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AN IMPLEMENTATION OF INFRARED THERMOGRAPHY IN
MAINTENANCE PLANS WITHIN A WORLD CLASS
MANUFACTURING STRATEGY
by
Petar M. TODOROVI]a*, Dušan R. GORDI]a, Milun J. BABI]a,
Branislav M. JEREMI]a, Micaela DEMICHELAb, Ivan D. MA^UI]a
aFaculty of Engineering, University of Kragujevac, Kragujevac, Serbia
bDipartmento Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Torino, Italy
Original scientific paper
DOI: 10.2298/TSCI120111044T
The objective of the paper is to show the implementation of infrared thermography
within world class manufacturing maintenance strategy. The results from infrared
thermography inspections in a food processing and packaging solutions company
were presented. Applicability of the infrared thermography, during a two-year pe-
riod, caused a substantial reduction of the potential breakdown in the pilot area.
Upon feasibility confirmation, the proposed method was spread to other production
equipment of the company.
Key words: infrared thermography, condition monitoring, maintenance, world
class manufacturing
Introduction
The global maintenance strategy encompasses the process of constant change and ad-
aptation due to increasing demands, technical development, and modifications of management
strategies in companies [1, 2]. The initial approach of the problem-oriented maintenance, tar-
geted at the elimination of various problems, has recently been generally replaced by the pro-
cess-oriented maintenance strategy. Its main objective is prevention as a substitution for tradi-
tional corrective activities. The traditional, event-based breakdown maintenance is now just a
supporting element of the modern maintenance strategies. The majority of maintenance activi-
ties have been replaced by the time-based preventive maintenance (PM), and especially with a
condition-based preventive maintenance approach, also knownas condition-based maintenance
(CBM) [3, 4].
During the last few decades, more attention has been given to the maintenance of tech-
nical systems. The reasons are numerous; first of all – the health and safety of employees, then
energy consumption, environmental protection and, naturally, an increase of total profit through
optimal management of maintenance costs.
The term world class manufacturing (WCM) was first used by Hayes and Wheelwright
in 1984. Since then, the concept has been embraced, expanded, and enhanced by a number of au-
thors, who have reinforced some of Hayes and Wheelwright's ideas, adding some new practices
and ignoring others [5]. WCM is a concept of manufacturing strategy created in the United
States and successfully implemented in Japanese industry during the early eighties of the 20th
century [6]. It was created as the evolution of total productive maintenance (TPM). Its final ob-
Todorovi}, P. M., et al.: An Implementation of Infrared Thermography in ...
THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987 977
* Corresponding author; e-mail: petar@kg.ac.rs
jective is a production system that operates based on just-in-time (JIT) production and total
quality management (TQM) principles [7]. WCM brings about changes to the management
strategy, especially at an operational level, which is considered to be crucial for a company. This
concept provides a system of continuous improvement through the application of systematic
and practical methodologies based on facts and calculations by transparent and visual means. It
includes all employees: from workers at a production level, up to top management [8].
All segments of factory performance are improved through the WCM concept. Im-
provement of human resources is realized through changes in way of thinking regarding equip-
ment and quality management and through constant training and education in order to upgrade
the general and specific knowledge level of every employee as much as possible [7]. Equipment
performances improvement is achieved through increasing of its efficiency resulted from imple-
mentation of advanced and intensive maintenance and early equipment management activities.
It means that there are no rejections at the beginning of the production, maintaining the highest
quality – “the first time is good”. By changing the “working culture”, in relation to employees'
attitude to work, the improvement of efficiency of the whole factory can be achieved. The key
point is to develop a flexible organization that constantly aspires towards increased knowledge
and improvements, whereby, using not only engineers and managers, but all of its available
manpower [9].
The fact that some authors [10] took a step further by defining a new phrase – world
class maintenance, speaks in favour of the importance of maintenance. At the core of world class
maintenance there is a new partnership among manufacturing or production people, mainte-
nance engineering, and technical services in order to improve overall equipment effectiveness
(OEE). It is a program of zero breakdowns and zero defects aimed at improving or eliminating
losses.
