The application of reliability to product and process engineering has provided a tool for the anticipation of operating failures; through the development of field tests, as well as the analysis of failures and their corresponding probabilities of occurrence, as these offer the possibility of developing robust products and processes capable of manufacturing them.
Thus, many of the production problems can be prevented through reliability techniques, and with this, it is sought to obtain products according to the customer's expectations, with regard to their durability and quality. (Acuña, 2003)
However, usually the topic of reliability engineering produces confusion between the concepts of reliability, risk and security; Since, as mentioned, the notion of reliability analysis has been adopted on a regular basis, to refer to failures or the operation of processes and equipment. However, the term risk analysis is used more broadly to characterize, in addition to failures or the operation of processes and equipment, the study of safety parameters, translated into terms of possible damage or risks in the system itself, or to people, facilities and goods, to the company, the environment, the community or third parties. (Cicco, sf)
Consequently, in the current era, after the efforts to manufacture products that meet the requirements established by customers, which are becoming more and more demanding; Actions are directed to create and design products and processes that meet these expectations, throughout the development of their useful life. Since as expressed (Acuña, 2003): "The study of the probability of failure that allows to better estimate the life of the product, is a decisive element to achieve the objective of any quality system: To achieve complete customer satisfaction"
What is Reliability Engineering?
Reliability engineering focuses on fault elimination processes through the use of various analytical tools that allow to improve processes, activities, resources, designs and others, within corrective, preventive and predictive maintenance tactics.
The term reliability is described by the (Real Academia Española, 2014) as the probability of a good functioning of something. Therefore, extending its meaning, reliability is defined as the probability that a good or process will function properly during a given period under specific operating conditions, for example, conditions of pressure, temperature, friction, speed, stress or vibration level., among others.
At present, most of the goods and services are obtained and marketed until they reach their recipients, through the so-called productive system, which varies from one organization to another, both due to their size, the number of people who work in them and the value of the facilities and equipment used for this purpose. And characterized by containing various phases throughout its life cycle, where the first of them is construction and start-up, until the normal operating regime is reached. During the second phase, called operation, is the genuinely productive period, in which the system is subjected to failures that hinder or even temporarily or permanently interrupt its operation. Thus, the purpose of maintenance is precisely to reduce the negative incidence of such failures, either by reducing their number or mitigating their consequences. (Ponce & Campoverde, 2013)
In this way, it is said that something fails when it stops providing the service for which it was intended or when undesirable effects appear, according to the design specifications with which the good or process in question was built or installed.
In general, everything that exists, especially if it is mobile, deteriorates, breaks or fails over time, that is, it suffers depreciation and deterioration, whether in the short, medium or long term. The mere passage of time causes in some assets, obvious decreases in their characteristics, qualities or benefits. For this reason, the study of failures in products, equipment and systems, is what reliability engineering is all about.
In this sense, the legitimation of the quality of the different products and services offered in the market has been a universal concern, since providing the user with a quality product is a matter of utmost importance to guarantee the success of the companies. For this reason, to ensure rapprochement with the consumer, organizations often resort to large marketing campaigns that allow them to set the good image of their product in their audience. However, it is imperative to fully comply with the characteristics communicated to the consumer, even more so, when the lives of human beings depend on the correct functioning of the product or service, since they must comply with high levels of quality and guarantee their correction. In the same way it happens with various projects created, which somehow, after their consummation,could represent negative social, environmental and economic consequences; unfortunately, the incorrect validation of quality criteria has led through history to great disasters in society.
Figure 1. Reliability of the production system (Campo, 2006) (See PDF)
In relation to the aforementioned, it is considered that someone or something is reliable if it can be trusted, since we associate reliability with the ability to reliably depend on something or someone.
In the case of the productive systems implemented in each organization, these are intended to satisfy a specific need according to their line of business and activity; being necessary that they work in a specific way in a certain environment. However, as already mentioned, all systems reach an instant in their cycle, in which they cannot satisfactorily comply with what they were designed for, since it must be remembered that every product or system deteriorates only with the passing time, causing failures that have repercussions to a greater or lesser extent, depending on their magnitude and when they occur.
So, if the designed systems need to be reliable, but we are aware that at some point they will suffer deterioration and subsequent failure, the level of reliability or safety of satisfactory operation will depend on the nature of the objective of the system, anticipating that the user can operate it without high risk.
On the other hand, reliability is clearly an essential factor in the safety of products launched on the market, since, to achieve the objectives of adequate functional performance, limitation of life cycle costs and safety, the design phase is the moment when a major influence on them can be achieved. Consequently, most of the reliability studies and the methods developed for their assurance focus on the product design stage.
