HAL (Le Centre pour la Communication Scientifique Directe), Jun 26, 2013
The influence of friction conditions in grinding processes is very important in terms of product ... more The influence of friction conditions in grinding processes is very important in terms of product results and abrasive wear. However, the knowledge of those conditions is limited due to the complexity of the grinding process itself, and to the difficulty to obtain adequate experimental data. In this paper a new test bench designed to overcome the limitations of the present experimental studies is presented. The test bench is based on the classical Pin-on-Disc configuration but adapted to reproduce the high relative speeds (up to 50m/s) and contact pressures (up to 5MPa) characteristics of shallow grinding processes. The test bench allows measuring pin temperature and contact forces which can be used for the characterization of friction phenomena. The paper includes an experimental study developed in the new test bench where the contact conditions between steel and abrasive have been assessed. The study has served to identify a sticking phenomenon of steel on the abrasive surface and also to assess the influence of relative contact speed in friction conditions.
Proceedings of the XV Ibero-American Congress of Mechanical Engineering
This work describes a machine vision system workflow to automatically estimate the broaching tool... more This work describes a machine vision system workflow to automatically estimate the broaching tool wear. The proposed system offers the possibility to evaluate the evolution of wear under different machining conditions and to decide when a tool should be replaced, guaranteeing the quality of the machined part and avoiding catastrophic tool breakage. In addition, the paper discusses the advantages of the proposed method over the traditional and widely used ISO 3685:1993 based methods, which are highly influenced by the operator. The proposed method uses a novel wear area segmentation technique based on Machine Learning artificial intelligence, generating highly reproducible values, saving technicians labor-intensive tasks, and obtaining values with high accuracy. The results show a strong relationship between the values obtained by the proposed automatic method and the experimental ones, with errors below 0.17% and 2.88% corresponding to the MSE and MAE respectively.
Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slab... more Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slabs, or tubes. Thus, the abrasive cutting-off process is applied when requiring precision cutting and productivity at a moderate price. Cut-off tools are discs composed of small abrasive particles embedded in a bonding material, called the binder. This work aims to compare the cutting performance of discs with different composition, in dry cutting of steel bars. To do that, disc wear was measured and disc final topography was digitalized in order to determine both disc surface wear patterns and if the abrasive particles bonding into the binder matrix was affected. In addition, X-Ray inspection gave information about the abrasive grit-binder bonding. Therefore, the method here presented allows identifying discs with a superior abrasive-cutting capability, by combining profilometry and tomography to define micrometrical aspects, grit size, and binder matrix structure. Results led to the conc...
The scope of this work is to present a reverse engineering (RE) methodology to achieve accurate p... more The scope of this work is to present a reverse engineering (RE) methodology to achieve accurate polygon models for 3D printing or additive manufacturing (AM) applications, as well as NURBS (Non-Uniform Rational B-Splines) surfaces for advanced machining processes. The accuracy of the 3D models generated by this RE process depends on the data acquisition system, the scanning conditions and the data processing techniques. To carry out this study, workpieces of different material and geometry were selected, using X-ray computed tomography (XRCT) and a Laser Scanner (LS) as data acquisition systems for scanning purposes. Once this is done, this work focuses on the data processing step in order to assess the accuracy of applying different processing techniques. Special attention is given to the XRCT data processing step. For that reason, the models generated from the LS point clouds processing step were utilized as a reference to perform the deviation analysis. Nonetheless, the proposed ...
The present times are changing and need new formulas that satisfy the need for effective transfer... more The present times are changing and need new formulas that satisfy the need for effective transfer between universities and companies. In the Basque Country, attending to this demand the Aeronautics Advanced Manufacturing Center (CFAA) has been founded. This center belongs to the University of the Basque Country (UPV/EHU) and has several companies related to this strategic sector as partners. The CFAA, equipped with the latest machinery and technology, born to be a catalyst for research activity in the field of advanced manufacturing for aeronautical sector, focusing its activity on the called Pillar 2 of the MRL scale (Manufacturing Readiness Level) as the proximity to the final application. Belonging to the UPV/EHU, this center allows stays of doctoral students, students for performing their master and bachelor’s degree projects. This implies a high quality training, and closer to reality, in manufacturing technologies.
