trade-offs between push and pull systems in …

Turkish Journal of Physiotherapy and Rehabilitation; 32(3)

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www.turkjphysiotherrehabil.org 12957

TRADE-OFFS BETWEEN PUSH AND PULL SYSTEMS IN IMPROVING

SUPPLY CHAIN PERFORMANCE - A CASE STUDY IN THE STATE COMPANY

FOR AUTOMOTIVE & EQUIPMENT’S INDUSTRY, BABEL / ALEXANDRIA

Haitham Obaid Hammadi Al-Dulaimi1, Dr. Asfad Murtada Said2

1,2 Middle Technical University, Administrative Technical College /

Baghdad, Department of Business Administration [email protected], [email protected]

ABSTRACT

This research sought to trade-off between the push and pull systems to improve the performance of the supply

chain, by studying and testing the possibility of applying both the push and pull systems in the saloon car assembly

line (Saba), the research sample, which is one of the lines of the saloon car assembly plant (the research

community) And measuring the extent of the impact of each of them on improving the performance of the supply

chain and comparing them according to specific criteria by building two simulation models of the two systems,

as the research aims to determine the best system for the Plant ,that improves the performance of its supply chain,

and the starting point of this research was from The following main question: “What is the best supply chain for

the assembly line of (Saba) saloon cars: the chain operating by the pull system, or the chain operating by the push

system?”

The importance of research appears in guiding the concerned party to adopt the best system (push or pull) in

building its supply chain. The research was directed to adopting the case study approach in building two supply

chains: the first works with the push system, and the second works with the pull system by using the simulation

method and adopting the (Excel) software in designing both programs, and then comparing the performance of

the two chains using criteria(the ability to deliver, Flexibility, costs , profits) and choose the best chain . This

research reached a number of conclusions, as the most important conclusion is that despite the superiority of the

chain that operates with the push system in some criteria such as the high production quantity and the low amount

of depletion, the chain that operates with the pull system has excelled in the standards of the lowest cost and

higher profits.

Keywords: Push system, pull system, supply chain, supply chain management, performance criteria.

I. INTRODUCTION

In the era of globalization, supply chains are treated as interconnected organizations at different locations that enable

partners to gain a competitive advantage, as supply chains are responsible for the entire product life, starting from the

preparation of materials and management of processing, to production, manufacturing, distribution and customer

service. In recent years, companies have realized the potential of effective Supply Chain Management (SCM) in

managing day-to-day operations. However, many companies fail to develop effective performance measures for their

supply chain performance and in order to achieve the supply chain goal of meeting customer demands faster and more

efficiently than competitors, they need to engage in continuous improvement processes to achieve effective

performance measures.

The graceful philosophy is one of the many initiatives that large companies around the world are adopting in order to

maintain their competitive edge in the ever-increasing global market, the focus of the Lean system is to eliminate

activities that do not add value by using a set of tools called Lean production tools.

The lean system distinguished between two important types of production systems; the "push" system, which plans

the products to be produced away from customer demand forecasts, and the surplus production is stored in anticipation

of unexpected demand.

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As for the second type, it is the "pull" system that allows the production of products based on the customer's request,

and therefore does not allow the presence of any stock.

The rarely of research that dealt with the effect of applying both systems (push and pull) in improving the performance

of the supply chain motivated the researchers to take the link between these two topics with research and analysis,

based on this, the research problem lies in the following question:

“What is the best supply chain for the assembly line of (Saba) saloon cars: the chain operating by the pull system, or

the chain operating by the push system? ”

As for the importance of the research, it was embodied in guiding the concerned party to adopt the best system (push

or pull) in building its supply chain. The researchers chose the saloon car assembly plant (the research community) -

one of the car factory plants of the General Company for the Automotive Industry and Equipment Babel / Alexandria,

which includes a number of saloon car assembly lines, and the saloon car assembly line (Saba) as the research sample

, because it is one of the most demand and sold plant lines, as demand sometimes exceeds the production capacity of

the line, and at the same time, the pieces and parts needed to assemble cars are being prepared from a supply source

located outside the country, which may result in the possibility of delay and reluctance in the processing of these

pieces and parts in the event of a high or sudden demand in the future, which in turn affects the performance of the

supply chain and its ability to meet the entire demand, and this is what motivated the researchers to try to apply both

the push and pull systems to the car supply chain, the research sample and the comparison between them and the

choice of the chain the best. This research adopted the (case study) approach in order to identify the problem and

collect the necessary data and information, through field coexistence, observation and personal interviews, as well as

reviewing the company's records and documents.

II. RESEARCH METHODOLOGY

First: The Research Problem:

The research problem is divided into two axes:

A- Cognitive problem

The subject of the supply chain is one of the most vital topics in the field of production and operations management

after the great development that took place in its concept, which moved it from “logistics” to “supply chain”, which

motivated researchers to address this topic with research and analysis after organizations turned into intertwined

networks And interacting from the supply chains that started with the customer’s request and ended with his

fulfillment after the chain started with the supplier and ended with the customer.

Both the “push” and “pull” systems are production systems, the first “push” focused on production according to

production capacity, regardless of demand, and stored what was not sold to meet sudden demands. The “pull” system

is a production system adopted by the lean system, because it works according to the customer's request only, and

then it fills the production line with excess production and costly storage. Although the researches dealt with both the

supply chain and the push and pull systems in research and study, it neglected the relationship and influence between

them, and this is what motivated the researchers to take the link between them in research and study.

B- Applied problem

The field coexistence of the two researchers in the “General Company for the Automotive and Equipment Industry,

Babylon / Alexandria” and in (Saloon Car Assembly Factory / Saba Car Assembly Line) indicated the following:

1. There is a wide and increasing demand for the (Saba) car of the research sample.

2. The presence of some problems in the supplying of pieces and parts for the car (Saba) the research sample, because

these pieces and parts are all imported from abroad, so there is a delay in supplying in some months due to the

delay at the borders resulting from inspection and customs procedures, As well as the delays that occur due to

compensating for the shortage of pieces and parts from the supplying company

3. Demand exceeds production capacity in other months, which leads to a deficit in meeting demand.

4. There is no specific production system that the factory follows in production, as sometimes the push system is

used and sometimes the pull system is used.



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This motivated the researchers to test the effect of both the push and pull systems on the vehicle supply chain, the

research sample through the main research problem, which is:

“What is the best supply chain for the assembly line of (Saba) saloon cars: the chain operating by the pull system, or

the chain operating by the push system ? ”

Through this, many of the following questions arise:

1. How can the supply chain that operates with the push system be applied in the assembly line of saloon cars (Saba)?

2. How can the supply chain that works with the pull system be applied in the assembly line of saloon cars (Saba)?

3. What are the appropriate performance criteria to measure the performance of both types of chain in the saloon car

assembly line (Saba)?

4. What is the best performance chain for the saloon car assembly line (Saba)?

Second: The importance of research:

The importance of the research that it is a case study that applied both systems in a practical way, albeit hypothetically,

using simulation, but it was based on real and actual data from the reality of managing the assembly line under

research.

Based on this and through the results and conclusions reached by the research, its importance to the company is

embodied in the following:

1. Clarify the advantages and benefits of applying the push system in the studied supply chain, as well as the costs,

revenues and profits associated with the application of this system.

2. Clarify the advantages and benefits of applying the pull system in the studied supply chain, as well as the costs,

revenues and profits associated with the application of this system.

