Loading...
7 results
Search Results
Now showing 1 - 7 of 7
- 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
- Using an Artificial Neural Network Approach to Predict Machining TimePublication . Rodrigues, André; Silva, Francisco; Sousa, Vitor F. C.; Pinto, Arnaldo; Pinto Ferreira, Luís; Pereira, Maria Teresa RibeiroOne of the most critical factors in producing plastic injection molds is the cost estimation of machining services, which significantly affects the final mold price. These services’ costs are determined according to the machining time, which is usually a long and expensive operation. If it is considered that the injection mold parts are all different, it can be understood that the correct and quick estimation of machining times is of great importance for a company’s success. This article presents a proposal to apply artificial neural networks in machining time estimation for standard injection mold parts. For this purpose, a large set of parts was considered to shape the artificial intelligence model, and machining times were calculated to collect enough data for training the neural networks. The influences of the network architecture, input data, and the variables used in the network’s training were studied to find the neural network with greatest prediction accuracy. The application of neural networks in this work proved to be a quick and efficient way to predict cutting times with a percent error of 2.52% in the best case. The present work can strongly contribute to the research in this and similar sectors, as recent research does not usually focus on the direct prediction of machining times relating to overall production cost. This tool can be used in a quick and efficient manner to obtain information on the total machining cost of mold parts, with the possibility of being applied to other industry sectors
- 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
- 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.
- 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
- 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.
- 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.