Today, companies cannot afford to have process or asset failures. The current competitiveness of business and the globalization of markets have made organizations worry about the quality of their products but without neglecting profitability.
To obtain both quality and profitability, companies must avoid failures in their systems, processes or machinery. In response to this need, Reliability Engineering arises. This is a very important topic that is discussed below.
The work is understood as follows, it begins with basic definitions of the topic to achieve the contextualization of subsequent topics.
Then the topic of Operational Reliability, its definition and parameters that compose it, is covered. Later, it talks about cost of reliability, methods for the analysis of reliability and finally it closes with the benefits of Reliability Engineering.
RELIABILITY ENGINEERING
Reliability Engineering is defined as a branch of Engineering that is responsible for the study of fault elimination processes through the use of various analytical tools that allow improving processes, activities, resources, services, among others (SPM, 2014).
Although there are several definitions of Reliability Engineering, they all handle the same core word. This word is "Fail".
It is called failure to the situation in which (Zapata, 2011):
- The component or system partially or fully fails to fulfill its function There is an unacceptable difference between the expected and the observed performance.
There are two causes that cause failures, these are:
- Technical or physical defects. These are specific to the machine or system, include design, materials, manufacturing, construction, assembly and maintenance. Operational or procedural errors. These arise from human factors, for not following directions, for lack of knowledge or for not understanding procedures for example.
Component or system failures can cause effects ranging from inconvenience and inconvenience to some of the users to severe impact on society. Failures can also lead to potentially dangerous or risky situations for users or the environment, different from those accepted or allowed (Zapata, 2011).
Therefore, every component or system is required to offer quality, safety and reliability and availability.
According to the model of the ISO 9000 standard, quality is the “degree to which a set of inherent characteristics meets the requirements” (ISO, 2008), and when speaking of a requirement it refers to the established need or expectation.
That a system or component has safety means that its use does not imply danger to users or the environment.
The availability refers to must be in an operable state when required, ie in a timely manner.
The fourth requirement is reliability. This word means that it must fulfill its function for the required time under specified operating conditions. It is also defined as “the probability that a component or system can fulfill its function under the specified operating conditions during a given time interval” (Pemex, S / f).
Probability is the classic measure to assess reliability. However, there are many other widely used measures, therefore, reliability is a generic term that describes all these measures without necessarily being related to probability (Zapata, 2011).
Most of these measures correspond to statistical averages or expected values that are called “reliability indices”.
Some examples are.
- Average life: Time expected for a failure to occur in a non-repairable component. Frequency of failures per year: Number of failures expected per year.
OPERATIONAL RELIABILITY
Operational Reliability is defined as a chain of continuous improvement techniques, which introduce analysis methods and new technologies; with the purpose of perfecting the service, planning, execution and control of production (of goods or services) (Espinosa, 2011)
Operational reliability seeks to avoid in the integral system, which is composed of people, processes and assets for the fulfillment of functions within a specific operational context.
It is made up of four parameters: human reliability, process reliability, maintainability and equipment reliability; which interact in an optimal way to obtain a lasting and long-term improvement.
Process reliability: it is associated with the correct performance of the procedures, obtaining the established parameters in order to respect the established conditions (Arata, 2009).
Equipment reliability: or also known as reliability of supplies; it refers to the integration between the different processes or internal units, such as operation, supply, development to have the supply when required (Arata, 2009).
Human reliability: it is related to the involvement, commitment and competencies that people have with the activities that correspond to them and the organizational structure to achieve it (Arata, 2009).
Maintainability: set of actions aimed at maintaining or reconditioning a component, equipment or system, in a state in which its functions can be fulfilled. Understanding as a function any activity that a component, equipment or system performs, from an operational point of view (Arata, 2009).
Maintenance can be divided into preventive and corrective. Preventive maintenance can be defined as the scheduling of equipment inspection activities that must be carried out in certain periods based on a quality control monitoring plan. The purpose of preventive maintenance is precisely to prevent errors, in order to keep the system under the optimal conditions specified from the start.
