José Albajez - Academia.edu (original) (raw)

Papers by José Albajez

CIRP Annals, 2012

Limited tool life of nickel mould inserts represents an issue for the mass-production of polymer ... more Limited tool life of nickel mould inserts represents an issue for the mass-production of polymer optics with complex micro three-dimensional geometries by injection moulding. TiN coating was applied to a nickel insert for the injection moulding of polycarbonate micro Fresnel lenses. Surface wear was monitored at different intervals during production on different tool locations. 3D micro optical dimensional microscopy, surface replica technique and SEM-EDS were employed to characterize wear of the micro features. Results showed wear decreasing at higher distance from the gate. After 24500 moulding cycles the measured height reduction of 23 µm high ribs was on the order of 400 nm to 1000 nm.

Measurement Science and Technology, Jan 31, 2020

Polymer laser powder bed fusion (LPBF) surfaces can be challenging to measure. These surfaces com... more Polymer laser powder bed fusion (LPBF) surfaces can be challenging to measure. These surfaces comprise complex features including undercuts, deep recesses, step-like transitions, a large range of measurement scales and unfavourable optically materials properties. While recent research has begun to examine the nature of these surfaces, there has not yet been significant effort in understanding how different measurement instruments interact with them. In this paper, we compare the results of LPBF surface topography measurements using a series of different instrument technologies, including contact stylus, focus variation microscopy, coherence scanning interferometry, laser scanning confocal microscopy and x-ray computed tomography. Measurements are made on both side and top surfaces of a cubic polyamide-12 LPBF sample. Different instrument behaviours are highlighted through qualitative visual inspection of surface reconstructions. Further comparisons are then performed through evaluation of profile and areal surface texture parameters and statistical modelling of surface topographies. These analyses allow for the identification both of discrepancies between texture parameters and discrepancies between local topographies reconstructed from measurements. Instrument repeatability metrics are also presented for each measurement of the test surfaces. Results show that discrepancies in measurements made on the acquired datasets are often similar in magnitude to the size of the features present on the surfaces. Conclusions are drawn regarding the suitability of various surface measurement instruments for polymer LPBF surfaces.

Micromachines, 2019

Nanotechnology applications demand high accuracy positioning systems. Therefore, in order to achi... more Nanotechnology applications demand high accuracy positioning systems. Therefore, in order to achieve sub-micrometer accuracy, positioning uncertainty contributions must be minimized by implementing precision positioning control strategies. The positioning control system accuracy must be analyzed and optimized, especially when the system is required to follow a predefined trajectory. In this line of research, this work studies the contribution of the trajectory definition errors to the final positioning uncertainty of a large-range 2D nanopositioning stage. The curve trajectory is defined by curve fitting using two methods: traditional CAD/CAM systems and novel algorithms for accurate curve fitting. This novel method has an interest in computer-aided geometric design and approximation theory, and allows high relative accuracy (HRA) in the computation of the representations of parametric curves while minimizing the numerical errors. It is verified that the HRA method offers better pos...

Procedia Engineering, 2015

Different systems are recently developed to obtain effective positioning at nanometer scale with ... more Different systems are recently developed to obtain effective positioning at nanometer scale with increased working ranges. For this purpose, a two-dimensional nanopositioning platform (NanoPla) has been design and manufactured. To assure the demanding metrological performance the drive and control system is being defined and validated. Based on four home-made linear motors as actuators, this work is focused on the study of the control-loop for 1D-and 2D-cases with the aim of the preliminary modelling and posterior implementation. The different required blocks are presented and an initial controller solution is proposed to achieve the established positioning requests.

Jornada de jóvenes investigadores del I3A, 1970

En el proceso de medición con un Laser Tracker, antes de iniciar la toma de datos, es necesario q... more En el proceso de medición con un Laser Tracker, antes de iniciar la toma de datos, es necesario que se estabilice la fuente láser, este proceso lleva unos 20 minutos. Sin embargo, el proceso de estabilización térmica de la estructura es mucho más lento. En el trabajo que aquí se presenta, se ha estudiado dicho proceso que tiene lugar durante las primeras horas y su importancia metrológica.

