Reliability engineering of large jit production systems

This paper introduces the rationale and the fundamental elements and algorithms of a reliability engineering methodology, and discusses its application to the design of a large, multi-cell and heterogeneous production system with just-in-time (JIT) deliveries. The failure analysis and the non-reliability costs assessment of such systems is a complex task. In order to cope with such complexity, a two level hierarchical modelling and evaluation framework was developed. According to this framework, the internal behaviour of each manufacturing cell and the overall flow of materials are described, respectively, by local and global models. Local models are firstly obtained from the failure and repair processes of the manufacturing equipment. Then, these models are combined with the failure propagation delays introduced by the work-in-process buffers in order to obtain the system level model. The second part of the paper addresses several design issues of the production system that directly impact the reliability of the deliveries, such as the layout of the plant, the redundancy of the manufacturing equipment and the capacity of the work-in-process buffers. A distinctive feature of the reliability evaluation algorithm resides on the ability to deal with reliability models containing stochastic processes with generalized distributions. This fundamental requirement comes from the fact that repair and failure propagation processes typically present hyper-exponential distributions, e.g., lognormal distributions, that can’t be assessed using the conventional reliability techniques. The paper will also explain how the behavioural and structural characteristics of JIT production systems were explored in order to implement effective evaluation algorithms that fit the requirements of this class of systems.DST -Department of Science and Technology, Government of Kerala(600/09

Statistical Process Control automation in the final inspection process: an industrial case study

This case study arises from the need to make more robust and effective quality assurance procedures of the products by automating the final inspection process. The case study explains how the automation of the inspection process was performed in a company from the automotive sector. Knowledge, involvement and commitment of operators and respective managers should not be neglected because their reaction against the change procedures influence the success of any automation performed. The successful introduction of automation contributed to a more efficient process and from the pilot station to the remaining stations problem solving and continuous improvement was evidenced.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT - Fundacao para a Ciencia e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

Estimating maintenance costs of a wind turbine pitch control system

Wind turbines are nowadays the principal source of wind energy production. However, the technical information publicly known about these machines is still very scarce. Indeed, information related to failure modes, unavailability and maintenance costs of these systems remains confidential and only is held by manufacturers. To be able to optimize the efficiency, to guarantee the security and to negotiate better warranty and maintenance contracts, it is necessary to know more information about the operation and maintenance and replacement costs of subsystems of a wind turbine. To this end, this paper presents a short literature review of what has been published so far about this issue, and, based on two years of operation, analyses an active power control system of 21 identical wind turbines, installed in a wind farm in Portugal. The emphasis of this study is on the operation, availability and maintenance, and replacement costs of the active pitch control device, which automatically manages the position and operation of blades according to wind direction and speed, thus maximizing the electrical power gathered from the natural forces. Moreover, the paper provides an estimation for the total maintenance cost of this device, one of the most important components of the wind turbine, thus allowing wind farm companies to carry out financial and economic analysis of maintenance contracts that probably will be the rationale for better contract negotiations with manufactures. The result and the analyses that have been reported may also contribute for further studies on the reliability and maintenance policies of wind turbines.This work was financed with FEDER Funds by Programa Operacional Fatores de Competitividade – COMPETE and by National Funds by FCT – Fundação para a Ciência e Tecnologia, Project: FCOMP-01-0124-FEDER-022674.info:eu-repo/semantics/publishedVersio

Key inefficiencies and improvement opportunities in the textile sector: A case study

The textile sector in Portugal has a relevant economic and social importance. In this sector, dyeing and finishing are a significant part of the value chain of a textile product and the majority of companies are SMEs, lacking specialized human resources. Most of these companies have human and technological resources necessary for a smooth operation, however, they may lack management resources that allow efficient performance of the dyeing/finishing processes. The objective of this work is to highlight the organizational inefficiencies of a SME in a dyeing and finishing textile company, in Portugal, identifying their wastes, and improvement opportunities, highlighting the barriers and obstacles to the adoption of quality management and lean manufacturing principles. This paper presents the diagnosis of the performance of an SME in the textile sector, in Portugal. Through a case study, identifies key inefficiencies and wastes, documents the dyeing and finishing process, and detects problems using Quality and Lean tools. These inefficiencies can be translated by productivity losses or an increase of operational costs making the company less competitive. To overcome these problems and to improve production process performance, improvement suggestions were developed.FCT - Fundação para a Ciência e a Tecnologia (UID/CEC/00319/2013)info:eu-repo/semantics/publishedVersio

Performance indicators in the construction industry: a study with Portuguese companies

