Improvement of a Manufacturing Process

The case study of Corticeira Amorim (Equipar)

Francisco Delgado

Department of Engineering and Management, Instituto Superior Técnico

Abstract
Corticeira Amorim, company where this study is conducted, is the world leader in this sector and
gives a continuous focus to the improvement of its processes and products. Consistent with this
strategy, this study aims to improve the manufacturing process of one Corticeira Amorim’s
products, the agglomerated corks produced in the factory of Coruche (Equipar). To achieve the
proposed objective, the application of Theory of Constraints was identified as appropriate. This
theory argues that improving a manufacturing process is possible by identifying the constraint
and improving it.
In this work one cycle of the Theory of Constraints is performed. The Mechanical Finishes
production stage was identified as the constraint and several improvements have been
proposed to solve it, which were promptly implemented at the shop floor. The resolution of this
constraint was achieved, meaning an increase of 27% in the capacity of the manufacturing
process. This value results in a potential annual gain of approximately 1.5 million euros.

Keywords: improvement, manufacturing process, theory of constraints

world leader in the cork industry. Also

1. Introduction
noteworthy is the great investment this
Portugal is actually the world leader in the
organization does on innovation and
production and distribution of cork. In terms
development, especially for improving their
of production holds 49.6% of the global
processes and products.
share, which corresponds to an annual
production of 100,000 tons in cork products.
This paper will focus on the manufacturing
It is also the largest exporter, exporting
process of agglomerate cork stoppers, at
annually the equivalent of about EUR
the factory located in Coruche (known as
845,370,000, which corresponds to 64.7%
Equipar). This process will be analyzed in
of world exports. In an increasingly
detail using a methodology proposed based
competitive environment and with the
on the Theory of Constraints.
higher level of service demanded by
customers, only companies able to diversify
2. Theory of Constraints
its portfolio of activities and provide efficient
2.1 The Context
and low-cost processes are the ones which
Theory of Constraints (TOC) is a
can survive. Within this context this study is
management philosophy created and
done in collaboration with the company
developed by Goldratt (Goldratt et al., 1984;
Corticeira Amorim. This company is the
Goldratt et al., 1986; Goldratt, 1994, 1997).

1
The TOC concept concentrates on how to This step guarantees that TOC can be
manage the constraint of the system, the considered as a continuous improvement
bottleneck resource or capacity constraint philosophy.
resource (Goldratt et al., 1984).
In the beginning it was not well received in Pretorius (2014) suggests some in-between
the academic world. But several academic decision points in addition to the five
studies proved the great impact this theory focusing steps. There are two main points
could achieve once implemented. Amongst which worth mentioning. The first point is
those studies, the ones made by Aggarwal located after the second step and it is
(1985), Johnson (1986) e Koziol (1988) important to decide whether it is possible to
were determinant for the acceptance of subordinate the system to the decisions
TOC in the academic world as well as for made in the previous step. The second
the business companies. point is located after the completion of the
third step, where the author suggests that
2.2 The five TOC focusing steps before proceeding to the fourth step one
For implementing TOC successfully five should examine whether the
steps were suggested by Goldratt et al. implementation of the previous steps (2 and
(2005). 3) allowed the removal of the constraint. If
this has happened is not necessary to
Step1: identify the system’s constraint. develop the fourth step. But if the constraint
In this step, the constraint is identified. The identified still remains then the fourth step
constraint is the activity in the system should be studied.
whose capacity is less than the demand
placed on it. This is a key step, because 2.3 Comparison between TOC and other
since the constraint determines the system continuous improvement philosophies
performance, the maximum performance Several studies illustrate that the
can only be achieved by knowing where the application of this theory leads to better or
constraint is (Pretorius, 2014). at least the same outcome when comparing
it to the application of others continuous
Step2: exploit the system’s constraint. improvement technics like lean or just-in-
In this step the utilization of the constraint is time (Cook, 1994; Holt, 1999). Also
exploited by maximizing the efficiency of Pirasteh et al. (2006) did a comparison
the constraint activity. Chou et al. (2012) where the application of lean and six-sigma
state that this step can be implemented by was made to a first group of factories and to
eliminating all waste or non-productive time another group of factories it was applied
activities at the constraint. lean, six-sigma and TOC. The results after
this application were really significant,
Step 3: subordinate all other factors to showing that the last group had a much
decisions made in step 2. better performance.
The non-constraint activities should be
synchronized with the constraint in order 2.4 Applications of TOC in the industry
not to produce excess inventory. In this way Pegels et al. (2005) state that TOC is
the production in non-constraints is widely used in the industry, mainly because
determined by the capacity of the constraint of its potential in identifying problems and
and not by their own potential. optimize them, achieving process
improvements in terms of productivity and
Step 4: elevate system’s constraint. efficiency.
Once further system improvement is not
possible with exploiting and subordination, Draman et al. (1998) studied a successful
the next possible step would be the implementation of TOC to an industry
increase in capacity of the constraint whose primary products were custom-
activity to eliminate it as a constraint. This formulated paints. This study is relevant
means that additional equipment should be because it shows how the change in the
acquired in the necessary quantity to working philosophy can have a great deal
eliminate the constraint identified in the first of impact optimizing a manufacturing
step. process. As results of implementing TOC to
the industry, the plant started producing
Step 5: if the constraint has been broken, batches in 8 to 36 hours while it used to
go back to step 1 to prevent inertia to take six to ten days.
become the next constraint.