(Caro, López, & Miñana, The reliability engineering of computer systems through EMSI, 2013)
As a result, reliability engineering studies the longevity and failure of products, equipment and processes, in order to find their causes, applying scientific and mathematical principles that provide greater understanding in this regard and, later, allow to identify improvements that are implemented. in designs, to increase their useful life or to limit the adverse consequences of failures. (Caro & García, The importance of statistical thinking in reliability engineering, 2012)
Definition: Reliability is the probability that a device will adequately perform its intended function over time, when operating in the environment for which it was designed. (Garcia, 2013)
The important thing is that the client, with the products and systems they acquire, satisfy their needs, through the benefits expected of them and with a high level of security and confidence in their correct operation. For this reason, it is necessary to consider reliability as a discipline, from the analysis of the need identified in the market, to the withdrawal of service of the system or designed product, in an integrated way with the rest of the logistics support disciplines. (Sols, 2000)
It should be noted that four specific and important attributes stand out in the definition shown, referring to reliability engineering:
- Probability Adequate functioning Qualification with respect to the environment Time
Reliability Engineering Background (Cicco, nd)
One of the factors that have a crucial impact on the productivity of companies is the reliability of systems, for example, work methods, equipment and facilities. And therefore, the optimization of productivity requires the consideration of the reliability factor from the strategic planning of the organization, with respect to the risks inherent to the corresponding business activity.
The first indications in the quantification of the reliability appeared in the aeronautical industry, consolidating later in the aerospace industry; When in the United States, in the late 1940s, efforts to increase reliability focused on product quality, as significant advances were made in the development of projects, materials, testing instruments, etc., trying to increase the useful life of said products or of the production systems from which they came. In the same way, notable progress was made in the area of maintenance, especially in the means and techniques dedicated to preventive maintenance.
Since the early fifties, the issue of security began to be given greater importance, especially in the aerospace and nuclear field; requiring the use of reliability in military equipment, in order to minimize the probability of failure of any equipment in war.
Later, in the sixties, in the United States of America, various functional tests of components and systems were carried out; obtaining various records that were analyzed in each failure mode and their corresponding effects; In order to do so, define the preventive actions that should be taken on the subject of security.
Thus, in the complex work of risk assessment in nuclear power plants, a wide spectrum of accidents was analyzed, classifying them according to their possibilities of occurrence and assessing their potential consequences for the population and for the environment. (Cicco, sf)
Risk analysis
Initially, it should be noted that the term risk is defined by the (Royal Spanish Academy, 2014) as the possibility of damage to people, property and the environment, in a certain period of time.
However, after the probability of the occurrence of an adverse event, problem or damage and the consequences thereof, the risks must be evaluated and the best way to manage them must be determined, which constitutes a great challenge; since it is difficult to appreciate all its origins and foresee all its effects with a control measure, since there will always be a certain degree of uncertainty. However, thanks to its evaluation and the clarity of its complexity, it facilitates decision-making regarding the nullity or reduction of its effects. A risk analysis is made up of three stages (Cicco, nd):
Phase I: Risk assessment
Stage in which the system to be analyzed is defined and potential risks are identified, that is, a general review is implemented using techniques such as:
What-lf1Checklistn: It is a process risk review procedure that, properly conducted, allows the identification of a wide spectrum of risks. The consensus between areas of action (production, process, security, etc.), on how to move towards safe operations; and an easy-to-understand report serves as training material. It is a basic method for the development of other analysis techniques.
Preliminary Risk Analysis (APR): This is a technique that allows a general review of the risks that will arise in the operational phases, classifying them in order to establish a priority of preventive and corrective actions. It generates a range of control measures and is essential in highly innovative systems.
Phase II. Risk management
Qualitative and quantitative study of the sequentiality of accidents and failures, through the application of techniques such as:
Operational and Risk Study: This is a technique that aims to analyze specific risks of a process plant, as well as operational processes that may compromise its ability to obtain the projected productivity. It generates a range of measures that allow the reduction and elimination of the identified risks and the reduction of operational errors. It is essential in new projects, extensions and studies of existing units.
Analysis of Failure Modes and Effects: It is a technique conceived for the detection and control of risks originated in the equipment, as it identifies critical components and generates a relationship of countermeasures. It favors an increase in the reliability of the system through the treatment of components that cause failures of critical effect, since once the design of the product has been carried out, and before proceeding to its manufacture, its different components are reviewed, checking if they meet the necessary characteristics for its correct operation. In this way, to facilitate this review, possible errors that may occur in the operation of the product are shown and solutions are generated in order of importance, before the product is placed on the market and goes into operation.
