Theory of toc constraints and the logistics chain

The deep bibliographic analysis carried out in this research was aimed at embodying the "state of the art and practice" on the object to be treated, the restrictions in the logistics chain. In a first approach, the term of continuous improvement is conceptualized as well as the different improvement philosophies that are convulsing the business environment, the latter from a critical perspective, proposing their virtues and deficiencies; then going on to analyze the reason for a systemic approach in logistics management, making a breakdown of the term and arriving at practical conclusions for entrepreneurs and finallythe Theory of Restrictions as an essential management philosophy in decision-making and the importance of its application for the excellent management of restrictions in the logistics chain.

1.1 Continuous Improvement. Fashion or necessity?

"Organizations are created to generate money through sales (throughput), says Dr. Goldratt 1991, if throughput is not achieved, then why does the organization exist?"

Escorches, 1990, states that:… ”organizations are created with a specific purpose since none has been created exclusively for their existence. This is based more explicitly when analyzing that in organizations all those resources destined to obtain a result are coordinated or what is the same, the parts are constituted with a view to achieving a final result, that is, that every true organization supposes A conscious purpose is based on the ordering, with precise purposes, of a set of conditions that regulate both the relationships between men and their relations with the rest of the organization's resources, if this does not work, disorder will predominate, irregularity and lack of coordination and, therefore, the need to undertake a Continuous Improvement Process (PMC) ”.

Continuous Improvement is a philosophy of work and life, which aims to permanently challenge the established goals to achieve higher levels of effectiveness and excellence that achieve customer satisfaction and delight, better results for the organization, the community and better quality of life for employees.

Or in other words: “Continual improvement is a management system and philosophy that organizes employees and processes to maximize value and customer satisfaction.

As a global management system, continuous improvement provides a series of tools and techniques that can lead to outstanding results if implemented consistently over a period of several years. " Currently, the development and even survival of an organization that does not aim for continuous improvement is unthinkable. (Héctor R. Formento).

1.1.1 Continuous Improvement Processes

The PMC is nothing more than taking measures that eliminate the limitations that organizations have, for their improvement in all spheres, considering that every organization has at least a small number of limitations. These measures must be taken continuously and this requires the effort of people directly or indirectly related to the company's production. When PMC is applied, everyone must be involved: managers and workers alike. This process requires knowledge and improvement of said personnel.

If an organization needs to improve its performance, it will have to undertake a process of continuous improvement. Each word in this term has a specific message: process: indicates a related sequence of actions, steps, and not just a set of ideas; improvement: means that this set of actions increases the profitability results of the company, starting from variables that are appreciated by the market (quality, services, volume, assortments, terms and prices) and that give a differential advantage to the company in relation to with your competitors; and continuous: it implies that all means of competition where competitors make movements to gain a position in the market, the generation of advantages must be constant (Pilar Arana, 1994).

Goldratt, 1991, defines continuous improvement… “Anything that improves the overall result, profits, is an improvement. Anything else serves to feed our egos. Continual improvement, he says, requires a leap toward throughput. But it is not enough for one part of the company to make that leap. All functions and levels of the organization must do it together.

Continuous Improvement is a rational and iterative way of raising the status quo of the organization. (Abat, Molina, Caballero, 2006)

Every improvement is a change. And any change is perceived as a security threat ”. Therefore, companies seeking to make a difference must find ways to overcome the natural emotional resistance that arises with anything that appears to threaten personal safety.

Goldratt, 1995 states, “The only way out is to cut the link between improvement, which is positive, and change, which is perceived as negative.

How can we do it?

One of the main allies of a company is the intuition of its own employees. By unleashing intuition, people become owners of change, thus cutting the tie.

Throughput, is the magic word in Dr. Goldratt's vocabulary, which defines it in the term of pesos and cents, it is the rate at which a system generates money through sales (a product that is manufactured, but not sold, does not qualify; it only increases finished product inventory).

To eliminate limitations and improve the performance of any organization, a PMC should be undertaken, which all of them in general aim to:

Define the goals to be achieved, to attack or eliminate the evaluated causes and prioritize them; Analyze the causes and root factors that imply those deviations and prioritize them according to their influence; Define the actions and projects to eliminate the causes or overcome the deficiencies; Implement the actions and monitor their impact, review, modify and intensify them according to whether the result is being achieved or not; Determine productivity and quality levels and their deviation; Evaluate the results and the new situation achieved; Recognize and reward the achievements achieved; Start a new cycle.

For the above stated is that different authors have been given the task of defining how to develop a PMC. IMAI, 1989, defines five necessary steps for the same.

Straighten: which includes differentiating between unnecessary and necessary and discarding unnecessary. Putting things in order: things that should stay in order so that they are ready to be used when they are needed. Cleaning: this step is to keep clean the workplace Personal hygiene: making cleanliness and neatness a habit, starting with the person himself / herself Discipline: means following the procedures in the workshop.

The steps to follow to face a PMC raised by IMAI constitute very general precepts.