3. Determining the best chain for the research line, which is the assembly line of the (Saba) car, by applying both

systems and comparing them, and this will lead to choosing the best chain for the company based on the criteria

(The ability to delivery, flexibility, cost, profits) Which enables it to achieve higher profits and a more competitive

position, which is the goal of any company.

Third: Research objectives

The research objectives stem from the research problem, which are summarized in the following objectives:

1. Implementation of the supply chain that operates with the push system in the assembly line of saloon cars (Saba).

2. Application of the supply chain that operates with the pull system in the assembly line of saloon cars (Saba).

3. Comparing the performance of both types of chains based on criteria; The ability to delivery, flexibility, cost and

profitability.

4. Choosing the best-performing chain and recommending the company to adopt it.

Fourth: Research Methodology

The researchers adopted the case study method in diagnosing and studying the current reality the factory supply chain,

because it is the most appropriate method in testing the preference of both options over the other (push and pull

systems) in improving the performance of the supply chain, as the subject of the research needs the following data:

A. Data related to the equipment, its sources and duration .

B. Data related to production capacity and demand for the research sample car

C. Data on costs, prices and sales.

This requires daily coexistence with production processes and collecting the necessary data and information through

personal interviews, field observation and the use of official records, for the purpose of identifying problems and

finding appropriate solutions to them.

Fifth: The limits of the search

1. Spatial boundaries:



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The (Saloon Car Assembly Factory), which is one of the factories affiliated to the State Company for the Automotive

Industry and Equipment Babel/Alexandria, was chosen to be a research community for several reasons:

A. The plant includes a number of automobile production lines that are characterized by a high demand from

customers.

B. In providing the pieces and parts that are used in production, the factory relies on imports for supplying, which

leads to the risks of delaying their arrival, which is reflected in the speed in meeting the demand for products.

C. Given the circumstances and obstacles of delaying the supplying of the pieces and parts entering production

against the increasing demand for products, this motivates the research of the possibility of differentiation between

the push and pull systems in production, in a way that improves the performance of its supply chain.

2. Temporal borders:

The research included two types of temporal boundaries, namely:

A. The temporal borders of field coexistence to obtain data and design the simulation programs and obtain results,

which is the period from (15/2/2021) to (15/5/2021).

B. The temporal limits of the data obtained and analyzed and the construction of the simulation programs on its basis,

which is the data for the year 2018, because it is the closest and most recent year in terms of stability in demand

and production, as both demand and production were greatly affected by the repercussions of the COV19.

Sixth: Research community and sample

The State Company for the Automotive Industry and Equipment, Babylon/Alexandria - Saloon Car Assembly Plant

was chosen to be a site for conducting the applied (practical) aspect of the research. Saloon assembly line (SAIPA),

saloon assembly line (Peugeot), saloon assembly line (Samand) and saloon assembly line (BYD), as the researchers

chose the SAIPA saloon assembly line (Saba) as a sample for research, due to its distinction as the most demanded

and selling assembly line among the rest of the lines, and therefore any improvement in the performance of its supply

chain will lead to a clear improvement in sales and profits for the factory as a whole.

Seventh: Methods of collecting data and information

1. Theoretical aspect:

The theoretical aspect has been enriched based on what has been presented in books, periodicals, letters and theses

related to the axes related to (lean production, push and pull systems, supply chain).

2. The practical aspect:

For the purpose of obtaining the data necessary to build the practical aspect of the research, the following sources

were adopted:

1. Field visits to get acquainted with the capabilities of the factory, as this required visiting the factory and

coexistence with its conditions, as well as direct observation of the production line and supply chain of the

research sample.

2. Documents and records related to demand, production, costs and sales.

3. Personal interviews and meetings with those in charge of production and supply operations.

Eighth: Data analysis methods and tools

1. Quantitative tools

The mathematical equations shown in the practical side were used to extract the following values:

A. Every of stored the first and last period of pieces and parts.

B. Weekly available capacity and weekly demand.



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C. Reorder point in both the push and pull systems.

D. Amounts of storage, depletion and accumulated storage.

E. Costs, revenues, and profits related to each of the two types of chain.

2. Statistical tools

It was mainly based on a simulation model (Monte Carlo) in the design of the two supply chains; the first that works

with the push system, and the second that works with the pull system, based on the data of 2018.

3. Software used

For the purpose of building the two simulation programs, the (Excel) program was used, which includes the synthesis

of random numbers and the construction of conditional equations.

Ninth: The procedural scheme of the research

The procedural scheme of the research embodies the path of the practical side of the research, as shown in Figure (1):

Figure (1) The procedural scheme of the research

Source: Prepared by the researchers

III. THE THEORETICAL ASPECT

The First axis: The Push and Pull Systems

The lean system is the first system that clearly and accurately distinguished between the push and pull systems as two

production systems, each with its own characteristics and tools, although it considered the pull system to be the most

appropriate in application when adopting the lean systems, and hence, when the push and pull systems are dealt with

research and analysis It is necessary to address lean production first and then enter into the concepts of both the push

system and the pull system.

First: Lean Production

1. Lean Production Concept



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There have been many proposals by researchers in explaining the concept of Lean Production, some of them

considered it a term synonymous with the term (JIT), and some considered it more comprehensive and that the

instantaneous production system is a part of it, while some asserted that both systems synonymous in the term (Said,

2011: 184), while others considered it a disciplined approach to engineering and production that includes a number

of elements, most notably (production on time), and some of them indicated that There is some ambiguity in the

differentiation between the two systems, as they interpreted agility in production as doing things better and continuing

to reduce waste at every stage of production, as this philosophy includes a set of tools that support its implementation

and these tools are called simultaneous production tools ( Abd & Jawad, 2019: 322), and Table (1) shows the opinions

of some writers and researchers on the concept of lean production.

Table (1) The opinions of some writers and researchers on the concept of lean production

the definition Author and year Is a flexible operating system that uses much fewer resources (activities,

people, inventory and floor space) than a traditional system, as well as the

tendency of lean systems to achieve greater productivity, lower costs,

shorter cycle times, and higher quality than non-lean systems.

(Stevenson, 2018: 609)

It is an attractive way to achieve competitive excellence in manufacturing,

by giving more value to the customer while reducing the consumption of

resources and time, by eliminating any interruption in the flow of

materials and information.

( Pawlik, 2019: 31)

An integrated approach of activities that seeks to identify all sources of

waste and loss , such as excess inventory, high costs, and defects in work,

in order to diagnose activities that do not add value by excluding them and

providing a high quality product that meets the customer's desire.

(Ali, 2019: 25-26)

Source: Prepared by the researchers based on the above sources

The researchers view that lean production is an integrated production system that aims to maximize the value added

by each production activity by detecting sources of waste and loss, and working to remove unnecessary steps,

resources and delays that do not add value from the production system by conducting Continuous improvements,

which in turn lead to the provision of high quality products that meet the customer’s desires.

2. Principles of Lean Production

(Elnadi, 2015: 47-48) pointed out that the principles of Lean production are defining customer value, managing the

value flow, developing the production flow, using drawing techniques and striving for perfection.

However (Feldmann & Gorj, 2017:54) believes that the principles of Lean production are to increase the benefit or

value to the customer, define the value stream, reduce waste, create a continuous flow, settle or seek to reduce the

volume of production Control by pull system Striving for perfection through standardization Optical control Enable

stops Using stable, flexible and reliable technology.

