Browsing by Author "Sousa, Vitor F. C."
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- Applying the SMED Methodology to Tire Calibration ProceduresPublication . Santos, Vítor; Sousa, Vitor F. C.; Silva, Francisco J. G.; Matias, João C. O.; Costa, Rúben D.; Pinto, Arnaldo; Campilho, RaulDue to the automotive industry’s strict demands, customers submit constant production pressure, leading to the adoption of new methodologies, techniques, and management ideas. The goal is always to minimise losses and waste. These demands also affect the maintenance department, which has to keep the balance between machines’ availability for production and ensuring that the machines’ proper running conditions translate into excellent-quality products. Thus, continuous improvement and correct management of maintenance activities are crucial for a company to maintain effective production, without defects, breakdowns, and accidents. Nevertheless, some maintenance activities should also prevent the degradation of equipment conditions in order to produce high-quality products. This paper presents an improvement of maintenance activities conducted on equipment that produces large tires. The main problems and technical difficulties of Machine Tolerance Check (MTC) activities are explored by analysing existing documents, internal knowledge, and changes to working methods. We discuss the implementation of the SMED (Single-Minute Exchange of Die) methodology in calibration procedures, as this method is commonly applied to machines’ setups to reduce downtime. At the end of the study, a 31% decrease in the duration of machine tolerance check activities was achieved, which led to a significant increase in the equipment’s availability
- Automating Equipment towards Industry 4.0: A New Concept for a Transfer System of Lengthy and Low-Stiffness Products for AutomobilesPublication . Vieira, Diogo; Silva, Francisco J. G.; Campilho, R.D.S.G.; Sousa, Vitor F. C.; Pinto Ferreira, Luís; Sá, José Carlos; Brito, MarleneSeveral products with a high length/section ratio and with a relatively low stiffness are used in the automotive industry, causing several problems because of a lack of stiffness. One of the examples where this occurs is in the production of Bowden cables, where automation has played a very important role in the flexibility of processes and product quality. Within this product family, conduits, one of the components of Bowden cables, have proven to be one of the points of continuous improvement. Currently, the production process for this type of component is done in a fully automated way, which proves the importance of automation. However, the need to manufacture different references means that the equipment used needs to be characterized by its high flexibility. This work aims to develop a new transfer system for conduit preparation machines, which are focused on increasing the range of references possible to manufacture without affecting the quality and productivity of the equipment. Thus, a new concept of conduit transport has been successfully developed, able to deal with lengthy conduits without lacking quality or experiencing breakdowns of the equipment. The concept used to overcome this problem can be extended to other equipment with similar problems, even in the manufacturing of other kind of products.
- Build-Up an Economical Tool for Machining Operations Cost EstimationPublication . Silva, Francisco J. G.; Sousa, Vitor F. C.; Pinto, Arnaldo; Pinto Ferreira, Luís; Pereira, Maria TeresaCurrently, there is a lack of affordable and simple tools for the estimation of these costs, especially for machining operations. This is particularly true for manufacturing SMEs, in which the cost estimation of machined parts is usually performed based only on required material for part production, or involves a time-consuming, non-standardized technical analysis. Therefore, a cost estimation tool was developed, based on the calculated machining times and amount of required material, based on the final drawing of the requested workpiece. The tool was developed primarily for milling machines, considering milling, drilling, and boring/threading operations. Regarding the considered materials, these were primarily aluminum alloys. However, some polymer materials were also considered. The tool first estimates the required time for total part production and then calculates the total cost. The total production time is estimated based on the required machining operations, as well as drawing, programming, and machine setup time. A part complexity level was also introduced, based on the number of details and operations required for each workpiece, which will inflate the estimated times. The estimation tool was tested in a company setting, comparing the estimated operation time values with the real ones, for a wide variety of parts of differing complexity. An average error of 14% for machining operation times was registered, which is quite satisfactory, as this time is the most impactful in terms of machining cost. However, there are still some problems regarding the accuracy in estimating finishing operation times