Measurement, Feb 1, 2019

Verification of workpieces is typically performed in the post-process with coordinate measuring m... more Verification of workpieces is typically performed in the post-process with coordinate measuring machines, thereby increasing the manufacturing cycle time. However, machine tools presently can perform contact measuring operations by using a probe. Moreover, there is a growing need for in-process inspection of workpieces. Therefore, using the machine tool itself for the verification whilst the workpiece remains clamped to the machine can lead to an improvement in manufacturing efficiency, cost reduction, higher energy saving and better equipment productivity. However, the use of touch probes as a measurement tool in manufacturing requires some preparatory works. Firstly, the accuracy of the machine tool should be improved to reduce the influence of its geometric errors. Secondly, the uncertainties in calibration and measuring procedure should be determined to obtain the measurement uncertainty. This study presents a new tool that can analyse the effect of different verification parameters in calibration uncertainty based on Monte Carlo method. On the basis of the actual tests performed on a milling machine and its geometric errors, the effect of laser tracker measurement noise in calibration uncertainty is investigated.

Procedia Manufacturing, 2019

Nowadays, machine tool accuracy is a competitive element. To improve it, machine tools are verifi... more Nowadays, machine tool accuracy is a competitive element. To improve it, machine tools are verified and compensate periodically reducing the influence of their geometric errors. As geometric errors have systematic behavior, their influence can be compensated after verification. However, verification itself is influenced by random uncertainty sources that affect verification results. Within all influences on machine tool volumetric verification, laser tracker measurement noise is a random uncertainty source that is not usually considered. However, it should not be ignored and can be reduced through an adequate location. This paper presents an algorithm able to analyze the influence of laser tracker location, taking into consideration its specifications and machine tool characteristics. To do that, the developed algorithm provides a zone around MT to locate the measurement system using the Monte Carlo Method. Moreover, it provides the probability distribution function of laser tracker influence related to LT location zone. Therefore, if MT is used as a traceable measurement system, its uncertainty cannot be smaller than LT location uncertainty.

Sensors, Jun 26, 2019

Volumetric verification is based on the machine tool (MT) kinematic model, along with its geometr... more Volumetric verification is based on the machine tool (MT) kinematic model, along with its geometric errors. Although users often ignore the uncertainty of verification, the use of the MT as a traceable measurement system in the manufacturing process has increased the need for professionals to be aware of it. This paper presents an improvement in the MT kinematic model, introducing in it the influence of verification uncertainty sources. These sources have been classified into four groups: the MT, the measurement system itself, the measurement strategy, and the optimization strategy. As the developed model exhibits non-linear behavior, the Monte Carlo method was used to determine the influence of the measurement system on verification uncertainty using synthetic tests. In this manner, an improved estimation of the MT uncertainty can be obtained. Therefore, if the MT is used as a traceable measurement system, its accuracy should not be higher than the laser tracker (LT) verification influence. It hence shows the importance of LT influence.

Measurement, Apr 1, 2009

The necessity of improving the quality of the products together with the pressure for reducing th... more The necessity of improving the quality of the products together with the pressure for reducing the production cycle has driven the manufacturers of parts and products to look for accurate but faster ways to perform the inspection tasks. Analog probes, also known as scanning contact probes, are being one of the most used solutions for coordinate measuring machines (CMM) users owing to their ability to collect large amounts of points and execute fast measurements. Likewise, the probe is one of the most important subsystems of a CMM and is one of the main responsible for the accuracy of a measurement and of the flexibility of CMMs. However, most of the studies on scanning CMMs do not separate the performance of the probing system from other error sources of the CMM. Since analog probes are precision equipments themselves, their performance should be studied separately from the rest of the components of the CMM in order to characterise behaviour, independently on the machine where they are working, and, therefore, to improve their accuracy. This paper presents a new out-of-machine calibration technique with sub-micrometer repeatability for passive contact analog probes. The sub-micrometer repeatability is obtained from the use of kinematic couplings which, in this case, have the peculiarity of being indexing (able to be placed and interchanged in different positions). The proposed calibration system has been applied to two analog probes: a serial-kinematics 3-degrees-of-freedom probe and a parallel-kinematics 6-degrees-of-freedom probe. From the results of extensive experiments in and out of the CMM it can be concluded that the out-of-machine calibration technique is useful to determine the static errors of passive analog probes that are not able to be obtained from in-machine scanning tests. Finally, an optimisation process is proposed and applied to the parallel-kinematics probe obtaining a sensible improvement of its accuracy.

