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THE ROLE AND MEANING OF EFFECTIVE USE
OF EQUIPMENT IN THE ENTERPRISES FROM THE MINING
SECTOR
Kinga STECUŁA, Silesian University of Technology 1
Jarosław BRODNY, Silesian University of Technology 2
Abstract:
The article presents issues concerning the effective use of equipment
in the production enterprise. It discusses the concept of Total Productive Maintenance
(TPM), which is a complex approach to the maintenance process, with its basics and the
benefits resulting from its use. Using this strategy improves the efficiency in the use
of devices and their durability by reducing failures, wastes, downtime, accidents,
disruptions, errors and damages. In this process it is also very important to increase
awareness and responsibility of employees who operate these devices. Next, the article
presents a method of calculating the OEE indicator which is the base of quantitative
evaluation of the TPM strategy. Based on data from the production enterprise from the
mining sector, values of the OEE indicator for the tested machine and for the production
line consisting of four machines have been calculated.
1. Introduction
The changing market environment, rapidly growing competition, technological
progress and the increasing demands and needs of customers mean that both
manufacturing and service companies must take care of constant development, improve
effectiveness of use, implement innovation and look for ways to build competitive
advantage. With regard to the production companies a very important role is played by the
appropriate organization of the production process and maintenance of equipment
at a high level of production efficiency. The rational use of equipment, their reliability and
effectiveness are very important. In practice, it sometimes happens that the companies do
not exploit the full potential of equipment in the areas of their availability, performance and
quality of products, which causes the reduction in their revenues.
Therefore, issues related to effective use of any type of equipment, especially
the machines, should be analyzed in detail in every enterprise. Also in the mining industry,
which is confronted with many social and economic problems, issues related
to the effective use of technical equipment should undergo more detailed analysis.
The article discusses the role and meaning of the effective management
of maintenance in the mining enterprise and presents the examples of using the OEE
1 MSc Eng. Kinga Stecuła, PhD student
Silesian University of Technology, Faculty of Organisation and Management
Zabrze 41-800, Roosevelta 26-28 street, Poland, e-mail: kinga.stecula@polsl.pl
2 PhD Eng. with ‘habilitation’ Jarosław Brodny, Associate Professor
Silesian University of Technology, Faculty of Organisation and Management
Zabrze 41-800, Roosevelta 26-28 street, Poland, e-mail: jaroslaw.brodny@polsl.pl
indicator to calculate the effectiveness of use of a single production machine
and of a four-machine system.
2. Total Productive Maintenance
The Total Productive Maintenance (TPM) is a method of maintenance management in
the production enterprises, assuming a comprehensive approach and based
on organizational and management techniques. The main aim of this strategy is to provide
and increase the availability and reliability of machines in all stages of the production
process [6].
The TPM concept is primarily focused on maintaining a high level of machine parks,
but it also refers to the human resources. TPM involves all the employees
of the company in the maintenance of equipment in failure-free and faultless conditions
and in the maintenance of continuity of production. This is done mainly
by eliminating losses and deficiencies [5].
The purpose of the TPM strategy is prevention, understood as taking action
in maintenance in order to avoid possible failures and defects, and inseparably associated
with losses [7]. It is assumed that the concept of TPM must be taken
by all employees who while performing entrusted actions aim to eliminate unintended
events and achieve what are called "three zeros" [4]:
• zero accidents
• zero damage and failure
• zero downtime.
The mentioned zero values are more theoretical; however, they are very important
points of reference in the pursuit of continuous improvement. Assumed exploitation actions
in TPM should be mainly aimed at preventing unintended events.
Striving for the ideal state, assuming zero distortion and zero errors,
the employees learn how to identify and eliminate losses. Effectively implementing the
concept of TPM avoids the 16 types of losses that may occur in manufacturing processes
(Figure 1).
TPM assumes taking preventive actions due to the fact that only regularly maintained
and serviced machines can be optimally used. In order to provide more effective
prevention of failures and downtime, maintenance standards should be applied and the
wearing parts should be replaced on a regular basis. The high quality of the machine
translates into increased quality of the product which is aimed at meeting the needs and
expectations of customers. Maintaining the quality must become a task of every employee
who is obliged to know the machine well and be responsible for the products [3].