2
In another study done by Umble et al. dashed line. Extrusion is the stage where
(2006) the application of the Theory of the agglomerate body of technical stoppers
Constraints in a Japanese tool is produced from a mixture of granules and
manufacturing company was made. To chemicals with binding, plasticizing and
improve the system the five focusing steps lubricant properties through mechanical
were applied and some significant compression. Then Mechanical Finishes
achievements were obtained. Setup times (MF) is where by abrasive polishing the
had been reduced throughout the plant, cork stoppers achieve their final
improving the product flow through the dimensions. In the Washing stage,
system. Overall productivity had an bleaching agents and disinfectants are
increase of 20%. WIP inventory and lead used to treat the cork stoppers. Finally, with
times had both been reduced by 50%. the Sorting stage it is possible to ensure
visual quality standards that were agreed
3. Case-study with customer. Already out of the limits of
This work was developed in a factory of this study the final stages of production take
Corticeira Amorim (Equipar), the world place, which depends on the type of client
leader in selling cork stoppers. In this and can be either Packing or Marking.
factory, located in Coruche, agglomerated
cork stoppers for still, sparkling and cider To finish the description of the case study it
wine are produced. This factory is able to is important to remark that there are mainly
produce on average 1.5 millions of cork two types of cork stoppers produced in this
stoppers each day. The main objective of factory. The main difference between both
the study was the improvement of this groups is the size. The smallest cork
manufacturing process and if possible to stoppers belong to the group AGLO, used
increase its capacity. As studied in the mainly in table wines. The biggest ones
literature review this could be possible by belong to the group ESP, which are mainly
applying TOC to the process. The to sparkling or cider wines. The machines in
application of TOC in this factory was done each stage for producing each group need
to part of this factory where some stages of to be different or at least need to be
the process occur. The manufacturing equipped with different equipment.
process in study is divided in the following
steps as illustrated in Figure 1. 4. TOC Application
To improve the agglomerate cork stoppers
production the five focusing steps of TOC
Grinding
were implemented using the methodology
illustrated in Figure 2. This methodology
results from the five focusing steps in
Mechanical addition to the two in-between points
Extrusion
Finishes proposed by Pretorius (2014). This
methodology was followed and the study
began by examining point 1: identifying the
Washing Sorting constraint.

At this point it is important to note that the

main purpose of applying the Theory of
Packaging/ Constraints was to increase the productive
Printing capacity by improving this manufacturing
process.
Figure 1 – Manufacturing process of cork
stoppers 4.1 Identify the system’s constraint
In the first step of TOC application the
The first step of the process is Grinding, constraint should be identified. In order to
where the granulate which will be part of do so, the capacities of the different steps
the cork stoppers is formed. Afterwards the were measured and calculated.
four stages under study occur. These
stages, under study, are bounded by a

3
 Figure 2 – Methodology proposed based on TOC to improve a manufacturing process

First, some measurements were made to stage with less capacity may not represent the
determine the processing times for each step. constraint of the process. This analysis was
Equation (1) was used to validate the amount performed and the efficiency of each stage is
of measurements taken: illustrated in Table 1.
2
 Z s 
n   (1) Table 1 – Efficiencies of manufacturing stages
 Ax 

