Repositório RCAAP

Adhesively-bonded joints have become more efficient due to the improvement of adhesives’ characteristics. On the other hand, with the use of composites in structures it is possible to reduce weight. Due to this, new techniques are being explored, including adhesively-bonding different materials. Nowadays, in many high performance structures, it is necessary to combine composite materials with other light-weighted metals such as aluminium or titanium. This work reports on an experimental and numerical study for hybrid scarf joints between composite and aluminium adherends, and considering different values of the scarf angle (α). The numerical analysis by Finite Elements (FE), using the software Abaqus®, enabled the obtainment of peel (σy) and shear stresses (τxy), which are then used to discuss the strength between different joint configurations. Cohesive zone modelling (CZM) was used to predict the joint strength and the results were compared to the experiments for validation. The joints’ behaviour was highly dependent on α, and CZM were validated for the design process of hybrid scarf joints.

Manufacturing industries are currently experiencing important changes towards digitization and autonomous production control, which is known as Industry 4.0. However, the profitability of some companies, namely Small and Medium Enterprises (SMEs), and of some industrial sectors does not allow for great investments, meaning that is necessary to undertake simple changes that potentially can lead to significant gains. This is the case for the metalwork company under study, where wastes related to the large parts movement and non-conformities detected before and after the parts delivered to the customers have been identified. The elimination of these wastes can contribute to a significant increase in the profitability of the company. The use and integration of several Lean tools made it possible to achieve this goal for this company. Amongst other improvements on productivity and waste reducing, a 59% reduction in the time required to move parts of up to 1000 kg, a reduction of 2.04% on the external non-conformities (i.e. on non-conformities detected outside the company) and 3.99% on the internal non-conformities, was achieved.

The deep knowledge about manufacturing processes, as well as their optimization, present themselves as indispensable factors in the search for the best product quality. It is this point of view of continuous improvement that makes companies in profitable and sustainable way. This paper presents a study about unwinding tension of textile cords in the cap ply manufacturing process, using machines called cap-strips for production. In this work, tension can be understood as the tensile force exerted on the cord. This study determines the influence of unwinding tension on the physical and shrinkage properties of the cord, as well as on the properties of cap ply, namely green adhesion and peel adhesion. Furthermore, the impact of cord tension on tire uniformity and the manufacturing process itself was also studied. All conclusions are based on the performed experiments and the execution of statistical tests. This work allows to conclude that the unwinding tension of the textile cords have some impact on the cap ply properties but have no influence on the tire uniformity.

Cohesive zone modelling (CZM) is widely used for predicting the strength of adhesive joints. The key variable for crack path modelling is the critical strain energy release rate (GC), which can be separated into the tensile (GIC) and shear (GIIC) components. In shear, the End Notched Flexure (ENF) test is widespread. However, other test methods exist and could be a viable replacement. This work aims to make a numerical evaluation between the ENF and Four-Point End Notched Flexure (4ENF) tests to determine GIIC of a ductile adhesive (SikaForce® 7752) and to provide shear CZM laws for further application in design. An inverse technique was used to obtain the shear CZM laws of the adhesive. It was concluded that the GIIC values obtained by the ENF and 4ENF tests are in good agreement. The numerical analysis led to unique shear CZM laws for both tests, with similar results.

Purpose: This study comprised two main goals. The first goal demonstrates how LT (Lean Tools) allows the highest impact during the implementation phase.The second goal consisted of introducing procedure changes based on the Management of Human Resources through Lean Leadership tool. The target for these two objectives is to achieve an increase of 5% in machine occupancy rate and a reduction of 10% regarding the costs of defective products per hour. Methodology/Approach: The research methodology is a Action-Research/Research-Action developed by Professor Kurt Lewin of MIT that goes through cycles of five stages: Diagnosis; Planning; Implementation; Evaluation, Conclusions. Findings: Regarding the two objectives above mentioned, it was observed an increase of 8.5% in machine occupancy rate and a reduction of 27.9% regarding the costs per hour of defective products. It was created an additional motivation in the employees and very satisfying results in every production. Research Limitation/implication: The study is limited to a Portuguese Small and Medium-sized Enterprise (SME) in the metalworking sector. Originality/Value of paper: Lean tools can be rapidly and easily implemented and quickly understood by the workers. With that implementation, the occupation of the machines has increased and the defects and their costs have decreased, so the added value grows.