One of very important factors affecting TPM in the organization is teamwork which
actively involves all employees. It should change the previous division of labor on people
or departments engaging in the production, repairing or retooling of the machines.
According to the basics of TPM every employee should be and feel responsible for the
maintenance of the machinery in the best possible condition [2].
It can be assumed that the benefits of implementing TPM concept refer to two aspects:
human and machine. The effectiveness of the entire production process increases due to
teamwork, jointly made decisions and a great sense of responsibility for work and
operating machines.
Figure 1. 16 types of losses.
Source: Bryke M., Jak skutecznie zbudować i wdrożyć kulturę TPM?, „Inżynieria & Utrzymanie Ruchu
Zakładów Przemysłowych” 2011, number 9 (77).
3. OEE indicator
The basic measure that is used to quantify the TPM strategy is OEE (Overall
Equipment Effectiveness), comprising three factors: availability (A), performance (P)
and quality (Q) [1].
The availability is defined as the ratio of operating (actual) time, which is the real work
time of the machine (tr), to the theoretical time (tt) at which the machine is dispositional:
t
r
t
t
A
The performance is described as the product of total production (p) and the theoretical
(ideal) cycle time (tc) divided by operating (actual) work time of the machine (tr):
r
c
ttp
P*
The quality is defined as the ratio of acceptable (good) units (pa) to the total production
units (p):
16 types of losses
8 availability losses
5 productivity losses
3 production losses
Failures
Shutdown
Minor
stoppages
Start-up losses
Tool change
Set up and
adjusting
Defects and
rework
Speed losses
Management
losses
Operating
motion
Line
organization
Logistics
Energy losses
Tool losses
Yield losses
Measurement
and set up
p
p
Qa
After calculation of these factors it is possible to determine the value of OEE indicator
which is a product of them:
QPAOEE **
The value of OEE indicator should be regularly determined to compare its changes
during time. This allows current monitoring of its value and helps with making appropriate
decisions in improving each of the analyzed factors.
4. Calculating the OEE indicator in the enterprise from the mining sector
The company X wanting to improve the effectiveness of machine work decided
to make the quality of the products better. Table 1 presents OEE data which has been
collected in eight following days of work. At the beginning, the company produced 1600
pieces of the product X, of which 160 were defective. Then, the company started to pay
more attention to their quality in order to reduce the number of defective products. On the
eighth day of quality improvements implementation, the number of unacceptable products
already amounted to 122, so it decreased by more than 23%. According to this, the quality
rate, which was at first 90%, increased to 92,13%. However, the increase in product
quality resulted in an extension of unplanned interruptions like settings, regulations and
other downtime and losses of time, longer observation of products by employees, and
decline in the pace of work. All these elements resulted in a decrease in actual machine
work time, which caused the gradual decline in the availability rate from 92,05%
to 86,36%. Both, the real machine work time and the number of produced products were
declining over time but the ratio of these two values was increasing over time, so the value
of the performance rate was gradually increasing.
During eight days an increase in the quality rate and the performance rate has been
observed. During that time the availability rate has decreased. All the three rates and the
OEE value in eight following days are shown in Figure 2.
It can be concluded that the value of OEE has decreased from 76,36% on the first day
to 75,73% on the last day, despite the improvement in quality and performance in the
enterprise. The example shows that efficiency must be approached comprehensively,
improving all of its areas, because focusing only on its individual components
is an inconsistency.
The value of OEE can also calculated for the set of machines, processes, positions,
lines or production cells. Then, all the data on each of the three components
of the indicator must be collected for each machine separately. Next, availability,
performance and quality must be calculated for each of the machines. Then, the arithmetic
average value of each factor must be calculated separately. The last stage is to multiply
factors. The effect of it is obtaining the average value of OEE for a few selected machines,
positions or processes.
