Abstract: This paper presents a computer-based methodology to support the design for additive manufacturing of metal components. Metal additive manufacturing, and in particular powder bed fusion systems, are playing a prominent role in the industry 4.0 scenario. The state of the art concerning design methods and tools to support design for additive manufacturing is reviewed by the authors. The key phases of product design and process design to achieve lightweight functional designs and reliable processes are deepened, and the computer-aided technologies to support the approaches implementation are described. Indeed, the state of the art design for additive manufacturing general workflow can be enriched by holistic approaches, use of numerical simulation, and integration and automation between the required tasks. The paper provides a methodology based on the systematic use of numerical simulation to achieve the optimization of both products and associated processes. To take advantage of the holistic perspective, the approach relies on the use of integrated product-process design platforms, allowing to streamline the digital process chain. Product design is based on the systematic integration of topology optimization and automatized tools for concept development and selection and subsequent product simulation driven design refinement. Process design is based on a systematic use of process simulation to prevent manufacturing flaws related to the high thermal gradients of metal processes and minimize residual stress and deformations. This is achieved by working on both the build cycles layouts and the 3D models’ distortion compensation. An automotive use case of product and process design performed through the proposed simulation-driven integrated approach is provided to assess the actual method suitability for effective re-designs of additive manufacturing high-performance metal products. The bridged gaps are systematically outlined, and further developments are discussed.

Keywords: Computer-aided engineering | Design method | Design optimization | Finite element method | Integrated design | Process simulation

Abstract: Additive Manufacturing (AM) Powder Bed Fusion (PBF) metal processes enable significant design freedom, addressing design complexity in high-end sectors. To build performant products, several Design for Additive Manufacturing guidelines must be considered. Nevertheless, it is still noticeable a lack of reliability for AM processes, which is a key factor to guarantee both the expected enhanced product requirements and the manufacturability. Even though few rules and best practices to mitigate defects are provided either by standards or equipment suppliers, they are still missing approaches to predict build failures and process flaws, and therefore achieve faultless build processes. This work suggests a concurrent product and process design approach, in which Computer Aided Engineering tools are involved in both product and process design to identify the components’ shapes that match the expected performance and a feasible PBF build layout. An automotive component is the use case, whose design based on topology optimization and product validation is enriched by integrating the associated process simulation. The build process is modeled by (a) the additive manufacturing simulation to identify flaws and resources usage, and (b) the thermo-mechanical finite element -based simulation to predict residual stress and distortions. The approach based on CAD platforms integrates product and process design to reduce design iterations, trial-error practices, and build failures.

Keywords: Design for Additive Manufacturing | Finite Element Analysis | Laser Powder Bed Fusion | Process simulation | Product-process design

Abstract: Additive Manufacturing processes based on metal deposition are continuously evolving due to the extensive application potentials. Currently, they present a widespread use in manufacturing of large parts and constructions, as well as reparation of damaged components. A promising application is the Remanufacturing of existing components to produce functional design variants. A key phase for its development is the study and control of residual stress and deformations induced by the process. In fact, thermal gradients and cooling rates are more intensive than those related to the other metal additive manufacturing processes and their effect impacts on functional and assembly product requirements. This work provides the study of a laser-based Direct Metal Deposition process, supported by numerical simulation and experimental validation. The aim is to set up a framework for reliable simulations to drive the design of high performance components, which are optimized with respect to both product and process requirements. Process planning and deposition strategies highly affect heat dissipation and thermal cycles, thus, predictive techniques can be embedded in integrated product-process design approaches to avoid flaws and contain components shrinkage and deformation. The process is developed by building specific specimens, performing thermo-mechanical simulations, and comparing 3D capturing result and computed result. The simulation phase can thus be considered as a key step to structure a Design for Additive Remanufacturing workflow. Further developments concern the application of such approaches to the design of high performance components to be produced by Directed Energy Deposition process.

Keywords: Direct metal deposition | Distortion | Finite element analysis | Metal additive manufacturing | Process simulation

Abstract: The production of large-sized optical components with complex shapes requires several phases, including surface finishing. Currently, mainly skilled workers can correctly perform this operation, divided into the successive steps of grinding and polishing, leading to long production times, poor reproducibility of results, and exposure to human error. For this reason, the industry is trying to move towards automation involving, for example, high-precision machine tools and machining centers. However, these solutions require high investment costs and long setup times. Using robotic cells helps to reduce these expenses, manufacture larger components, and increase the flexibility in the production chain. In this research, we present an unconventional approach to the robot-assisted grinding of optical samples made of borosilicate crown glass. The samples were guided by a six-degree-of-freedom industrial robot on a rotating grinding disc while imposing to them different trajectories with complex geometry. We avoided regular grinding patterns, which are easily recognizable by human eyes and affect the quality assessment, by superposing multiple relative movements between the machined surface and the abrasive grains. The ground surfaces of the samples were characterized based on average roughness values, profile error data, and surface topography images. Finally, we selected the best robotic grinding procedure matching the trajectory and strategy with optimal surface quality, processing time, and productivity. The suggested methodology not only shortens the manufacturing sequence by eliminating manual methods but also provides components with optical properties within the required specifications for subsequent polishing steps.