IOP conference series, Oct 1, 2021

Additive manufacturing (AM) is a free-form build process in which an object is created adding mul... more Additive manufacturing (AM) is a free-form build process in which an object is created adding multiple layers. AM process is characterized by on-demand freeform part manufacturing with multiple materials and not for big production batches. There are different types of additive technologies that are capable of building pieces in diverse materials. For this study, various types of materials were tested in a fused deposition modeling (FDM) process using a standard workpiece and the build process was simulated in CURA software. The aim is to show the variability of the energy and the CO2 equivalent emissions produced in FDM manufacturing technology depending on the material used, specimen orientation, and the production batches. Variability in the material choice and the orientation of the piece was found for the environmental performance.

Key Engineering Materials, Jun 1, 2014

The results of this paper suggest that there is a serious problem in the curricula definition of ... more The results of this paper suggest that there is a serious problem in the curricula definition of some degrees. It is necessary to analyze the educational activities, teaching methodologies and evaluation systems for the Bachelor’s and Master’s degrees at the institutional level. This will allow for improvements in the evaluation of competence acquisition. Therefore, it is necessary to review the definition of the curricula while paying special attention to the relationship between competences and courses because the current study has detected notable discrepancies. The courses must be evaluated through competences or, more precisely, through the results of the learning process. This would considerably improve an evaluation model of the progress and results on the learning acquired by graduated students in terms of competences and would match what is established in the current regulation. When analysing the results for any two students, a simple comparison based on grades is not realistic, as it depends on the subjectivity of instructors and teachers during the grading process. By contrast, an evaluation based on competences is much more objective and comparable and would demonstrate which university reaches a better level of both general and specific competence achievement. The results of the aforementioned procedure are of interest to employers, enabling them to search and hire the best students in the desired field of study.

Procedia Engineering, 2013

IOP conference series, Oct 1, 2021

Traditionally, measuring both macro and micro geometries with a single device has been challengin... more Traditionally, measuring both macro and micro geometries with a single device has been challenging in metrology. Coordinate Measuring Machines (CMM) are common devices for the inspection of large features, while optical microscopes can achieve resolutions in the order of micrometers in small areas. X-Ray Computed Tomography (XCT) has become a solution not only to characterize both micro and macro geometries, but also to inspect internal features without destroying the sample. In this field, various reference standards have been developed in order to verify the capabilities of XCT systems, these artefacts include geometrical features or profiles for roughness inspection. This paper shows the design and develompent of a reference standard for XCT test which includes internal and external geometrical features and profiles for macro and micro geometrical inspection. The model is manufactured by additive manufacturing (AM), easing the process of fabrication of the artefact and allowing to test the capabilities of this technology to produce reference standards.

Jornada de jóvenes investigadores del I3A, 1970

En este trabajo se presenta el diseño inicial de una plataforma de desplazamiento en dos dimensio... more En este trabajo se presenta el diseño inicial de una plataforma de desplazamiento en dos dimensiones en un rango de 50 mm x 50 mm. Se explican los componentes utilizados, como materiales, sensores, accionamientos, etc. para lograr resoluciones nanométricas y precisiones submicrométricas, así como las pruebas realizadas a los mismos.

International Journal of Mechatronics and Manufacturing Systems, 2017

In order to provide an effective positioning along a wide working range with nanometre resolution... more In order to provide an effective positioning along a wide working range with nanometre resolution, a two-dimensional stage platform has been designed and manufactured. In view of the demanding metrological performance, the drive system and control strategy are being analysed and developed. Thus, this paper describes the preliminary modelling of the control when using four custom-made Halbach linear motors as a driving system. Firstly, the 1D control case is defined and validated by simulation. The different required blocks of the loop are presented and an initial controller solution is proposed to achieve the established positioning features. Secondly, the 2D scheme is presented to define all the needs of the whole control, including all sensors and actuators of the system. In addition, this work justifies the hardware and software selected, as an optimal low-cost solution for the developed long-range stage prototype.

As a result of the progress in the multidisciplinary nanotechnology field the demand for precisio... more As a result of the progress in the multidisciplinary nanotechnology field the demand for precision positioning systems has sensibly increased in the last years. In this line, a novel two-dimensional moving nano-platform (NanoPla) is being designed. The set requirements of the initial prototype are not only high positioning accuracy and resolution but also long working range (50x50 mm), increasing the number of potential applications. The presented paper demonstrates an illustrative part of the complete state-of-art realized, justifying and concluding with an optimal positioning system. Different long range stages have been considered and classified depending on their structure, motion system and relative motion between sample and probe. The final result is the definition of a three-layer and two-stage architecture to characterize surface topography of larger areas with an integrated Atomic Force Microscopy (AFM) system. In order to meet the requirements (nanometer resolution and submicrometer accuracy) several different precision engineering principles and finite elements method software have been used.