The adaptation of universities to the European Higher Education Area (EHEA) plays an essential ro... more The adaptation of universities to the European Higher Education Area (EHEA) plays an essential role in society, creating new knowledge, transferring it to students by means of new and more active methodologies aimed at learning that will enable students to put everything they learn into practice. However, such methodologies are not equally applicable in all subjects. Subjects such as Manufacturing Technology, taught at different levels in both undergraduate and graduate levels, are descriptive to a great extent. This descriptive nature must be supported by new technologies if these subjects claim to be more attractive to students. In this paper some examples of successful case studies are presented. They represent the new way of understanding the teaching replacing the old concept of traditional classroom lecture by more interactive ones and, therefore, more attractive to students.
Temperature measurement in grinding has been a widely analyzed field in the study of the process.... more Temperature measurement in grinding has been a widely analyzed field in the study of the process. Temperatures in grinding are too difficult to measure due to the high gradients in the ground workpiece. A lot of different methods have been employed by many researches in the last years. In this paper the use of thermocouples is analyzed attending to the mathematical characterization of their response. It will be shown that correct modeling of the thermocouple’s response permits the avoidance of the problem of thermal inertia, making thus possible the use commercial thermocouples for temperature measurement in grinding.
Advances in Non Conventional Materials Processing Technologies, 2012
Grinding is a stochastic process applied in the last stages of the manufacturing cycle. In last d... more Grinding is a stochastic process applied in the last stages of the manufacturing cycle. In last decades, grinding research has focused on prediction of thermal damage on ground workpiece since it is of considerable importance from both research and industrial perspectives. A number of numerical and analytical thermal models have been carried out so far. However, new grinding processes such as peel grinding, creep feed grinding and others such as plongee grinding need new models which consider the effect of higher depth of cuts, but there is no information about the minimum depth of cut to consider the elimination of grounded material in FEM models. This article establishes the frontier from which the removed ground material should be physically eliminated to obtain an accurate FEM thermal model. Results show valuable information to decide which kind of model (with or without element elimination) is enough accurate for their purpose and application.
Advances in Non Conventional Materials Processing Technologies, 2012
The process of Wire Electrical Discharge Machining (WEDM) has experienced a dramatic growth in th... more The process of Wire Electrical Discharge Machining (WEDM) has experienced a dramatic growth in the last years. Together with the new requirements imposed by customer needs, globalization of the markets has brought about a new scenario in which competitiveness is the keyword. In the case of WEDM, it is only possible from a perspective that integrates developments in hardware, software and know-how, to generate the required added-value with respect to competitors. For instance, it is not enough to give an answer to the demand of a high-speed first cut: economy must be achieved together with a high accuracy and using low-cost wires. In this paper the research actions currently running aiming at the development of a new generation of WEDM machines are presented. The objective of this paper is to present an integrated research approach focused on industrial needs, covering the following aspects: Accuracy and productivity; automation and machine intelligence; eco-efficiency.
ABSTRACT The use of fluids in grinding is necessary to carry out an optimized process that avoids... more ABSTRACT The use of fluids in grinding is necessary to carry out an optimized process that avoids any kind of damage in the ground workpieces. However, the use of fluids in machining processes presents some problems as the economic one and the environmental one. The present work analyzes the industrial viability of a new solution to avoid the use of fluids in grinding, the MCG system. This system combines the use of a MQL (Minimum Quantity Lubricant) commercial system and a gas supplied at low temperatures. In this case the grinding of a component of the engine of a competition motorcycle with the MCG (Minimum Coolant Grinding) system is compared with the classic fluid flow system.
ABSTRACT Electrical Discharge Machining (EDM) is a non-conventional machining process whose therm... more ABSTRACT Electrical Discharge Machining (EDM) is a non-conventional machining process whose thermoelectric nature makes it suitable for the machining of any material, regardless of its hardness and of its brittleness, as long as it conducts electricity. Despite EDM is a popular process in industry, the fact that it involves phenomena of very distinct natures (electrical, thermal, chemical and metallurgical) together with the difficulty inherent to the experimental study of the discharge process, there is a lack of scientific knowledge about it. The present work aims to help in this sense, providing a novel modeling tool capable of simulating discharge superposition, which allows the prediction of surface topographies and temperature fields due to discharges. Based on the comparison between results of simulations (material removal rates and surface topographies) and experimental measurements the discharge process can be characterized using an inverse method. Here, the basis of the developed model will be presented, together with the methodology employed to find out the parameters which define discharge properties. Results obtained with this inverse method have been included.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 26, 2013
The influence of friction conditions in grinding processes is very important in terms of product ... more The influence of friction conditions in grinding processes is very important in terms of product results and abrasive wear. However, the knowledge of those conditions is limited due to the complexity of the grinding process itself, and to the difficulty to obtain adequate experimental data. In this paper a new test bench designed to overcome the limitations of the present experimental studies is presented. The test bench is based on the classical Pin-on-Disc configuration but adapted to reproduce the high relative speeds (up to 50m/s) and contact pressures (up to 5MPa) characteristics of shallow grinding processes. The test bench allows measuring pin temperature and contact forces which can be used for the characterization of friction phenomena. The paper includes an experimental study developed in the new test bench where the contact conditions between steel and abrasive have been assessed. The study has served to identify a sticking phenomenon of steel on the abrasive surface and also to assess the influence of relative contact speed in friction conditions.