This paper aims to study the use of performance indicators (PIs) by business managers in the civil construction sector in a region that encompasses eight districts located in the north of Portugal. Through the literature review, it was possible to gather a list of twenty potential PIs used in this sector. Subsequently, a questionnaire was applied to a sample of construction companies from this region. A statistical analysis of the data collected allowed to identify the twelve most used and most important PIs for the companies surveyed. The results indicate that the companies involved in this study mainly use the traditional financial measures, however, recognize that non-financial measures, namely the customer satisfaction index, employee satisfaction, internal customer satisfaction index, and the training of employees, are increasingly important for the success of companies. The study also analysis the criteria to select PIs, its main benefits, and difficulties faced by companies on their usage.INCT-EN - Instituto Nacional de Ciência e Tecnologia para Excitotoxicidade e Neuroproteção(UID/CEC/00319/2019

Application of lean production principles and tools for quality improvement of production processes in a carton company

"27th International Conference on Flexible Automation and Intelligent Manufacturing, FAIM2017, 27-30 June 2017, Modena, Italy"This work presents an industrial case study focused on improving the quality of production processes, using lean production tools. The analysis of the initial situation was done using cause-effect diagrams, Pareto’s analysis, study of setup times and performance indicators, allowing identifying the main problems, such as high setup times, low availability of machines, lack of organization in the working area. Improvement proposals were implemented in the bonding section, like the SMED methodology, the 5S technique and visual management. As result it was achieved an average reduction of 47% in the setup time, corresponding to 10114€ of monthly profit.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

PHM overview on battery models approaches

The Battery Management Systems (BMS) brought a new impetus to the battery energy management which lead to an increase in battery life. But the BMS fails when the State of Charge (SoC), State of Health (SoH), State of Life (SoL) or Remaining Useful Life (RUL) prognostics systems do not provide the required accuracy. Despite the increase of complexity and accuracy of battery models, the poor performance with floating temperature and load profiles persists. With the development of innovative products on wide-ranging applications, the battery materials, technologies, reliability and safety are being pressed to their limits. Therefore, a huge amount of work is still necessary, not only on the development of new battery technologies but also on the BMS, battery models and metrics accuracy improvements. The paper gives a comprehensive overview of the applicability, accuracy, weaknesses and advantages of the most recent battery models. The paper will also discuss how the Prognostics Health Management (PHM) can support a technologic impetus on battery affairs with battery models and metrics accuracy improvements.info:eu-repo/semantics/publishedVersio

Knowledge management in a dynamic manufacturing context: a case study

Continuous improvement or just improvement is a necessity for companies in a dynamic environment. To be more competitive companies must adapt to the changing internal and external environment. To adapt implies making decisions and taking actions in an informed way. Assuming that Knowledge is widespread over the company, companies may develop knowledge management systems (KMS) to capture and disseminate knowledge, but there is not a universal set of requirements to do it. This paper shows, through a case study, a methodology to manage knowledge developed by a renowned manufacturer of electronic products. In this company, it is studied the impact of process improvement on management practices and collaborators behavior. The development of a KMS, in a dynamic context, is discussed and assessed through a survey. The features of this system allow us to consider it as a KMS. The KMS leverages the use of collaborative tools and supports the verified performance improvements.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013

Quantification of uncertainty of performance measures using graph theory

In this paper, the graph theory is used to quantify the uncertainty generated in performance measures during the process of performance measurement. A graph is developed considering all the sources of uncertainty present in this process and their relationship. The permanent function of the matrix associated with the graph is used as the basis for determining an uncertainty index.This work was financed with FEDER Funds by Programa Operacional Fatores de Competitividade – COMPETE and by National Funds by FCT –Fundação para a Ciência e Tecnologia, Project: FCOMP-01-0124-FEDER-022674

Graph theory approach to quantify uncertainty of performance measures

In this work, the performance measurement process is studied to quantify the uncertainty induced in the resulting performance measure (PM). To that end, the causes of uncertainty are identified, analysing the activities undertaken in the three following stages of the performance measurement process: design and implementation, data collection and record, and determination and analysis. A quantitative methodology based on graph theory and on the sources of uncertainty of the performance measurement process is used to calculate an uncertainty index to evaluate the level of uncertainty of a given PM or (key) performance indicator. An application example is presented. The quantification of PM uncertainty could contribute to better represent the risk associated with a given decision and also to improve the PM to increase its precision and reliability.FCT – Fundação para a Ciência e Tecnologia within the Project Scope: PEst- OE/EEI/UI0319/2014