1. Introduction
The great competition in national and international markets forces companies to develop strategies based on four fundamental factors: price, quality, reliability and delivery time (Anderson, 1990). The implementation of reliability as engineering in the organization is the result of the need that most organizations present today.
Reliability engineering arises from the need to anticipate failures and the probability of their occurrence in processes or products. Which is why reliability engineering provides the opportunity to design robust processes capable of manufacturing high-quality products; preventing any production problem that arises in the organization, whose objective is to satisfy the client's needs such as: durability, quality, price, delivery time, reliability and above all that the organization is capable of producing it according to the operating technology of manufacturing and the budget you have.
It goes without saying that the success of an organization in today's market is defined by the quality and price of the product that an organization offers to customer demand and how capable the organization is of delivering a product with flawless performance. for the useful life of the product offered to the customer.
2. Conceptual framework
Before entering the unknown world of reliability engineering, it is essential to define some highly relevant concepts in order to understand this topic. The following are brief but specific definitions of a few concepts:
2.1 Product
Any manufactured good that fulfills a specific function for a user or customer; Thus, this product can be a machine, a piece of equipment or any general consumer good (Acuña Acuña, 2003).
2.2 Engineering
Engineering is that discipline that is responsible for the study and application of a set of scientific knowledge and techniques for the creation, improvement and implementation of structures or the same technology for solving problems that affect humanity. This science is based mainly on mathematical, physical and natural science knowledge, to develop economic forms that facilitate the implementation of certain materials and the forces of nature for the benefit of humanity and the environment.
2.3 Reliability
(R (t)). The author of the book Reliability Engineering Jorge Acuña Acuña (2003), defines reliability as the probability that a product unit performs satisfactorily fulfilling its function during a designed period of time and under previously specified conditions.
2.4 Probability
Numerical result of a random event, for which its causes are known or unknown and which must be of a magnitude between zero and one
2.5 Design time period
It means that the operation of the product is not forever, but until an adequate level of customer satisfaction is achieved.
2.6 Pre-specified conditions
It means that the process is not developed under any conditions, but under those established in the design and very clearly described in the instructions for use and useful life of the product, so if the product is used under non-prescribed conditions it is very likely that period The shelf life of the product is shorter than the original time.
2.7 Failure
It is the effect that originates when a component, equipment, system or process stops fulfilling the function that it is expected to perform (PEMEX, 2013).
2.8 Reliability vs trust
Reliability works as a unit of measurement of the performance of the operation of a product in a use and the manufacturing process, while confidence represents the real value of the quality parameters of a product and its characteristics (statistical).
2.9 Quality control (in processes)
It is the control process that consists of verifying certain characteristics that the product or raw material must have, in order to foresee the presence of faults or defects in the product or raw material that leave the customer unsatisfied, representing economic losses for the organization.. Its application in reliability engineering is very useful as it serves as a standard evaluation tool to prevent imperfections or failures that may occur during the use of the finished product.
3. Background
The concept of reliability arises during the Second World War due to the need to achieve high reliability in military equipment, in order to reduce equipment failures. Over the years, this concept has evolved into an important area of research based on mathematical and statistical concepts. The following will show how the evolution of reliability engineering was.
In the past, organizations considered the maintenance of equipment and facilities as an expense unit that functioned as an operational, equipment and development limiting factor, however with the introduction of new administrative concepts, the emergence of new tools and strategies that are used by intelligent organizations to improve the efficiency and effectiveness of their processes, quality and price of their products, customer retention and most importantly remain an organization with a good position in the market that generates large Profits.
Everything that is mentioned above has led large organizations to raise awareness about equipment maintenance, causing them to abandon past beliefs that maintenance was a unit of expense and adopt a new organizational culture; which consisted in perceiving maintenance as a result unit (Image 2) that contributes to the business (instead of representing losses), broadens its action in the development of investment projects (maintainability) and encourages the participation of the people of the organization (productive maintenance and continuous improvement).
Evolution of the perception of the concept of maintenance in the organization
Spending unit
- Represents losses Limiting factor: operational, equipment and organizational development
Result unit
- Contributes to the business Sustainability Productive maintenance Continuous improvement
But this new thinking was limited by defining maintenance as a reactive role, where corrective actions were given preference to those planned. In the next stage of the evolution of this thought, it was characterized by developing preventive maintenance from a basic cyclical way to predictive maintenance. Finally comes the improvement maintenance (Image 1).