Preventive maintenance
Maintenance represents one of the most important pillars for a company that operates
within the WCM strategy. Generally, the PM program is applied for equipment which directly
affects workplace safety, continuous flow production, and energy efficiency. PM is a mainte-
nance policy in which selected physical parameters associated with an operating machine are
measured and recorded, intermittently or continuously, for the purpose of analyzing, comparing
and displaying data and information obtained to support decisions, related to the operation and
maintenance of the machine [11]. It can be disaggregated into two specific sub-categories:
– statistical-based PM (the information generated from all breakdowns facilitates
development of statistical models for predicting failure and thus enables the development of
a preventive maintenance policy), and
– condition-based PM, i. e. condition-based maintenance (CBM) (CBM is the application of
various technologies and methods in order to determine the current condition of machinery).
CBM is a maintenance program that recommends maintenance actions based on the
information collected through condition monitoring. CBM attempts to avoid unnecessary main-
tenance tasks by taking maintenance actions only when there is evidence of abnormal behav-
iours. If properly established and effectively implemented, a CBM program can significantly re-
duce the maintenance cost by reducing the number of
unnecessary scheduled PM activities. As shown in fig.
1, a CBM program consists of three key steps [12]:
– data acquisition step (information collecting), to
obtain data relevant to system health,
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978 THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987
Figure 1. Three steps in a CBM program
– data processing step (information handling), to handle and analyze data or signals collected
in step 1, for better understanding and interpretation of data, and
– maintenance decision making step, to recommend efficient maintenance policies.
The main goal of CBM is to discover and prevent potential breakdowns. This is ac-
complished by measuring diagnostic parameters and then, based on certain criteria, a conclusion
is made on whether they are within allowed limits or not.
The most prevalent methods of condition monitoring are those based on [11, 13]:
– measuring and analysis of vibrations,
– monitoring of thermal condition (IR thermography), and
– oil and wear particle analysis.
As a precondition for good implementation of CBM within the WCM concept, it is
necessary to have equipment for machine condition diagnostics, such as instruments for the
measurement of vibration levels, infrared (IR) thermography cameras and instruments for oil
and wear particle analysis. Using these instruments for continuous monitoring, continual evalu-
ation of the causes of production equipment breakdowns can be done.
Introduction to IR thermography and its applications
Any object at a temperature above absolute zero (–273 °C) emits electromagnetic radi-
ation in the form of rays which fall into the IR portion of the electromagnetic spectrum (from 1 to
1000 µm). IR thermography is a non-contact, non-intrusive technique, which enables us to see
thermal energy. The energy emitted by a body is mainly a function of its surface temperature, so
IR thermography may be considered as a two-dimensional technique of temperature measure-
ment [14].
IR thermography basically includes a camera, equipped with a series of changeable
optics, and a computer. The core of the camera is the infrared detector, which absorbs the IR en-
ergy emitted by the object and converts it into electrical voltage or current. Any object emits en-
ergy proportional to its surface temperature. In fact, IR thermography converts the energy radi-
ated from objects in the IR band of the electromagnetic spectrum into a visible image, where
each energy level may be represented by a colour, or a grey level.
The IR thermography, as a non-contact temperature measurement method, is widely
used for: the measurement of the heat loss of buildings [15, 16], calculation of potential heat
generated waste in production processes [17, 18], detection of defects, cracks, splits or other dis-
turbances in a material [19], visualisation of heat developed in friction surfaces [20, 21], inspec-
tion of energetic installations [22], the determination of thermal stress of machines [23], etc.IR
thermography is also used in medicine, insurance companies, product quality inspection, etc.
As a diagnostic method for condition monitoring of industrial equipment, the IR
thermography gains more significance within the PM strategy. Additionally, development of
portable IR cameras, available to a large number of users, has influenced the fact that the IR
thermography inspection becomes (together with the vibrodiagnostic method) the main activity
for the diagnostics of technical systems within a CBM. Using this method, the whole range of
potential breakdowns of a technical system could be detected without the need to interrupt the
production process. Therefore, the maintenance personnel can plan their work by knowing in
advance their priorities, thus, minimizing the need for troubleshooting, allowing them to orga-
nize the appropriate manpower, get the necessary materials and shorten the repair time.
