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High quality standards and components downsizing are two main quests of the engineering designers in the nowadays automotive industry. To this aim, lightweight materials as aluminum are used. Moreover, most parts of the automotive chassis made of aluminum are assembled by means of welding techniques. Lightweight materials, such as aluminum, are more and more adopted in chassis design even if the assembly process represents a challenge from a technological point of view, especially due to the distortions caused by the welding process. In case of thin aluminum structures, non-convenient distortions occur due to a combination of effects of fixturing and cooling (after welding) process. The reduction of distortions or almost their prediction is still a very challenging issue, so that no conclusive technique has been found to exclusively fix the problem yet. In this paper, a “design for welding” approach is proposed as an integrated product design and process simulation method, with the aim of predicting the final distortion of an aluminum welded automotive chassis. Thermal-Elastic-Plastic (TEP) finite element analyses (FEA) simulations are capable to provide acceptable results, but require high computational efforts, especially in case of complex geometries as car chassis. To overcome this problem, in this paper, the local-global FEA approach has been adopted with satisfactory results. A top-class car automotive aluminum chassis has been chosen as a case study.

Additive Manufacturing (AM) is a key technology in current industrial transformations thanks to the significant benefits that can bring to high-level sectors. Nevertheless, AM-based design approaches require improvements that are fundamental to exploit the potentials of the technology and reduce the lack of process consistency. This work focuses on integrated Design for Additive Manufacturing (DfAM) approaches for product-process design, to meet both functional and technological targets. The key aspects of process design and issues are summarized and the design method to perform metal AM process optimization is presented. The aim is therefore to minimize process-induced defects and flaws of AM-based manufacturing of metal products, such as residual stress and distortions. The approach consists of industrialization task improvement based on modelling optimization and build optimization sub-phases supported by numerical process simulation. Integration of CAD platforms allows embedding these steps to be performed downstream of the product design, which can be achieved through functional or multifunctional optimization techniques as well (e.g. topology optimization, latticing, graded structures/materials). The design method is finally applied to perform the industrialization phase of a high-performance automotive component. The case study is a formula SAE topology optimized brake caliper to be produced by Selective Laser Melting (SLM) process. Process simulation-driven studies on modelling and build preparation subphases (i.e. orientation definition, supports generation, model distortion compensation) are conducted to support the process design. The study demonstrates the part scale level method’s suitability to industrial context to improve industrialization in the redesign of components to be produced by metal AM.

Las companias fabricantes de automoviles continuamente promueven la innovacion de los productos de automocion y los procesos de fabricacion relacionados, basandose principalmente en metodos dedicados para el diseno de chasis de automocion y en los procesos de montaje con soldadura relacionados a ese diseno. Los primeros de ellos buscan mejorar la calidad final de todo el chasis a traves de optimizacion del ratio rigidez/ peso y a traves del uso de materiales de alto rendimiento. Los segundos buscan mejorar el rendimiento del chasis y reducir los costes de produccion total reduciendo los residuos mediante lineas de soldadura roboticas reconfigurables. Por consiguiente, se requieren nuevas metodologias de diseno integradas que tengan en cuenta las restricciones y especificaciones de las fases de diseno del proceso/producto, a la vez que se sugiere un uso concurrente de metodologias numericas y herramientas de simulacion para evaluar la configuracion de los sistemas roboticos y la programacion de los robots. Esta investigacion presenta una metodologia de diseno novedosa que busca reducir las desventajas de las actuales metodologias por medio de la evaluacion de operaciones de ensamblado antes de diseno en detalle del chasis y del diseno conceptual del sistema de fijacion, explotando las herramientas asistidas por ordenador. En particular este trabajo se centra en la fase de proceso de la metodologia de diseno, que busca integrar las herramientas de programacion offline de robots, para predecir las distorsiones de soldadura debido a la modificacion de los parametros de entrada del robot de acuerdo con los valores de tolerancia requeridos. Los resultados experimentales en relativos al submontaje de un chasis de referencia que se une siguiendo procesos de soldadura basados en herramientas asistidas por ordenador demuestran la efectividad del metodo propuesto. Palabras clave: Metodo integrado basado en CAD, analisis de tolerancia acumuladas, prediccion de distorsiones de soldadura, ensamblaje de soldadura robotica.