Nucleation and Atmospheric Aerosols, 2009

ABSTRACT In this paper the design and development of a new prototype for measuring lineal displac... more ABSTRACT In this paper the design and development of a new prototype for measuring lineal displacements with micrometric resolution are presented. This device is based on the use of opto-electronic sensors (photodiodes) with a mechanical displacement system. This generates a more compact and lower cost solution than the commercial ones (LVDT, optical encoders, etc.) usually utilized for measuring in a range of 10 mm with a resolution of tenths of micrometers. The mechanic system for the displacement comes from a relative movement between a linear guide and its slide unit. The final goal of this prototype is the calibration of machine tools with less expensive self-centering probes than the nowadays available commercial ones. Firstly, the properties and behavior of the photodiodes have been analyzed in order to verify that they are adequate for this appliance. In the following tests carried out the fulfillment of the square law has been verified but the system repeatability has been severely affected by the temperature. As a solution for this problem several options have been proposed, either by a mathematical compensation or, in an indirect way, by using a double measuring system with another LED and photodiode as reference elements. © 2009 American Institute of Physics.

Procedia Engineering, 2013

ABSTRACT The nanotechnology field has been developing strongly in recent years and ultra-precisio... more ABSTRACT The nanotechnology field has been developing strongly in recent years and ultra-precision measuring systems are nowadays required. A new two-dimensional moving platform with 50x50 mm range of travel, nanometer resolution and sub micrometer accuracy is being designed by the authors in order to be integrated with an Atomic Force Microscope (AFM). In this work the definition, design and experimental characterization of a homing sensor system for this 2D moving platform is presented. The homing sensor system will allow the generation of an absolute reference for the 2D platform on the X-Y axis and in θz, rotation of the XY plane in the Z axis, defining an initial cero for the measuring system which is based on laser encoders

Procedia Manufacturing, 2017

Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.

Procedia Manufacturing, 2017

Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.

CIRP Annals, 2012

Limited tool life of nickel mould inserts represents an issue for the mass-production of polymer ... more Limited tool life of nickel mould inserts represents an issue for the mass-production of polymer optics with complex micro three-dimensional geometries by injection moulding. TiN coating was applied to a nickel insert for the injection moulding of polycarbonate micro Fresnel lenses. Surface wear was monitored at different intervals during production on different tool locations. 3D micro optical dimensional microscopy, surface replica technique and SEM-EDS were employed to characterize wear of the micro features. Results showed wear decreasing at higher distance from the gate. After 24500 moulding cycles the measured height reduction of 23 µm high ribs was on the order of 400 nm to 1000 nm.

Measurement Science and Technology, Jan 31, 2020

Polymer laser powder bed fusion (LPBF) surfaces can be challenging to measure. These surfaces com... more Polymer laser powder bed fusion (LPBF) surfaces can be challenging to measure. These surfaces comprise complex features including undercuts, deep recesses, step-like transitions, a large range of measurement scales and unfavourable optically materials properties. While recent research has begun to examine the nature of these surfaces, there has not yet been significant effort in understanding how different measurement instruments interact with them. In this paper, we compare the results of LPBF surface topography measurements using a series of different instrument technologies, including contact stylus, focus variation microscopy, coherence scanning interferometry, laser scanning confocal microscopy and x-ray computed tomography. Measurements are made on both side and top surfaces of a cubic polyamide-12 LPBF sample. Different instrument behaviours are highlighted through qualitative visual inspection of surface reconstructions. Further comparisons are then performed through evaluation of profile and areal surface texture parameters and statistical modelling of surface topographies. These analyses allow for the identification both of discrepancies between texture parameters and discrepancies between local topographies reconstructed from measurements. Instrument repeatability metrics are also presented for each measurement of the test surfaces. Results show that discrepancies in measurements made on the acquired datasets are often similar in magnitude to the size of the features present on the surfaces. Conclusions are drawn regarding the suitability of various surface measurement instruments for polymer LPBF surfaces.