In this equation n is the number of

observations required given the error A, Z is
the confidence interval considered, s After performing these three steps of the
represents the estimated standard deviation proposed methodology, the values
and x is the average time of measurements representing the productive capacity of the
already done. After making these measures various stages of the process shown in Table 2
and validate them, it was possible to calculate were obtained.
the daily capacity of each processing activity.
Table 2 – Capacities of different steps
According to the procedure illustrated in Figure
2, following the calculation of the capacities the
supplying systems should be analyzed. This
analysis is important to know if these systems
are a hindrance to the proper running of the
different stages. This analysis showed that for
all stages, except MF, its supplying system In this table the activity with less capacity is
was adjusted. The supplying of MF is done highlighted. It is possible to conclude that the
through a conveyor belt, which was not constraint for both types of cork stoppers was
adjusted to the maximum capacity of this the stage Mechanical Finishes. It is also
stage. The study done to this conveyor belt possible to conclude that, due to its constraint,
pointed that it restricted MF to 75% of its the process capacity was of 1.5 million cork
available capacity. stoppers per day.

Thereafter the third point of the first step (1. After this, the last point of the first step of the
Identify) of the methodology proposed was methodology in use was studied. At this point
examined. At this point the efficiencies of the the objective is to confirm the previous findings
various stages of the process were studied. with the observation of reality. For this an
The relevance of this study is because, due to experience took place for over four days, by
the efficiencies of the respective stages, the setting the production in this factory to the

4
maximum possible. During this experiment the
main purpose was to count the intermediate
inventory between different stages. By doing
this counting it was expected to find out in
which of the stages the inventory was
accumulated in higher proportions. This stage
would be the constraint of the process.

Figure 3 illustrates the accumulation of

Figure 5 – Number of batches between Washing
inventory between Extrusion and MF and as and Sorting
can be observed an average of about 9
batches per day were accumulated. In conclusion of this experiment, it can be
observed that the stage where inventory is
accumulated in higher proportions is MF. This
result confirmed the previously calculations
showing that MF was the constraint.

It is important at this point to describe the

current situation of MF, since it represents the
constraint. The actual scenario is illustrated in
Figure 6. It is made up of three different types
Figure 3 – Number of batches between Extrusion of milling machines. The first type of machines
and MF (M1), represented in the first line of Figure 6, is
where the stoppers achieve the final diameter.
Figure 4 represents the accumulation of Then in the second type, represented as M2 in
inventory between MF and Washing. As can Figure 6, the stoppers achieve its final length.
be seen the trend line demonstrates that the Finally the third type of machine (M3) make a
inventory was decreasing. However it should chamfer in the cork stoppers.
be noted that during day 2 one of the Washing
machines broke down and so this why in this 4.2 Exploit the system’s constraint
day there is a tipping point. To exploit the constraint the three areas shown
in Figure 2 will be explored and if possible
improved.

4.2.1 Improve Supplying System

The supplying of MF is done through seven
deposits (six with automatic activation and one
manual), which supply the cork stoppers to the
first type of machines in MF, the fourteen M1’s.
Between the deposits and the M1’s a single
conveyor belt does the connection. This means
Figure 4 – Number of batches between MF and that in each supply a single deposit can be
Washing
supplying the cork stoppers and only one M1
can be receiving them.
Finally the accumulation of inventory between
Washing and Sorting is shown in Figure 5 and
An analysis done to the supplying of MF
as can be observed there was an accumulation
indicated that it limits this stage to 75% of its
of about 6 batches per day.
full capacity. Knowing this fact it was extremely
important to study this process and if possible
suggest options to improve it.

AGLO ESP
14 13 12 11 10 9 8 7 6 5 4 3 2 1
M1:
M2:
M3:
Figure 6 – Actual scenario in MF

5
The option of increasing the quantity of cork production lines are allocated to group ESP
stoppers in each supply was the one studied. A and the last six are allocated to group AGLO.
single calculation was done to know what was
the variation needed in order to adjust the The purpose of this analysis was to know the
supplying system to the full capacity of MF. By best allocation for this process. The best
defining an objective equal to the capacity of allocation would be the one where the
MF, it was possible to find that in order to capacities were the most equally distributed
improve this process a variation of 33% for according to their necessities. To do so several
each deposit was needed. Knowing this, the simulations were performed by imposing some
study was then divided in the two types of restrictions and by defining the objective as the
deposits. equation (2):