Easy-to-use collaborative robotics solutions, where human workers and robots share their skills, are entering the market, thus becoming the new frontier in industrial robotics. They allow to combine the advantages of robots, which enjoy high levels of accuracy, speed and repeatability, with the flexibility and cognitive skills of human workers. However, to achieve an efficient human–robot collaboration, several challenges need to be tackled. First, a safe interaction must be guaranteed to prevent harming humans having a direct contact with the moving robot. Additionally, to take full advantage of human skills, it is important that intuitive user interfaces are properly designed, so that human operators can easily program and interact with the robot. In this survey paper, an extensive review on human–robot collaboration in industrial environment is provided, with specific focus on issues related to physical and cognitive interaction. The commercially available solutions are also presented and the main industrial applications where collaborative robotic is advantageous are discussed, highlighting how collaborative solutions are intended to improve the efficiency of the system and which the open issue are.

This paper proposes the analysis of the tolerances (values, types, datum) and their effects on a mechanical assembly, as a high-performance car engine, by means of a Computer-Aided Tolerancing software. The 3D tolerance stack-ups are investigated to assess the fulfillment of the functional requirements as well as the performance specifications of the assembly. Moreover, after identifying the tolerances that mainly affect the product variability, we finally propose some corrective actions on the tolerances and assess their functional allocation, tightening or relaxing their values, ensuring assemblability and cost reduction.

The Dimensional Management (DM) is well known as the reference methodology for the management of dimensional and geometric variations of industrial products. Over the years, it has assumed a central role, thanks to the development of a specific design approach, known as Design for Tolerancing (DfT). Based on the Geometric Dimensioning and Tolerancing (GD&T) symbolic language, DfT allows to check and verify functional and qualitative requirements from the early design phases. Although its strength and potential to improve design optimization, DfT industrial application is still limited. Consolidated design practices, complexity of tolerance specification process, lack of support from Computer-Aided tools still limit the tolerance specification to final validation of product design. The paper aims to define a tolerance specification model for systematic application of GD&T specification. The model formalizes the identification and translation of product requirements on the components geometry, through the definition of the main step of tolerance design. Based on the integration between the GD&T-based approach and parametric three-dimensional CAD modelling, the model has been applied to validate the GD&T and the tolerance specification of two mechanical assemblies with common features. The methodology proves its general effectiveness to support engineers in tolerance design and selection of the most suitable GD&T schemes.

The structural properties of cast aluminum parts are strongly affected by the solidification in the production process. The solidification dynamics determines the Secondary Dendrite Arm Spacing (SDAS), directly affecting the structural strength of the alloy. Simulation techniques enable the integrated design of chassis parts and their production equipment. However, in order to effectively predict the SDAS formation, the simulation models need to be investigated and calibrated. The present research investigates the SDAS formation models and identifies a robust relation to be used in Design by Simulation phases for AlSi7Mg0.3 parts.

Additive Manufacturing is having a great trend since its implementation possible benefits have been widely discussed and efforts in technology improvements are having impact on process reliability and industrial application. The aims of this work are to analyze the current and forthcoming scenario of methods for the specific development of parts to be produced by metal AM including topology optimization as a basic design step and to demonstrate that systematical design approaches can be introduced in order to better exploit potentials offered by AM implementation. The general framework composed by the main tasks is introduced and discussed. Key factors such as advance in different design solutions exploration, product-related and process-related design constraint implementation in the design phase and method effectiveness in product development lead time minimization are presented. Linear and iterative workflows are described, considering features, decision making points, pros and cons, possible variants and research hints. A strong connection between methods and actual means is highlighted and workflow implementation using standard and integrated commercial tools is considered. Such methods are related to several automotive case studies presented in order to demonstrate their applicability and to show actual results and possible further development.