On the other hand, the author Martínez, 1990, emphasizes that: that company whose objective is to achieve excellence and turn manufacturing into a source of innovation and competitive advantage must undertake the following phases:

Changes in operations Changes in the manufacturing system Changes in the organization as a whole

Although the authors consider that it is not necessary to act in these phases simultaneously.

These points constitute a way to approach a PMC in a global way.

On the other hand, the teachers of quality, Ishikawa, 1988, Deming, 1989, Jurán, 1990 and Crosby, 1991 raise the essential characteristics of the factors present in any process of change explained from different points of view, but that have common points:

Inspection is never the solution for quality improvement, and neither is police attitude; Senior management participation and leadership are essential to generate the much-needed culture in which everyone is committed to achieving quality; A The program to evaluate quality requires the effort and long-term commitment of the entire organization, in addition to the investment necessary for training; Quality comes first and work schedules are secondary; Implementing new strategies aimed at troubleshooting; the problem is in the system and only management can change the system.

1.1.2 Total Quality. A continuous improvement approach

A quality improvement project consists of a problem (or improvement opportunity) that is defined and for the resolution of which a program is established. Like any program, it must have resources (material, human and training) and work deadlines. Quality Improvement is achieved project by project, step by step, following a structured process like the one cited below:

Verify Mission Diagnosis Root Cause Fix Root Cause Maintain Results

When it comes to quality, the Total Quality (TC) approach also has its roots in continuous improvement. Omachonu, 1995, defines TC as the integration of all the functions and processes of an organization, in order to achieve continuous improvement of the quality of the goods and services that are produced in it. The goal is to achieve customer satisfaction.

TC is based on several ideas. It involves thinking about quality in terms of all the functions of the company and is a process from beginning to end, where interrelated functions are integrated at all levels.

It is a systems approach that considers all the interactions between the various elements of the organization. Thus, the overall efficiency of the system is greater than the sum of the individual opportunities of its subsystems.

The growing acceptance and use of TC has been the result of three trends:

1. Reaction to the increasingly intense internal and global competition.

The customer demands quality. The customer we find in the market is an evolved customer, a more demanding consumer. This customer is not willing to tolerate lack of quality, poor service and does not accept excuses. Quality is profitable. Quality is a source of wealth, only companies that are characterized by the quality of their products and services survive in the marketplace, they achieve notoriety and prosper. Total quality improves staff morale;

2. Where quality is poor, it is easy for frustration, conflict and confusion to occur; Loss of time, a lot of work and little satisfaction are generated, which in the long run leads to loss of competitiveness, loss of personnel;

3. It aims to revolutionize the role of man in the company and bring out the limited resources that each human being has.

Need to integrate the functions of the organization.

Synergy of the organization ". The customer is king."

The acceptance of TC in a wide variety of industries and services.

The authors who write about the TC philosophy address key elements such as: general strategies to follow to undertake the processes, the role that senior management must play as manager of the same, the importance of creating a business culture that counteracts the resistance to change and involve all staff; However, these authors do not offer ways or methods to achieve it.

1.1.3 Process Reengineering or Continuous Improvement

Reengineering is a method by which the main business processes are fundamentally redesigned, from start to finish, using all available technology and organizational resources, oriented by the needs and specifications of the client, to achieve spectacular improvements in critical and contemporary measures of performance, such as cost, quality, service, and speed.

According to Hammer and Stanton, it is fundamentally rethinking business processes and radically redesigning them, in order to achieve dramatic performance gains. The key factors of the concept are: the orientation towards the processes, the radical change and the great magnitude of the expected results.

It is a technique by which the operation of processes within a company is analyzed in depth in order to completely redesign and improve radically.

Process reengineering arises as a response to the inefficiencies of functional organization in companies and follows a structured method consisting of:

Identify the key processes of the company. Assign responsibility for these processes to an "owner". Define the limits of the process. Measure the operation of the process. Redesign the process to improve its operation.

While continuous improvement can be conceived as a process of quantitative changes, reengineering is, as it is a radical transformation, a qualitative change. It is no longer just about moving through a learning or experience curve, it is about jumping into a new curve.

The original concept of reengineering has been harshly criticized from various angles. Most of these criticisms correspond to reengineering processes that have failed. Without a doubt, reengineering offers us excellent possibilities to significantly improve the productivity of an organization, but the design of the change and its implementation must take into account the experience generated in the business world in recent years.

The major criticisms of reengineering have focused on the wrong way in which the role of organizational culture and employees in the process was originally approached. This criticism was joined by even its most notorious proponents, acknowledging that many failures were a consequence of this simplistic view of the aforementioned issues.

1.1.4 Benchmarking an approach

The continuous process of measuring and comparing an organization with leading organizations anywhere in the world, in order to obtain information that helps them carry out actions to improve their performance, is called Benchmarking or comparative performance studies.

Benchmarking is a tool by virtue of which the best practices in a certain process are identified, which are analyzed and incorporated into the activity of the company.

