=Paper=
{{Paper
|id=Vol-3126/paper34
|storemode=property
|title=Possibility of implementation a real-time production planning system to reduce the environmental impact of the production line in the case of the electroplating
|pdfUrl=https://ceur-ws.org/Vol-3126/paper34.pdf
|volume=Vol-3126
|authors=Mikołaj Grotowski
}}
==Possibility of implementation a real-time production planning system to reduce the environmental impact of the production line in the case of the electroplating ==
https://ceur-ws.org/Vol-3126/paper34.pdf
Possibility of Implementation a Real-Time Production Planning
System to Reduce the Environmental Impact of the Production
Line in Tthe Case of Tthe Electroplating Line
Mikołaj Grotowski1
1
AGH University of Science and Technology, ul Antoniego Gramatyka 10, Kraków, Poland
Abstract
The industry now has to increasingly reduce its negative impact on the environment. This is
due to both the growing environmental awareness of consumers and the "European Green Deal"
policy and the preceding "Circular Economy" policy. One of the methods of reducing the
negative impact on the environment is the optimization of the production process. In the case
of electroplating lines, optimization problems of this type are included in the "Hoist Scheduling
Process" (HSP) category. Previous research on the optimization of this type of processes has
focused solely on the aspect of increasing efficiency. This work presents the problem of creating
a multi-criteria algorithm that comprehensively improves the production process, also
optimizing it in terms of its overall impact on the environment. The current proposals for
solutions to HSP class problems have been presented, which additional factors must be taken
into account in the approach consistent with the Circular Economy and with the use of which
parameters we can regulate such a process.
Keywords 1
HSP, Circular Economy, European Green Deal, RHSP
1. Introduction operations (part cleaning and rinsing), metal
coating operations, and finishing operations
(rinsing, passivation and drying).
The electroplating processes are carried out on
Bathing operations in bathtubs must not be
specific production lines. They are different for
interrupted. The duration of each of them has a set
two reasons. One is the limitations of the physico-
minimum and possibly maximum length, due to
chemical processes used during production, the
the requirements of the technological process; for
other is specific solutions for transporting
example, the thickness of the coating depends on
products inside the line.
the area to be coated, the concentration of the bath
and the amperage. When the operation time is
1.1. The specificity of the shorter than the minimum value, the coating will
electroplating line be too thin; if it exceeds the maximum length, the
parts may be damaged or the production cost may
In the electroplating plant, the products must increase because too much metal is deposited.
be bathed in special tubs (tanks) containing Some operations only have a minimum time, no
various electrolytic baths. An example of such a maximum time; which means that the product can
line is shown in Figure 1. For each product, the spend any time in the bath. Other operations have
processing (dipping) sequence is known in a strictly defined execution time, i.e. the minimum
advance and includes three steps: preparation and maximum times are the same.
ISIT 2021: II International Scientific and Practical Conference
«Intellectual Systems and Information Technologies», September
13–19, 2021, Odesa, Ukraine
EMAIL: mikolaj.grotowski@agh.edu.pl (A. 1)
ORCID: 0000-0002-0313-670X (A. 1);
©️ 2021 Copyright for this paper by its authors. Use permitted under Creative
Commons License Attribution 4.0 International (CC BY 4.0).
CEUR Workshop Proceedings (CEUR-WS.org)
indicate consecutive items of that type. Products
A1, A2 and B1 are in the process of bathing at the
initial schedule; during its duration, at the loading
station 0, the production of the products A3, B2
and C1 (marked with colors) begins.
Figure 1: An example of an electroplating line
(Manier and Bloch, 2003)
Each operation is performed in one bathtub.