Additive Manufacturing based on Powder Bed Fusion processes enables the construction of end-use functional metal components, making it feasible to design several level of geometrical complexity. Nevertheless, the printing process leads to material and shape defects, residual stress and induced distortions on final components that mainly are caused by the high thermal gradients associated to the intense and nonuniform power energy sources used to selectively melt metal powders. In this paper, techniques to reduce or prevent these effects are summarized. The more broadly Design for Additive Manufacturing approach based on the use on CAD platforms for product-process design is the backbone upon this research is based on. Specifically, the work presents a design method to predict drawbacks and improve the industrialization subphase. Laser-based Powder Bed Fusion technique is considered and the implementation and validation of the Selective Laser Melting process simulation is performed in order to support the method. Two case studies are presented. The former demonstrates the simulation implementation feasibility through a CAD platform. The latter validates the simulation results compared to experimental data for further method application.

Human and robot collaboration represents an interesting development direction for traditional industrial robotic solutions. Especially for those cases where the operations are difficult to automate or burdensome for manual execution, the mutual exchange of human sensitivity and robot repeatability represents an effective approach. Nevertheless, industrial robots are poorly involved for collaborative tasks since specific safety countermeasures are required to avoid all the potential hazards. Consequently, the design and assessment of safety solutions represents a fundamental phase to estimate feasibility of industrial collaborative solutions. The presented work proposes a computer-aided approach to identify, assess and optimize the safety systems that enables the collaborative usage of industrial robots. It exploits the capabilities of virtual controller-based offline programming packages to design in advance the safety countermeasures. An initial consistency test validates the response of the selected tool with respect to the safety functionalities. Subsequently, a virtual replica of a potential industrial collaborative solution has been developed. As a result, it has been possible to mimic the behaviour of such a system with respect to Speed and Separation Monitoring collaborative method.

Recent research results on human–robot interaction and collaborative robotics are leaving behind the traditional paradigm of robots living in a separated space inside safety cages, allowing humans and robot to work together for completing an increasing number of complex industrial tasks. In this context, safety of the human operator is a main concern. In this paper, we present a framework for ensuring human safety in a robotic cell that allows human–robot coexistence and dependable interaction. The framework is based on a layered control architecture that exploits an effective algorithm for online monitoring of relative human–robot distance using depth sensors. This method allows to modify in real time the robot behavior depending on the user position, without limiting the operative robot workspace in a too conservative way. In order to guarantee redundancy and diversity at the safety level, additional certified laser scanners monitor human–robot proximity in the cell and safe communication protocols and logical units are used for the smooth integration with an industrial software for safe low-level robot control. The implemented concept includes a smart human-machine interface to support in-process collaborative activities and for a contactless interaction with gesture recognition of operator commands. Coexistence and interaction are illustrated and tested in an industrial cell, in which a robot moves a tool that measures the quality of a polished metallic part while the operator performs a close evaluation of the same workpiece.

Close-Range Photogrammetry is a widespread and efficient technique in the 3D acquisition of artefacts, particularly in fields like Cultural Heritage. Despite this wide usage, also due to a convenient quality/cost ratio, it shows some limitations due to light conditions as well as the artefact surface finishing. In this paper, we would like to report the assessment of a photogrammetry approach to 3D capture metal reflective surfaces, such as bronze, which is a widely used material in ancient statues. To this aim, we propose a photogrammetry workflow based on systematic steps capable of overcome some of the main issues of reflective surfaces. To validate this approach, the developed 3D model is compared to a more accurate model of the same artefact, obtained with a 3D scanner. As a case study, we selected the Principe Ellenistico, an ancient bronze statue conserved in the Museo Nazionale Romano (Rome, Italy), of which a photogrammetric model is firstly developed and then compared to the scanned one.

The presented paper suggests a design method which seeks to identify the best scheduling of human robot collaborative (HRC) operations with respect to a required safety level. The human behavior along manufacturing scenarios is effectively forecasted through dedicated computer-aided tools. Consequently, this method stresses the usage of virtual environment to replicate both human postures and robot encumbrances over the manufacturing operations. Moreover, it proposes a safety index formulation for HRC systems based on the minimum distance between human and robot (H-R). As results, the approach returns the safety index for every possible combination of H-R operations. Subsequently, a scheduling algorithm suggests the operations sequence depending on the expected value of the safety index, providing an evaluation of the time needed to complete the process. The method is validated on surface control phase involved in post-processing of parts produced by laser powder bed fusion (L-PBF) Additive Manufacturing.