Phases of Benchmarking according to Marisol Pérez Campaña:

Planning: In this phase the specific points are defined, in which it is necessary to make improvements and to which Benchmarking will be applied, the most competitive companies or organizations in the activity or activities on which it is going to be carried out are indicated and selected the study, developing a study plan in which the objective of data collection is determined.

Analysis: The necessary data is obtained in the companies or organizations on which the comparison will be carried out, carrying out a study of the data to know the strengths of the company and compare them with the internal data, the negative or positive differences are quantified current and projected in order to outline future actions and close the analysis cycle.

Integration: The improvement objectives to be achieved are set and an action plan is determined for each of them, establishing an internal process that allows the integration of the objectives, it is important to sensitize the staff at all levels of the company.

Action: Development and execution of the definitive action plan, continuous monitoring of the plan evaluating the improvement results and the quantification of the contribution of these results to the operational plan.

Maturity: Reach the desired leadership situation, definitive and full integration of Benchmarking in the Business Management process.

There are several definitions of what Benchmarking is, and although they differ in some aspects, it can also be noted that they agree or present a series of common elements. Most of them highlight the fact that Benchmarking is a continuous process and not a recipe that when applied in the company solves its problems, but a process that will be applied over and over again in the constant search for best practices in the industry.

Benchmarking is usually criticized as it is considered an espionage technique; especially in the case of the practice of Competitive Benchmarking. Other authors see it as a copy that reduces creativity and that, in the long term, is detrimental.

Another argument is the refusal of companies to assimilate imported procedures or processes.

1.1.5 Theory of Constraints. True continuous improvement

Goldratt, 1995, argues that to carry out a PMC it is necessary to continuously use the direction of the limitations, which consists of principles of systematic reasoning, allowing the identification of the underlying problems, the construction of valid and complete solutions and the creation of immune implantation plans.

His theory is known as Theory of Constraints or Limitations (TOC) and constitutes one of the most innovative approaches currently available in management theory and which has had a rapid spread in the business world.

Probably one of the problems that arise in the "Business Sciences" is that of managerial fashions, which occur when a famous author writes a book, gives lectures and carries out consultancies and consultancies that lead to the dazzling of academics and executives alike, with the negative result that in many cases these trends are perceived as: "what has to be done now, what was done before is useless".

Although the authors of the books on TOC are not explicit in this sense, it is clear that what they propose is not a recipe nor does it require the denial of previous advances, on the contrary, the foray into TOC requires that the company be at a level of important evolution. It is necessary that the quality of suppliers, process and products is controlled and assured, that the company has information systems working and that it has a clear system of programming and control of production and inventories. That is, rather than replacing them, TOC is a vision that seeks to build on and build on the advances made with the application of other techniques, tools, and philosophies. TOC has two fully distinguishable parts, which (according to the authors) have their maximum results when applied simultaneously:the methodology for group problem solving (thought processes) and the operational logic (with implications in production, logistics, personnel scheduling, resource management and therefore, accounting and finance in the company).

TOC's approach to continuous improvement is a perfect complement to Total Quality Management (TQM) by concentrating (TQM) efforts with pinpoint precision on the point in the system where such efforts will be most effective.

Goldratt, 1995, says in a nutshell that TOC (Teorhy of Contraints) refers to thought processes and their application, where "thought processes" means the systematic method of constructing "common sense".

Everything else is a result, that is, it consists of principles of systematic reasoning, allowing the identification of underlying problems, the construction of valid and complete solutions and the creation of immune implementation plans.

According to Héctor de Bernardo, 2000, TOC is a systemic methodology for managing and improving a company.

TOC is a philosophy that is based on causality to optimize the performance of the organization by focusing effort only on limiting factors. (Abat, Caballero, Molina. 2006).

The TOC is composed of a set of methods supported by cause and effect processes oriented towards the continuous improvement of organizations and people.

The central idea of the Theory of Limitations (TOC) is that every real subsystem, such as a for-profit company, must have at least one limitation. If this were not true, the system would produce an infinite amount of what it is trying to achieve. In the case of a for-profit company, it would produce infinite profits. Since a limitation is a factor that prevents the system from achieving more than what it intends, this concept is applicable to any type of system that has predetermined objectives and in which different resources are involved in achieving them; then an entrepreneur or company manager, who wants to achieve more benefits, must control the limitations.

It is really not possible to choose in this matter. Either the limitations are controlled or they control everything else.

The constraints will determine the results of the system, whether they are known and managed or not.

The OCD developed by Dr. Eliyahu Goldratt, assumes that any system has at least one restriction. If not, you could generate an infinite number of products.

Thinking in this way, the theory of constraints is easily explained through the use of the "chain" analogy: "a chain is only as strong as its weakest link."

If we look at the organization as a chain, where each department is a link, what restrictions does our organization have to achieve its goal? Only by focusing on the weakest link, on the constraint, can we achieve substantial improvement.