IR thermography investigation results and discussion
This study examines the implementation of the IR thermography inspection within the
WCM strategy in a Serbian food processing and packaging solutions company. The company is
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THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987 979
part of a large multinational enterprise which generally adopts the same approach to business
policy within all of its facilities in the world.
The IR thermography testing methodology has mostly been determined by the WCM
strategy which is implemented in a company. According to the recommendations by the WCM
strategy, a specific equipment or part of the production zone (declared as the "pilot area") is usu-
ally chosen, at which point it is estimated that the application of a new method (in this case, IR
thermography in maintenance plans) could provide the most appropriate information on the ef-
fectiveness and benefits of the proposed method. The effectiveness of the proposed method in
the pilot area is assessed through a set of key performance indicators (KPI). After the feasibility
confirmation in the pilot area, the application of the proposed method gradually spreads to other
equipment and other parts of the production zone.
The IR thermography investigation in the company was realized during a two-year pe-
riod. The company engaged an external service for the IR thermography investigations. During
the 1st year, the so called “pilot project” of the IR thermography investigations was launched in
the facility for PVC-paper packaging production – the pilot area. The objective of the investiga-
tion was to define the present condition of a group of different technical systems. The obtained
information was the basis for further investigations and the main reference to determine whether
specific changes or problems occur as well as to give suggestions to readjustment of critical
points.
The measurements were realized with two types of IR cameras:
– the Infrared Solutions IK 21 IR camera based on a scanner sensor with 120 × 120 pixels
resolution; with noise-equivalent temperature difference (NEDT) <0.4 °C at 30 °C; a
spectral range 8 to 14 µm; temperature range 0 to 350 °C; accuracy 2 °C or 2% of full scale;
and operating temperature range 0 to 40 °C, and
– the Flir ThermaCAM P640 IR camera based on a focal plane array (FPA) uncooled
micro-bolometer sensor with 640 × 480 pixels resolution; with NEDT <0.06 °C at 30 °C;
spectral range 7.5 to 13 µm; temperature range –40 to 500 °C in two ranges (optional up to
2000 °C); accuracy ±2 °C or ±2% of reading; operating temperature range –15 to 50 °C.
For the analysis and quantification of differences in the thermography images, the fol-
lowing software applications were used: Snap View 2.1 (fig. 2) and ThermaCam Researcher.
The mechanical and electrical components suitable for non-contact, IR temperature
measurements were included in this diagnostic and monitoring program. In most cases, electri-
cal and electronic equipment was selected: transformers, switchgear, industrial fuses,
contactors, DC motors, etc. All measurements
were performed under full-load and real operat-
ing conditions. The inspected equipment (70
measurement points) is shown in tab. 1.
The interpretation of the observed tempera-
ture differences DT[°C] from the anticipated val-
ues can be followed in the general guidelines pre-
sented in tab. 2 [24]. The previous experience,
optimal load and component characteristics
should also be taken into consideration while de-
fining tolerability criteria. However, these rules
should be used with caution, and before making a
final decision one should take into account other
factors such as safety, criticality, and reliability.
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980 THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987
Figure 2. Software for the analysis of IR
thermography images (IK 21 IR camera)
Table 1. Equipment covered within IR thermography investigation
No. of subset Machine No. of measurement points
1 Coating machine 21
2 Cooling station 8
3 Main power station 10
4 Compensation station 8
5 Printing machine 16
6 Shrinking tunnel 4
7 Transformers 3
TOTAL 70
Table 2. Guidelines for the observed temperature differences (DT) from the
anticipated values
DT [°C] The description of condition and recommended activities
1-10 NORMAL: There is a small possibility of physical damage. It is recom-
mended to fix the problem during the next regular maintenance.