Evolution from reactive maintenance to improvement maintenance
Image 1. Evolution from reactive maintenance to improvement maintenance
Improved maintenance incorporates and applies aspects such as: maintenance focused on reliability, life cycle analysis and continuous improvement (Image 2), developing models and methodologies, in order to improve the genetics of facilities and equipment, increasing efficiency and process efficiency while minimizing costs, this is when reliability engineering takes place.
Aspects that improve maintenance considers
Image 2. Aspects considered by the improvement maintenance
Below is shown in image 3 the process that leads to the incorporation of reliability engineering in improvement maintenance.
Process that gives rise to reliability engineering
Image 3. Process that gives rise to reliability engineering
3.1 Concurrent engineering
Concurrent engineering "CE" is based on simultaneity in the manufacture of the product and its production process. Concurrent engineering is the set of activities or multidisciplinary tasks to carry out a process, to design a process with multidisciplinary activities it is necessary to carry out a design of the production process in parallel, which will increase reliability by facilitating the identification of failures from the origin of the production process and its manufacturing design. Concurrent engineering can be studied from four different perspectives:
- Manufacturing and Assembly Design Design for Quality Design for Life Cycle Design for Cost
3.1.1 Design of manufacture and assembly (DFMA)
It is a methodology used as part of the integrated design and development of products and processes (IPPD), which, based on rules and principles, guide the design team to generate concepts of parts that are easy to manufacture, have an economical manufacture while maintaining their quality and easy to assemble.
3.1.2 Design for quality
The process of designing a product or service is a critical phase, probably the most critical for it. A suitable design and development process will guarantee that the organization is in a position to respond to customer needs by translating them into specific specifications (dimensions, performance, response time…). An inadequate design process will be a burden that the new product will carry from its birth and that will prevent the desired customer satisfaction objectives from being achieved (González & AEC, 2006).
The generic design process consists of six phases, the first four are related to the four stages of the system life cycle and the last two are not related to the design and development of the product, but serve as a source of information to meet the needs the client's. The following are the stages: 1) contact with the client, 2) planning phase of the entire process, 3) carrying out design activities, 4) prototyping for tests and qualifications, 5) production of the design and 6) sale of the products.
The methodologies that can be implemented by organizations, during the development of the generic design and that are related to reliability engineering to avoid failures or imperfections in the products are the following:
QFD or Quality Function Deployment.
It is used as an integral tool for the design process, which defines the characteristics of the final product or service, its components, the testing and inspection operations to be carried out and the necessary documentation for production (González & AEC, 2006).
AMFE or Modal Analysis of Failures and Effects.
Preventive tool that allows choosing between different design alternatives and avoiding possible future problems.
DOE or Design of Experiments.
Statistical methodology that allows establishing the characteristics of products and components.
RAM parameters o Reliability, Availability, Maintainability.
The RAM parameters are statistical tools to establish final quality characteristics of the products, to carry out the testing and qualification activities.
3.1.3 Life cycle
Reliability study is facilitated by considering the life cycle of the system, as it helps to establish reliability values that satisfy the customer. The life cycle of a product is determined by four stages (Acuña Acuña, 2003) see image 3:
Lifecycle
4. Reliability
To address the issue of reliability engineering it is necessary to first introduce ourselves to the true concept of reliability in the organization. Reliability is the probability that a product unit performs satisfactorily fulfilling its function during a designed period of time and under previously specified conditions (Acuña Acuña, 2003).
Currently the greatest challenge within an organization is determined by the ability of its members to make predictions about the occurrence of unwanted events or also known as failures, whose purpose is to avoid or prevent major negative impacts that may harm When an organization is able to predict the occurrence of such failures, the organization benefits by saving considerable sums of money, for this reason more and more organizations are forced to incorporate reliability engineering.
The impact of reliability engineering in organizations is considerable, as it stands out as a quantitative methodology compared to traditional methodologies that were qualitative. Reliability engineering calculations are used for decision making in economic and production aspects within an organization.
4.1 Objectives:
Apply engineering knowledge to prevent or reduce the frequency of failures.
Identify and correct the causes of catastrophic or repetitive failures.
Define methods to reduce failures if their causes have not been identified and corrected.
Apply techniques to estimate reliability in new designs and analyze reliability data.
4.2 Importance of reliability in the organization
The function of reliability engineering is to make the continuous maintenance improvement process dynamic by incorporating and disseminating knowledge, intelligence and qualitative analysis, thus favoring the operational result for the benefit of the business business. Reliability engineering allows redesign of the master plan, maintenance programs; In order to carry out manufacturing processes at a lower overall cost (direct costs, active costs, unavailability costs.