While (Belvedere & Grando, 2017:111) the principles of lean production are defined as (value, flow, pull, and

perfection).

Second: Push & Pull Systems

The competitive environment for manufacturing and production processes is becoming more difficult, as companies

in an already cost-focused sector are forced to control their costs while seeking new markets, or to improve their

flexibility and responsiveness to maintain existing markets. The effect of this includes increased product diversity,

reduced order volume, and reduced lead time, leading to increased complexity of operations, which when considering

the static and inflexible nature of manufacturing capacity lead to significant challenges in the areas of production

planning and control, )Puchkova, et .al, 2016: 66). At the same time, the demand for customer service and cost

pressure continues to increase in this challenging environment, Production control strategies (PCS) play a major role,

as they manage the flow of materials between work stations, and thus are a major driver of delivery performance,

inventory levels and production cost.



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Determining and assigning appropriate control strategies is a challenging task, especially when production systems

have to deal with changing demands, inaccurate forecasts, and unstable processes, as this poses a great need for a

production control strategy in order to achieve high delivery performance, quality and flexibility at the lowest possible

cost In complex production systems, it is necessary to have a correct production control strategy (PCS) in place

(Karrer, 2012: 1) and push and pull systems are the two main production control systems.

1. Push System (Traditional Production)

A. Concept of Push System

The push system is the method often used in traditional systems that do not focus on lean systems, which involves

using demand forecasts and producing the item before it is ordered. The customer, (Krajewski,2016: 232). the focus

is on using information about customers, suppliers and production to manage the flow of materials , the name of the

push system comes from the way the system works, as materials and parts are manufactured and then sent to the next

stage after that (i.e. another stage in production or storage), and then the system pushes the materials through the

production line according to a schedule.

A push system aims to produce goods or ensure services are provided well in advance of demand, and operates

according to a schedule or plan created from potentially inaccurate predictions, as large quantities of materials are

pushed from one process or machine to another regardless of whether There was a need for storage, and this leads to

fully exploiting the energies of machines, equipment and processes. (Schroeder, et.al, 2018:118)

The views of writers and researchers on the concept of the push system varied, some of them considered it part of the

Material Requirements Planning (MRP) system, while others considered it a system synonymous with it. Table (2)

shows the opinions of some writers and researchers on the concept of the push system.

Table (2) The views of some writers and researchers on the concept of the push system

the definition Author and year It is a system that aims to produce goods or ensure services are provided a

period in advance of demand, often according to a schedule or plan created

from potentially inaccurate forecasts as large batches of materials are pushed

from one process or station to another regardless of whether storage is

necessary or not.

(Schroeder, 2018 : 118)

It is a system that includes plans for products to be produced based on

expectations, which are stored as finished goods at the end of the supply

chain.

(Fowler, et.al , 2019: 1)

It is the system that is able to meet the demand from the stock while achieving

the highest energy use, but this may lead to an excess of storage. (Liu,et.al,2020:119)

Source: Prepared by the researchers based on the above sources.

The researchers view that the push system is a production system that works on planning the products to be produced

away from the expected demand of the customer, as the surplus production is stored to meet the sudden or unexpected

demand.

B. The movement of information and materials in the push system during the production process

According to the push system, materials and information are pushed into the supply chain from the beginning (raw

materials) to the end (the final customer) on the basis of demand forecasts, since at the end of the chain the final goods

are waiting for customer's orders. Naturally, there is stock in different forms (raw materials, semi-finished, and

finished goods) at different points in the supply chain, just in case it's needed. (Sarbjit , 2017: 492)

C. Advantages Of The Push System

The pull system is one of the traditional systems used in production by many companies, which, when working with

it, achieve a number of advantages. (Zahrawi, 2009: 51) confirmed that the advantages of the payment system are

limited to the following:

A. It is the safest method among the traditional methods of inventory management .



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B. Under this system, the production manager can stop the production of a partial component if the production

process of another component is disrupted and does not allow the production of the final product, and this is for

the purpose of avoiding the accumulation of inventory.

C. Assisting in stocking adjustments, as new supply orders cannot be issued unless actual storage needs arise.

While (Puchkova, et.al, 2016: 66) identified the advantages of the push system as follows:

A. Parts are released to the next station as soon as possible to avoid shortages in final stations.

B. Reducing delivery time because many semi-finished or finished products are available before ordering.

C. Avoiding the problems of fluctuation in demand as much as possible because there is storage at each station.

D. Disadvantages Of The Push System

Although the push system has achieved many advantages, it is not without some problems, as (Zahrawi, 2009: 51-52)

pointed out the defects of the push system as follows:

A. This method assumes that demand is known in advance and needs are determined accordingly, making it

unsuitable for external changes, as well as an element of uncertainty.

B. Needs are identified and collected based on estimated data, as when they are relied upon, they lead to problems

in responding to external changes represented by delayed delivery on the one hand, and internal changes

represented by production deviations on the other hand.

C. Scheduling takes place after the materials and components identification stage, which leads to a discrepancy

between the quantities that should be produced, and the calculation of production dates for those quantities.

While (Puchkova, et.al, 2016: 66) identified some of the defects that the push system can perform as follows:

A. The high cost of maintaining storage, as there is a storage of raw materials, storage under operation and storage

of finished products.

B. A decrease in inventory turnover, a high risk of inventory obsolescence and a decrease in service levels, which

leads to a decrease in profits.

Pull Systems (Lean Manufacturing)

A- Concept of pull system

Before the advent of the pull system, most organizations followed the push system, but in the past two decades the

pull system has displaced the push system, and these systems have led to the development of the Lean Production

System and the Kanban System (Sarbjit, 2017: 30) .

In contrast to a push system, in a pull system, each individual station of the assembly line waits for the upstream

station to demand its intermediate products before starting work, and the single station produces only what is required

from the upstream operations in the first place as it starts working only when the outputs is pulled through Initial

request.

This system allows the factory or manufacturing plant to support more variance in the production line, even to the

point where each product is completely customized to meet the specific demands of the customer, (Nelson, 2016:30

), meaning that the raw materials and parts are pulled from the back of the factory towards the front (in the opposite

direction), as they become finished goods, so this system achieves an optimal production at the rate of customers

using the same products.

Many writers and researchers have called this system a number of names such as: Toyota Production System (TPS),

production without storage, General Electric (GE) work experiment, simultaneous production (JIT) , as it works The

pull system is in an opposite way to the push system, Table (3) deals with the opinions of some writers and researchers

regarding the concept of the pull system.



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Table (3) The opinions of some writers and researchers about the concept of the pull system

the definition Author and year It is a method in which the quantity of work performed at any stage of the

process is determined only by the demand for materials from the immediate

subsequent stage.

(Nicholas,2018:11)

It is a system that allows the production of products based on the actual demand

of the customer without the presence of stock for the final product. Fowler, 2019 : 1 ) )

Systems are working to meet the demand through production, and is

characterized by flexibility in dealing with changes in demand operations, but

may lead to a long delivery period.

(Liu, et.al ,2020 : 1)


While the researchers view the pull system as a production system that allows the production of pieces and parts or

finished products based on the actual market (customer) demand, and therefore does not allow any stock.