In other words: if the constraints determine the speed of the organization to reach its goal, it makes sense that focusing on the constraint will allow it to achieve a substantially faster rate of througphut generation.

TOC is a management approach whose set of instruments answers the questions: What to change? (What is the problem ?, what is the restriction?), What to switch to? (What am I going to do instead? What is the solution?) And how to bring about change? (How to implement the solution in my company, despite resistance to change?). This theory aims to focus the attention of entrepreneurs and unleash their creativity towards results that have to do with the objective of the system, as well as with the elements with the greatest impact in achieving these objectives. That is why the way of conducting changes constitutes the pillars of this scheme of thought or continuous improvement.

The theory of constraints allows changing the paradigms under which organizations operate, achieving notable improvements in their performance and higher profits.

A restriction is nothing more than any element that prevents a company from improving in relation to a goal pursued.

Constraints are what prevent the organization from achieving its highest performance in relation to its goal; they are, in general, erroneous decision criteria, says Héctor de Bernardo, 2000.

The important derivation of this theory is that the decisions and actions that are taken with the intention of improving the economic objective of the company must be focused towards the restrictions. Thus, to the extent that these are identified, used and raised, the company will improve its profitability. As there are always restrictions to doing the following, it becomes a process of continuous improvement.

The theory of constraints is based on the principle that all firms have at least one "critical constraint" (a weak link), which prevents them from generating infinite profits. These restrictions were classified into two types:

physical restrictions; political restrictions.

A physical restriction is any element of the production system whose capacity is lower and / or its cycle is greater than what is demanded to satisfy the final objectives of the system, these restrictions are normally: the market, manufacturing and the availability of material cousin.

Political restrictions are the possible schemes, paradigms and mechanisms that prevent obtaining the results expected by the goal (Goldratt, 1995). These are usually behind physical restraints.

This theory aims to develop a comprehensive management system of the company through the recognition and use of critical resources, with the aim of reducing inventories in processes and reducing production times.

In short, the first phases of TOC can be defined as the search and resolution of bottlenecks in industrial processes, the systematic use of "good sense" and the identification and overcoming of perverse paradigms, which attack productivity and profitability. of bussiness.

Within the theory of constraints (TOC), three parts can be defined:

A set of tools for problem solving, known as thinking processes (TP), which aims to answer logically and systematically the three essential questions of a continuous improvement process: what to change? change ?, how to cause change ?. A set of management tools for daily activities resulting from thought processes that can be used to significantly improve vital managerial activities such as communication, change implementation and empowerment Innovative and proven solutions, created through the application of thought processes, in specific areas such as production, distribution and project management, among others. This is the focus of this research.

A system only shows its limitations when it is pushed to extreme situations. A system is in an extreme situation when:

he is at the maximum of what he can give; the maximum is demanded of him but he is not giving it.

Goldratt, 1995, argues that managers who want to make real progress must learn to break through limitations rather than just accept them. This vision is reflected in the five steps of focusing on continuous improvement:

1. Identify the constraint (s) of the system.

It means finding the points, the resources that are not enough, in order to define to what extent these limit the overall performance of the system. In this step it should be borne in mind that:

the number of restrictions is extremely limited; do not waste the use of a restriction; the value of the magnitude of the impact of the restrictions on the organization must be appreciated;

2. Decide how to exploit the constraint (s) of the system.

Exploiting simply means getting the most out of it, not wasting the limitation; the non-restrictions must supply all that the limitation must or needs to consume, but no more;

3. Subordinate everything else to the previous decision.

Subordination defines the roll of operations that are not constrained. Its purpose is to protect the set of decisions related to the exploitation of limitations during daily operations, that is, in this space the system restriction (s) should be opened;

4. Raise the constraint (s) of the system.

It means that it is time to:

lift the limitation (s); add more and more of the things we did not have enough; break the constraint (s); move the company forward;

5. If the limitation has been broken, go back to step 1.

If the five steps are successfully followed and especially inertia is not allowed to slow down the process, an organization can break the limitation one after the other and continue to progress. Do not allow inertia to cause system throttling. If a limitation has been broken, something will immediately become a limitation.

The process is always the same, regardless of the restriction, says Héctor de Bernardo, 2000.

Then all efforts should be directed to effectively identifying and managing the new limitation. The policies established for maintaining the old limitation must change or be removed. If this procedure is not started, the process will stop or even regress, as the disenchantment spreads.