Through observation of the deposit activated Cap ESP  Nec ESP

manually, it was possible to conclude that the Objectiv  min (2)
conveyor belt of this deposit was too slow and  Cap AGLO  Nec AGLO
few cork stoppers were supplied at each time.
By consulting the Maintenance department of By performing this calculation it was possible
this factory, the replacement of this belt’s to achieve a configuration that respecting
engine was the best option. After the industrial some restrictions presented better results than
director’s approval this engine was the current situation. In this new scenario an
implemented. To know the success or failure of improvement of approximately 81% was
this application a supply through this deposit achieved, in terms of a more even distribution.
was done and analyzed. As a result it showed In the current allocation the difference
a better performance of 103%, which calculated by equation 1 between the two
compared to the 33% needed, indicated the groups was 307,674 stoppers. With the new
success. scenario this difference is only 58,926
stoppers. This new scenario is presented in
Following this, the study of the six remaining Figure 7 and it will be implemented in this
deposits was carried out. Again, in factory in the near future.
collaboration with the maintenance
department, it was concluded that there were 4.2.3 Efficiency
two options for increasing the number of corks The efficiency of this activity was measured
supplied per second. The first would be to and 70% efficiency was the outcome. Having
have a larger tray and the second to extend efficiency lower than 100% the study of several
the hole of these deposits. This second option activities performed in Mechanical Finishes
could only be implemented after the first. If not was judged as important.
part of the stoppers would fall onto the floor.
These two improvements were performed and 4.2.3.1 Workers organization
several tests were done. As results of these After having observed the distribution of work
tests, improvements between 90% and 130% and have talked with the workers, the
were achieved for the six deposits. Again identification of potential improvements in
comparing these values with the 33% needed terms of human resources was made.
the success of this implementation was
observed. The need to implement improvements was due
to the fact that the workers did not have well
4.2.2 Machines allocation allotted tasks and were not allocated to specific
At this point it is important to remember that areas, which increased the response time
this stage is divided in two main groups, which against possible problems, such as the
are the groups of cork stoppers produced in machines being jammed for long periods of
this Equipar. The actual organization can be time.
seen in Figure 6, where the first eight