The product may require the same operations to
be performed several times, so it can be placed in
the same bathtub several times. Such a bathtub is
referred to as multifunctional; the other bathtubs
are single-functional. Figure 2: Gantt diagram of a sample schedule
When the bathing time in a certain tub is much (Feng et al., 2015)
longer than in others, such a bath can be
duplicated, which means that it has more than one When the crane stops for a moment above the
available space for a product, or that there are bathtub, while the product is immersed and taken
several bathtubs in which the same operation is out of the bathtub (time to drip the products or
performed (so-called parallel baths). processing stabilize the crane), both the crane and the bathtub
of multiple products). are busy. If this time is very short, it can be
Product processing begins with loading onto a omitted or added to the time of transport or
carrier (PCB frame, basket or bolt barrel). Then, bathing operation (this is what their publications
handling and transport devices (cranes or hoists) say). If this time is too long for this, the schedule
move the carrier from the bathtub to the bathtub. of transport and bathing operations will have to
All cranes are identical. They move along one overlap.
track (above the bathtubs), so they cannot pass All transport times are known in advance. The
each other. planning procedure must take these into account
The transport operation consists of several as they are as long as the processing times. No
stages. First, the crane moves empty from its breaks in the operation of the crane are allowed
current location to the tub containing the carrier to during the transfer of the carrier, with the
be transferred. Here it grabs the carrier, lifts it exception of the dripping and stabilization stages,
above the bathtub and stops so that the electrolyte the durations of which are known. Other breaks
can drip off (to reduce contamination of may damage the products, e.g. by oxidizing the
subsequent bathtubs). It then carries the carrier to surface of the products for too long.
the next tub in the appropriate sequence for that In a simple system, there is one line and all
product. Here the crane stops again to stabilize transport operations are carried out by cranes
itself and lowers the carrier to immerse it in the traveling along one track along the line. The
new tub. After that, the crane is free and can complex system consists of several parallel lines
perform another transfer operation. During some and includes additional cranes for transverse
bathing operations the crane must remain over the transport (between the lines). The synchronization
bath to hold the product; thus, in the course of of cranes moving along and between the lines
such operations, both the tub and the crane are must be ensured.
occupied. Scheduling is generally intended to maximize
Figure 2 (Feng et al., 2015) shows an productivity, production volume per unit of time,
exemplary schedule with all types of operations: eg per hour or shift. Sometimes other optimization
product transport, empty runs, product processing criteria are taken into account, e.g. maximization
(baths); the loading / unloading station 0 and the of the degree of use of selected resources, or
tubs 1-6 are lined up in the order shown in the minimization of product completion times.
diagram, and the order of the baths is according to Scheduling may also aim at the robustness of
the numbers of the tubs. In this diagram, there are the schedule, defined as its resilience to random
three product types A, B and C. The numbers fluctuations in operation times. It enables the
schedule to be performed without any changes number. Numerous proposals for solutions to this
(under all technological conditions). Reliability variant can be found in the literature.
can be achieved through time buffers of all
operations (schedule clearances, planned machine 2. Predictive hoist scheduling problem
and product downtime), which ensure timely (PHSP) consists in setting the schedule for the
commencement of subsequent operations despite next time period, shift or day:
delays in previous operations. A robust schedule • The number and type of products to be
might possibly allow for minor timing changes made in a given period are known in advance,
(operation start times), but the sequence of but different in each subsequent period.
operations and resource allocation would remain • It is necessary to take into account the
unchanged. If the schedule is not reliable and an initial state of the system at the beginning of a
operation is delayed, it is usually necessary to given period.
change the schedule remaining to be performed.
Regardless of the optimization goal (criterion), 3. The dynamic hoist scheduling problem
it should be achieved while observing all (DHSP) is the computation of a new schedule
technological conditions of the process, namely for all operations every time a new part enters
the limitations related to the processing sequence, the line.
the minimum and maximum limits of processing • The number and type of products to be
times, the capacity of resources (tubs, cranes and made are not known in advance, new orders for
carriers) and the time during which the crane must products appear unexpectedly already during
lower the carrier into the bathtub between two the execution of the schedule.
successive transport operations. • The schedule for making earlier products
The planning of bathing and transport may be changed.