Micromachines, 2019

Nanotechnology applications demand high accuracy positioning systems. Therefore, in order to achi... more Nanotechnology applications demand high accuracy positioning systems. Therefore, in order to achieve sub-micrometer accuracy, positioning uncertainty contributions must be minimized by implementing precision positioning control strategies. The positioning control system accuracy must be analyzed and optimized, especially when the system is required to follow a predefined trajectory. In this line of research, this work studies the contribution of the trajectory definition errors to the final positioning uncertainty of a large-range 2D nanopositioning stage. The curve trajectory is defined by curve fitting using two methods: traditional CAD/CAM systems and novel algorithms for accurate curve fitting. This novel method has an interest in computer-aided geometric design and approximation theory, and allows high relative accuracy (HRA) in the computation of the representations of parametric curves while minimizing the numerical errors. It is verified that the HRA method offers better pos...

Procedia Engineering, 2015

Different systems are recently developed to obtain effective positioning at nanometer scale with ... more Different systems are recently developed to obtain effective positioning at nanometer scale with increased working ranges. For this purpose, a two-dimensional nanopositioning platform (NanoPla) has been design and manufactured. To assure the demanding metrological performance the drive and control system is being defined and validated. Based on four home-made linear motors as actuators, this work is focused on the study of the control-loop for 1D-and 2D-cases with the aim of the preliminary modelling and posterior implementation. The different required blocks are presented and an initial controller solution is proposed to achieve the established positioning requests.

Jornada de jóvenes investigadores del I3A, 1970

En el proceso de medición con un Laser Tracker, antes de iniciar la toma de datos, es necesario q... more En el proceso de medición con un Laser Tracker, antes de iniciar la toma de datos, es necesario que se estabilice la fuente láser, este proceso lleva unos 20 minutos. Sin embargo, el proceso de estabilización térmica de la estructura es mucho más lento. En el trabajo que aquí se presenta, se ha estudiado dicho proceso que tiene lugar durante las primeras horas y su importancia metrológica.

Measurement, Feb 1, 2019

Verification of workpieces is typically performed in the post-process with coordinate measuring m... more Verification of workpieces is typically performed in the post-process with coordinate measuring machines, thereby increasing the manufacturing cycle time. However, machine tools presently can perform contact measuring operations by using a probe. Moreover, there is a growing need for in-process inspection of workpieces. Therefore, using the machine tool itself for the verification whilst the workpiece remains clamped to the machine can lead to an improvement in manufacturing efficiency, cost reduction, higher energy saving and better equipment productivity. However, the use of touch probes as a measurement tool in manufacturing requires some preparatory works. Firstly, the accuracy of the machine tool should be improved to reduce the influence of its geometric errors. Secondly, the uncertainties in calibration and measuring procedure should be determined to obtain the measurement uncertainty. This study presents a new tool that can analyse the effect of different verification parameters in calibration uncertainty based on Monte Carlo method. On the basis of the actual tests performed on a milling machine and its geometric errors, the effect of laser tracker measurement noise in calibration uncertainty is investigated.

Procedia Manufacturing, 2019

Nowadays, machine tool accuracy is a competitive element. To improve it, machine tools are verifi... more Nowadays, machine tool accuracy is a competitive element. To improve it, machine tools are verified and compensate periodically reducing the influence of their geometric errors. As geometric errors have systematic behavior, their influence can be compensated after verification. However, verification itself is influenced by random uncertainty sources that affect verification results. Within all influences on machine tool volumetric verification, laser tracker measurement noise is a random uncertainty source that is not usually considered. However, it should not be ignored and can be reduced through an adequate location. This paper presents an algorithm able to analyze the influence of laser tracker location, taking into consideration its specifications and machine tool characteristics. To do that, the developed algorithm provides a zone around MT to locate the measurement system using the Monte Carlo Method. Moreover, it provides the probability distribution function of laser tracker influence related to LT location zone. Therefore, if MT is used as a traceable measurement system, its uncertainty cannot be smaller than LT location uncertainty.

Sensors, Jun 26, 2019

Volumetric verification is based on the machine tool (MT) kinematic model, along with its geometr... more Volumetric verification is based on the machine tool (MT) kinematic model, along with its geometric errors. Although users often ignore the uncertainty of verification, the use of the MT as a traceable measurement system in the manufacturing process has increased the need for professionals to be aware of it. This paper presents an improvement in the MT kinematic model, introducing in it the influence of verification uncertainty sources. These sources have been classified into four groups: the MT, the measurement system itself, the measurement strategy, and the optimization strategy. As the developed model exhibits non-linear behavior, the Monte Carlo method was used to determine the influence of the measurement system on verification uncertainty using synthetic tests. In this manner, an improved estimation of the MT uncertainty can be obtained. Therefore, if the MT is used as a traceable measurement system, its accuracy should not be higher than the laser tracker (LT) verification influence. It hence shows the importance of LT influence.