B- The movement and flow of information and materials in the pull system during the production process

Under the pull system, the customer's request pulls the materials into the supply chain, as the system waits for the

final customer to signal his need for a good or service before producing it in order to work on fulfilling it, then the

signal is sent from the customer visually to the source in the various stages of production through a supply chain, to

determine when production and delivery should take place, as no initial process of producing a good or providing a

service is allowed until it is requested by a customer Post-production (Schroeder, 2018:118), production inventories

only enter the company or are produced by an earlier process According to what can be absorbed by subsequent

processes, as if production has pull from stock (Pereira, et.al, 2019:1472), and none of the work stations is started to

operate until requested by the customer, as the last one is dispatched its requirements to its previous station, and only

when the previous station is ready for the parts assembly process, the first station begins the production process

(Nelson, 2016:35).

C- Advantages Of The Pull System

The pull system is one of the lean production systems that when applied, achieves many advantages, as (Navnath,

et.al, 2016: 339 ) pointed out the advantages of the pull system as follows:

A. The process is simple and understandable as a result of providing quick and accurate information.

B. Reducing the costs associated with the transmission of information.

C. Achieving flexibility and speed of response to changes.

D. Reducing excess energy in the process.

E Avoid overproduction.

F. Delegating responsibility to production line workers.

While (Puchkova, et.al, 2016: 66) stated that the pull system achieves some advantages such as; High service levels,

low inventory level, and then low production costs.

While (Al-Rubaie, 2018: 230) confirmed that production according to the pull system achieves an improvement in

production efficiency in many aspects, including:

A. Reducing the sources of waste and loss represented by storage, which is one of its types.

B. Increasing the value of improving operations, as well as improving quality, which in turn increases customer

satisfaction, which is reflected in increasing its competitiveness.

C. Optimum utilization of resources, by using the least amount of materials, workers, equipment, spaces, and obtaining

good performance on time, which is reflected in reducing costs and increasing profits.



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D- Disadvantages Of The Pull System

Although the application of the pull system leads to many advantages, it is also not without some disadvantages, as

(Al-Kasasbeh, 2011: 37) sees that the disadvantages that result from this system are summarized as follows:

A. The system may not work well, when the location of the suppliers is far from the company's location.

B. The implementation of this system requires the approval of a limited number of products, as it is suitable for

repeated production environments with the need to meet certain conditions, as well as the requirements for

reorganizing the organization and the required preparations for meeting stops in the production line, as well as

identifying areas in which problems appear.

Whereas (Mashkoor & Jassem, 2012: 10) identified the defects of the pull system as follows:

A. The possibility of some problems related to the supplying of requests, as requests may arrive late, or they may be

incomplete, or it is possible that the organization of those requests has been inaccurate.

B. The possibility of machinery and equipment malfunctions, or the absence of some workers, which may lead to

delays in fulfilling the customer's request.

While (Puchkova, et.al, 2016: 66) sees that the pull system may face some difficulty in meeting the differences in

demand, due to the low levels of inventory.

The Second axis: the supply chain

First: The Emergence and Concept of supply chain

Supply chains have developed extensively over more than two decades, playing a critical competitive role in today's

increasingly turbulent market, by harnessing the potential, such as the capabilities and skills offered by supply chains,

as well as building and strengthening relationships with both customers and suppliers, as companies can reduce

inventories, reduce costs, enhance responsiveness and improve strategic focus, in terms of design, implementation

and capital investments (Po- Lynn, 2019: 7), there are those who confuse the concept of supply chain. And the concept

of logistics as two terms for one concept, but in fact, that logistics is part of the supply chain and not synonymous

with it, as it is responsible for the flow of information, goods, cash and services in the supply chain (Stevenson, 2018

: 654). As for the supply chain, it is a much broader concept, as there are many opinions of writers and researchers

about the concept of supply chain, and Table (4) shows the opinions of some writers and researchers regarding the

concept of supply chain.

Table (4) views of some writers and researchers about the concept of supply chain

the definition Author and year It is a chain of interrelated functions, to supply materials or parts to

one or more stations that produce final products and distribute them

to markets or deliver them to end customers.

(Al-Rubaie, et .al, 2019: 191)

It is a network of organizations and processes, in which a number

of different organizations (suppliers , manufacturers, distributors,

retailers) collaborate and coordinate together along the entire value

chain to obtain raw materials, then turn them into final products,

and deliver these products final to final customers.

( Ivanov, et.al , 2019: 7 )

It is a dynamic process, involving a complex flow of information

and materials obtained through multiple functional areas inside and

outside the company.

(Avelar-Sosa ,et.al, 2019: 11)


The researchers sees that the supply chain is the pulsating artery of the organization, which includes a network of

activities, facilities, and interconnected and sequential functions that are responsible for the supplying and flow of

materials, information and final products, starting with the suppliers, passing through the transformational

(production) processes, all the way to the markets or final customers.



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Second: The concept of supply chain management

The concept of supply chain management arose from practice, and grew through the need and change in response to

various threats, challenges and opportunities, for the purpose of achieving balance and synchronization of the

functions and activities of the organization with the functions and activities of its suppliers, in order to achieve

consistency and harmony in the flow of information, materials and services in the form that It fits with the

requirements and desires of customers. (Al-Saffar and Obaid, 2016: 221).

Although the term supply chain management appeared for the first time in the nineties of the last century, no agreement

was reached even on an acceptable and globally specific definition of supply chain management. Therefore, some

researcher's perceptions of this concept will be summarized in Table (5).

Table (5) The views of some writers and researchers on the concept of supply chain management

the definition Author and year It means designing and managing seamless, value-added processes across

organizational boundaries in order to meet the actual needs of the end

customer.

(Schroeder,2018: 345)

It is a complete group of methods used to efficiently integrate all elements

of the supply chain, including suppliers, manufacturers, inventories, and

warehouses, so Products are manufactured and distributed at the right

place, at the right time and in the right quantities, in order to reduce

system-wide costs. and at the same time meet service level requirements.

Khan & Yu,2019: 2) )

It means the management and coordination of the flow of products, from

the supplier through the manufacturing and distribution chains reaching the

final consumer.

Madhani,2020:41))


Supply chain management can be defined as managing the network of relationships within the company and between

organizations and interrelated business units that consist of material suppliers, purchases, production facilities,

logistics services, marketing and related systems, that facilitate the process of forward and reverse flow of materials,

Services, funds and information from the original producer to the final consumer, in order to add value and increase

profitability through efficiencies and customer satisfaction.

Third: The importance of supply chain management

The successful management of the supply chain is the key to the long-term success of the organization, as

(Christopher, 2016:12) confirm that supply chain management can work to reduce or eliminate stock temporary that

exist between organizations in the chain, from by sharing information about current demand and inventory levels.

While (Al-Rikabi, 2018: 32) pointed out that the supply chain management initiatives contribute significantly to

increasing the speed of response to the customer and delivery on time, as well as reducing stocks and waiting times,

and building strong relationships with all from customers and suppliers.

While (Madhani, 2020:32-33) indicates that supply chain management as an integrated function is the lifeblood of the

organization, as it enables simple supply chain management (SCM) to:

A- Enhancing business performance by achieving the best value for customers.

B- Increasing organizational effectiveness and profitability, by enhancing integration between companies and their

suppliers, through developing supplier partnerships and strategic alliances.



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C- Enhancing the competitiveness of the company, if an appropriate strategy for the supply chain is chosen in the

global competition market.