Proceedings of the XV Ibero-American Congress of Mechanical Engineering
This work describes a machine vision system workflow to automatically estimate the broaching tool... more This work describes a machine vision system workflow to automatically estimate the broaching tool wear. The proposed system offers the possibility to evaluate the evolution of wear under different machining conditions and to decide when a tool should be replaced, guaranteeing the quality of the machined part and avoiding catastrophic tool breakage. In addition, the paper discusses the advantages of the proposed method over the traditional and widely used ISO 3685:1993 based methods, which are highly influenced by the operator. The proposed method uses a novel wear area segmentation technique based on Machine Learning artificial intelligence, generating highly reproducible values, saving technicians labor-intensive tasks, and obtaining values with high accuracy. The results show a strong relationship between the values obtained by the proposed automatic method and the experimental ones, with errors below 0.17% and 2.88% corresponding to the MSE and MAE respectively.
Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slab... more Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slabs, or tubes. Thus, the abrasive cutting-off process is applied when requiring precision cutting and productivity at a moderate price. Cut-off tools are discs composed of small abrasive particles embedded in a bonding material, called the binder. This work aims to compare the cutting performance of discs with different composition, in dry cutting of steel bars. To do that, disc wear was measured and disc final topography was digitalized in order to determine both disc surface wear patterns and if the abrasive particles bonding into the binder matrix was affected. In addition, X-Ray inspection gave information about the abrasive grit-binder bonding. Therefore, the method here presented allows identifying discs with a superior abrasive-cutting capability, by combining profilometry and tomography to define micrometrical aspects, grit size, and binder matrix structure. Results led to the conc...
The scope of this work is to present a reverse engineering (RE) methodology to achieve accurate p... more The scope of this work is to present a reverse engineering (RE) methodology to achieve accurate polygon models for 3D printing or additive manufacturing (AM) applications, as well as NURBS (Non-Uniform Rational B-Splines) surfaces for advanced machining processes. The accuracy of the 3D models generated by this RE process depends on the data acquisition system, the scanning conditions and the data processing techniques. To carry out this study, workpieces of different material and geometry were selected, using X-ray computed tomography (XRCT) and a Laser Scanner (LS) as data acquisition systems for scanning purposes. Once this is done, this work focuses on the data processing step in order to assess the accuracy of applying different processing techniques. Special attention is given to the XRCT data processing step. For that reason, the models generated from the LS point clouds processing step were utilized as a reference to perform the deviation analysis. Nonetheless, the proposed ...
The present times are changing and need new formulas that satisfy the need for effective transfer... more The present times are changing and need new formulas that satisfy the need for effective transfer between universities and companies. In the Basque Country, attending to this demand the Aeronautics Advanced Manufacturing Center (CFAA) has been founded. This center belongs to the University of the Basque Country (UPV/EHU) and has several companies related to this strategic sector as partners. The CFAA, equipped with the latest machinery and technology, born to be a catalyst for research activity in the field of advanced manufacturing for aeronautical sector, focusing its activity on the called Pillar 2 of the MRL scale (Manufacturing Readiness Level) as the proximity to the final application. Belonging to the UPV/EHU, this center allows stays of doctoral students, students for performing their master and bachelor’s degree projects. This implies a high quality training, and closer to reality, in manufacturing technologies.