Measurement, Apr 1, 2009

The necessity of improving the quality of the products together with the pressure for reducing th... more The necessity of improving the quality of the products together with the pressure for reducing the production cycle has driven the manufacturers of parts and products to look for accurate but faster ways to perform the inspection tasks. Analog probes, also known as scanning contact probes, are being one of the most used solutions for coordinate measuring machines (CMM) users owing to their ability to collect large amounts of points and execute fast measurements. Likewise, the probe is one of the most important subsystems of a CMM and is one of the main responsible for the accuracy of a measurement and of the flexibility of CMMs. However, most of the studies on scanning CMMs do not separate the performance of the probing system from other error sources of the CMM. Since analog probes are precision equipments themselves, their performance should be studied separately from the rest of the components of the CMM in order to characterise behaviour, independently on the machine where they are working, and, therefore, to improve their accuracy. This paper presents a new out-of-machine calibration technique with sub-micrometer repeatability for passive contact analog probes. The sub-micrometer repeatability is obtained from the use of kinematic couplings which, in this case, have the peculiarity of being indexing (able to be placed and interchanged in different positions). The proposed calibration system has been applied to two analog probes: a serial-kinematics 3-degrees-of-freedom probe and a parallel-kinematics 6-degrees-of-freedom probe. From the results of extensive experiments in and out of the CMM it can be concluded that the out-of-machine calibration technique is useful to determine the static errors of passive analog probes that are not able to be obtained from in-machine scanning tests. Finally, an optimisation process is proposed and applied to the parallel-kinematics probe obtaining a sensible improvement of its accuracy.

IOP conference series, Oct 1, 2021

Additive manufacturing (AM) is a free-form build process in which an object is created adding mul... more Additive manufacturing (AM) is a free-form build process in which an object is created adding multiple layers. AM process is characterized by on-demand freeform part manufacturing with multiple materials and not for big production batches. There are different types of additive technologies that are capable of building pieces in diverse materials. For this study, various types of materials were tested in a fused deposition modeling (FDM) process using a standard workpiece and the build process was simulated in CURA software. The aim is to show the variability of the energy and the CO2 equivalent emissions produced in FDM manufacturing technology depending on the material used, specimen orientation, and the production batches. Variability in the material choice and the orientation of the piece was found for the environmental performance.

Key Engineering Materials, Jun 1, 2014

The results of this paper suggest that there is a serious problem in the curricula definition of ... more The results of this paper suggest that there is a serious problem in the curricula definition of some degrees. It is necessary to analyze the educational activities, teaching methodologies and evaluation systems for the Bachelor’s and Master’s degrees at the institutional level. This will allow for improvements in the evaluation of competence acquisition. Therefore, it is necessary to review the definition of the curricula while paying special attention to the relationship between competences and courses because the current study has detected notable discrepancies. The courses must be evaluated through competences or, more precisely, through the results of the learning process. This would considerably improve an evaluation model of the progress and results on the learning acquired by graduated students in terms of competences and would match what is established in the current regulation. When analysing the results for any two students, a simple comparison based on grades is not realistic, as it depends on the subjectivity of instructors and teachers during the grading process. By contrast, an evaluation based on competences is much more objective and comparable and would demonstrate which university reaches a better level of both general and specific competence achievement. The results of the aforementioned procedure are of interest to employers, enabling them to search and hire the best students in the desired field of study.

Procedia Engineering, 2013

IOP conference series, Oct 1, 2021

Traditionally, measuring both macro and micro geometries with a single device has been challengin... more Traditionally, measuring both macro and micro geometries with a single device has been challenging in metrology. Coordinate Measuring Machines (CMM) are common devices for the inspection of large features, while optical microscopes can achieve resolutions in the order of micrometers in small areas. X-Ray Computed Tomography (XCT) has become a solution not only to characterize both micro and macro geometries, but also to inspect internal features without destroying the sample. In this field, various reference standards have been developed in order to verify the capabilities of XCT systems, these artefacts include geometrical features or profiles for roughness inspection. This paper shows the design and develompent of a reference standard for XCT test which includes internal and external geometrical features and profiles for macro and micro geometrical inspection. The model is manufactured by additive manufacturing (AM), easing the process of fabrication of the artefact and allowing to test the capabilities of this technology to produce reference standards.