In the last decade, it has been common to observe a competition between coatings achieved via physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques on cutting tools used in machining processes. The tool’s substrate material can immediately condition the coating process selection. However, there are also materials capabe of adapting to any of the coating processes. Hence, the capabilities demonstrated by a given coating when created with one technique or another are usually different due to the intrinsic characteristics of each coating process, such as temperature and stress levels. In this work, to study the machining behavior of a super duplex stainless steel, PVD- and CVD-coated tungsten carbide inserts with different coatings were used in order to identify the wear mechanisms that affect each of the coatings and the workpiece’s surface quality, evaluated through different roughness parameters. The vibration level produced throughout the various tests was also registered in an attempt to associate the type of coating or insert failure with the level of vibrations generated in the CNC (Computer Numeric Control) machining spindle. This allowed us to conclude that the tools coated with TiAlN via PVD showed better wear behavior, as well as creating workpiece surfaces with less roughness. Thus, it was clear that this coating presents strong advantages in the machining of the super duplex stainless steel chosen for this work, being an innovative work due to the combination of materials used and the approach in terms of vibration analysis applied to milling

The Information and Communication Technology (ICT) provide new strategies for disseminating information and new communication models in order to change attitudes and human behaviour concerning to education. Nowadays the internet is crucial as a means of communication and information sharing. To education or tutorship will be required to use ICT, supported on the internet, to establish the communication of teacher-student and student-student, disseminating the content of the subjects, and as a way of teaching and learning process. This paper presents an intelligent tutor that aims to be a tool to support teaching and learning in the field of the electrical engineering project.

The machining process evolution has been accompanied by the improvement of tool performance, being this mainly due to the development of thin coatings, mono and multi-layered, providing the most appropriate set of properties for each machining condition. On the other hand, duplex stainless steels have registered a strong increase in demand, which, in many cases, requires the use of machining processes in order to obtain the final shape accurately. Taking into account these two aspects, this paper aims essentially to evaluate the performance of two cutting inserts with PVD and CVD coatings, used in rough milling operations of duplex stainless steel. The cutting parameters and machining conditions were those recommended by the manufacturer and were kept unchanged in all performed tests. The behavior of the PVD- and CVD-coated cutting tools was assessed using three different facets: (a) surface roughness analysis, (b) tool wear evaluation, and (c) the monitoring of vibration levels produced during each test. CVD (TiN/TiCN/Al2O3)-coated inserts showed very good suitability to be used as tools for roughing milling operations when machining super duplex stainless steels.

The food industry is increasingly demanding in terms of the quality and appearance of its product packages. The present study focuses on identifying the main wear mechanisms developed during the stamping process of these packages. During the stamping process, the presence of a tin layer on the surface of the sheet used creates difficulties in the stamping due to the transfer of material from the sheet to the tool, addition of the coefficient of friction, and premature wear of some surfaces of the tool where the contact is more pronounced. In order to understand and avoid these phenomena, a TiAlN coating deposited by a physical vapor deposition (PVD) process was used, which was studied in the laboratory to analyze the evolution of the friction force on the contact and to verify the reaction of the coating on contact with tinplate. Afterwards, the tool was coated and practical tests were performed on the stamping. The obtained results allow confirmation of a significant improvement of the wear behavior of the tool when provided with the coating and also verify that this coating presented better wear resistance than others previously tested in the same working conditions.

The purpose of this paper is to examine settings for the Open Innovation Arena. In greater depth, this paper aims to analyse and reveal which factors influence the formation of an appropriate arena for doing open innovation and furthermore to prescribe how a firm can create an effective arena to gain access to external knowledge. This paper presents a review on open innovation literature with the purpose of examining the current understanding of factors influencing a firm’s capacity to embrace and practice open innovation as well as understanding what is critical when fitting outside systems. It presents the results of a survey conducted among 25 researchers from INESC TEC, the Portuguese Institute for Systems and Computer Engineering, Technology, and Science. The study concludes that conditions, namely culture, leadership and strategy, are the main drivers to an open innovation arena, highlighting culture as the most important one.