The adaptation of universities to the European Higher Education Area (EHEA) plays an essential ro... more The adaptation of universities to the European Higher Education Area (EHEA) plays an essential role in society, creating new knowledge, transferring it to students by means of new and more active methodologies aimed at learning that will enable students to put everything they learn into practice. However, such methodologies are not equally applicable in all subjects. Subjects such as Manufacturing Technology, taught at different levels in both undergraduate and graduate levels, are descriptive to a great extent. This descriptive nature must be supported by new technologies if these subjects claim to be more attractive to students. In this paper some examples of successful case studies are presented. They represent the new way of understanding the teaching replacing the old concept of traditional classroom lecture by more interactive ones and, therefore, more attractive to students.
Temperature measurement in grinding has been a widely analyzed field in the study of the process.... more Temperature measurement in grinding has been a widely analyzed field in the study of the process. Temperatures in grinding are too difficult to measure due to the high gradients in the ground workpiece. A lot of different methods have been employed by many researches in the last years. In this paper the use of thermocouples is analyzed attending to the mathematical characterization of their response. It will be shown that correct modeling of the thermocouple’s response permits the avoidance of the problem of thermal inertia, making thus possible the use commercial thermocouples for temperature measurement in grinding.
Advances in Non Conventional Materials Processing Technologies, 2012
Grinding is a stochastic process applied in the last stages of the manufacturing cycle. In last d... more Grinding is a stochastic process applied in the last stages of the manufacturing cycle. In last decades, grinding research has focused on prediction of thermal damage on ground workpiece since it is of considerable importance from both research and industrial perspectives. A number of numerical and analytical thermal models have been carried out so far. However, new grinding processes such as peel grinding, creep feed grinding and others such as plongee grinding need new models which consider the effect of higher depth of cuts, but there is no information about the minimum depth of cut to consider the elimination of grounded material in FEM models. This article establishes the frontier from which the removed ground material should be physically eliminated to obtain an accurate FEM thermal model. Results show valuable information to decide which kind of model (with or without element elimination) is enough accurate for their purpose and application.
Advances in Non Conventional Materials Processing Technologies, 2012
The process of Wire Electrical Discharge Machining (WEDM) has experienced a dramatic growth in th... more The process of Wire Electrical Discharge Machining (WEDM) has experienced a dramatic growth in the last years. Together with the new requirements imposed by customer needs, globalization of the markets has brought about a new scenario in which competitiveness is the keyword. In the case of WEDM, it is only possible from a perspective that integrates developments in hardware, software and know-how, to generate the required added-value with respect to competitors. For instance, it is not enough to give an answer to the demand of a high-speed first cut: economy must be achieved together with a high accuracy and using low-cost wires. In this paper the research actions currently running aiming at the development of a new generation of WEDM machines are presented. The objective of this paper is to present an integrated research approach focused on industrial needs, covering the following aspects: Accuracy and productivity; automation and machine intelligence; eco-efficiency.
ABSTRACT The use of fluids in grinding is necessary to carry out an optimized process that avoids... more ABSTRACT The use of fluids in grinding is necessary to carry out an optimized process that avoids any kind of damage in the ground workpieces. However, the use of fluids in machining processes presents some problems as the economic one and the environmental one. The present work analyzes the industrial viability of a new solution to avoid the use of fluids in grinding, the MCG system. This system combines the use of a MQL (Minimum Quantity Lubricant) commercial system and a gas supplied at low temperatures. In this case the grinding of a component of the engine of a competition motorcycle with the MCG (Minimum Coolant Grinding) system is compared with the classic fluid flow system.
ABSTRACT Electrical Discharge Machining (EDM) is a non-conventional machining process whose therm... more ABSTRACT Electrical Discharge Machining (EDM) is a non-conventional machining process whose thermoelectric nature makes it suitable for the machining of any material, regardless of its hardness and of its brittleness, as long as it conducts electricity. Despite EDM is a popular process in industry, the fact that it involves phenomena of very distinct natures (electrical, thermal, chemical and metallurgical) together with the difficulty inherent to the experimental study of the discharge process, there is a lack of scientific knowledge about it. The present work aims to help in this sense, providing a novel modeling tool capable of simulating discharge superposition, which allows the prediction of surface topographies and temperature fields due to discharges. Based on the comparison between results of simulations (material removal rates and surface topographies) and experimental measurements the discharge process can be characterized using an inverse method. Here, the basis of the developed model will be presented, together with the methodology employed to find out the parameters which define discharge properties. Results obtained with this inverse method have been included.
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Papers by Naiara Ortega