Keywords: Borosilicate crown glass | Industrial robot | Superposed trajectories | Surface grinding | Surface quality

Abstract: The tolerance-cost optimization plays a central role in the design of industrial components, due to its implications in all production stages. To reduce development times and increase product quality, the systematic application of tolerance-cost optimization from the early design phases requires a deep knowledge of the tolerance effects on both product performance and production cost. However, many factors still hamper its industrial diffusion, comprising three improvement areas: data and parameters sharing, flexibility to application complexity, and integration of simulation tools. Data and parameters sharing are a key factor since directly affect the representation and information transfer of tolerances and manufacturing processes. Both tolerances-cost relations and optimization structure must be properly represented, through a knowledge modelling framework. The present paper introduces an interoperability framework for the Computer-Aided tolerance-cost optimization. Through creating instances for tolerance and manufacturing process information, the interoperability is implemented defining a systematic sequence of steps to breakdown the multi-disciplinary optimization structure. Starting from the assembly structure, with the extraction of information from the 3D models to its transfer for parametric modelling into tolerance simulation and cost estimation environments, the interoperability framework identifies input-output relations and highlights the integration provided by multi-disciplinary optimization structure. The application of the presented framework on an archetypal case study provides an analysis of the suitability of the method, highlighting the further improvements. In this way it is possible to improve the interoperability between design and simulation virtual environments, to optimize tolerances in a concurrent a multi-disciplinary manner.

Keywords: Cost estimation | Model based definition | Multi-disciplinary optimization | Tolerance design | Tolerance-cost optimization

Abstract: Nowadays the rehabilitation process involves the patient and the therapist, that must interact to recover the motion of limbs and the strength of related muscles to restore the initial functionalities. The therapy relies on the experience and sensitivity of the therapist that identifies the rehabilitation exercises which are necessary to recover the expected ability. To prevent inappropriate practices an interesting aid may come by mixing collaborative robots, namely Cobots, and additive manufacturing technologies. The proper integration of a Cobot assistant and custom-printed training objects enables a significant improvement in the effectiveness of the therapy action and the related user experience since the programmed trajectories can mimic the movements related to activities of daily living. To this aim, this work describes an integrated approach to support the design of Cobot assisted rehabilitative solutions. The object selected by the patient and therapist, the motion pattern, the clamping area, and loads on the limb represents the design requirements. The motion trajectories defining the specific training tasks are the starting point to the optimal placement within the Cobot workspace. Specifically, manipulability maps can provide an objective evaluation of the locations where the exercises are performed at the best of workspace and configuration of the Cobot. A simple upper limb rehabilitation exercise based on a demonstrative handle has been selected to prove the effectiveness of the proposed approach. The results confirm that the manipulability index can be adopted to drive the preliminary design of the Cobotic solution toward a feasible configuration.

Keywords: Assisted Rehabilitation | Cobot | Integrated Design | Manipulability Index | Occupational Therapy

Abstract: When humans and robots work together, ensuring safe cooperation must be a priority. This research aims to develop a novel real-time planning algorithm that can handle unpredictable human movements by both slowing down task execution and modifying the robot’s path based on the proximity of the human operator. To achieve this, an efficient method for updating the robot’s motion is developed using a two-fold control approach that combines B-splines and hidden Markov models. This allows the algorithm to adapt to a changing environment and avoid collisions. The proposed framework is thus validated using the Franka Emika Panda robot in a simple start–goal task. Our algorithm successfully avoids collision with the moving hand of an operator monitored by a fixed camera.

Keywords: hidden Markov models | human–robot interaction | obstacle avoidance | splines

Abstract: Within the road to decarbonization scenario, it becomes increasingly central to analyze the sources of emissions from different perspectives and select the more sustainable design approach for the development of new products. Among many sectors, lightweighting can reduce costs related to energy and fuel consumption. Potentially, it is also possible to reduce emissions, both for air and land transport, especially considering vehicles in the context of electrification and green transition. This paper provides an approach for the quantitative estimation of CO2 emissions along the lightweight design of vehicles components. The approach is based on a Life Cycle Assessment (LCA), which includes aspects ranging from product design and production to the use phase, and possible upgrading and recycling. Two lightweight design strategies are considered, using either conventional or unconventional technologies, which are respectively based on Design for Machining and Design for Additive Manufacturing. These methods can be scaled in high-end sectors, as both are characterized by high flexibility and customization, which allow the implementation of lightweight designs for small batch sizes. An automotive component is used as a case study, performing the product-process design based on Computer-Aided Technologies (CAX) for both approaches. The CO2 assessment is performed, considering all the drivers relating to the stages of the product life cycle. Additive Manufacturing is confirmed as more energy intensive, but the additional mass saving over the vehicle use phase returns emissions reduction compared to the whole life cycle.