A die for Al alloy casting must be designed to achieve the expected quality levels. Moreover, the casting unit cost must be regarded as the objective function to be minimised. It can be expressed as a function of the quantity of materials and energy to be used, cycle time and equipment investment. This work compares the performance of the die with inserts manufactured using the usual 1.2343 steel with that of the innovative 1.2383. The latter is considered due to its enhanced thermal conductivity, despite being more expensive. Simulation experiments are designed to evaluate different die layouts. The quality design solutions are evaluated against the cost objective function in order to identify the optimal die choice. A case study on gravity die casting (GDC) of an AlSi7Mg0.3 engine head shows faster solidification dynamics when using 1.2383 instead of 1.2343 steel. This reduces the feeder volume, thus increasing the production yield and speeding up the cycle time with a leverage effect. The higher investment cost for the inserts is rapidly returned thanks to the reduction in variable costs. The Return On Investment (ROI) with the improved die in the new solution is short compared with the life of the die.

El uso de métodos decisionales para la solución de problemas de diseño de ingeniería debe abordarse en un punto de vista "humano". Por lo tanto, lo fundamental es la identificac ón de problemas y necesidades de diseño, que se convierten en un punto de vista orientado al diseñador. Los métodos basados en la decisión se clasifican sistemáticamente en métodos MCDM, Métodos de Diseño Estructurado y Métodos de Estructuración de Problemas. Los resultados están organizados para ofrecer una primera referencia al diseñador en una selección preliminar de métodos basados en la decisión. El documento muestra el uso heterogéneo de los métodos basados en decisiones, que tradicionalmente se espera que resuelvan algunos otros problemas de diseño específicos, que también se han usado en diferentes contextos de diseño. Además, varios problemas de diseño, que surgieron durante el proceso de revisión, se han señalado y discutido en consecuencia. De esta revisión surgieron resultados útiles para la ampliación del estado del arte en los métodos de diseño basado en decisiones en un contexto de diseño de ingeniería.

This paper deals with the use of reciprocal frames in temporary gridshell structures, such as architectural pavilions in expositions and installations. These architectural examples can benefit from the use of short, easy to handle, generally joint-free, and repeatable “modules” in order to create particular self-supporting structures. The lightweight and interwoven grid obtained by connecting short elements according to the reciprocity principle is structurally efficient and, at the same time, aesthetically pleasing, mainly due to the resulting tessellation. The paper firstly investigates the connection between efficiency and aesthetics. The last part of the paper investigates some temporary architectural pavilions from both an aesthetical and parametric point of view. In order to deepen our understanding of these structures, they are re-modelled according to a bottom-up approach by means of a constraint-based parametric CAD modeller. In this way, a reciprocal frame can be explored and modified by the parametric arrangement of its generative elements, which, like a natural organism, grows in self-generating forms.

This work investigates vibration-supported, force-controlled fine machining with elastic bonded mounted points for automated fine processing of mould steel samples. The aim is to compare conventional robot- or machine-tool-based face grinding with a vibration-supported grinding process. The influence of vibration support on the surface topography is investigated primarily to minimize kinematically caused grinding traces. First, the state of the art for the production of tool moulds and vibration-supported fine machining is explained. On this basis, the potentials for the reduction of grinding marks through vibration support for an increase in the degree of automation are derived and the experimental procedure is introduced. Subsequently, robot-based grinding tests with vibration support are carried out and compared with conventional grinding tests. After the tests carried out, the results are evaluated using tactile and optical measuring methods.