4.3 Mathematical function of reliability
Reliability is defined as the probability Pr that a component functions during a period of time t. Its mathematical expression is defined by a random variable T as the time to failure of the component when T≥0.
R (t) = Pr T ≥ t
The function R (t) is used as an estimator of reliability
4.4 Study perspectives of reliability engineering
The study of reliability engineering is responsible for the probabilistic characterization of failures, to make forecasts and establish proactive actions to eliminate or mitigate the effect that the failure may produce. In the study of reliability engineering, two schools coexist with two approaches (PEMEX, 2013):
- Reliability based on the probabilistic analysis of the time to failure or failure history (Statistical Based reliability Analysis). It is the branch of reliability that studies the random variable “time to failure”. The basic input for this type of analysis are databases where equipment failure histories are stored (failure time and repair times) Reliability based on probabilistic analysis of deterioration or physical failure (Physics Based Reliability Analysis). It is the branch of reliability that considers that a failure is the last phase of a deterioration process and concentrates and concentrates on trying to understand how the failure occurs, in other words, it studies the “physics of the deterioration process”.
4.5 Reliability cycle
Next, image 4 shows the reliability cycle (González, Lara Hernández, & Gordillo, 2009), where the interaction between reliability engineering, failure rates, maintenance and facility redesign is shown.
Reliability cycle
Image 4. Reliability cycle
4.5.1 Database
It is necessary that each organization has a database or inventories, where they have listed the types of failures that can occur within the organization. There is a methodology for the collection and classification of failures within the industry, this methodology is cited in ISO 14224 (Troffé). According to ISO 14224, the types of failures are divided into three categories, considering the depth:
- Failure mode: oriented to the "operator" what is seen Failure mechanism: apparent cause, (wear, abrasion, etc.) technical maintenance Failure cause: circumstances during design, manufacture or operation "Specialist"
It is very important to mention that the objective of the ISO 14224 standard is to facilitate the collection, exchange and analysis of data based on common points of view. The standard recommends a minimum amount of data that should be collected and focused considering two aspects:
- Requirements for the type of data that will be collected to be used in various analysis methodologies Standardized data formats: to facilitate the exchange of data on reliability and maintenance between plants, owners, manufacturers and contractors.
4.5.1.1 Data taxonomy
In order to collect the data and analyze them in an orderly and clear way, the OREDA project developed a taxonomy based on the ISO 14224 standard.
4.5.1.2 Main Categories of the database
For each category of equipment the database is divided into three separate databases:
- Inventory: where each piece of equipment is described, with its data collected. Maintenance: contains information on the corrective and preventive maintenance program scheduled for each piece of equipment.; for example: maintenance action, interval, man-hours, etc. Failure Inventory: describes all the failures that an equipment has suffered in a given period (one record for each failure event).
The main areas in which this data is being used are:
- Reliability that is, failure events and failure mechanisms; Availability / Efficiency that is, availability of equipment, availability of systems, availability of production plants; Maintenance that is, corrective and preventive maintenance, maintainability of maintenance; Safety and environment: en i.e. equipment failures with adverse consequences for safety and / or the environment
4.5.1.3 Stage 2 Process design:
Process design is also related to the life cycle of the system, which was mentioned earlier (Giudice & Pereyra, 2005). The design of the processes establishes the modality of development of the productive activities according to the type of product to be elaborated and conditioned by the technologies selected to carry out these operations. It resides in the choice of inputs, operations, flows and methods for the production of goods and services, as well as their detailed specification. This stage is not only about designing new processes, but also about redesigning the process.
4.5.1.4 Stage 3: detailed engineering
In this stage the details of the required production resources are considered and improvements are made to the conceptual design, this stage is part of the life cycle of the system or product.
The scope of activities in this stage is as follows (Rivera, 2009):
- Detailed review of basic engineeringTechnical specifications of equipment and materialsFunctional specificationsDimensioning of conduits, pipes and electrical installationsList of equipment, instrumentation, accessories and materialsDetail plans of the installations: Layout of pipes and conduits, isometrics, architectural details, electrical single lines.
4.1.5.5 Stage 4 maintenance:
Maintenance or Maintainability deals with the duration of shutdowns for failures and shutdowns for maintenance or how long it takes (ease and speed) to restore the state of the equipment to its operational condition after a shutdown due to failure or to perform a planned activity. Maintainability characteristics are usually determined by the design of the equipment, which specifies the maintenance procedures and determines the duration of repair times.