Keywords: Computer Numerical Control | Environmental sustainability | Greenhouse gas emissions | Lightweighting | Powder Bed Fusion | Product-process design

Abstract: The grinding of mold inserts used for injection molding aims to improve the surface roughness according to precise quality standards. The insert surface must also have a surface topography that facilitates the release of the plastic material at the end of the injection process. In particular, fine machining lines must be parallel to the extraction direction from the mold to avoid the sticking of plastic material and subsequent surface damages compromising the functionality of the finished product. However, this step in the production chain is most often conducted manually. This paper presents an analytical model to grind a truncated cone-shaped mold insert for the mass production of plastic cups. The automated solution consists of a flexible robotic system equipped with a rotating external axis to improve the accessibility of the tool to the surface to be machined. The tool path programming requires the development of an analytical model considering the simultaneous motion of the insert and the robot joints. The effectiveness of the developed model is evaluated in terms of final surface quality, grinding lines direction, and total process time. The automated strategy developed can be easily implemented with machine tools and applied to inserts with different axisymmetric geometries.

Keywords: Automated fine machining | CAM programming | Grinding lines | Mold insert | Robot manufacturing

Abstract: The present work describes an automotive component design optimization process through a systematic approach. The redesign aims to improve product performance by Powder Bed Fusion metal Additive Manufacturing. The approach allows to match Topology Optimization and Design for Additive Manufacturing by exploiting benefits provided by CAD platforms that integrate CAD, CAE and CAM tools. The Systematic Concept-Selection-Based Approach aims to make redesign simple and effective, allowing design solutions exploration while containing product design lead time. Topology Optimization is the key phase to achieve lightweight design by a double-level optimization approach. In particular, the technique is setup to produce different design variants, whose subsequently undergo a Trade-off study to perform the concept selection step. Finally, one final redesign occurs and a design refinement step is performed to achieve product optimization. The case study is a high performance internal combustion engine piston, which has been redesigned to be produced by Selective Laser Melting process with benefit of weight reduction.

Keywords: Automotive | Design for additive manufacturing | Design method | Re-design | Topology optimization

Abstract: Model-based Definition (MBD) is a known design approach that aims to an effective integration of Product Manufacturing Information (PMI) within geometrical data. By means of MBD, product requirements and specifications based on Geometric Dimensioning and Tolerancing (GD&T) can be directly associated to 3D models, improving interoperability between design and simulation virtual environments. However, especially in industrial settings, many challenges still limit MBD diffusion, such as limited knowledge and application of GD&T rules, inconsistent representation of PMI, lack of methodological and organizational approach based on PMI. As a consequence, the Dimensional Management practice based on GD&T cannot be systematically applied, and the full potential of Computer-Aided specific tools remains unexpressed. In this paper, the effective implementation of MBD for PMI during both product and process design is proved through its direct application on tolerance-cost optimization. Thanks to 3D semantic annotations, a model-based framework is suggested to validate functional requirements of a mechanical assembly and to assess production efforts, enhancing the integration between tolerance analysis and manufacturing cost tools. The interrelation of GD&T schemes enables the automated transfer of the data linked to annotations toward Computer-Aided Tolerancing (CAT) and Product Cost Management (PCM) virtual environments. Consequently, PMI guides the simulations during the multi-disciplinary optimization, proving its effectiveness in communicating engineering information and enabling the transition to digital manufacturing though MBD.

Keywords: Geometric dimensioning and tolerancing (GD&T) | Model-based definition | Product manufacturing information | Tolerance-cost optimization

Abstract: Additive manufacturing is even more capturing the interest of vehicle manufactures. Its adoption enables design potentials such as parts customization, lightweighting or functional integration. Deep adoption of additive manufacturing and integration of topology optimization design techniques enable the calculation of light components, while additive manufacturing makes it feasible by adding subsequent layers of material. Design for additive manufacturing guidelines address these challenges by enabling the build of such complex shapes thanks to parts consolidation and features integration. Several prototypes of such lightweight design concerning chassis, body, and structures have been provided, but the lack of structured and objective approaches limits the application in normal production. This work integrates Key Performance Indexes (KPIs) into the Design for Additive Manufacturing (DfAM) approach for an effective adoption of selection of trade-off studies for the selection of best product variant and process setup. The trade-off involves KPIs related to structural product requirements and laser Powder Bed Fusion process cost estimation, to return functional components that address the best ratio between weight reduction and expected manufacturing cost. Proof of the method effectiveness and its application to lighten real components is demonstrated by applying the approach to reduce the weight of a steering support system for a Formula SAE race car. The objectivity of the trade-off promotes the extensive adoption to other vehicle components for substantial fuel efficiency improvement and emissions reduction perspectives.