AGLO ESP AGLO ESP

14 13 12 11 10 9 8 7 6 5 4 3 2 1
M1:
M2:
M3:
Figure 7 – Proposed scenario for MF

6
Knowing this, the following procedure was that on average it takes about 5 minutes per
proposed and implemented. It is important to batch.
state that in MF there are three workers.
As MF can be producing eleven batches, in the
 Worker 1: beginning of each shift the identification of all
Firstly the role of the first worker was analyzed. batches would consume about 55 minutes to a
The M1’s are the machines with the lowest single worker. Since this is a secondary task,
production capacity and because of that the this time is too high and represented an
ones who need special attention. Therefore it inefficiency because it did not allow the worker
was decided that the main role of the first to perform its priority tasks. Identified this
worker is to monitor the line with M1’s. As a situation it was suggested that whenever a
secondary function he or she can help monitor batch started being produced its identification
the second line, constituted by the M2’s. So sheet should be filled. This was a usual
the priority area of this first worker is the first procedure during the shift but with this
line in Figure 6 and Figure 7 and the suggestion the same should be done in the
secondary one is the second line in the same end of the shift. So between shifts all batches
figures. are properly identified. With this suggestion the
workers during their shift do not need never to
 Worker 2: devote more than 5 consecutive minutes to this
The second worker shall be responsible for task, which differs from the previous situation
overseeing the remaining machines. Its area of in which they could spend 55 minutes
operation is the line of M2’s and the one with dedicated to it. Having examined this point with
M3’s in Figure 6 and Figure 7. the industrial director, it was decided to
implement this suggestion.
 Specialized Worker:
Finally the last worker, the specialized one,  Second problem:
remains responsible for the functions already The second problem is caused by workers,
assigned to him, like changing machines, who at the end of each shift stopped the
change abrasives and clean wheels. In machines. This was done after the registration
addition he has to do all other functions which of the amount of stoppers produced on each
in the current situation are executed by all machine. If this was not done, the machines
workers, such as moving the empty/full continued to produce stoppers that would only
baskets, make the necessary records and be counted as produced in the next shift. This
cleaning the area. His area of operation due to point was considered as an inefficiency,
the duties performed would have to be the because the machines were able to work and
whole area of MF. deliver product, but they were not producing. It
was observed that between shifts the
With this new work method, it is possible to machines remained without producing for on
organize the work being done in MF. By average 10 minutes. If we account 200
assigning specific tasks to each worker it stoppers produced per minute and per
would be possible to increase the efficiency in machine, and knowing that MF can be
this stage, mainly because the two workers producing eleven batches at each time this
responsible for overseeing the machines do leads to a value of 22,000 stoppers which are
not have any tasks allotted besides the not produced. As in each day there are three
overseeing of machines. With that it would be shifts, this represents a daily loss of about
possible to reduce the stopping times of the 66,000 cork stoppers. To overcome this
machines caused by a jam. situation the following was suggested: at the
end of each shift the workers should record the
4.2.3.2 Problems between Shifts amount of stoppers produced without stopping
Another inefficiency found is related with the machines. This was only possible to be
problems between working shifts. There were implemented after careful discussion with the
mainly two problems. workers, in which the benefits have been
demonstrated.
 First Problem:
The first problem is that the workers did not 4.2.3.3 Changing Machines
identify the last production batches. So when a Another inefficiency found in this stage was
shift began its work, some batches were not related to machines changing. These changes
properly identified. To know the impact of this often happen in MF and occur whenever a
problem, the time needed to fill the identifying production line needs to start producing a
sheets of batches was measured and found different type of cork stopper than the one
which is currently being produced. This change
is made by the specialized worker, who needs
7
to change all the machines that will produce because the machines are jammed. For this
the new cork stoppers. There are two types of purpose it was decided to gather data that
changes which are going to be discussed next. would allow performing the calculation of this
investment payback.
 First Type:
The first type of change happens when the The data gathered for this purpose was the
new stoppers to be produced belong to the number of daily jams in the machines, the
same group as the stoppers being produced. percentage of these jams that affect the
This type of change has a daily frequency. productivity and each machine average
Several observations were made and studied productivity. The earned time, meaning the
to know the best way to perform these time that could be reduced by this device in
changes. It was noted that to optimize this terms of identification of unexpected stops, is
process it should be avoided a regular the variable that the payback will depend on.
situation, the displacement of the worker who This is because it is not possible to know what
is making the change. These displacements the earned time would be. So the calculation of
often occur because workers either forget to the payback considering some values for the
take all the necessary tools or because they earned time was done and is represented in
cannot take them all at once. During this Figure 8.
displacement the machine remains stopped,
and this is the reason why this is an
inefficiency. To assist workers and improve
their performance, acquiring a tools car, such
as already exists in other areas of the factory
was suggested. The study of the payback of
this investment had as result a value of 0.59
years. Realizing the advantages of purchasing
this tools car and its profitability the decision to
make the investment was done. The Figure 8 – Payback of the device proposed for
some values of earned time
investment was then performed and the new
car is currently being used.
This study was shown to the industrial director,
who, by analyzing the values of the payback
 Second Type:
achieved, considered it an important
The second type of changes occurs when the
acquisition. But given the amount of
new type of stoppers to be produced belong to
investment required, this equipment was not
a different group than the type of stoppers
readily acquired but will be a priority for future
currently being produced. This type of change
investments.
occurs every three months and takes about 8
hours, which corresponds to a shift, to be
4.3 First PI
carried out. This type of change is more
Having completed the second step of the
complex than the one studied before. The
Theory of Constraints, in which one attempts to
study of work was developed and several
solve the constraint, the first intermediate point
inefficiencies were found. To overcome these
should be analyzed (see methodology shown
problems and after meeting with the industrial
in Figure 2). At this point the decisions
director it was suggested the implementation of
suggested in this cycle should be verified to
some boxes which contain all the material
know if they have an impact on other stages,
needed to perform these changes. The
and if so these stages should be adapted so
advantage these boxes bring to this process, is
that the process can be uniform. After a careful
that workers do not need to search for the
analysis it is possible to conclude that the
material and the material is ready to be used.
decisions made in section 4.2 only have a
With the implementation of these boxes the
direct impact on MF and therefore it is not
time needed to perform this change was
necessary to develop the third step of the
reduced for 2 hours, which represents an
Theory of Constraints.
improvement of 75%.
4.4 Second PI
4.2.3.4 Auxiliary equipment
As identified in the methodology shown in
Finally, the fourth point concerning the
Figure 2, at this point the results from the
increase of efficiency is related to the
previous steps must be verified.
investment in auxiliary equipment. The
equipment considered to have a great impact
Starting from the initial situation represented in
on efficiency was a device that would include
Table 2, in which the orange color represents
sensors and lights to warn whenever the
the capacity of the constraint. This is the stage
machines stop producing. This happens mainly
8
of the process with less capacity in terms of In conclusion, it should be noted that by
stoppers produced per day. changing the system constraint to another
stage, it is also observed that the process
Following this analysis Table 3 represents the overall capacity increases. In the first table,
results after solving the first aspect identified Table 2, where the initial situation is
as a limitation of the identified restriction. This represented, the capacity of the process was
aspect was the improvement of the supplying limited by MF and thus was 1,526,667
system (section 4.2.1). In this study it was stoppers. On the other hand in the last table,
possible to conclude that the supplying was Table 5, the capacity is limited by Extrusion,
now adjusted to MF capacity, so the resolution meaning a new capacity of 1,938,745
of this problem allowed an increase in the stoppers. Then it can be concluded that the
capacity of 366,680 stoppers for ESP group implementation of the Theory of Constraints is
and 359,251 for AGLO group. Adding these effective in improving manufacturing
values to the capacity of the MF shown in processes, resulting in an increase of capacity
Table 2, the values in Table 3 are achieved. As of 412,078 cork stoppers. This variation means
results it can be observed that for the stoppers an increase in capacity of 27%. Thereby
belonging to type ESP, MF remains the reflecting the increased capacity registered in
constraint, however Extrusion becomes the economic terms a final calculation was
new constraint for the group AGLO. performed. By doing the multiplication of the
capacity variation, the number of working days
Table 3 – Situation after improvement of and the average price per stopper, it is
Supplying System possible to obtain as results a potential
increasing sales of about 1,545,293 euros in a
year.