- Cutting Forces Assessment in CNC Machining Processes: A Critical ReviewPublication . Sousa, Vitor F. C.; Silva, Francisco José Gomes da; Fecheira, José S.; Lopes, Hernâni M. L; Martinho, Rui Pedro; Casais, Rafaela B.; Ferreira, Luís PintoMachining processes remain an unavoidable technique in the production of high-precision parts. Tool behavior is of the utmost importance in machining productivity and costs. Tool performance can be assessed by the roughness left on the machined surfaces, as well as of the forces developed during the process. There are various techniques to determine these cutting forces, such as cutting force prediction or measurement, using dynamometers and other sensor systems. This technique has often been used by numerous researchers in this area. This paper aims to give a review of the different techniques and devices for measuring the forces developed for machining processes, allowing a quick perception of the advantages and limitations of each technique, through the literature research carried out, using recently published works
- Experimental study on the wear evolution of different PVD coated tools under milling operations of LDX2101 duplex stainless steelPublication . Sousa, Vitor F. C.; Silva, Francisco J. G.; Alexandre, Ricardo; Fecheira, José S.; Pinto, Gustavo Filipe; Baptista, AndresaDuplex stainless steels are being used on applications that require, especially, high corrosion resistance and overall good mechanical properties, such as the naval and oil-gas exploration industry. The components employed in these industries are usually obtained by machining, however, these alloys have low machinability when compared to conventional stainless steels. In this work, a study of the wear developed when milling duplex stainless-steel, LDX 2101, is going to be presented and evaluated, employing four types of milling tools with different geometries and coatings, while studying the influence of feed rate and cutting length in the wear of these tools. Tools used have been provided with two and four flutes, as well as three different coatings, namely: TiAlN, TiAlSiN and AlCrN. The cutting behavior of these tools was analyzed; data relative to the cutting forces developed during the process were obtained; and roughness measurements of the machined surfaces were executed. The tools were then submitted to scanning electron microscope (SEM) analysis, enabling the identification of the wear mechanisms that tools were subjected to when machining this material, furthermore, the early stages of these mechanisms were also identified. All this work was done with the goal of relating the machining parameters and cutting force values obtained, identifying, and discussing the wear patterns that were observed in the coating and tools after the milling tests, providing further information on the machining of these alloys.
- Hybrid Manufacturing Processes Used in the Production of Complex Parts: A Comprehensive ReviewPublication . Sebbe, Naiara P. V.; Fernandes, Filipe; Sousa, Vitor F. C.; Silva, Francisco J. G.Additive manufacturing is defined as a process based on the superposition of layers of materials in order to obtain 3D parts; however, the process does not allow achieve the adequate and necessary surface finishing. In addition, with the development of new materials with superior properties, some of them acquire high hardness and strength, consequently decreasing their ability to be machined. To overcome this shortcoming, a new technology assembling additive and subtractive processes, was developed and implemented. In this process, the additive methods are integrated into a single machine with subtractive processes, often called hybrid manufacturing. The additive manufacturing process is used to produce the part with high efficiency and flexibility, whilst machining is then triggered to give a good surface finishing and dimensional accuracy. With this, and without the need to transport the part from one machine to another, the manufacturing time of the part is reduced, as well as the production costs, since the waste of material is minimized, with the additive–subtractive integration. This work aimed to carry out an extensive literature review regarding additive manufacturing methods, such as binder blasting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet laminating and vat polymerization, as well as machining processes, studying the additive-subtractive integration, in order to analyze recent developments in this area, the techniques used, and the results obtained. To perform this review, ScienceDirect, Web of Knowledge and Google Scholar were used as the main source of information because they are powerful search engines in science information. Specialized books have been also used, as well as several websites. The main keywords used in searching information were: “CNC machining”, “hybrid machining”, “hybrid manufacturing”, “additive manufacturing”, “high-speed machining” and “post-processing”. The conjunction of these keywords was crucial to filter the huge information currently available about additive manufacturing. The search was mainly focused on publications of the current century. The work intends to provide structured information on the research carried out about each one of the two considered processes (additive manufacturing and machining), and on how these developments can be taken into consideration in studies about hybrid machining, helping researchers to increase their knowledge in this field in a faster way. An outlook about the integration of these processes is also performed. Additionally, a SWOT analysis is also provided for additive manufacturing, machining and hybrid manufacturing processes, observing the aspects inherent to these technologies.