10-30
WARNING: There is a small possibility that there may be damage to
nearby components. It is recommended to fix the problem in the near fu-
ture; check load breakdown and adjust them accordingly; inspect for
possible physical damage; check neighbouring components for physical
damage.
>30
DANGER: Danger exists – needs immediate repair, if possible; replace
the inspected component; carefully inspect all neighbouring compo-
nents; perform a follow-up IR inspection after the repairs to ensure that
no damage has been overlooked.
After a one year period, the investigations were repeated on the same samples. The ob-
tained results from both measurements are shown in tab. 3. The results of the measurements
gave answers concerning the need to introduce the IR thermography inspections into already ex-
isting maintenance plans. Furthermore, these inspections introduced new maintenance plans for
other technical systems and equipment in the company. The IR thermography shows huge po-
tential as a method which is applicable to a wide range of production equipment, installations,
buildings, processes, etc.
Table 3. IR thermography investigation results
Year Normal Warning Danger No. of measured points
1st year 43 17 10 70
2nd year 62 7 1 70
In order to show what the levels of measured temperatures were, the printing machine
subset will be explained in more detail. The printing machine lay-out is presented in fig. 3 with
measuring points (T-thermography) and belonging temperatures (tab. 4). There are 16 measur-
ing points identified: 6 measurement points at the DC motors and 10 measurement points at the
electro cabinets.
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982 THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987
Figure 3. The layout of printing machine with the measuring points' positions (T1-T16)
Table 4. Temperatures on electro equipment of the printing machine
Printing machine
Measurement point 1st year 2nd year
T[°C] Mark T[°C] Mark
T1 61.1 Normal 52.5 Normal
T2 53.2 Normal 52.5 Normal
T3 69.1 Warning 61.0 Normal
T4 58.6 Normal 58.7 Normal
T5 68.1 Warning 62.3 Normal
T6 52.5 Normal 52.8 Normal
T7 61.5 Normal 72.6 Warning
T8 65.2 Normal 76.5 Warning
T9 62.4 Normal 59.5 Normal
T10 61.8 Normal 57.8 Normal
T11 67.6 Warning 64.0 Normal
T12 120.4 Danger 62.3 Normal
T13 63.2 Warning 62.0 Normal
T14 41.3 Normal 40.7 Normal
T15 45.8 Normal 48.2 Normal
T16 53.6 Normal 52.8 Normal
The factors which can affect accuracy of the measurement results, shown in tab. 4,
could be identified as: the selection of the emissivity coefficient, environment, technical specifi-
cations of the used camera, and the human factor. As already mentioned, the energy actually de-
tected by the detector in the IR camera depends on the emissivity of the surface under measure-
ment. The environment can affect the measuring result either through energy added as reflected
by the surface of the surroundings, or through a portion of energy absorbed by the atmosphere
between the camera and the object. The accuracy of the used IR camera is ±2 °C or ±2 % of the
reading. Reducing the influence of the human factor on accuracy of measurement results can be
minimized through theoretical and practical education of the involved personnel.
Previous analysis indicates that there are numerous factors that affect the accuracy of
the measurement results shown in tab. 4. The temperature of some individual components and
parts could be verified by the available and applicable contact measurement methods in order to
provide verification of results from the IR thermography. In most cases the price of the observed
component, is significantly lower than the cost of damage that may arise in the event of its fail-
ure. This implies that sometimes it is better to replace a suspicious element, with detected in-
creased temperature (or take some other action to restore its condition) than to go into an
in-depth analysis of the causes of its current state, represented by the increased temperature.
After the 1st year of inspection, a relatively large number of measurement points were
marked as “danger”. For these points, urgent correction activities were specified for the elimina-
tion of the causes of the high temperature (poor contacts on the tested electric equipment were
the cause). The necessary changes of components or reconstruction were realized, and the total
condition during the second inspection was considerably more favourable.
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The measurement points marked as “warn-
ing” need to be analyzed in more detail and
monitored at a later period. For the majority of
measurement points which had been marked as
"warning" during the 1st year inspection, it was
determined that the temperature increase did
not occur within the observed zones during the
2nd year inspection. Therefore, for the 2nd year
measurement they were marked with “normal”
(as an example: points T11 and T13 in tab. 4).