4.5: if the constraint has been broken, go

back to step 1 to prevent inertia to become
the next constraint.
Then it is important to analyze the results Theory of Constraints is a continuous
(Table 4) after the implementation of a better improvement philosophy and therefore the
allocation of machines (section 4.2.2). This methodology in Figure 2 is represented as a
new allocation causes the MF to no longer be cycle. Thus after elimination of the identified
the constraint to both groups of cork stoppers. constraint one must return to the first step of
The new constraint of the whole process is this methodology. It is important to note that in
now the Extrusion stage. The restriction a system there will always be a constraint. By
identified in the first step is now eliminated. returning to the starting point it is ensured the
identification of the new restriction and its
Table 4 – Situation after implementing a better improvement are performed.
machines allocation
Before ending this cycle it was decided to do a
final analysis to know what the limit of
efficiency that MF could have was. These
values are especially important for those in
charge of this factory, in order to make an
effective process control. The calculations
In addition and after the implementation of the were made and the values are represented in
suggestions made in section 4.2.3, it is still Table 6. These values were calculated for both
expected to increase the efficiency of MF by groups of stoppers: ESP group has an
5%. Thus, increasing the average efficiency of efficiency limit of 64%, while for AGLO group
70% to 75% it is possible to get new values for the efficiency should not be less than 58%.
the capacities of this stage, which are shown in
Table 5. This table illustrates that MF is now Table 6 – Limit values of efficiency for MF
better protected against possible and Efficiency
unexpected inefficiencies. ESP 64%
Table 5 – Situation after efficiency improvement AGLO 58%

5. Conclusion
To conclude this paper it should be pointed out
that the objective initially proposed to improve
the process and the consequent increase of its
capacity has been reached. To accomplish

9
this, the methodology shown in Figure 21 that Industrial Engineering and
represents the TOC was followed. In the first Management), IST, Lisbon.
step Mechanical Finishes was identified as the Draman, R. H., & Salhus, V. (1998). Painting a
constraint of the process, a process which had Better Process. Industrial
a production capacity equal to 1,526,667 cork Management.
stoppers per day. In the second step Goldratt, E. M. (1994). It’s Not Luck (N. R.
alternatives have been suggested and Press Ed.). Great Barington, MA.
implemented to improve this stage. These Goldratt, E. M. (1997). Critical Chain (N. R.
alternatives were focused on three main Press Ed.). Great Barrington, MA.
issues: improvement of supplying system, a Goldratt, E. M., & Cox, J. (1984). The Goal (N.
better machines allocation and an R. Press Ed.). Croton-on-Hudson, NY.
improvement of efficiency. The third and fourth Goldratt, E. M., & Fox, R. F. (1986). The Race
steps due to the type of suggested alternatives (N. R. Press Ed.). Croton-on-Hudson,
and to its success were not implemented. As NY.
result, the elimination of Mechanical Finishes Goldratt, E. M., & Weiss, N. (2005). Significant
as the constraint was possible. By achieving enhancement of academic
that an increase of capacity to 1,938,745 achievement through application of the
stoppers per day was achieved, this equals a Theory of Constraints (TOC). Human
27% increase in capacity. With this result it is System Management, 24(1), 13-19.
concluded that the stated objective was Holt, J. R. (1999). Candid comparison of
successfully attained. operational management approaches.
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