operations in electroplating plants is known in the
literature as the hoist scheduling problem (HSP). Another variant is the "Dynamic Hoist
At the same time, the schedule of the crane's sheduling problem" (DHSP). It occurs when
movements determines a certain schedule of the orders change over a short period of time, which
processing (bathing) operations. Within the so- makes it impossible to use one repeated cycle of
called The scheduling theory, this problem introducing products to the production line. Along
belongs to the group of scheduling tasks without with the change of orders, the order of placing
waiting (between operations) and without products on the line and the sequence of transport
interrupting the operation. operations should be dynamically changed. The
plan is defined at regular short intervals and
1.2. Algorithm classification adapted to current needs. In the literature, you can
find several examples of algorithms that meet the
requirements of dynamic scheduling.
Highlighting task classes in the literature
4. Reactive hoist scheduling problem
1. Cyclic hoist scheduling problem (CHSP) (RHSP) is the real-time scheduling of
consists in determining a cyclically repeated upcoming operations where the cranes must be
sequence of crane movements: dynamically assigned to subsequent transport
• The number and type of products are operations. Third level heading
known in advance and the same in each cycle.
• It is necessary to minimize the length of The last option is the " 4. Reactive hoist
the transition phase between two consecutive sheduling problem" (RHSP). In this variant,
production cycles (schedules). the schedule is created and modified on an
ongoing basis. This allows not only to
The simplest and best-described variant is the smoothly adapt to current orders, but also to
Cyclic hoist scheduling problem (CHSP). It react to random events on the production line.
occurs when we assume that the subsequent Until recently, it was not possible to create
production cycles are the same, and the last such algorithms due to the complexity of
element of the cycle is followed by the first one calculations and limitations in the capabilities
again. This allows you to plan production for of computers. It seems, however, that the
larger orders, when we know in advance what development of both computer hardware and
products we want to put on the line and in what
computational methods allows the conclusion
that algorithms RHSPs are now possible to These variables are partially dependent, for
create. The first articles about them appear, but example the reduction of the process time may be
so far no working RHSP algorithm has been due to the fact that it is carried out at a higher
published. temperature or by using a solution with a higher
concentration.
1.3. Variants of production lines These changes not only make the NP problem
difficult, like all HSP problems, but also make it
non-linear.
There are various configurations of production
lines with transport cranes. The line with one
conveyor is the easiest to describe in the 1.5. Conditions that must be met in
algorithms. (Fig 1) Most of the algorithms in the order to be able to apply the
literature it refers to such a configuration.
However, there are often other variants in actual
algorithm to reduce the impact of
lines. A very common variant is one in which the production on the environment.
line has two cranes moving on common tracks.
This means that although in theory both cranes Due to the fact that many process parameters
have access to the entire line, it is currently limited that the algorithm is to control are relatively
by the location of the second lift. This is due to the dynamic, it seems that only RHSP class
fact that the cranes cannot pass each other (Fig. 2). algorithms can give the appropriate effect. This is
Another variant is that there are two cranes, but due to the fact that the existing galvanizing lines
they have their own track sets and are mounted in do not provide for continuous control of these
a way that allows them to pass each other, this parameters, but only periodic corrections. Hence,
arrangement also occurs in two variants, in one of for example, the algorithm can determine the
the cranes can always pass each other, and in the initial concentration of the solution, but it should
other one of them (external) must not carry the modify the parameters on an ongoing basis when
load when passing. These variants of settings are the concentration changes during the production
especially difficult to implement in algorithms. of one batch of products. It should accordingly
Other variants are lines with two conveyors, in regulate the time of individual operations, and
which each conveyor has its own separate section with its change, the sequence of subsequent
of the line that serves and variants with more products.
conveyors. Due to the complexity of the calculations, it
should divide the calculations into parallel
1.4. Changes in the structure of the threads, thanks to which it will be possible to use
the methodology of parallel processing. Due to the
problem resulting from the fact that most of the electroplating lines do not
environmental approach. have high-power computing facilities, an
interesting option seems to be the optimization of
The basic change in the environmental calculations in terms of the use of GPUs of PC
approach is that instead of a single criterion, i.e. computers. The challenge in creating an algorithm
line productivity, optimization must be multi- in this way is the division into independent
criteria. Productivity continues to be the primary functions and adapting the computational part to
criterion as it determines both the economic the specific capabilities of graphics cards.