Table 1. Overall Equipment Effectiveness in the enterprise X.
day
1
2
3
4
5
6
7
8
A
Planned work time of the
machine [minutes]
440
440
440
440
440
440
440
440
b
B
Unplanned break (failures,
settings, e.t.c.) [minutes]
35
37
38
44
49
52
55
60
C
C
Real machine work time
[minutes]
405
403
402
396
391
388
385
380
D
D
Availability [%]
92,05
91,59
91,36
90,00
88,86
88,18
87,50
86,36
E
E
Total production [units]
1 600
1 594
1 589
1 580
1 570
1 561
1 554
1 550
F
F
Theoretical cycle time
[seconds]
14
14
14
14
14
14
14
14
G
G
Operating (real) time
[seconds]
15
15
15
15
15
15
15
15
H
H
Performance [%]
92,18
92,29
92,23
93,10
93,69
93,87
94,18
95,18
I
I
Unacceptable units [units]
160
154
150
144
136
129
126
122
J
J
Acceptable (good) units
[units]
1 440
1 440
1 439
1 436
1 434
1 432
1 428
1 428
K
K
Quality [%]
90,00
90,34
90,56
90,89
91,34
91,74
91,89
92,13
L
L
Overall Equipment
Effectiveness [%]
76,36
76,36
76,31
76,15
76,05
75,94
75,73
75,73
Source: own study.
Figure 2. The change of the value of OEE indicator and of its components during the research.
Source: own study.
Table 2 shows the calculated values for the four machines in the enterprises
of the mining industry. Based on this example it can be concluded that the overall
effectiveness of the use of these machines, for which the average availability is 93,89%,
the performance – 91,54% and the quality - 98,32%, achieves a level of 84,51%.
Table 2. Calculating the OEE indicator for the four machines: M1, M2, M3, M4.
machine
M1
M2
M3
M4
OEE for the
system
Availability [%]
93,18
90,48
97,73
94,19
93,89
Performance [%]
91,46
94,74
97,67
82,30
91,54
Quality [%]
97,33
99,13
98,33
98,50
98,32
Overall Equipment
Effectiveness [%]
82,95
84,96
93,86
76,36
84,51
Source: own study.
5. Conclusions
The aim of the implementation the Total Productive Maintenance strategy
is a comprehensive improvement of maintenance in the enterprise and an increase
in the effectiveness of equipment. Correct implementation and using the basics of TPM
strategy are necessary to achieve the expected results. Removing failures, reducing the
duration of setup and adjustment result in increased availability. Moreover, it is extremely
important to eliminate deficiencies, losses, damages, downtime and errors, minimize the
duration of unplanned interruptions, prevent accidents and react rapidly when they take
place. In terms of quality, improvement efforts should be made to reduce the number
of defective goods produced, because in addition to the elimination of waste costs are
reduced.
The proposed measure of effectiveness is the Overall Equipment Effectiveness
indicator, which is the product of three rates: performance, availability and quality.
The increase in the values of all three components of OEE is crucial, because
it guarantees increased enterprise effectiveness. Properly used, the TPM concept
translates into achieving measurable material and immaterial benefits by the company and
may be used as a tool to gain a competitive advantage that is particularly important
in the mining sector.
Bibliography:
[1] Brown M., Managing Maintenance Planning & Scheduling, Wiley Publishing Inc.,
Hoboken, 2004.
[2] Bryke M., Efektywność warunkiem przetrwania Kaizen, czyli skuteczne metody
zwiększania produktywności, „Zarządzanie Jakością”, 2005, number 1.
[3] Bryke M., Jak skutecznie zbudować i wdrożyć kulturę TPM?, „Inżynieria
& Utrzymanie Ruchu Zakładów Przemysłowych”, 2011, number 9 (77).
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eksploatacją i utrzymaniem ruchu systemów technicznych, Oficyna Wydawnicza
Polskiego Towarzystwa Zarządzania Produkcją, Opole, 2012.
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do zarządzania, ZETOM, Warszawa, 2006.
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Zakładów Przemysłowych” 2015, number 3 (108).
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Press, Portland, 1988.