Its fundamental characteristic is to inspect the equipment in a planned way to detect failures during their initial phase and correct them at the appropriate time.
We refer to unscheduled maintenance or better known as corrective maintenance to the action of correcting the defects detected within a system or component, it consists of detecting errors and repairing them in the shortest possible time to return the system to its function.
COST OF RELIABILITY
In every system there is a relationship between its reliability and the cost it causes. As the level of reliability increases, the level of investment required increases and vice versa (Graph 1). The cost of reliability must be weighed against the overall benefits for both the user and society. The acceptable level of reliability depends on what users and society as a whole are willing to pay for it. This acceptable level of reliability may be different from the mathematical optimum.
Cost of Reliability. Author: Arata, 2009.
RELIABILITY ANALYSIS METHODS
Below are some useful methods or tools for Reliability analysis.
- It is a subjective assessment where numerical indices are not established. Examples: “It will not fail”, “It is very reliable”, “This equipment is better than that one”. It is not used to compare alternatives or do economic analysis. It is known as "engineering judgment." Historical. The component or system is studied based on the data of its past operating behavior. With this data, historical indices or performance measures are established, which are generally statistical. Example: Average failure frequency. Analytical. The component or system under study is represented by means of a mathematical model (equation or set of equations) and the reliability indices are evaluated by means of direct mathematical solutions. Examples: Block diagrams and Markov process.Probabilistic. The variables are considered random, that is, they do not have a fixed value nor is there a function that allows them to determine their value at a given instant of time. The occurrence of certain values of the variable is expressed in terms of probability, that is, that a failure occurs or not. Diffuse logic. It is a mathematical discipline that allows working with information that is not exact to be able to carry out system evaluations. It is ideal for modeling systems that cannot be solved by a simple or precise mathematical model. Simulation.The random behavior of the component or system is simulated in a computer program and the reliability indices are evaluated indirectly by means of numerical techniques. Example: Monte Carlo simulation.
BENEFITS
The main benefits of Reliability engineering are summarized as shown below
- Reach customer expectations on the functionality and useful life of the equipment Reduce the foreseeable risks inherent to the operation of the equipment and the dangers to health Improve the Reliability and Availability of the systems (reduce failure rates and decrease times out of service) Achieve production objectives Improve product marketing and guarantees.
CONCLUSIONS
The main objective of Reliability engineering is to increase the reliability of assets or processes, reducing or avoiding failures, thus also increasing their availability, and finally to observe those actions in the profitability of the business.
It is an area of engineering closely linked to maintenance, but its implementation covers more than just the operational area. Since the entire organization must contribute to the achievement of operational reliability.
It not only seeks how to efficiently run a machine, but how to make this management an effective process that contributes to the final achievement pursued by the business.
It is of the utmost importance that companies seek to improve their processes by avoiding organizational waste, in order to raise their levels of competitiveness.
Because of this, this subject represents great areas of opportunity for both organizations and us.
BIBLIOGRAPHY
- Arata, A. (2009). Engineering and management of operational reliability in industrial plants. Chile: Ril. Benbow, D., & Broome, H. (S / f). The Certified Reliability Engineer's Manual. Espinosa, F. (2011). Equipment operational reliability. Chile: UT. García, O. (2009). Comprehensive Maintenance Management Based on Reliability. Colombia.ISO. (2008). Retrieved on November 22, 2015, from the International Organization of Standardization: www.normas9000.com/que-es-iso-9000.htmlPemex. (S / f). Reliability Engineering. Retrieved on November 22, 2015, from Pemex Virtual Learning: www.aprendizajevirtual.pemex.com/nuevo/guias_pdf/guia_sco_ingenieria_confiabilidad.pdf Pérez, I. (2007). Fuzzy logic for beginners. Caracas: UCAB.SPM. (2014). Retrieved on November 22, 2015, from SPM engineering in maintenance: www.spm-ing.com / ingenieria-de-reliability.phpZapata, C. (2011). Reliability in Engineering. Colombia: Publiprint Ltda.
