Marta María Marín

Surface Roughness Evaluation Based on Acoustic Emission Signals in Robot Assisted Polishing

The polishing process is the most common technology used in applications where a high level of surface quality is demanded. The automation of polishing processes is especially difficult due to the high level of skill and dexterity that is required. Much of this difficulty arises because of the lack of reliable data on the effect of the polishing parameters on the resulting surface roughness. An experimental study was developed to evaluate the surface roughness obtained during Robot Assisted Polishing processes by the analysis of acoustic emission signals in the frequency domain. The aim is to find out a trend of a feature or features calculated from the acoustic emission signals detected along the process. Such an evaluation was made with the objective of collecting valuable information for the establishment of the end point detection of polishing process. As a main conclusion, it can be affirmed that acoustic emission (AE) signals can be considered useful to monitor the polishing process state.

Modeling strategies for efficient FE simulation of localised-incremental forging processes

The numerical simulation of Localised-Incremental Forging (LIF) is a challenging task. The analysis of LIF operations is often difficult, especially when several strokes are necessary to obtain the final shape of the part. The use of FE models is mandatory because incremental operations throughout a workpiece are difficult to analyse with conventional analytical methods. It is known that, in general, implicit FE models give more robust results than explicit FE models; however, with the former methodology there are several problems that must be faced. With the main goal to extend the analysis capability of LIF operations, some explicit FE models are developed in this paper and results are compared to those obtained by implicit methodology. It can be concluded that taking into account these guidelines, the developed models could be further used in the analysis of multi-strokes LIF operations, where more complicated trajectories will be required.

Application of Different Simulation Strategies for the Analysis of Multi-Stroke Localised-Incremental Forging Operations

The analysis of LIF operations is often difficult, especially when several strokes are necessary to obtain the final shape of the part. The use of FE models is highly recommended and it is known that implicit FE models give more robust results than explicit FE models; however, with the former methodology there are several problems that must be faced. With the main goal to extend the analysis capability of LIF operations, some explicit FE models are developed in this paper and results are compared to those obtained by implicit methodology. It can be concluded that taking into account these guidelines, the developed models could be further used in the analysis of multi-strokes LIF operations, where more complicated trajectories are going to be used.

Accuracy Analysis of Fringe Projection Systems Based on Blue Light Technology

Some manufacturers of 3D digitizing systems are developing and market more accurate, fastest and affordable systems of fringe projection based on blue light technology. The aim of the present work is the determination of the quality and accuracy of the data provided by the LED structured light scanner Comet L3D (Steinbichler). The quality and accuracy of the cloud of points produced by the scanner is determined by measuring a number of gauge blocks of different sizes. The accuracy range of the scanner has been established through multiple digitizations showing the dependence on different factors such as the characteristics of the object and scanning procedure. Although many factors influence, accuracies announced by manufacturer have been achieved under optimal conditions and it has been noted that the quality of the point clouds (density, noise, dispersion of points) provided by this system is higher than that obtained with laser technology devices.

An Approach to Integrating Tactical Decision-Making in Industrial Maintenance Balance Scorecards Using Principal Components Analysis and Machine Learning

The uncertainty of demand has led production systems to become increasingly complex; this can affect the availability of the machines and thus their maintenance. Therefore, it is necessary to adequately manage the information that facilitates decision-making. This paper presents a system for making decisions related to the design of customized maintenance plans in a production plant. This paper addresses this tactical goal and aims to provide greater knowledge and better predictions by projecting reliable behavior in the medium-term, integrating this new functionality into classic Balance Scorecards, and making it possible to extend their current measuring function to a new aptitude: predicting evolution based on historical data. In the proposed Custom Balance Scorecard design, an exploratory data phase is integrated with another analysis and prediction phase using Principal Component Analysis algorithms and Machine Learning that uses Artificial Neural Network algorithms. This new extension allows better control over the maintenance function of an industrial plant in the medium-term with a yearly horizon taken over monthly intervals which allows the measurement of the indicators of strategic productive areas and the discovery of hidden behavior patterns in work orders. In addition, this extension enables the prediction of indicator outcomes such as overall equipment efficiency and mean time to failure.

Mechanical Analysis of Indentation Processes According to Geometrical and Lubrication Parameters

Some of the new technological trends in metal forming processes are focused on the development of net shape or near net shape forming processes, the resurgence of incremental technologies and the consideration of environmental factors that result in more sustainable processes. On this basis, indentation is an interesting field because of its characteristics: lower forces are required, complex dies are not necessary and they can be used as an alternative to some forging operations. In this study an indentation process has been simulated by the Finite Element Method assuming plane strain conditions. The geometrical parameters considered are the width, w, and the height, h, of the workpiece and they are related to the width of the punch, B. For the simulation of different lubrication conditions a Coulomb friction model between the workpiece and the punch has been assumed. The friction coefficient has been chosen in such a way that either frictionless and high friction conditions have been covered. Under thes...

Analysis of Force Signals for the Estimation of Surface Roughness during Robot-Assisted Polishing

In this study feature extraction of force signals detected during robot-assisted polishing processes was carried out to estimate the surface roughness during the process. The purpose was to collect significant features from the signal that allow the determination of the end point of the polishing process based on surface roughness. For this objective, dry polishing turning tests were performed on a Robot-Assisted Polishing (RAP) machine (STRECON NanoRAP 200) during three polishing sessions, using the same polishing conditions. Along the tests, force signals were acquired and offline surface roughness measurements were taken at the end of each polishing session. As a main conclusion, it can be affirmed, regarding the force signal, that features extracted from both time and frequency domains are valuable data for the estimation of surface roughness.

Learning Activities through Academic Papers Focused on Forming Processes

This work analyses the learning tasks, related to forming processes, realized by students of a Master degree focused on Manufacturing Engineering. The forming processes include bulk deformation and sheet forming. The objective of these activities is to identify if these practices are linked to research and development or technological innovation. The students must select works from database of international scientific journals and analyze the contents. The results show that the students have identified 62 papers from 21 different journals and of authors from 17 countries; mostly traditional processes (bending, extrusion, deep-drawing, mainly) have been chosen and studied, recognizing important advances in them; moreover the learning tasks have contributed to the acquisition the basic, general and specific competences.

Manufacturing Engineering Education: Study of the Continuous Evaluation Activities on UNED

In this study, the continuous assessment activities are analyzed on the learning results. The subjects chosen belong to the field of Manufacturing Engineering. The subjects analyzed are taught in Bachelor´s Degree in College of Industrial Engineering. The continuous assessment activities were designed to propose in both obligatory and elective subjects. The number of the students in obligatory subjects is usually higher than in the other type. In this paper, the data were extracted from the last three academic courses. From the analysis of the results it can be affirmed that, in general, students who carried out assessment activities, improved their academic results.

Incremental versus continuous load-lubrication procedure in the determination of friction conditions by the ring compression test

This work presents the differences found when using two types of methodology (continuous and incremental) in the application of load-lubricant during ring compression tests. Friction calibration maps have been obtained by conducting ring compression tests to flat rings of aluminium alloy UNS A97075-T6 with molybdenum disulphide (MoS2) as lubricant. Accordingly, in order to determine the particular values of the Coulomb friction coefficient, the problem was simulated using an elasto-plastic model with the finite element code Abaqus/Standard. A friction coefficients map from experiments and finite element simulation is drawn to compare the friction coefficient values derived from the continuous and incremental procedure. A comparison with experiments done with graphite powder as lubricant is also presented. Results of this investigation show that friction curves are affected by the methodology of load-lubricant application, and some guidelines about the use of these maps depending on the actual process conditions are provided.