The comparative presentation of the ob-
tained results of IR thermography investiga-
tions from the 1st and 2nd year are given in fig. 4. It can be concluded that after the two-year pe-
riod, the condition was significantly better in comparison to the beginning of testing, due to the
activities that followed the first inspection. The number of dangerous points was reduced from
10, at the beginning, to only 1, which represents a 90% improvement.
Some representative IR thermography pictures are shown in figs. 5-7. A DC motor
with corresponding IR thermography pictures (measurement point T3 from fig. 3 and tab. 4) are
presented in fig. 5. In the 1st year, a small motor used for the cooling of a larger DC motor was
indicated as the hot point of the system, so the whole system was marked with a “warning” label
(fig. 5b). The Measurement in the 2nd year (fig. 5.c) shows that the temperature did not increase,
in comparison to the measurement from the 1st year, so this point is now labelled as “normal”.
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984 THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987
Figure 4. The structure of results on the
measured points
Figure 5. DC motor
(a) motor position on printing machine,
(b) IR picture from the 1st year,
(c) IR picture from the 2nd year
(for color image see journal web site)
Figure 6, shows an IR thermography picture of six industrial electric fuses, captured in
the 1st year of investigation. It can be seen that the electric fuse on the left is much warmer than
the others, which means that there has been a poor contact or damage to the fuse which was a dis-
tinctive threat to the functioning of the technical system. At this point, emergency activities
were carried out to resolve the causes of the increased temperature, and thus avoiding sudden
breakdowns as well as material and financial damage.
In the 2nd year of investigation the same electric fuses were captured and one measure-
ment marked as “danger” is shown in fig. 7(a). As can be seen, two fuses had a normal tempera-
ture, but there was found to be a new possible failure on the contact of the third electric fuse,
which was replaced immediately. The maximum temperature on the fuse was about 352.3 ºC
which is significantly over the allowable limits.
Figure 7(b) shows the IR thermography pictures of an electro cabinet with the temper-
ature of all components below 45 ºC.
After successful implementation of the IR thermography inspections in the pilot area,
where relevant results had been obtained and a significant improvement in the implemented
CBM method had been realized, the factory management decided to spread IR thermography in-
spection to all other areas where it is possible to achieve savings in energy, improve safety, im-
prove effectiveness, and reduce costs in general. The IR thermography inspection within WCM
can be a very powerful tool against failures and in the monitoring of machine conditions, but
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THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987 985
Figure 6. The detected high temperature on
the IR picture of electric fuse as the possible
cause of breakdown
(for color image see journal web site)
proper training of the maintenance worker should be given. Additionally, the company is
equipped with a special area for training in order to minimize the human factors which can affect
accuracy of the IR thermography measurement results.
Conclusions
Based on the analysis of IR thermography inspection in order to determine the potential
breakdowns of production equipment, presented in the paper, one can conclude the following.
·Modern industrial environment strives for zero breakdown of production equipment which
imposes the implementation of contemporary maintenance strategies, predominantly those
based on CBM.
·The IR thermography inspection is the one of the most prevalent condition monitoring
methods. During the equipment inspection, production equipment functions in real
operation regimes and there is no need to interrupt the production process, which eliminates
related costs.
·For the presented investigations, in a two-year period, the number of potential failure causes
was lowered by 90% and the maintenance time and costs were decreased.
·Company policies consider all points with a "danger" label as a successfully prevented
breakdown, and cost calculation is performed with the assumption that breakdowns at the
points have occurred. Unfortunately, the cost reduction data are not available because the
company considers it to be confidential information.
·The company is spreading the IR thermography to other areas where it is possible to achieve
savings in energy, such as heating, ventilation, air-conditioning installations, and building
inspections.
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Paper submitted: January 11, 2012
Paper revised: March 15, 2013
Paper accepted: April 15, 2013
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THERMAL SCIENCE: Year 2013, Vol. 17, No. 4, pp. 977-987 987