When applying the TOC philosophy as a continuous improvement process, the following principles should be taken into account (Goldratt, 1995):

The capacity of a plant must not be balanced. The system is oriented towards the balance of flow, not capacity; The level of utilization is a resource that is not a bottleneck, it is not determined by its own capacity, but by some other restrictions in the system. Because of this they are supposed to be bottlenecks based on other system constraints; Keeping a resource active does not mean that it is being used. Programs must be generated that maximize finished production and minimize inventories and unforeseen effects; The time that is lost in a bottleneck is time that is lost in the entire system, it is convenient to use the least possible time in the preparation of the bottleneck resource; The time saved in a non-bottleneck operation is of no value,It is advisable to plan as many changes as possible in the time available, to process small batches or minimize inventories; Bottlenecks govern both finished production and inventories; Safety inventories should only be used to ensure that the expected level of momentary production is maintained; The transfer lot does not have to be the same as the production lot; subdividing the production batch into a transfer batch allows to improve the fluidity of the operation; The production batch must be variable and not fixed; The programming must be carried out considering all the limitations of the system simultaneously.both finished production and inventories; Safety inventories should only be used to ensure that the expected level of momentary production is maintained; The transfer lot does not have to be the same as the production lot; subdividing the production batch into a transfer batch allows to improve the fluidity of the operation; The production batch must be variable and not fixed; The programming must be carried out considering all the limitations of the system simultaneously.both finished production and inventories; Safety inventories should only be used to ensure that the expected level of momentary production is maintained; The transfer lot does not have to be the same as the production lot; subdividing the production batch into a transfer batch allows to improve the fluidity of the operation; The production batch must be variable and not fixed; The programming must be carried out considering all the limitations of the system simultaneously.The production batch must be variable and not fixed; The programming must be carried out considering all the limitations of the system simultaneously.The production batch must be variable and not fixed; The programming must be carried out considering all the limitations of the system simultaneously.

Considering the principles on which this philosophy is based, the company must be analyzed as an interrelated system of links or parts based on a specific goal.

Most companies can be seen as a related sequence of processes that transform inputs (raw materials) into salable outputs (final product).

In TOC the chain analogy is often used. If you want to improve the strength of a chain, what is the most effective way to achieve it? Will we focus on the largest link? Do we apply uniform improvements to all links? Or should we try to identify the weakest link and then concentrate our efforts on strengthening that precise link?

It is clear that the last proposal will produce the most benefit relative to the effort put in.

Continuing with this analogy, the procedure to follow to reinforce the chain is very clear.

First, identify the weakest link, which is the limitation. This identification can be easy, because most of the processes in a company try to control fluctuations in demand and accidental interruptions by maintaining safety inventory at each step of the process. These inventories of work in progress hide problems, obscure interdependencies and make it difficult to identify the true limitation of the system. Second, do not expect the system to be subject to excessive load, if the chain is stressed by a greater load than the weakest link can bear, the chain will break. The weakest link should set the pace of the entire system. Third, focus improvement efforts on the weakest link. Fourth, if improvement efforts are satisfactory,Eventually the weakest link will improve to the point where it is no longer the weakest link. Any subsequent efforts to improve the previous weakest link will yield little or no benefit. At this point, the new weakest link must be identified and improvement efforts directed towards it.

The theory of restrictions proposes a new way of managing companies, without ignoring the importance of previous approaches and seeking at all times a recognition of the simplest concepts.

This approach is obviously very attractive for managers in organizations, considering that its postulates promote a return to less complex financial metrics that can be understood by those in the company outside the financial function. In its development, the theory of restrictions recognizes that the basic objective of a company is the generation of money, so it weighs the importance of the wealth creation process for shareholders and other interest groups in the company. Undoubtedly, one of the most important contributions of the theory of constraints is that it clearly defines that it is not necessary to use 100% of the resources, since only maximum use of those resources with constraints is desirable.

If a resource is not considered a restriction, it should not be used more than what those with restrictions allow, since this creates problems for the company such as inventories, high levels of costs and waste in its broadest meaning.

When viewed in detail, the financial implications of the theory of constraints do not go beyond a simple grouping of accounts or cost categories. In any case, this does not detract from its merit, since this new grouping allows a better visualization of the company's performance and, above all, avoids concentrating efforts on sometimes unsuccessful activities such as cost allocation processes. Its premise of not making the "non-assignable" "assignable", far from being an offense against the traditional accounting technique, is simply an invitation to focus efforts on performance improvement and not on complex and expensive techniques that do not necessarily end in good results (Manotas Duque, Manyoma Velásquez; 2002).

In general, we can conclude that OCD is a causal relationship that makes the qualitative and quantitative leap that other management philosophies seek, concentrating attention on the critical points that inhibit the scope of "The Goal".

At this point, it is important to underline that OCD does not divorce from any of the aforementioned philosophies, but rather they complement and enrich each other, achieving synergy between them.

All of these philosophies are valid; In this case, the TOC is considered the most complete, although it suffers from how to proceed to implement it, because the stages that make up the process of determining the limitation are very general, where it is not established in the literature how to proceed, since the determination of limitations relies only on experience-based conceptual analysis and does not provide a structured procedure.

1.2 Logistics. Fundamental tool for competitiveness

The new competitive reality presents a battlefield where flexibility, speed to market and productivity will be the key variables that will determine the survival of companies. And this is where logistics plays a crucial role, from the efficient management of the flow of goods and services to the final consumer.

Logistics is a term that has evolved over time. It is frequently associated with the distribution and transportation of finished products; However, this is a partial appreciation of it, since logistics is related to the administration of the flow of goods and services, from the acquisition of raw materials and inputs at a point of origin, to the delivery of the finished product in the point of consumption.

