaporator verification.
r
the BP
filter to becomes
the entrance of
regulator
sealed

anormaleme
weak point 1 3 5 15 MPT:
Verification

7.Critical elements

ELEMENT Criticality >= 12

Regulator 15

condenser 15

evaporator 12.

Crown 15

After setting a critical threshold c>=12, we have the table below. So here are the...
actions to be taken at the level of:

Management of spare parts

An important element of the maintenance policy is the choice to constitute or

not a stock of parts, tools and products to cope with breakdowns and to carry out the
preventive maintenance. Whether it's to be able to intervene quickly in after-sales service
To sell or quickly repair a production machine, it is beneficial to have the parts.
to replace, under penalty that the timelines for restoration are not prohibitive. The
determination of the coins to hold, of the quantity of each of these coins depending on
failure probabilities and the required availability rate is a logistics problem of
support that will not be detailed here, but which should of course be taken into account if one wants
ensure the availability of a piece of equipment or a complex system.
Maintenance team management

Policies regarding maintenance personnel must focus on the following points:

a) the number, relating to the scale of operations.
b) the methods of selection, training, and promotion.
c) professional skills.
d) the number of controllers and control practices.
e) the salary scale and incentives.
f) security programs.
Working conditions and safety cannot be overlooked. Maintenance must be
to be concerned about possible accidents involving its staff and those caused to others by
his presence. Any work preparation will begin with the writing of instructions (work
electric, fire work, fall hazards, poisoning, contamination, explosion, etc.
will end with a definitive restoration (protections, instructions, etc.). As a
A member of the interview is part of the Health and Safety committee; it is their responsibility to study any
modification, protection to be made on the equipment to eliminate the risk of accidents.
Political management of maintenance.

Maintenance policies range from total absence to very detailed definitions.

elaborated. Often the person in charge is left to their own initiative, the instruction being that the
machines run at minimal cost. The forecast is unknown: revisions are seen
general stops because we are replacing the machine, and machines left abandoned
while they will be very solicited. In other cases, the management sets maintenance and
in agreement with her specific objectives as well as the necessary means, this for a time
determined. At the deadline, we take stock and revise the objectives. The maintenance manager
So know the line to follow and maintain the maximum freedom in decision-making.
taken at its level. A true maintenance policy or strategy must combine
means of intervention, technical, economic, financial, and human. It is based on the
profitability. It takes into account the moments. Sometimes we will seek the minimum cost during the period

of austerity, at times the maximum availability during periods of growth. Studies of

Reliability allows us to define the probabilities of failure, thus the necessary means.
management control allows verifying that maintenance is nearby
the optimum, and that choices are made based on expected gains: an expense
important may be more profitable than a lower expense if there is a gain in time or duration
of life, or availability or quality of the product.
In this policy, we must focus on forecasting random failures for the studies.
of inspection (maintenance following diagnosis), made from systematic assessments and
periodicals. The life of the material is studied over several years. These reliability studies will
to serve in determining the probabilities of failures, therefore in the consumption of parts
detached and the different charges. It is only from this data that one can elaborate
the forecasts and the maintenance budget. With a maintenance policy and a good
strategy we no longer endure the breakdown as it is planned and budget control remains a
normal control, because in the strategy, we will have to calculate the probability of breakdown occurrence
and their consequences in order not to suffer them anymore, and we will seek to make every action profitable

of maintenance. Maintenance will then need to consider the:

Long-term forecasts: related to the company's policy allowing scheduling
charges, stocks, investments in equipment.
Medium-term forecasts: the desire to maintain the company's operational potential
ensures the immobilization of equipment at times that cause the least disruption
possible the manufacturing program. Therefore, it is necessary to provide adequately and sufficiently
early the maintenance intervention schedule. This having an influence on
the scheduling of productions.
Short-term forecasts: in this case, the maintenance service will strive to reduce the
equipment downtime and the costs of its interventions. Knowing that the
cost and capital reductions are only possible if the equipment and
interventions were the subject of a preliminary study, so it is necessary to prepare the work
and to study the operating conditions, possible failures, and the conditions
execution of interventions. The technical service related to this function must provide all the
qualitative and quantitative information that may influence specific policies
of the company.