Failure Tree Analysis: A quantitative-qualitative analysis technique that allows a highly unwanted eventuality or catastrophic event to be addressed in a logical and systematic way. It can provide probabilities of occurrence of the event and identifies the simultaneous failures triggering catastrophes. It produces excellent results in complex systems, where other methods are ineffective.
Consequences and Vulnerability Analysis: This is a technique that allows the quantitative and qualitative assessment of the consequences of catastrophic events with wide repercussions, as well as the vulnerability of the environment, the community and third parties in general.
Phase III: Risk communication
In risk analysis, technical aspects are discussed among managers, evaluators, and private sector stakeholders; Therefore, when deciding the best way to control a risk and to implement prevention or containment measures, communication between risk managers and the public and private sectors is of utmost importance, since points are taken into account from an ethical, social, environmental and economic point of view.
It should be noted that, with the application of these techniques from Phase 1, it is possible to define the strategies to be adopted for the management of detected risks. On the other hand, derived from the growing demands of public opinion and legislation, today, organizations must quantify their risks, establish the basis of their severity and frequency in a formal way and not in an empirical and subjective way.
In summary, management based on reliability and risk analysis allows defining the strategies to be followed for effective risk management, thus establishing those that are acceptable, how serious a possible accident would be, how much should be invested in prevention and protection, how unacceptable risks can be reduced, which solutions would optimize the cost-benefit ratio, which risks should be transferred to the insurance market and which should be absorbed by the company itself.
Taking these considerations into account, the requirements for quality, reliability, safety, maintenance and availability of systems and products translate into productivity. And to optimize it, from the strategic planning of the organization, the risks inherent to its business activity and the ways of scientifically managing them must be considered. (Cicco, sf)
Quality-reliability ratio of products
Reliability is applicable not only to machines, equipment or products, but to all the processes that make up the value chain of organizations, and therefore has a direct impact on the results of the company, since it affects safety aspects, integrity of the environment, product quality and customer service, etc., contributing to the cost-benefit ratio.
Likewise, the buyer for his part, in addition to the desire for a good price, is interested in the reliability of what he acquired, since the customer expects the availability of the product's operation over a long period of time. However, remembering that reliability is that part of the quality that includes the behavior of the units during a certain period of time and under given use conditions, these must be observed for the correct operation of the unit. Therefore, when products are designed, two systems are used to improve reliability and reduce the probability of failure:
Improvement of individual components: Often a finished product does not work properly unless all of its sub-components are working properly. In these cases the reliability of the different subcomponents must be greater than the desired reliability of the finished product.
Include redundancy: Redundancy is obtained if one of the components fails and the system can resort to another to replace it, therefore, to increase the reliability of the systems, redundancy is added, that is, components are backed up. (Padilla, sf)
Finally, for the achievement of a high level of reliability in the products, the planning or design stage is decisive, since the adequate choice of components for their manufacture is made and the required parameters of reliability of the planned product are built.
Reliability of the production system
The reliability of the productive system of an organization is based on an effective management of the various elements involved. Some aspects that, when properly managed, contribute to creating reliability in the production systems of companies are described below.
Equipment reliability is understood as the probability that it will break down, present operating problems or require repairs in a given period. Likewise, reference can be made to the reliability of a service, process, work team or collaborator, such as the probability that it operates under the conditions established for its work. In this context, there are three ways to improve the reliability of a computer:
Component Design Improvement: To calculate the reliability of a system in which each individual component has its own reliability index, simply multiply the reliability indexes of each independent component. Therefore, to improve the overall reliability of the system, it is necessary to renew the design of its different components.
Pokayoke is one of the techniques used to prevent possible errors in the production system, and seeks to design error-proof products, processes and systems, trying to make wrong actions more difficult, making it possible for erroneous actions to be easily corrected, avoiding errors. actions that cannot be rectified and allowing easy error detection. All this, using control methods that, for example, turn off the machines or block the operating systems, preventing the same defect from occurring; or implementing warning methods for abnormalities that have occurred, alerting the worker by activating a specific light or sound.
Reduction in the number of equipment components: Production equipment and systems are composed of different individual components related to each other. Each component performs a specific function, so a failure in it can cause a global failure of the system. Thus, for example, a failure in the hard disk of a computer will cause the entire equipment to stop working, even though the rest of its components work correctly. Therefore, one way to increase the overall reliability of the system would be to reduce the number of components that comprise it.