Bernard Lalonde and Martin Christopher define logistics as the union of the management of materials with physical distribution.

The Spanish Logistics Center defined this activity based on two basic functions: materials management, in charge of material flows in the supply of raw materials and components and in manufacturing operations, up to the packaging of the finished product; and distribution management, which considers packaging, inventory control of finished products, through handling, storage and transportation processes until the product is delivered or customer service.

Dr. Antun, from the Autonomous University of Mexico, defines logistics in its broadest sense as: relationalization of flow management, that is, synchronizing the flow of goods and the information management of an economic organization.

According to Parada Gutiérrez, 2003, Logistics addresses the study of the set of activities that are developed on the material, informational and financial flows from an origin to a destination with a systemic and integrated vision with the aim of providing internal or external customers with the organization a quality service at the right time with a minimum of expenses.

Logistics is the art and science of managing the organization of technical activities, related to the needs, the conception and handling of the letters that support the objectives, forecasts and operation of the company, as well It is defined by SOLE (Society for Logistics Egineers, USA).

This concept has been nurtured by the benefits of the JIT approach, MRP and other modern production management systems, reaching our days with the name of Business Logistics or Supply Chain Management, as a way of directing production processes under the perspective that the four fundamental parts of the process (supply-production-physical distribution-logistics of the residuals), should work fused, harmoniously integrated, as the only way to achieve an adequate level of customer service at the lowest possible cost, without causing damage to the environment (Cespón, 2001).

Logistics is the business activity that inherently manages all the flows in the system, in correspondence with the stakeholders (Abat; Caballero; Molina, 2006).

It is the efficient management of coordinating and integrating a set of activities required to plan, execute and control the material flows as well as the flows associated with it from the supply, within the company and to the consumer (customers), taking as an object to be delivered the product at the right time, in the desired quantity, in the required conditions and all at the lowest possible cost.

Logistics is a process that the organization goes through “horizontally”, affecting each of its functions and tasks, and, as such, it is necessary to generate an adequate information system that allows all actors to be involved, that is, measure and control the global value generation process. These interrelationships of logistics activities with each other and between these and each of the areas of the company, suggest an integrated system where each and every one of the activities requires adequate coordination to optimize the operation of the business process, reduce costs and promote a better level of customer service.

The idea of integration is based on the fact that the value for the customer is not generated in a specific place, but throughout the entire logistics chain. Logistics management thus becomes an important tool in the competitive strategy of organizations figure 1.

Figure 1: Path of competitiveness. Source: Acevedo; I. Gomez (2001).

The business logistics system has a heterogeneous definition, where its material component parts will be identified. If the material flow, which is the backbone of logistics, is taken as a reference, then the following subsystems of the logistics system can be identified (Taboada, 1993):

Provisioning.

It includes all those activities that allow those raw materials, materials, parts and components that are required to move from the supplier points to the company. This subsystem is also responsible for the movement of these materials from the raw material warehouse to the production areas. It comprises, therefore, activities of transport, handling, storage, inventory management, quality control, among others;

Production.

This subsystem is in charge of the manufacturing itself, that is, the transformation of the different work objects (raw materials, materials, etc.) into finished products, so it necessarily includes, in addition to manufacturing activities, transportation, storage, handling, quality control, inventory management, among others;

Physical distribution.

Through this subsystem it is possible to bring the finished products that were delivered to them by the previous subsystem to consumers. It includes the execution of storage, handling, transportation, packaging, inventory management, among others.

In this way, all those activities that involve the movement of raw materials, materials and other inputs are part of the logistics processes, as well as all those tasks that offer adequate support for the transformation of said elements into finished products: purchases, storage, inventory management, maintenance of facilities and machinery, security and plant services (supplies of water, gas, electricity, fuels, compressed air, steam, etc.).

Logistics activities must be coordinated with each other to achieve greater efficiency throughout the production system.

For this reason, logistics should not be seen as an isolated function, but as a global process of generating value for the client, id est, an integrated process of tasks that offers a greater speed of response to the market, with minimal costs, where It is appreciated that logistics management is the process of planning, implementation and control of the flow and efficient and economic storage of raw materials, semi-finished and finished products, as well as the associated information.

These interrelationships between the logistics activities among themselves and between these and each of the company's areas, suggest an integrated system, where each and every one of the activities requires adequate coordination to optimize the operation of the business process., reduce costs and promote a better level of customer service.

1.2.1 Why see Logistics Management as a system?

Much has been said so far about the need to apply a systemic approach in logistics management, but until today there is no scientific basis for the aforementioned, so the authors set about the task by using statistical techniques of validate this systemic approach as well as the need for its application in companies.