Jornada de jóvenes investigadores del I3A, 1970

En este trabajo se presenta el diseño inicial de una plataforma de desplazamiento en dos dimensio... more En este trabajo se presenta el diseño inicial de una plataforma de desplazamiento en dos dimensiones en un rango de 50 mm x 50 mm. Se explican los componentes utilizados, como materiales, sensores, accionamientos, etc. para lograr resoluciones nanométricas y precisiones submicrométricas, así como las pruebas realizadas a los mismos.

International Journal of Mechatronics and Manufacturing Systems, 2017

In order to provide an effective positioning along a wide working range with nanometre resolution... more In order to provide an effective positioning along a wide working range with nanometre resolution, a two-dimensional stage platform has been designed and manufactured. In view of the demanding metrological performance, the drive system and control strategy are being analysed and developed. Thus, this paper describes the preliminary modelling of the control when using four custom-made Halbach linear motors as a driving system. Firstly, the 1D control case is defined and validated by simulation. The different required blocks of the loop are presented and an initial controller solution is proposed to achieve the established positioning features. Secondly, the 2D scheme is presented to define all the needs of the whole control, including all sensors and actuators of the system. In addition, this work justifies the hardware and software selected, as an optimal low-cost solution for the developed long-range stage prototype.

As a result of the progress in the multidisciplinary nanotechnology field the demand for precisio... more As a result of the progress in the multidisciplinary nanotechnology field the demand for precision positioning systems has sensibly increased in the last years. In this line, a novel two-dimensional moving nano-platform (NanoPla) is being designed. The set requirements of the initial prototype are not only high positioning accuracy and resolution but also long working range (50x50 mm), increasing the number of potential applications. The presented paper demonstrates an illustrative part of the complete state-of-art realized, justifying and concluding with an optimal positioning system. Different long range stages have been considered and classified depending on their structure, motion system and relative motion between sample and probe. The final result is the definition of a three-layer and two-stage architecture to characterize surface topography of larger areas with an integrated Atomic Force Microscopy (AFM) system. In order to meet the requirements (nanometer resolution and submicrometer accuracy) several different precision engineering principles and finite elements method software have been used.

Nucleation and Atmospheric Aerosols, 2009

ABSTRACT In this paper the design and development of a new prototype for measuring lineal displac... more ABSTRACT In this paper the design and development of a new prototype for measuring lineal displacements with micrometric resolution are presented. This device is based on the use of opto-electronic sensors (photodiodes) with a mechanical displacement system. This generates a more compact and lower cost solution than the commercial ones (LVDT, optical encoders, etc.) usually utilized for measuring in a range of 10 mm with a resolution of tenths of micrometers. The mechanic system for the displacement comes from a relative movement between a linear guide and its slide unit. The final goal of this prototype is the calibration of machine tools with less expensive self-centering probes than the nowadays available commercial ones. Firstly, the properties and behavior of the photodiodes have been analyzed in order to verify that they are adequate for this appliance. In the following tests carried out the fulfillment of the square law has been verified but the system repeatability has been severely affected by the temperature. As a solution for this problem several options have been proposed, either by a mathematical compensation or, in an indirect way, by using a double measuring system with another LED and photodiode as reference elements. © 2009 American Institute of Physics.

Procedia Engineering, 2013

ABSTRACT The nanotechnology field has been developing strongly in recent years and ultra-precisio... more ABSTRACT The nanotechnology field has been developing strongly in recent years and ultra-precision measuring systems are nowadays required. A new two-dimensional moving platform with 50x50 mm range of travel, nanometer resolution and sub micrometer accuracy is being designed by the authors in order to be integrated with an Atomic Force Microscope (AFM). In this work the definition, design and experimental characterization of a homing sensor system for this 2D moving platform is presented. The homing sensor system will allow the generation of an absolute reference for the 2D platform on the X-Y axis and in θz, rotation of the XY plane in the Z axis, defining an initial cero for the measuring system which is based on laser encoders

Procedia Manufacturing, 2017

Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.

Procedia Manufacturing, 2017

Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.