Fourth: Supply Chain Performance Metrics

Regardless of whether the supply chain supports services or manufacturing, managers need performance measures to

assess the effects of changes to supply chains (Krajewski, 2016:508), as it is important for the organization to maintain

an efficient supply chain. By reducing inventory levels and costs as much as possible for the purpose of achieving this

goal, organizations often resort to using a number of quantitative measures, also called performance indicators or

performance measures, to measure supply chain performance (Russell & Taylor, 2011:439) The outputs of these

metrics can be used to assist the organization during the decision-making process or to take corrective action on it, in

order to ensure its survival and continuity in the turbulent business environment.

He defined (Menhat, 2017: 42) performance measures as measures used to determine the effectiveness and

efficiency of the task in question. There are several types of supply chain performance measures, which are considered

quantitative measures, namely:

1- Stock Measurements: Inventory is an essential element in supply chain management, and all stock measurement

methods start with quantitative calculation of units, quantity or weight. However, inventories are measured by three

basic indicators: (a) the average total value of inventory, (b) weeks of supplying, and (c) inventory turnover, as shown

in equations (1 , 2 and 3):- (Krajewski, 2016:508)

A- The average total value of the stock: It represents the value of all materials in the organization's stores, as in

Equation No. (1):

B- Weeks of supply: It is the measure of inventory that can be obtained by dividing the average total value of

inventory by the cost of sales per week (the cost of the unit sold) as in equation No. (2):- (Russell & Taylor,2011:440)

C- Inventory turnover rate: It is obtained by dividing the annual cost of sales by the average total value of inventory

that is kept during the year, as in equation No. (3) :- (Russell & Taylor, 2011:439)

2- Financial measures: The method of designing and managing the supply chain has a significant financial impact

on the organization, so several financial measures are used to measure the performance of the supply chain:-

(Krajewski, 2016:508)

A- Total Revenue: Measuring the performance of the supply chain is linked to time, and the performance of the

majority of manufacturers and service providers can be measured on the basis of the time when the materials are

supplied from the suppliers, as the delivery of products to customers on time leads to an increase in total revenue, due

to earning Customer satisfaction, which leads them to purchase the organization's products increasingly, and this

indicator can be measured through Equation No. (4):- (Said & Ali, 2018: 304)

Average Total Inventory Value = Raw Materials + Work-in-Production + Finished Production..(1)

Average total value of inventory

Weeks of supply = ---------------------------------------------- …. (2)

Weekly sales cost

Annual cost of sales

Inventory turnover = --------------------------------------------------- …… (3)

Average total value of inventory



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B- Cost of sales: The presence of effective management of the supply chain leads to a reduction in the costs of

production and materials, as the costs of materials are determined through the financial arrangements related to the

suppliers, while production costs appear during the design and implementation of the supply chain, as well as the

percentages of defective, as well as the existing expertise along the supply chain has an impact on process costs.

Any improvement in these measures is reflected in the cost of sales and then on the total revenue of the organization,

as well as its impact on the marginal contribution, which means (the difference between the variable cost of producing

the commodity and the price), as reducing production and materials costs, as well as the costs of failure. (Defective),

leads to an increase in the marginal contribution, and then achieve high profits, this can be clarified through the

following two equations:- (Al-Lami & Salman, 2009: 36)

C- Return on assets: The return on assets is one of the important financial measures, as reducing the total investments

in treasury and fixed investments, or increasing the net income that results from better cost management, will lead to

an increase in the return on assets, which is a net Income divided by total assets. As shown in equation No. (7):

(Krajewski, 2016:511)

D- Working capital: Inventory weeks and turnover are a financial measure of another type, called working capital,

which is the money used to maintain existing operations, which requires an increase in inventory investment, by

reducing supplying weeks, or increasing turnover Inventory for the purpose of reducing pressure on working capital

by reducing inventory, as inventory turnover is achieved by improving relations with customers, as well as fulfilling

demand, and improving relations with suppliers, as reducing waiting times for suppliers leads to a reduction in the

number of weeks of supplying with Increasing inventory turnover, and this can be measured by equation No. (8): -

(Krajewski, 2016:511), (Al-Lami & Salman, 2009: 36-35)

3- Operations metrics: Operations metrics are considered as the important metrics that are used to measure the

performance of the supply chain. They include the following metrics:- (Ali, 2018: 51)

A- Productivity: Productivity is a measure of the relationship between inputs and outputs, through which results can

be obtained using production factors, as it can be measured through equation No. (9):-

B- Quality: It means quality that conforms to specifications .

4- Measures of demand fulfillment: they include indicators that are used to measure the performance of the

organization’s supply chain, and include the following:

Total Revenue = Number of units sold × Selling price per unit …..( 4 )

Cost of sales = Quantity of units sold × Cost per unit …… ( 5 )

marginal contribution = price - variable cost ……… ( 6 )

Net income

Return on assets = -------------------------------------- …….. ( 7 )

Net assets

Net working capital = Current assets - Current Liabilities ….. (8)

Outputs

Productivity = --------------------------------------- …… (9)

Inputs



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(Said and Ali, 2018: 305)

A- Demand accuracy: It means what has been accomplished from what is planned in the annual production plan, and

this means the difference between actual and planned production, as it can be measured by equation No. (10):-

B- The percentage of orders that have not been shipped.

C- The percentage of orders that were not delivered on time.

While (Menhat, 2017: 42) indicates that qualitative measures focus on the area that does not have a direct numerical

measure, and these measures include; (Customer satisfaction, flexibility, information and flow integration, effective

risk management, supplier performance).

1. Both (Abboud, 2019: 92-82) and (Idan, 2019: 105-94) indicated some of the supply chain performance criteria

that can be summed up As follows:

1- The criterion of ability to deliver: This criterion includes the average production quantity, the average depletion

quantity, and the average production halt period.

2- Flexibility criterion: This criterion includes the average amount of storage

3- Cost criterion: This criterion includes the average cost of production, average depletion cost, average inventory

cost, and average total cost.

4- Earnings criterion: This criterion includes both average revenues and average profits.

As the researchers chose these criteria because they can be measured quantitatively, so these criteria will be adopted

in measuring the performance of the supply chain that operates by the push system and the supply chain that operates

with the pull system and comparing them and choosing the best chain, as it dealt with the operational aspect of the

chain.

IV. THE PRACTICAL ASPECT

The first axis: Introducing the saloon car assembly plant (the research community)

1- Brief Introduction:

A saloon car assembly plant was established in 2013, and it was opened and work began on 1/4/2014 in cooperation

with the investor (Zamzam Spring Company), the plant is typical compared to other plants in the company, due to its

high production capacities and capabilities. The plant includes four lines for assembling and producing saloon cars,

arranged and organized in a way that fits with the space of the plant.

2 - factory Products

The factory collects several types of saloon cars of different models and sizes, according to the partnership contracts

that are contracted annually, which are:

• Iranian cars: SAIPA (Taiba and Saba), Peugeot (Babylon and Akkad), Samand (Sumer and Rana).

• Chinese cars: LIFAN (320, 620 and SUV), B Y D (F3 and G3).

Note that it is not possible to contract more than one type of car for the same company at the same time, since after

the contract on the agreed type ends, the contract is made for the other type, and so on.