For the study, the concepts that, in the authors' way of seeing, set a pattern in the evolution of the term logistics, it was possible to see that logistics in the first concepts is reduced only to the movement of materials, which later became management of the technical-material flow. In a later stage, new terms emerge, such as information related in conjunction with the material technical flow and customers, which will eventually become the center of this function. A function as old as storage begins to take its true role at this time when it is needed to respond to the requirements of a consumer who was beginning to become a customer.

Then, these advances caused extremely encouraging results in the financial flow of organizations, assumed at the same time as the vertebra of logistics management, all this leads to logistics becoming a fundamental tool for competitiveness, and what until now was referenced as related information develops to become information flow; The relationships between the actors and the need to tighten them (both social and economic) led to the zenith of the evolution of this term, moving from a business function to a management philosophy, that is, to Supply Chain Management, where The activities of several companies are coordinated with the objective of maximizing the profits of all of them (ACHIEVING THE GOAL).

In the evolution of the term, categories were appearing, which included a series of activities and even functions of logistics management, which are grouped by the authors within three fundamental dimensions: Management of technical-material flow, Customer focus and Effectiveness. The critical analysis of each of these dimensions leads to the generation of elements that are present in one way or another in the logistics process, particularized in each of these dimensions, being proposed for the consideration of specialists, chosen by the authors applying a sampling intentional based on the premise that they were aware of the subject in question, through a survey in which these elements were randomly placed on purpose.

The data collected through the survey were processed in the Statistic Program for Social Sciences (SPSS) using a Cluster analysis using the nearest neighbor method, deriving two variants of it: by cases, which are the respondents chosen by the authors. This analysis reported encouraging results for the authors, observing that at the distance of ten there are still great differences in the opinions of the respondents; This corroborates the authors' criterion that it is necessary to apply a systemic approach in logistics management because the discrepancies among the respondents lie in the greater or lesser importance given to the items belonging to each of the defined dimensions, but the coincidence is that they include in their selection items of all dimensions.

The other analysis carried out was the one by variables in which it is observed that at a distance as close as five the opinions of the respondents coincide in the variables handling, storage, inventories and transportation are fundamental in the logistics system as well as the planning and organization variables, Although these variables may have more or less value at the different decision levels, they are present in all the subsystems of the logistics chain, demonstrating the aforementioned need to apply a systemic approach.

In the second part of this questionnaire, the respondents define actors that, in their view, condition the Logistics Management of organizations. They can be grouped into three large groups: Customers, Transformers and Suppliers; Although there was a difference among the respondents regarding which actor to give greater relevance to, the authors consider that all of them in one way or another have a fundamental role and it would be inconsistent to assign a higher priority level to any of them. What is vital to define are the relationships between them, taking into account the degree of fragility and importance of each of the relationships established between them,It is necessary to emphasize that the ties between external actors and the organization in question are much more fragile and therefore more difficult to improve and maintain than those that can mediate between internal actors that, due to greater forces, will have to be overcome to achieve the maximum development of the organization.

1.3 Logistics and Management by Restrictions

The idea of integration is based on the fact that the value for the customer is not generated in a specific place, but throughout the entire logistics chain. Management by constraints thus becomes an important tool in the competitive strategy of organizations, so its starting point is to respond to the basic objectives of organizations.

For the implementation of management by restrictions, an analysis of the synchronization of the components of the logistics system is necessary, which will allow to achieve an agile flow to respond quickly to a changing and increasingly demanding demand, it is necessary to address the logistics system considering the following subsystems:

Supply Logistics, which groups together the functions of purchasing, reception, storage and inventory management, and includes activities related to the search, selection, registration and monitoring of suppliers. Plant Logistics, which includes maintenance activities and maintenance services. plant (supplies of water, electricity, fuels, etc.), as well as industrial safety and environmental care. Distribution Logistics, which includes the activities of dispatch and distribution of finished products to different markets, constituting a nexus between the production and marketing functions.

The Supply and Plant Services subsystems can be grouped under the name of Production Logistics, since both are closely related to the tasks of manufacturing goods and / or provision of services.

In the design of Logistics Systems it is necessary that there be close coordination between the subsystems. To achieve this goal is the central idea of the analyzes carried out in the different organizations, with the aim of guaranteeing the operational proportions between all the links according to the clients.

All of the above evidences the role of logistics management in determining the restrictions due to the impact of this on customer service.

Proper management of the flows of goods and services is of central importance, not only to achieve a reduction in costs associated with the supply, production and distribution processes, but also to offer a quick response to customer requirements.

Management by Constraints is a way to plan, organize, evaluate and control complex systems. Contrary to most managerial approaches, Management by Constraints is a systems approach methodology. Rather than treating a complex system as the sum of its independently managed parts, it approaches companies and organizations as a whole made up of interdependent parts.

Deming, in his book "The New Economics for Industry, Government and Education" (1993), characterized the systems approach as follows:

Optimization is the process of orchestrating the efforts of all components toward achieving the stated purpose. Optimization is a management task.