The key figure of merit for Maintainability is usually Average Time to Repair (TPPR). Qualitatively refers to the ease with which the equipment is restored to a working state. Quantitatively it is defined as the probability of restoring the operational condition of the equipment or mission time.
It is often expressed as:
Reliability cycle
Where μ = repair rate
This equation is valid for times, to make sure that they follow the exponential distribution
4.6 Estimating the reliability of a system
The reliability estimate of a system is carried out through a study, consisting of four stages according to Jorge Acuña (2003) shown in image 9.
- Definition of objectives and requirements for the reliability of the product or processes Disaggregation of the product or process into components and estimation of reliability for each of these components Prediction of the reliability of the product based on the reliability of its components Analysis of the product or process in order to determine strengths and weaknesses and take advantage of new opportunities for improvement.
4.6.1 STAGE 1. Definition of objectives and system reliability requirements
At this stage two factors are involved: the first is the voice of the customer captured by marketing and the second is the voice of the process captured by engineering; During this stage, the technological and engineering limitations regarding machines and materials are considered. To facilitate the analysis it is recommended to use the QFD tool.
4.6.2 STAGE 2. Disaggregation of the system into components and reliability estimation for each of these components.
The objective of dividing the system into its components and the components into its parts is to facilitate the determination of the reliability value of each of its parts. To perform the disaggregation it is recommended to use block diagrams and “gozinto” diagrams.
4.6.3 STAGE 3. Prediction of product reliability based on the reliability of its components.
The sum of the reliability of each of the components results in the reliability value of the final or complete product, the theory of probabilities is used to determine the reliability of the product or process.
4.6.4 STAGE 4. Analysis of the product or process in order to determine strengths and weaknesses and take advantage of new opportunities for improvement.
After calculating the reliability of the product or process during its design, the failures of the product during manufacturing and during its useful life should be studied. Here you can use the SWOT tool.
5. Conclusion:
It is necessary for organizations to adopt the reliability engineering methodology as a strategy, in order to position themselves in the market. It is said that for an organization to succeed today, it needs to worry about four aspects: price, quality, reliability and delivery time. Reliability is a quantitative measure of the functionality index presented by an element, equipment or installation, which helps in making decisions about the choice of a piece of equipment, element or installation.
Reliability is the probability that a component, equipment or system will operate without failure, in a specific period or time during a process and has a probabilistic value that varies from a value of 1 or 100%, when starting the operation and decreases until it takes a value of 0 when the fault occurs. This explains that the reliability varies from 100% to 0 between one failure and another.
Reliability engineering arises from the need to anticipate failures and the probability of their occurrence in processes or products. Which is why reliability engineering provides the opportunity to design robust processes capable of manufacturing high-quality products; preventing any production problem that arises in the organization, whose objective is to satisfy the client's needs such as: durability, quality, price, delivery time, reliability and above all that the organization is capable of producing it according to the operating technology of manufacturing and the budget you have.
It goes without saying that the success of an organization in today's market is defined by the quality and price of the product that an organization offers to customer demand and how capable the organization is of delivering a product with flawless performance. for the useful life of the product offered to the customer.
Bibliographic references:
- Acuña Acuña, J. (2003). Reliability engineering. Costa Rica: Editorial Tecnológica de CR. Obtained from: http://books.google.com.mx/booksArata, A. (sf). Engineering and management of operational reliability in industrial plants. Application of the R-MES Platform. Obtained from http://books.google.com.mx/booksGiudice, C., & Pereyra, A. (2005). Process design. Obtained from the National Technological University, Regional School of La Plata: http://www.frlp.utn.edu.ar/materias/oindustrial/apunte3.pdf González, E., & AEC, (. D. (February 2006). Quality and the design and development process.Obtained from: https://www.aec.es/c/document_library/get_file?uuid=c7afa03b-a8df-43c2-82f3-275d2058d9f6&groupId=10128González, RM, Lara Hernández, C., & Gordillo, FJ (November 18, 2009).Reliability-availability-maintainability estimates Groover, MP (1997). Fundamentals of Modern Manufacturing: Materials, Processes, and Systems. Pearson Education. Retrieved from: http://books.google.com.mx/booksReliability and Risk Management, SA (MARCH 10, 2012). Reliability engineering. Obtained from Rivera, A. (2009-09-29). Conceptual, basic and detailed engineering.Troffé, M. (sf). ANALYSIS ISO 14224 / OREDA.