3- Reasons for choosing

Demand accuracy = Planned production (expected) - Achieved production (actual) …… (10)



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The researchers chose the supply chain for the (Saba) car as the research sample because it is the car that witnesses

the largest demand and sales among the rest of the factory cars. Table (6) shows the amount of demand for (Saba)

cars in comparison to the demand for other cars Produced by the factory for the year 2018.

Table (6) The demand for saloon car assembly plant cars during the year 2018

Demand (car) Type of car 3628 SAIPA

1516 Peugeot 45 B Y D

Source: Prepared by the researchers, based on the data of the Marketing Department

This means that this type of car is the most important product for the plant and any improvement in its supply chain

will lead to a clear improvement in sales and profits for the plant.

4- The reality of the production capacity of the (Saba) car, the research sample

Production capacities vary according to the type of cars manufactured inside the factory, as the design capacity of the

(Saba) saloon car assembly line is the research sample of (4,500) cars annually, while the available capacity is (4000)

cars. annually.

5- The reality of supplying pieces and parts for the (Saba) car, the research sample

Pieces and parts necessary in the production processes for the saloon car assembly plant (the research community) are

obtained by direct contracting with the parent manufacturer outside Iraq (SAIPA, the Iranian manufacturer of Saba

and Taiba cars, and Iran Khodroa, the manufacturer of Samand and Peugeot cars).

The manufacturer company undertakes to supply the materials to the headquarters of the contracting company

according to specific times and in the form of batches that continue throughout the contract period. The duration and

timing of the arrival of batches of pieces and parts depend on the type of transportation and the conditions that

accompany the supplying operations in general, and the processing is as follows:

A- Supplying the pieces and parts for the car assembly line (Saba) research sample:

After contracting with the Iranian company SAIPA, it is responsible for supplying all the pieces and parts in

accordance with the contract concluded with it, Each batch includes the pieces and parts needed to assemble the car,

and the supplying is in batches every month or according to the production plan set by the company.

As for the pieces and parts needed to assemble the car, it comes in batches as mentioned above, and it consists of

boxes. Each box contains the pieces and parts needed to assemble a complete car and is divided into three groups

according to the size of the parts, namely (A, B, C), as group( A) includes large pieces such as; (engine, gearbox,

axle, etc.), while group (B) includes medium parts such as; (Tires, stopping systems, seats, electrical systems, etc.),

while Group (C) includes pieces and small parts such as; (bolts, nuts, clips and their parts...etc. ).

B - Supplying the car bodies:

The car bodies are shipped by special bodies carriers designed and prepared for this purpose, as the quantity arrives

in the form of batches, and in general, the supplying period for all pieces, parts and car bodies ranges between (1-3)

a week..

6-The reality of monthly demand and sales of the (Saba) car, the research sample

Table (7) shows the reality of each of the demand and monthly sales of the (Saba) car in the research sample.

Table (7) The monthly demand and sales of the (Saba) car for the year 2018

production and monthly sales Monthly demand Months 196 196 January



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228 240 February 320 380 March 172 172 April 312 312 May 296 320 June 224 280 July 248 248 August 320 360 September 320 360 October 240 380 November 300 380 December 3176 3628 the total

Source: Prepared by the researchers, based on the data of the Marketing Department

From Table (7), it is noted that:

1- The demand in some months, especially the last months of 2018, exceeds the available production capacity, which

amounts to (320) cars per month, which leads to a failure to meet the demand completely.

2- In some months, the demand was equal to the available capacity or less, but it is also noted that there is a deficit in

meeting this demand.

When the people in charge of the production line were asked, it was found that there are problems in the supplying of

pieces and parts, and these problems are:

A- The delay of pieces and parts within the limits for the pieces and parts that are shipped by land, as it takes several

days, as the time between the arrival of the car bodies and parts to the company’s warehouses is (1-2) days, due to the

inspection that Those batches are subject to him at the borders, as the inspection of parts requires a longer time at the

borders, knowing that the parts and car bodies depart from the supply company at the same time, but the delay occurs

at the borders, which leads to the arrival of the bodies before the parts in most cases.

B - Delays that occur due to compensating for the deficiency in the parts, whether (implicit or total, or the difference

of a specific material or the repetition of a malfunction in the parts), as it is returned to the manufacturer as it is

compensated in later batches, which leads to delays in fulfilling request.

C - Interruptions that occur in production due to the unavailability of stock of pieces and parts (first period stock)

involved in the assembly process that occur as a result of the delay in the supplying of those pieces and parts according

to the reasons mentioned above.

Hence, the researchers decided to classify the push systems (production on the basis of production capacity) and the

pull (production on the basis of (demand) according to the customer’s need) and compare them according to specific

criteria to determine the best system in improving the performance of the supply chain and responding to customer

demand in the light of standards ( The ability to deliver, flexibility, cost, profits).

The second axis: The Trade-off between push and pull systems

This axis aims to apply the push and pull systems in the researched production line and to identify their impact on

improving the performance of the researched supply chain and comparing them according to specific criteria by

building two simulation models for the two systems, as the simulation model for the two systems consists of three

main stages: The first stage It represents the inputs that include collecting data and information for the two models,

while the second stage represents the operations, which included the logical and computer design that simulates the

two systems, while the third stage included a presentation and discussion of the outputs of the two models in order

to reach the best system (push or pull) that can be Followed by the plant that improves the performance of its supply

chain.

The first stage: the simulation system inputs

Both the push and pull systems share some inputs, while each system differs in some of the other inputs:



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The first-term stock of (engine) current week = stocks last- term of (engine) for the previous week .. (1)

The first-term stock of (engine)for the current week = reorder point + stocks last term of (engine) for

the previous week .. (2)

Stocks last term of (engine) current week = stock first period (the engine) - required quantity of

engines . (3)

First: the common inputs between the push and pull systems

1- Design and available production capacity

The design capacity of the (Saba) saloon car assembly line is (4,500) cars annually, while the available energy is

(4000) cars annually, and by dividing the annual energy available by fifty weeks, the average weekly available energy

It is (80) cars.

2. Weekly demand

Table (8) shows the average weekly demand for (Saba) cars for 2018, which was prepared based on Table No. (7), as

the average weekly demand for each month was extracted by dividing each monthly demand by four weeks, This is

because the supplying periods are in weeks, so we need to extract the weekly demand.

Table (8) average weekly demand for (Saba) cars for the year 2018

Average weekly demand Months

49 January

60 February

95 March 43 April 78 May 80 June 70 July 62 August 90 September 90 October 95 November 95 December

3. The first period of inventory and the last period of inventory for engine

The engine is the most important nerve in the assembly of the car, and since all parts of the car are imported from the

same origin, which is the Iranian SAIPA company, and therefore the supplying time for all these parts is the same,

the engine was chosen to calculate the supplying period and the re-order point for it.

A - In the event that a new order is not received.