The aim of this paper is to analyze some critical issues in the Design for Additive Manufacturing workflow and evaluate the introduction of CAD platforms as backbone tools to shorten product development time and raise its efficiency. It is focused on the design of components to be printed by Powder Bed Fusion metal Additive Manufacturing. Even though the use of additive technologies firmly joins a CAD mathematical model and the actually printed component, the workflow from the concept to the definitive job may result in many sequential steps which have complex and slow relationships. Currently, at the state of art for the production of components specifically designed to be produced by additive manufacturing, there are issues both with the adoption of STL as interchange files and the not reversible sequence of tasks. For example, if a problem occurs in the part re-design during component industrialization, usually one must restart the work from the beginning. Thus, an improvement of the design workflow that could shorten time to product and improve both product performances and process quality and reliability, is necessary. In particular, the use of CAD platforms that integrates CAD and CAE tools has been investigated. An automotive case study, originally made by traditional subtractive technology (CNC milling), has been re-designed with topology optimization in order to be printed by Selective Laser Melting process with benefit of weight reduction. Design and industrialization tasks have been tested with respect to the selected integrated CAD platform, and potential improvements have been evaluated.

Continuous innovation in the field of high-end motor vehicle chassis demands optimization of the weight/stiffness ratio and to achieve high quality standards. The use of light materials, such as aluminum alloys, is therefore increasingly common in the design of the chassis, whose assembly process represents a technological challenge. Welding joining processes, and in particular robot-based welding, are widely used in automotive field despite causing distortions. To predict these deformations, finite element analyzes are performed, in particular thermo-elasto-plastic simulations, which are able to satisfactorily replicate the behavior of residual stresses and strains after cooling. However, such analyzes are computationally expensive making their application difficult to complex structures. This work would investigate an alternative solution to predict distortions that effectively returns the behavior of welded assemblies. A CAE-based model for TEP analysis of welded joints is proposed. As a case study, the T-welded junction between two aluminum alloy plates (T-Joint) was considered. The model is validated by a preliminary experimental campaign.

An effective sensor system for monitoring the pressure distribution on a car seat would enable researches on Advanced Driver Assistance Systems (ADAS) and comfort of occupants. However, the irregularities of the seat shape or those of the occupant clothes challenge the robustness of such a sensor system. Moreover, the position identification of bodies of different percentiles by few pressure sensors is difficult. So, a higher resolution pressure pad has been developed. The number of sensors is significantly increased by means of a matrix scan strategy. Tests on the pressure pad with different occupants proves its robustness in scanning the contact area.