Component redundancy: It seeks to increase the reliability of a device, after using redundant components in parallel, so that, if a component fails, the spare element immediately goes into operation. In this case, the existence of redundant equipment is usually common in those situations in which the failure of the system can cause significant losses for the organization and even cause the loss of human life. Thus, for example, hospitals have redundant power generators to allow an operation to continue when the main generator system fails. (National Open and Distance University, sf)
Reliability measures
The most widely used reliability measure is known as the product failure rate, which calculates the percentage of failures in relation to the total number of products inspected, IF (%), or the number of failures during a given period of time., IF (n).
It should be noted that on many occasions equipment failures occur during the first moments of their useful life, this phenomenon being called early mortality. However, these failures are usually due to misuse of equipment. Therefore, to avoid a high index of this indicator, many manufacturing companies subject their products to prolonged tests to detect problems before they are marketed. In addition, they provide initial warranty periods and include clear instructions for use or offer training courses; All this, with the purpose of not damaging the image of the brand, if a claim or return is filed due to product failure or even, avoiding a social or environmental problem that could cause serious damage. (National Open and Distance University, sf)
conclusion
As has been stated, the purpose of reliability engineering is clear, however, its application requires complex analytical and probabilistic models, since regularly, organizations have a large number of processes, equipment and products that are in different phases of development. their life cycle and, therefore, the associated costs are of a different nature. Therefore, given its complexity, it is essential to have computer tools that allow a simulation that reveals the possible results of the strategies to be implemented, to reduce or eliminate failures.
Also, as is known, in the current globalized environment, where there have been radical changes in technology, administrative and commercial theories. The quality of the products and services offered to the consumer is essential for permanence in the market, and therefore, through the use of statistical methods to improve, a change of focus is manifested towards the improvement of reliability, since it becomes in a fundamental characteristic to have the opportunity to compete in today's complex and sophisticated markets.
References
- Acuña, J. (2003). Reliability engineering. Cartago, Costa Rica: Editorial Tecnológica de Costa Rica. Assuring me. (November 14, 2014). Obtained from http://asegurandome.com.ve/sistema-de-gestion-de-riesgos-en-el-sector-asegurador/Campo, J. (August 20, 2006). Systems engineer. Virtual Learning System. Obtained from http://renacersantaclara.org/academico/mod/forum/discuss.php?d=145Caro, R., & García, F. (2012). The importance of statistical thinking in reliability engineering. Mathematical Thought, 25 - 34.Caro, R., López, V., & Miñana, G. (2013). Reliability engineering of computer systems through EMSI. Madrid, Spain: Comillas Pontifical University, Complutense University of Madrid. Cicco, F. (sf). Reliability engineering and risk analysis. Fundación Mapfre.García, F. (2013).Direction and Management of Production: An approach through simulation. Barcelona, Spain: Marcombo, SAPadilla, L. (nd). Total Quality TQM. Obtained from https://calidadtotaltqm.wikispaces.com/ConfiabilidadPonce, Í., & Campoverde, J. (2013). Study for a preventive maintenance program to reduce the high level of unforeseen stops in the electric motors of the Roasting department in the company Gusnobe SA. Milagro: State University of Milagro, Royal Spanish Academy. (2014). Spanish dictionary. Madrid, Spain: Espasa. Obtained from http://dle.rae.es/?id=Hpsj999Ros, JL (September 24, 2015). Industrial Technology I, at the IES Ramón Arcas de Lorca. Obtained from http://tecnoarcas1bachiller.blogspot.mx/2015/09/fases-de-diseno-deun-producto.htmlSols, A. (2000). Reliability, Maintainability,Effectiveness: A systemic approach. Madrid, Spain: Comillas Pontifical University. National Open and Distance University. (sf). Obtained from http://datateca.unad.edu.co/contenidos/102508/Administracion%20de%20procesos%20pr oductivos / leccin_45_confiabilidad_del_sistema_productiva.htmlVásquez, A. (March 28, 2016). Information systems audit. Retrieved from http://asipuj.blogspot.mx/2016/03/coso-committee-of-sponsoring.htmlmx / 2016/03 / coso-committee-of-sponsoring.htmlmx / 2016/03 / coso-committee-of-sponsoring.html
Thanks
Special thanks to the research professor Fernando Aguirre y Hernández, professor of the master's degree in administrative engineering attached to the Orizaba Technological Institute, for the technical contribution to the construction of this article and its direction in the process of learning systemic thinking. Likewise, to the National Council of Science and Technology (Conacyt) dedicated to promoting and stimulating the development of science and technology in Mexico, for financial support for postgraduate studies.
Production system: System that provides a structure that streamlines the description, execution and planning of an industrial process. These systems are responsible for the production of goods and services in organizations.
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