B - In the event of receiving a new order, then:

4- The weekly stock and the accumulated stock of (Saba) cars

Inventory of products is produced when production is higher than actual demand, while inability to meet demand

(depletion) occurs when it is the opposite and as follows:



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5- The amount of cars Running out (depletion) (Saba)

Second: the inputs for both the push and pull systems

The data on the re-order point for the push system differs from the pull system, because the average weekly production

in the push system depends on the average weekly capacity, while the average weekly production in the pull system

depends on the average weekly demand, as it will be clarified as follows:

1- Reorder point in the push system

The reorder point is the point or quantity that the stock reaches in order to launch a new order of a material, and since

all the pieces and parts for the car, the research sample is from the same origin, which is (Iranian SAIPA Company),

the choice was made on the most important part. In the car (the engine) to determine the re-order point for it, and for

the purpose of determining the re-order point for (the engine of the car), the following data should be available:

A- Average weekly production: Since the researchers here are designing the push system, the weekly production is

determined by the average available weekly energy, as the average weekly production was calculated by dividing the

available annual energy by fifty weeks as in equation No. (9)

4000

So, Average weekly production = ------------------- = 80 cars per week 50

B - The average waiting time: The commercial department in the company specified the supplying period between

(1-3) weeks, because the pieces and parts are supplied from an external source, which requires that the shipment be

subject to inspection as well as audit procedures and checks Customs duties within the borders, Table (9) shows the

waiting periods and the frequency of each period.

Table (9) Waiting times and frequency of each period in the push system

The amount of repetition for each period during the

year

Waiting times/week

7 1

8 2

Inventory = Production - Actual Demand ...... (4)

Accumulated stock = Previous week's stock + Current week's stock...... (5)

Accumulated stock after satisfying the demand = Accumulated stock - Running out(depletion) before

stock is satisfied... (6)

Running out(depletion) before stock is satisfied = Actual demand - production ........ (7)

Amount of running out(depletion) after satisfied of stock = running out before satisfied of stock -

accumulated stock …(8)

Available annual energy

Average weekly production = ---------------------------------- ………… (9)

50 weeks



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9 3

The average waiting time can be calculated as in equation No. (10):

(1×7 + 2×8 + 3×9 ) 50

So, Average waiting time = --------------------------------------- = ------------------ = 2 week

(7 + 8 + 9 ) 24

Accordingly, the reorder point is:

= 80 × 2 = 160 engines .

Thus, the order quantity will be (160) engines each time the supply order is requested according to the push system.

2- Re-order point in the pull system

According to the pull system, production is according to the demand that is determined weekly according to Table

(3), and for the purpose of determining the re-order point for (car engine) according to this system, the following data

should be available:

A- Average weekly demand: The average weekly demand was calculated by dividing the total annual demand in the

year by fifty weeks, as in equation No. (12):

3628

So, Average weekly demand = ---------------------- = 73 cars per week

50

B - Average waiting time : It is calculated as in equation No. (13) and with the same average waiting time that was

reached in the push system.

Therefore, the reorder point is:

= 73 × 2 = 146 engines

Thus, the order quantity will be (146) engines each time the supply is requested according to the pull system.

Third: The costs associated with the push and pull systems

Total (waiting times × Repetition of each period)

Average waiting time = -------------------------------------------------------------- …..(10)

Total repetitions

Re-order point = average weekly energy x average waiting time/week ...... (11)

Total annual demand

Average weekly demand = ---------------------------------- ………… (12)

50 weeks

Re-order point = average weekly order x average waiting time / week ...... (13)



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1- Manufacturing cost (production): The cost of assembling the car, based on what was stated in the records of the

Finance Department / Cost Division, is (340,000) Iraqi dinars per car, as the manufacturing cost (production) can be

calculated.as in equation No. (14), as follows:

2- The cost of storage: the cost of storage represents the costs resulting from the accumulation of products in stores

due to production in excess of demand, and the cost of storage represents a percentage taken either from production

or from the price of the final product, and this percentage is often between (10% -5%), and the researchers extracted

the cost of storage by taking (5%) from the price of the final product multiplied by the price of the same product,

which amounts to (8,500,000) dinars as in equation No. (15), and as follows:

Therefore, the cost of storage for one car is as follows:

= 5% × 8,500,000 dinars = 425,000 dinars .

3- The cost of Running out: The cost of running out is the lost opportunity cost of sales, as it is calculated as follows:

4- Total cost = production cost + inventory cost + running out cost……. (17)

5- Revenue = production quantity x the price of the final product ........ (18)

6- Profits = Revenue - Total cost ………. (19)

The Second Stage: The logical and computer design that simulates the two systems

First: the conditions of the two simulation models

1- The program simulates the push and pull systems according to the data obtained for the period from 1/1/2018 to

31/12/2018.

2- The two models addresses with the following basic variables:

A- Energy .

B- Demand .

C- Production.

D- Supplying (re-order point, supplying time).

E- Beginning and ending stock .

F - The amount of depletion.

G- Costs, revenues and profits associated with the two systems.

Second: Assumptions of the simulation models

1- The simulation was tested for fifty weeks .

Production cost = number of cars produced (production) x 340,000 dinars .... (14)

Storage cost = (5%) x car price ....... (15)

The cost of running out = the quantity of running out x the price of the final product ... (16)



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2- Production is according to the weekly capacity in the push system, regardless of the weekly demand .

3- The production is according to the weekly demand in the pull system, provided that it does not exceed the weekly

capacity .

4- A new order (re-order) is not issued unless the previous order has arrived .

5- There are no pending requests .

Third: Model simulation design on (Microsoft Excel 2010)

The mathematical rules and calculations related to the two models mentioned above have been translated into a

programming language according to the (Excel) program because this program is characterized by the following:

1- It contains many equations and statistical, mathematical and logical functions necessary for designing rules and

making calculations for the two models.

2- The ability to make changes easily and with high flexibility

3- The possibility of running the simulation for any period of time and for several times

4- Ease of generating random numbers: The( RANDBETWEEN (MIN, MAX)) function was used to generate random

numbers for the following variables:

A- Generating random supplying times:

Through the use of those in charge of the process of ordering pieces and parts for the car engine (the research sample),

the researchers indicated that the supplying times (which is the period between the launch of the order of the engines

and until they arrive and enter the factory) range from one to three weeks ( 1-3 ).

B- Generating random order quantities:

Table (8) in this topic indicates that the largest weekly order quantity during the year 2018 is estimated at (95) cars,

while the lowest weekly order quantity for the same year is estimated at (43).

The third stage: presentation and analysis of the outputs of the simulation process

At this stage, the outputs were presented and the results that were reached after conducting the simulation for both

models (the push and pull system) were presented according to the standards or criteria for the performance of the

supply chain, and then chosen the best system by comparing the performance standards of the push system model

with the performance standards For the pull system model, these criteria are:

1- The criterion of ability to deliver: (the average production quantity, the average depletion quantity, the average

period of stopping production).

2- Flexibility criterion: (the average amount of storage).

3- Cost criterion: (average production cost, average depletion cost, average inventory cost, average total cost).

4- Profit criterion: (revenues, profits).

Each program of the push system and the pull system was run according to five experiments for each program, and

these experiments indicated a relative stability in their results through the convergence of the output values of

quantities, costs and revenues.

Figure (2) and (3) show a model from the first page for each of the push and pull programs.



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Figure (2) The first page of the push system program

Figure (3) The first page of the pull system program

Table (10) shows a comparison between the performance results of the two supply chains (push and pull) according

to the performance indicators that have been approved and shown in the table.

Table (10) results of the performance of both chains (push and pull) according to the approved performance indicators

Pull system model Push system model Indicators No.

3204 3888 Average amount of production 1

197 9 The average amount of running out 2

1 2 The average duration of stop production 3

0 720 The average amount of inventories 4

1,089224000 1,321,920,000 Average cost of production 5



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1,671,100,000 74,800,000 The average cost of running out 6

0 8,146,485,000 The average cost of inventories 7

2,760,324,000 9,543,205,000 Average total cost 8

27,230,600,000 33,048,000,000 average revenue 9

24,893,916,000 23,786,910,000 average profit 10

Source: Prepared by the researchers, based on simulation program data.