[EN] The spatial characteristics of museum exhibitions may limit visitors’ experience of the artefacts on display. In the case of large artefacts, limited space may affect their whole visualization, or inhibit the visualization of the details farthest from the observer. In other cases, the storage of artefacts in distant sites (museums or archaeological areas) may influence their knowledge process or the possibility for comparative analysis. Moreover, the precarious state of preservation of some artefacts, with damaged or missing parts, makes it difficult to perceive their original appearance. To overcome these limitations, we propose an integrated approach based on 3D virtual models and Augmented Reality (AR) to enhance the fruition of artefacts, improving their visualization, analysis and personal/shared knowledge, also by overcoming space and time constraints. The final AR application is an easily accessible tool for most users from a mobile device, used both inside and outside museums, opening new perspectives for fruition. The framework encourages the use of free and open source software and standard devices, to maximize their dissemination and exploit the potential of such technologies, which is far greater than current use in the cultural heritage field. Selected case studies to test and validate the integrated framework are proposed, dealing with some Roman artefacts found in the area of Modena (Italy). The first is a Roman floor mosaic, found in Savignano sul Panaro (near Modena) in 2011, of which less than half of its original 4.5 x 6.9 m surface is preserved. The others are two Roman funerary lion sculptures: the first is one of two lions flanking the main door of Modena Cathedral, and the second, well-preserved but damaged, is housed in the Museo Lapidario Estense of Modena. Finally, the application was tested by museum experts and visitors both inside and outside the museum, and positively assessed. Highlights: Digital practice is not understood as a prerogative of a small number of people, but as a tool to guarantee and expand artefact fruition, using standard devices and free and open source software. Experimentation of new settings to re-contextualize artefacts and establish possible links among them, offering engaging and customized experiences to improve their accessibility and enjoyment. Promotion of artefact fruition not only in but also outside museums, such as in a classroom or an open and shared space, opening to new approaches in the fruition of cultural heritage., [ES] Las características espaciales de la exhibición en museos puede limitar en los visitantes la experiencia de los artefactosque se presentan. En el caso de artefactos de gran tamaño, la limitación de espacio puede afectar su visualización completa o inhibir la visualización de los detalles más lejanos al observador. En otros casos, el almacenamiento de artefactos en sitios lejanos y apartados (museos o zonas arqueológicas) puede influir en su proceso de conocimiento o en su análisis comparativo. Es más, el precario estado de conservación de algunos artefactos, con partes dañadas o perdidas, hace difícil percibir su aspecto original. Para superar estas limitaciones, proponemos un enfoque integrado de modelos 3D y realidad aumentada (RA) que mejore el disfrute de los artefactos, mejorando su visualización, análisis y conocimiento personal/compartido, incluso sobrepasando las limitaciones de espacio y tiempo. La aplicación final es una herramienta fácilmente accesible para la mayoría de usuarios mediante un portátil, que se use dentro, pero también fuera de los museos, abriendo nuevas perspectivas de disfrute. El enfoque promueve el uso de software libre y gratuito y herramientas estándar, con vistas a maximizar su amplia distribución y reivindicar las potencialidades de dichas tecnologías, que son superiores a su actual uso en el campo del patrimonio cultural. Se proponen casos de estudio seleccionados para testear y validar el enfoque integrado, a partir de algunos artefactos Romanos encontrados en la zona de Módena (Italia). El primero es un suelo de mosaico Romano, encontrado en Savignano sul Panaro (cerca de Módena) en 2011, que conserva menos de la mitad de sus 4.5 x 6.9 m de superficie originales. Los otros son dos esculturas funerarias romanas de león: el primero es uno de los dos leones que flanquean la puerta principal de la Catedral de Módena, y el segundo, bien conservado pero dañado, se almacena en el Museo Lapidario Estense de Módena. Finalmente, la aplicación se prueba por expertos del museo y visitantes dentro y fuera del museo, y se evalúa positivamente.

Surface polishing can be counted among the most challenging manufacturing operations, especially when high qualitative levels in terms of surface texture characteristics are requested, such as in the case of polishing operations for plastic injection moulds. Robot-based solutions for surface polishing and quality assessment operations have been proposed at the state of the art, but it still is required the involvement of skilled workers for process supervision and final tuning operations. The introduction of human-machine collaborative solutions opens new opportunities, as the use of symbiotic polishing approaches, where both the humans and the machines capabilities can be shared to improve process effectiveness. The current work proposes a human-robot collaborative approach for surface polishing processes that integrates state of the art robot-based polishing and surface quality assessment technologies in a human-safe shared working environment. As a proof of approach feasibility, the paper presents the prototype of a reconfigurable platform designed to implement a flexible human-robot collaborative scenario for execution of polishing and quality assessment operations. Preliminary demonstrative polishing sessions on simple and complex components validate the system effectiveness with respect to manufacturing efficiency and reconfigurability capabilities. The results obtained provide a first positive response that symbiotic approach can objectively improve the polishing processes.

Future intelligent vehicles will be capable to monitor driver distraction while autonomous driving. However, in case of system fault, the intelligent vehicle must also manage an adaptive strategy for the Airbag Control Unit, since the airbag deployment against an Out of Position occupant can be additionally harmful. Thus, the present research work investigates a possibility to monitor the driver position as a robust information to an intelligent vehicle. A seat is sensorized with a map of pressure sensors. The system layout and setup are discussed in details. Signal processing strategy and real driving experiments are reported.

Persian architecture is characterised by shapes and patterns, which can be analysed through mathematical models. Beside 2D patterns, many of the traditional geometric ornaments are realised on 3D surfaces such as domes or vaults. Literature mainly addresses the 3D problem by means of a 2D scheme, which is an important and synthetic representation but is not exhaustive and lacks of clarity. This paper proposes a framework based on the integration of 2D drawings, as in the traditional approach, and a photogrammetric 3D model based on a sample of standard resolution images (tourist pictures). The framework is tested on a muqarnas, a characteristic Persian ornament, in order to study and analyse its modular design and hierarchy of elements. As a case study, the entrance iwan of the Shah Mosque in Isfahan, Iran, is considered. The result is a link between the 3D patterns and the geometry of architectural elements, which completes and overcomes their schematic 2D representation.