Everyone wins from optimization. Anything that is not optimizing the system will bring losses to each of the components, at some point. Each group should have as its purpose the optimization of the larger system of which the group is a part. "

All of the above shows that the duty of each component is to contribute what is best for the system, and not to maximize its own production, profit, or sales, or any other measure of competitiveness. Some components may run at a loss to optimize the entire system.

The roots of the Management by Constraints as it has been raised is composed of definitions about systems, and principles of operation of the same. One of the central concepts of the Theory of Constraints, and the management prescriptions emerging from it, is the idea that complex systems have an analogy with chains: The entire chain is no stronger than its weakest link (the system constraint). Management by Constraints tries to exploit the potential of the total system by managing its weakest links.

In the turbulent business world, speed to market then becomes an essential tool to create value and achieve a good position in the competition race, hence the need to analyze two essential variables in the operation of systems:

Performance and cycle are the essential variables that are distinguished in the logistics flow according to (Acevedo, 1996). Each process has a throughput and takes place in a given cycle. The cycle is associated with the organization of the material flow management of the process in question. Performance is associated with the capacity of the process, a variable that does not have a static behavior, but is associated with a set of factors that undergo variations over time.

The definition of the concept of productive capacity has a high methodological significance, because all the procedures for its calculation and analysis are derived from it.

Different authors have approached this concept:

"It is the maximum amount of products to be obtained with the full use of the available productive fund" (Albertina Fundora, 1987); "It is the maximum production rate of an operation" (Schroeder, 1992); "It is the maximum possible production in a given period (or the volume of production of raw materials) in the nomenclature and quality demanded by customers, fully using and in correspondence with the regulated work regime, the equipment and the available production areas ”(Acevedo, 1996).

This concept, in its practical application, presupposes the following methodological principles:

The calculation of the productive capacity of the company is carried out by its workshop or aggregate considered as fundamental, which is defined as that point at which the highest work expense of the company is used, requires greater investments or the use of technology characteristic in obtaining finished products. The capacity of the system is given by the limiting link or bottleneck, whose optimization usually requires small investments, or only various technical-organizational measures; The production capacity is also determined by the structure of the assortments, whose variation It is associated with the variation in production capacity; The productive capacity must be calculated for the maximum use of the time fund of the equipment and productive areas,determining from the work regime considered as rational for the type of company analyzed, without deducting the effects on said regime due to problems of workforce, raw materials, etc.; The production capacity is expressed in the same unit in which it is expresses production, that is, in physical units and / or value; A key point in the calculation of production capacities is the use of the time expenditure regulations of the different product assortments of each workshop, sector or group of equipment; In the calculation of production capacities, all the productive equipment available to the company are considered; The variation in the quality and design of the products implies variation in the capacity (increase or decrease) given by the differences in laboriousness in magnitude and structure.

Therefore, in the foregoing, the following is considered:

The capacity balance of each process must be seen as a variable magnitude over time resulting from the evaluation of the situation of the process itself; of the company and the environment on the one hand and the actions of the management on the other, which seek to modify the different factors influencing capacity; The capacity balance must be a permanent attention of the management and covers the processes of all links in the logistics chain: manufacturing, service, storage and transport.

This presupposes the adequate integration between the capacity and cycle concepts, in which all the processes of the system are objectively executed, a key factor to achieve the competitiveness required by the current dynamics.

Today companies carry out their activities in a turbulent and increasingly competitive environment, having to work with little financial availability, eliminate inventories, reduce cycles and respond quickly to customers, which requires, as a condition of survival, to react quickly and effectively based on of the client, the market and the environment in general at the minimum cost.

1.3.1 Logistics Management by Restrictions. A current need.

Taking into account the current world's need to be competitive, the solution lies in placing the customer and their needs at the center of attention of the production systems and from these with a logistics approach and applying the TOC management philosophy to coordinate the efforts of the organization to satisfy them, defining the know-how of the procedure to follow.

To accelerate change and turn it into a true continuous improvement process, it is necessary to find a mechanism that allows the organization to be managed in a global way and to answer three questions in a continuous and systematic way: what to change, what to change to and how to bring about change.

As a result of the application of the TOC and with the identification and adequate management of the restrictions, significant improvements are achieved in a short time.

For this reason, to determine the restrictions of the production or service systems, starting from this logistic approach, it is necessary to develop the guidelines that allow to guide the execution of this study, which as a methodology can be used in any entity.

Conclusions

From the exhaustive bibliographic review carried out, the following conclusions can be reached:

The need for companies to undertake a Continuous Improvement Process, due to the turbulent scenario in which they operate, which increases environmental threats and endangers their survival, although it also provides them with a wide range of opportunities for their development and is These are the ones that must be strengthened. The theory of restrictions constitutes an integrating philosophy in logistics processes, due to its effectiveness and because it maintains the logic that every improvement process must maintain in any type of organization Management by restrictions must necessarily be applied with an approach logistics, which leads to the undertaking of continuous improvement processes to achieve a correct use of resources.The absence of a method for the implementation of TOC, which causes a subsequent study to be carried out to correct this deficiency.

Bibliography

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