- Investigations on the Wear Performance of Coated Tools in Machining UNS S32101 Duplex Stainless SteelPublication . Sousa, Vitor F. C.; Silva, Francisco J. G.; Alexandre, Ricardo; Alves, Gustavo R.; Baptista, Andresa; Fecheira, José S.Due to their high mechanical property values and corrosion resistance, duplex stainless steels (DSSs) are used for a wide variety of industrial applications. DSSs are also selected for applications that require, especially, high corrosion resistance and overall good mechanical properties, such as in the naval and oil-gas exploration industries. The obtention of components made from these materials is quite problematic, as DSSs are considered difficult-to-machine alloys. In this work, the developed wear during milling of the UNS S32101 DSS alloy is presented, employing four types of milling tools with different geometries and coatings. The influence of feed rate and cutting length variations on the tools’ wear and their performance was evaluated. The used tools had two and four flutes with different coatings: TiAlN, TiAlSiN and AlCrN. The cutting behavior of these tools was analyzed by collecting data regarding the cutting forces developed during machining and evaluating the machined surface quality for each tool. After testing, the tools were submitted to SEM analysis, enabling the identification of the wear mechanisms and quantification of flank wear, as well as identifying the early stages of the development of these mechanisms. A comparison of all the tested tools was made, determining that the TiAlSiN-coated tools produced highly satisfactory results, especially in terms of sustained flank wear.
- A New Concept of Jig Rotary Holder System for 3-Axis CNC Milling Machine Operated by the Main Machine ControlPublication . Silva, Francisco J. G.; Campilho, R.D.S.G.; Sousa, Vitor F. C.; Coelho, Luis F. P.; Pinto Ferreira, Luís; Pereira, Maria Teresa; Matos, J.This study aims to develop a new jig holding system that is able to be controlled by a Computer Numeric Control (CNC) installed on three-axis machining centers, which can drastically improve the productivity in machining operations, enabling the machining of unparallel plans in the same setup. An action research methodology was adopted for this work, which, through a practical approach, intends to generate transferrable knowledge to other organizations whose situations are like those in this study. Together, the practical actions and the knowledge acquired create the changes needed for improving these processes. By conducting a case study, it was observed that savings of about 40 % can be easily achieved for parts with low geometric complexity. If the complexity of the parts increases, it is expected that these savings can be even higher. The return of investment is less than 2 years, which is usually affordable for enterprises. Through this study, it was possible to develop a new jig holding system that can be attached to a three-axis CNC machining center and clearly expands its functions and productivity. With this system, it is possible to work in different planes of the part in sequence, as well as use a double-sided table for the jigs, doubling the production batch each time the machine is loaded. Moreover, a list of key settings has been created with the main requirements and recommendations to adopt this kind of production system, which can be highlighted as the main research output.
- A Novel Robotic Manipulator Concept for Managing the Winding and Extraction of Yarn CoilsPublication . Costa, Rúben; Sousa, Vitor F. C.; Silva, Francisco J. G.; Campilho, Raul; Pinto, Arnaldo; Pinto Ferreira, Luís; Soares, RuiWire rope manufacturing is an old industry that maintains its place in the market due to the need for products with specific characteristics in different sectors. The necessity for modernization and performance improvement in this industry, where there is still a high amount of labor dedicated to internal logistics operations, led to the development of a new technology method, to overcome uncertainties related to human behaviour and fatigue. The removal of successive yarn coils from a twisting and winding machine, as well as cutting the yarn and connecting the other end to the shaft in order to proceed with the process, constitutes the main problem. As such, a mobile automatic system was created for this process, due to its automation potential, with a project considering the design of a 3D model. This novel robotic manipulator increased the useful production time and decreased the winding coil removal cycle time, resulting in a more competitive, fully automated product with the same quality. This system has led to better productivity and reliability of the manufacturing process, eliminating manual labor and its cost, as in previously developed works in other industries
- Recent Advances in Turning Processes Using Coated Tools—A Comprehensive ReviewPublication . Sousa, Vitor F. C.; Silva, Francisco J. G.Turning continues to be the largest segment of the machining industry, which highlights the continued demand for turned parts and the overall improvement of the process. The turning process has seen quite an evolution, from basic lathes using solid tools, to complex CNC (Computer Numerical Control) multi-process machines, using, for the most part, coated inserts and coated tools. These coatings have proven to be a significant step in the production of high-quality parts and a higher tool life that have captivated the industry. Continuous improvement to turning coated tools has been made, with many researches focusing on the optimization of turning processes that use coated tools. In the present paper, a presentation of various recently published papers on this subject is going to be made, mentioning the various types of coatings that have recently been used in the turning process, the turning of hard to machine materials, such as titanium alloys and Inconel, as well as the interaction of these coatings with the turned surfaces, the wear patterns that these coatings suffer during the turning of materials and relating these wear mechanisms to the coated tool’s life expectancy. Some lubrication conditions present a more sustainable alternative to current methods used in the turning process; the employment of coated tool inserts under these conditions is a current popular research topic, as there is a focus on opting for more eco-friendly machining options.