A significant interest exists in measuring the thermal emissivity of building surfaces since high values combined with high solar reflectance allow rejecting solar energy absorbed by irradiated surfaces, whereas intermediate or low values permit to limit condensation of humidity, heat loss to the sky, or heat transfer through airspaces. The most used measurement method is probably that described by the ASTM C1371 Standard, which correlates the thermal emissivity to the radiative heat flux exchanged in the infrared between the sample surface, kept at ambient temperature, and the bottom surface of a hot emissometer head. With samples showing a low thermal conductivity, the ‘slide method’ modification is generally used: the hot head is allowed to slide above the sample in order to prevent this from warming up. The slide movement, however, is carried out by hand and time is needed to achieve a stabilized output, therefore the measurement may be time-consuming and also affected by the operator. In order to solve both problems, an automated approach is proposed here, in which the head is moved by the arm of a robot. This manages either the slide movement or the calibration with reference samples, interacting with a computerized data acquisition system that monitors the emissometer output.

Molds for metal casting are often internally coated in order to minimize the interaction between the steel surface of the mold and the melted metal during its pouring and solidification. However, the added coating increases the thermal interface resistance during the cooling process and it can thus affect the process itself. For example, numerical predictions and experimental results are matched only if the interface resistance is even quintupled in the presence of the usual interface coating, compared to the uncoated mold. In order to have a reasonable estimate of the interface thermal resistance, an easy to use measurement approach has been tested. This consists of contacting a cold and a hot samples of metals with known thermal properties, one at ambient temperature and the other one much hotter. The temperatures of the two samples, assumed to be uniform in each sample, are measured by thermocouples placed inside the samples through a hole, and the interface resistance is calculated from the time evolution pattern of those temperatures during the thermal transient that follows the instant in which the samples have been contacted.

Today the assembly lines of cars chassis are highly automated by robotic operations. Even in the top class automotive sector, the production of aluminium chassis involves numerous automated operations, such as TIG and MIG welding, riveting and gluing. This practice allows, on the one hand, to reduce time and costs, improve process repeatability and quality standards. On the other hand, it requires the quality improvement of the whole process (from supplied parts approval to welding reworks minimization). The industrialization phase of a new car chassis and the launch of its automated assembly line are particularly critical, even more if the line has already been designed and only minimally modifiable. Therefore, this paper proposes the implementation of a quality framework to manage the launch of an automated assembly line of a new aluminium chassis of top class cars, selected as a case study. The framework was implemented, aiming at improving the entire process quality, and finally validated by critically comparing the results obtained with those relating to models currently in production. Due to their importance to the final quality, we focused on the welding operations, which require actions both on process parameters and supplied parts approval (e.g. tolerances on parts end cuts). The new line shows a clear improvement compared to the past, with highly significant reduction of welding non-conformances, high quality level and lack of many critical issues of the previous lines thanks to corrective actions taken in the early process stages, during the pilot phase.

The recent trends in modern industry highlight an increasing use of robots for a wide range of applications, which span from established manufacturing operations to novel tasks characterized by a close collaboration with the operators. Although human-robot collaboration allows to relieve operators of exhausting works, an effective collaboration requires a straightforward interaction to foster the use of robot assistants. This paper provides a comprehensive survey on human-robot interaction approaches and related interfaces addressed to robot programming. An overview of on-line and off-line robot programming techniques is first presented. Then, novel intuitive interaction means, such as those based on multi-modal interaction, virtual and augmented reality, are considered. The paper aims at pointing out that collaborative robotics can effectively reduce operator’s physical workload if easy to use interfaces for robot programming are provided.