efficiency and the ecological cost of the energy
used. However, there are additional criteria, such 2. Conclusions
as the rate of consumption of solutions, the degree
of possible use of the solutions or the possibility As presented, the problem of using heuristic
of utilizing the active substance after the end of algorithms to solve HSP-type tasks under the
production. "Circular Economy" problem has not found a
The second important change is that, apart satisfactory solution to date. However, the
from the order in which the products are put on analysis shows that it is possible to construct such
the line, we also use the parameters of individual a solution. Previous tests on the laboratory
processing steps, such as solution temperature, simulation scale show that although the
concentration, process duration or current algorithms described in the literature are not
characteristics, as production control variables.
sufficient to solve the problem, they can be a on Information Control Problems in
starting point for further research. Simulation tests Manufacturing Moscow, Russia, June 3-5,
of the algorithm based on the work of Henrik J. 2009
Paul, Christian Bierwirth, Herbert Kopfer, (2007) [7] Sameh Chtourou, Marie-Ange Manier ,
with the author's further development showed that Taıcir Loukil - A hybrid algorithm for the
he is able to develop solutions for individual cyclic hoist scheduling problem with two
production batches. Its further development transportation resources - Computers &
should enable work in real real time, which will Industrial Engineering Volume 65, Issue 3,
enable the implementation of multi-parameter July 2013, Pages 426-437
control and multi-criteria evaluation. With the [8] Adnen ElAmraouia Mohsen Elhafsi - An
growing environmental requirements for efficient new heuristic for the hoist
production processes, it seems that the scheduling problem - Computers &
implementation of this type of solutions is a real Operations Research Volume 67, March
and relatively cheap solution to reduce the impact 2016, Pages 184-192
of production processes in electroplating on the [9] Jianguang Feng, Ada Che , Chengbin Chu
environment. Dynamic hoist scheduling problem with
multi-capacity reentrant machines: A mixed
3. Acknowledgements integer programming approach - Computers
& Industrial Engineering Volume 87,
September 2015, Pages 611-620
I would like to thank the employees of the
[10] 8. Yun Jiang and Jiyin Liu - Multihoist
Faculty of Management at AGH University of Cyclic Scheduling With Fixed Processing
Science and Technology, especially Dr. and Transfer Times - IEEE Transactions on
Waldemar Kaczmarczyk for help in research. Automation Science and Engineering, Vol.
4, No. 3, July 2007
4. References
[1] Bloch, Ch., Bachelu, A., Varnier, Ch,,
Baptiste, P. (1997) Hoist Scheduling
Problem: State-of-the-Art, IFAC
Proceedings Volumes, 30(14), pp. 127-133,
[2] Feng, J., Che, A., Chu Ch. (2015) Dynamic
hoist scheduling problem with multi-
capacity reentrant machines: A mixed integer
programming approach, Computers &
Industrial Engineering , 87, pp. 611–620
[3] Manier, M., Bloch, C. A (2003)
Classification for Hoist Scheduling
Problems, International Journal of Flexible
Manufacturing Systems, 15, pp. 37-55.
[4] Henrik J. Paul, Christian Bierwirth, Herbert
Kopfer, (2007) A heuristic scheduling
procedure for multi-item hoist production
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[5] Jianguang Feng, Ada Che , Chengbin Chu
Dynamic hoist scheduling problem with
multi-capacity reentrant machines: A mixed
integer programming approach - Computers
& Industrial Engineering Volume 87,
September 2015, Pages 611-620
[6] Etienne Chové, Pierre Castagna, Rosa Abbou
- Hoist Scheduling Problem: Coupling
reactive and predictive approaches -
Proceedings of the 13th IFAC Symposium