Through the results that have been presented for the indicators of the dimensions of supply chain performance

standards in Table (10), the following is evident:

1- The criterion of the ability to deliver: The high production quantities in the push system that operates according to

the production capacity led to meeting the demand for the product completely and in a way that exceeds the pull

system, which is produced according to the actual demand, which led to a reduction in the amount of depletion In it

than it is in the pull system, but this increase in production quantities had a clear reflection on the increase in the

period of production stops in the push system, which exceeded what it is in the pull system, due to the depletion of

the stock of pieces and parts (the stock of the beginning of the period) as a result of production excess over demand

.

2- The criterion of the dimension of flexibility: the increase in production quantities according to the push system had

a clear reflection in the increase in the amount of accumulated storage resulting from production in quantities that

exceeded the size of the actual demand compared to the pull system in which the amount of storage was non-existent,

which would result in costs added to The total cost of the final product, and although the accumulated storage in the

pull system has completely met the demand and significantly reduced the amount of depletion, the pull system has

worked to reduce the accumulated storage and make it equal to zero, which is one of the points that distinguishes This

system.

3- Cost dimension criterion: The cost criterion indicators refer to improving the performance of the supply chain in

this dimension, as production in quantities that exceed the volume of demand for the product depending on the

production capacity in the factory , which results in an increase in the volume or quantity of accumulated storage

according to the push system. This led to a reflection in the rise in the total cost of the product, as the average total

cost was (9,543,205,000) dinars compared to (2,760,324,000) dinars in the pull system, which had a prominent role

in reducing costs as a result of production according to demand , The reason for this is due to the higher production

costs and storage costs in the push system than the costs of production and depletion in the pull system.

4- Profits dimension criterion: The profit index is the most important criterion for any company in determining the

preference of any system over the other, despite the fact that the revenues generated in the push system were far

superior to those achieved by the pull system by a large difference of (5,817,400,000) dinars, but the profit index in

the pull system was higher, as the average profit reached (24,893,916,000) dinars compared to (23,786,910,000) dinars

in the push system, due to the higher total costs in the push system than pull system due to the high total costs of

production and storage, which affected the profits achieved for this system, so the difference, which averages

(1,107,006,000) dinars, can be reflected in improving and strengthening the financial position of the company and

investing it in other projects that are interest of the company in the future .

V. CONCLUSIONS AND RECOMMENDATIONS

The First Axis: Conclusions

The research conducted by the researchers reached a number of conclusions that resulted from the application of push

and pull systems to the supply chain of the (Saba) car, according to the two simulation systems, which are as follows:

1- The results related to the ability to deliver criterion indicated the following:

A- The push system is superior to the pull system with respect to the average production quantity, because the push

system produces according to production capacity regardless of the quantity of demand, while the pull system is

restricted by the quantity of actual demand.



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B- The pull system superior the push system with respect to the average amount of depletion, as it achieved a higher

amount of depletion than the push system achieved, because the push system is produced according to the production

capacity, so the storage fills the demand in the event that the demand for energy exceeds.

C-The push system superior the pull system with respect to the average production stops, as it has achieved an average

production stoppage by an amount higher than the average production stops achieved by the push system, due to the

lack or depletion of the initial stock of pieces and parts as a result of their use in the pull system, because it is a system

that is produced according to the production capacity, regardless of the quantity of demand, and this in turn may lead

to the depletion of the stock of the first period of those pieces and parts before the arrival of the required quantity

(ordered). from the source of supplying.

2- The results of the flexibility criterion, which includes an indicator of the average quantity of storage, indicated the

superiority of the push system over the pull system, because it is a system that is produced according to production

capacity, which led to a high amount of accumulated storage due to production in excess of the actual demand, unlike

the pull system Which worked to reduce the accumulated storage quantities and make them zero or equal to zero as a

result of production according to demand .

3- The results related to the cost criterion indicated the following:

A- The push system has superior the pull system with respect to the average cost of production, due to the increase in

the volume of production that follows the production capacity of the assembly line, in contrast to the pull system that

follows the actual demand.

B- The superiority of the pull system over the push system with respect to the average depletion costs, if the high

depletion costs in the drawing system are attributed to the lack of storage that meets the demand when the demand

exceeds the production capacity, unlike the push system in which the access costs were low, This is due to

compensating the amount of depletion in the push system from the amount of accumulated storage .

C - The superiority of the push system over the pull system in terms of average inventory costs, because it is a system

that is produced according to production capacity regardless of actual demand, which results in the generation of

accumulated storage as a result of excess production, which leads the company to bear high inventory costs compared

to the system pull whose inventory costs were completely non-existent, as a result of the lack of inventory from

production (cars) in this system.

D- The push system superior the push system with respect to the average total costs, because despite the low or non-

existence of depletion costs resulting from adequately meeting demand due to production according to the energy in

the push system, this was reflected in the high total cost resulting from it. Which exceeded what it is in the pull system,

which is produced according to demand, as the reason for this is the higher costs of production and storage in the pull

system than the costs of production and exhaustion in the pull system, which had a significant impact on the total

costs of assembling one car.

4 - The results related to the profit criterion indicated the following:

A - The superiority of the push system over the pull system with respect to average revenues, because it is a system

that works according to production capacity regardless of demand, which results in the formation of an accumulated

stock of excess production, through which the amount of running out in demand can be compensated when It exceeds

production capacity, which allows reducing lost opportunities, as well as increasing revenues compared to the pull

system in which there is no storage.

B - Due to the low total cost of the pull system compared to the push system, the average profits indicated a significant

superiority of the pull system over the push system, as although the push system achieved higher average revenues

than the pull system, the increase in the total costs of the push system had A clear effect on reducing profits compared

to the pull system.

5- Despite the superiority of the push system over the pull system in some criteria related to the performance of the

(Saba) supply chain, the profit criterion remains the most important criterion for evaluating the performance of any

supply chain, which was achieved via chain that operating by pull system .



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The Second Axis: Recommendations

Based on the findings of the research, the researchers recommend the company the following:

1. The application of the pull system instead of the pull system in the supply chain of the car (Saba), due to its

positive effect in improving the performance of this chain in terms of costs and profits and reducing waste in

storage.

2. Studying the possibility of applying the pull system to the supply chains of other factories that are witnessing an

increasing demand for their products from the public and private sectors.

3. Working with the re-order point method in determining the batches of the pieces and parts of the car in question

because of its positive effect in reducing the stopping periods, especially in the pull system.

4. Seeking to adopt accurate methods of forecasting the demand for (Saba) cars in particular and other cars produced

by the company in general for the purpose of providing the necessary requirements to meet this demand.

5. Studying the possibility of increasing production capacity and optimally exploiting it, by analyzing the stages of

production and delivery in the chain and diagnosing waste and loss sites and removing them for the purpose of

meeting the actual demand if it exceeds the current capacity in most cases.

6. Seeking to use some economically feasible pieces and parts produced by some Iraqi factories that can be included

in the process of assembling cars (such as tires, batteries, plastic parts, etc.) because they are manufactured inside

Iraq and therefore have a shorter supplying time than the pieces and parts that Imported from abroad

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