The main advantage of welding cast iron is to recover parts by repairing defects induced by casting processes (porosities, etc.), before they enter their working cycle, as well as repair cracks or fractures when already in service. This method contributes to decreased foundry industrial waste and avoids the additional energy costs of their immediate recycling. Therefore, it is necessary to have a welded joint with similar or better characteristics than the parent material. The major problem of welding cast iron is that this material has a very high content of carbon in comparison to steel (≈3%). Therefore, when it is heated by the very high temperatures from arc welding and during its process of solidification, very hard and brittle phases originate, known as ledeburite and martensite, and appear in the partially melted zone and in the heat-affected zone. Eventually, this problem can be solved by implementing heat treatments such as preheat or post weld heat treatments under specific parameters. Therefore, in this study, the aim is to collect data about the effects of heat treatments performed at different temperatures on welded joints of high strength ductile cast iron (SiboDur® 450), and to evaluate the effects of heat treatments performed at diverse temperatures on welded joints of this type of material, using Shield Metal Arc Welding and nickel electrodes. Mechanical strength, hardness, and microstructure were analyzed, showing that the best mechanical strength in the joint (380 MPa) was obtained using two passes of E C Ni-Cl (ISO EN 1071:2015) filler metal and post weld heat treatments (PWHT) of 400 °C for two hours.

Residual stresses (RS) of great magnitude are usually present in parts produced by Laser Powder Bed Fusion (PBF-LB), mainly owing to the extreme temperature gradients and high cooling rates involved in the process. Those “hidden” stresses can be detrimental to a part’s mechanical properties and fatigue life; therefore, it is crucial to know their magnitude and orientation. The hole-drilling strain-gage method was used to determine the RS magnitude and direction-depth profiles. Cuboid specimens in the as-built state, and after standard solution annealing and ageing heat treatment conditions, were prepared to study the RS evolution throughout the heat treatment stages. Measurements were performed on the top and lateral surfaces. In the as-built specimens, tensile stresses of ~400 MPa on the top and above 600 MPa on the lateral surface were obtained. On the lateral surface, RS anisotropy was noticed, with the horizontally aligned stresses being three times lower than the vertically aligned. RS decreased markedly after the first heat treatment. On heat-treated specimens, magnitude oscillations were observed. By microstructure analysis, the presence of carbides was verified, which is a probable root for the oscillations. Furthermore, compressive stresses immediate to the surface were obtained in heat-treated specimens, which is not in agreement with the typical characteristics of parts fabricated by PBF-LB, i.e., tensile stresses at the surface and compressive stresses in the part’s core.

Assembly lines are production systems designed to be oriented to the product and well known to be highly productive. Nevertheless, during this time-frame the product volumes could decrease and the assembly lines, previously very productive and efficient, becomes unproductive and inefficient. This happens in the car electronics components company where this study took place that due to customer´s demand decrease, produced volumes also decreased and provoked the appearance of wastes related with too much occupied space, unbalanced workstations, more capacity than needed, outdated standard work sheets, bottlenecks, to conclude, too many non-added value activities. This paper presents a reconfiguration proposal for two final assembly lines with the goal of adapt physically the lines to the actual production volumes and eliminate the existing wastes. The proposed reconfiguration translates into very positive gains for the company, namely, the release of 22% of the space occupied by the production lines, a reduction in the number of operators, a 50% increase in productivity for each of the lines and an increase in the utilization rate (23% for line 1 and 13% for line 2). In total, the monetary gains associated with these improvements were, approximately, of 125,600 m.u. per year.

This work refers to concepts and definitions of Lean Philosophy. The main targets were to study how waste reduction can be achieved on a production scenario, by identifying added-value operations, enhance productivity, levelling and over-processing reduction. The project behind this study is a massive one, which involves the installation of seven final production lines and more seven pre-assembly lines, being considered by the company, a project that must be as profitable as possible. After implementation and validation, costs were evaluated and the savings reached 10,9 % (2 159 000 €) considering all costs of industrialization.

This article presents the analysis of a process by using four distinct approaches, each of them recurring to different Lean tools in order to get a detailed and multidimensional overview of the process. The primary objective of this study was to identify activities which add value in the order fulfilment process of a metalwork company. In this context, one also addressed issues such as waste, problems and their causes, in order to define intervention priorities and select actions capable to enhance the performance and efficiency of the process. The secondary objective was to evaluate and compare the results of the analysis made through different mapping techniques. From this study results the proposal of a tool to identify perceived micro-inefficiencies, as well as the impact of these on the production sub-process. Designated as Perceived Waste Mapping (PWM), this method allowed one to estimate that the ratio between the value-added hours and the total number of work hours at the company will be approximately 30%, far from the figure of 84% registered in the existing time and production records.