This paper presents a knowledge based engineering environment methodology to support the designer in the correct setting of geometrical and dimensional tolerances in assemblies of mechanical components. The procedure is based on the definition of the functional requirements needed to allow the proper working of the assembly; in the further, a software tool is used to do a statistical analysis of the assembly relations, providing an estimation of the components waste due to poor compliance to the tolerances. A case study given by the design of a marine power transmission is presented: the methodology leads to the change of some tolerances to improve the design by reducing the number of waste components. The strength of the methodology is represented by the fact it can help unskilled designers in the correct setting of tolerances in drawings.

The integration of experiments with numerical simulations can efficiently support a quick evaluation of the welded joint. In this work, the MIG welding operation on aluminum T-joint thin plate has been studied by the integration of both simulation and experiments. The aim of the paper is to enlarge the global database, to promote the use of thin aluminum sheets in automotive body industries and to provide new data. Since the welding of aluminum thin plates is difficult to control due to high speed of the heat source and high heat flows during heating and cooling, a simulation model could be considered an effective design tool to predict the real phenomena. This integrated approach enables new evaluation possibilities on MIG-welded thin aluminum T-joints, as correspondence between the extension of the microstructural zones and the simulation parameters, material hardness, transient 3D temperature distribution on the surface and inside the material, stresses, strains, and deformations. The results of the mechanical simulations are comparable with the experimental measurements along the welding path, especially considering the variability of the process. The results could well predict the welding-induced distortion, which together with local heating during welding must be anticipated and subsequently minimized and counterbalance.

Machining using industrial robots is currently limited to applications with low geometrical accuracies and soft materials. This paper analyzes the sources of errors in robotic machining and characterizes them in amplitude and frequency. Experiments under different conditions represent a typical set of industrial applications and allow a qualified evaluation. Based on this analysis, a modular approach is proposed to overcome these obstacles, applied both during program generation (offline) and execution (online). Predictive offline compensation of machining errors is achieved by means of an innovative programming system, based on kinematic and dynamic robot models. Real-time adaptive machining error compensation is also provided by sensing the real robot positions with an innovative tracking system and corrective feedback to both the robot and an additional high-dynamic compensation mechanism on piezo-actuator basis.

Reconfigurable manufacturing systems (RMS) are considered the future of manufacturing, being able to overcome both dedicated (DMS) and flexible manufacturing systems (FMS). In fact, they provide significant cost and time reductions in the launch of new products, and in the integration of new manufacturing processes into existing systems. The goals of RMS design are the extension of the production variety, the adaption to rapid changes in the market demand, and the minimization of the investment costs. Despite the interest of many authors, the debate on RMS is still open due to the lack of practical applications. This work is a review of the state-of-the-art on the design of cellular RMS, compared to DMS, by means of optimization. The problem addressed belongs to the NP-Hard family of combinatorial problem. The focus is on non-exact meta-heuristic and artificial intelligence methods, since these have been proven to be effective and robust in solving complex manufacturing design problems. A wide investigation on the most recurrent techniques in DMS and RMS literature is performed at first. A critical analysis over these techniques is given in the end.

Fixture systems have a great importance in modern manufacturing and assembly because of the high number of scenarios in which they are used. Fixture design is a complex task since the system effectiveness depends both on position and type of locators. Several authors deal with the problem of determine the most suitable design for fixture systems but their investigation is commonly limited to the evaluation of the effects due to the locators position. In the present work a design method is proposed to evaluate the fixture systems considering also the locators type. Since it is possible to model the fixtures as multi-performance systems, the comparison is performed by introducing appropriate sensitivity indexes. The effectiveness of the design method is proved through the application to an automotive case study.

This paper reports about the design and modeling process of high performance servo-actuated mechanisms for automatic machines. Besides being a delicate and time consuming process, coupled simulations based on virtual prototyping finally offer the chance to integrate engineering methods proper of control system engineering and mechanical design. In particular, the main target of this work is to investigate how different virtual prototyping approaches, each having increasing level of detail, can contribute to the appropriate prediction of the expected machine performance. These results are then compared with experimental data obtained on a real servomechanism prototype. The comparison quantitatively demonstrate the improvement on torque prediction and position error reduction when detailed models of the controller and the electric motor dynamics are coupled with the mechanical system model.