Intralogistics is increasingly a matter of research and development as a form of optimization, automation, integration and management of the flow of materials and information that circulate within a business unit. With a strong connection to material handling equipment and automation solutions, intralogistics has proved to be one of the main factors responsible for something that is already happening: a fourth industrial revolution where it is possible to convert warehouses and manufacturing units into smart environments where the entire process can be controlled and supervised through a single system. It became necessary to develop more innovative and efficient solutions to the constant diversity of challenges proposed by the market. In this sense, it was proposed to develop something innovative within the area of Automated Storage and Retrieval Systems (AS/RS), a technology increasingly sought after by today's manufacturing plants. As such, the goal was to improve the most emergent AS/RS in recent years: the Pallet/Box Shuttle AS/RS. In order to achieve the proposed objective, it was necessary to analyze all the existing solutions in the market and, mainly, to find the main systems to be improved and the direction to follow in order to create a novel solution based on the existing advanced solutions. Moreover, regarding the recent needs required by the smart factories and Industry 4.0, it was intended that the new system would be able to make an optimized selection of products, forming sets or sub-sets of different products picking them from different places of the rack, a situation that is quite frequent in companies that produce and assemble equipment. The solution obtained shows that it is possible to increase the automation of the operations in the storage systems and improve the responsiveness of the system, taking this solution to a new level. Different products can be picked-up and put in a same box, providing a set of products/components able to be used in a production line or to be provided to a customer.

Value analysis methodology uses a structured and methodical job plan contemplating several steps to ensure success in its application. This paper intends to perspective the potential of value analysis application, namely in the furniture industry. To draw conclusions of this potential a case study was developed at an IKEA factory in Portugal. To characterize the customer needs in a clear language and to quantify the value of a product (a bookcase) produced in this factory, a value analysis study was developed. Functional analysis is the most known and distinctive phase of value analysis and is, nowadays, an autonomous tool. With this functional analysis, the authors intend to describe the functions that the product performs, to provide a better knowledge of the product, to evaluate the degree of satisfaction of the product through its functional performance and to facilitate the search for alternative solutions. The results obtained allowed us to reach some important conclusions about the application of value analysis in this type of industry and can be an initial step to promote the use of this tool in this kind of industry.

Embracing agility brings change to companies and everyone involved, so people have a fundamental role in project development. It is essential that teams have a good communication, motivation and concern about quality and client satisfaction, Agile Manufacturing is using Agile Project Management to provide the right team to performance difficult tasks and achieve goals. This paper proposes a team that deals with Agile Project Management, named as AGILE team, composed by a product owner, a team leader and team members, and a communication workflow proposal concerning the conjunction of 3 momentums (requirements analyze, planning and design) along the Agile Project Management. The proposed model is being implemented in a lightening manufacturing company in a very early stage.

Bringing the digital world and “digital natives” to hands-on engineering laboratory classes can be a challenge and an opportunity. Videos can be used, but is important that students know exactly what video to watch for each apparatus. That is why the possibility of accessing videos with QR codes is essential to build a bridge from concrete to digital content. The aim of this research is to evaluate the importance undergraduate engineering students attribute to instructional videos that explain the operating procedure of laboratory apparatus, and their reaction to the possibility of accessing them with quick response (QR) codes. Results show students attributed some importance to the videos and the QR codes in the laboratory are very helpful as means to quickly and easily access the videos.

Esta dissertação descreve as medidas e ações tomadas para a melhoria de processos produtivos de extrusão. Esta melhoria decorre em contexto empresarial numa empresa situada em Vila do Conde. A sua principal gama operatória prende-se com o fabrico de tubagens PEX (polietileno reticulado), tubo corrugado e ainda multicamada. Partiu-se inicialmente com três grandes objetivos: controlo de desperdícios, controlo e minimização de falhas e controlo de parâmetros de processo. Relativamente ao objetivo associado ao controlo de desperdícios foram elaborados procedimentos operativos de misturas que dão origem ao produto acabado (PE-Xb e PEXa), levou-se a cabo uma solicitação técnica com o objetivo de determinar a quantidade máxima de retração associada ao tubo de PE-Xb que culminou numa diminuição de tubo excedentário expedida. Elaborou-se ainda um procedimento de resolução de problemas. Relativamente ao segundo objetivo, controlo e minimização de falhas elaborou-se procedimentos operativos de arranque associados às linhas de trabalho para a padronização das tarefas. Quanto ao último objetivo, controlo de parâmetros de processo, fez-se o acompanhamento diário de fabricação e procedeu-se à elaboração de fichas técnicas auxiliares de arranque em função do produto, linha e matéria prima. O conjunto destas ações e de outras levadas a cabo deram origem a um aumento significativo de velocidades de fabricação de tubos. Para o cumprimento destes objetivos teve-se por base a implementação da metodologia dos 5S, ferramentas da qualidade tais como diagrama de Ishikawa e ainda o ciclo PDCA.