Keywords: 3D printers | Cost estimating | Economic and social effects | Emission control | Integration

Abstract: Geometric and dimensional deviations are the main contributors on quality and cost of products. Specifically, the selection of tolerance types and the appropriate allowable range plays a central role for an effective development process. Nevertheless, the trade-off between expected performances and target costs requires skills and interaction of many areas of engineering design, especially in the early design phases. Despite many tolerance-cost optimization practices are proposed by the research community several limitations still hamper the industrial application: among them, data and parameters sharing, flexibility to application complexity, and integration of simulation tools are the main ones. Focusing on a systematic framework, an integrated modelling and simulation environment is required to take full advantage of the concurrent use of engineering software. The present paper contributes to this aim by suggesting a Computer-Aided framework that integrates Geometric Dimensioning and Tolerancing simulations and manufacturing cost estimations in a multi-disciplinary optimization environment. Advanced tools are the cornerstones of the suggested framework, enabling easy identification of the main operational steps and providing the automation of the optimization. To be validated and demonstrate the effective applicability, the framework has been applied for the tolerance-cost optimization of an archetypal case study of an automotive engine assembly. The simulation models have been integrated within the optimization, providing several configurations of tolerances from which identify the optimal one. The analysis of optimization results allows to assess the efficiency of the method, highlighting further improvements to extend its robustness, flexibility, and application range.

Keywords: Computer-Aided design | Cost estimation | Model-based definition | Multi-disciplinary optimization | Tolerance design

Abstract: In this paper, the problem of robotic rehabilitation of upper limbs is addressed by focusing attention on the control of a standard collaborative robot for those training activities that can be performed with the aid of an end-effector type system. In particular, a novel admittance control, that constrains the motion of the robot along a prescribed path without imposing a specific time law along it, has been devised. The proposed approach exploits the features of the arc-length parameterization of a generic curve to obtain a simple control formulation able to guide the patient in both a passive or an active way, with the possibility of supporting the execution of the task with an additional force or opposing the motion with a braking force. Being the method independent from the particular curve considered for the constraint specification, it allows an intuitive definition of the task to be performed via Programming by Demonstration. Experimental results show the effectiveness of the proposed approach.

Keywords: Admittance control | Guidance virtual fixtures | Human-robot interaction | Rehabilitation

Abstract: Metal Additive Manufacturing technologies provide many advantages among industrial sectors. Most applications exploit design freedom for functional design enabled by Powder Bed Fusion processes, while Directed Energy Deposition systems are mainly restricted to the construction of large parts and reparation of damaged components. Nevertheless, the latter provide not only high deposition rates, but also high flexibility, and the possibility to process multi-materials, to grade and combine their characteristics for enhanced features and performance. Therefore, a rising application is the remanufacturing of existing components to produce functional design variants. Those parts can integrate different features and materials through direct deposition of metals over bounded areas. This work concerns the development of a Design for Additive Remanufacturing methodology for existing components with improved performances to be produced by the laser-based Direct Metal Deposition process. It relies on the use of CAD platforms for the integrated design of products and the associated processes. The design approach is based on the integration of CAE structural analysis and Topology Optimization, to define the location and the morphology of deposited structures. The design of an automotive suspension arm with enhanced performances is the use case to demonstrate the effectiveness of the approach, which could be extended to the remanufacturing of several bodies and chassis automotive subsystems.

Keywords: Design for Additive Manufacturing | Finite Element Analysis | Hybrid Manufacturing | Laser Metal Deposition | Remanufacturing | Topology Optimization

Abstract: The use of Topology Optimization techniques has seen a great development since the last decade. The principal contributor to this trend is the widespread use of Additive Manufacturing technologies to effectively build complex and performant structures over different settings. Nevertheless, the use of Topology Optimization in Design for Additive Manufacturing processes is not simple and research aims to fill the gap between theory and practice by evolving at the same time both approaches, workflows, and design software that allow their implementation. Since a strong connection between methodologies and tools exists, this work proposes a method to assess computer-aided design tools or platforms. This can be applied to sustain the key phase for selection and adoption of the computer-aided tools in industrial settings embracing Additive Manufacturing. The workflow for Topology Optimization implementation, the structure of the proposed evaluation approach, and its application, are presented to demonstrate effective usability. The automotive case study is the redesign of internal combustion engine piston to benefit of metal Additive Manufacturing based enhanced product performance. A preliminary finite element model is defined and a Topology Optimization based redesign is concurrently set up through four different commercial computer-based platforms. The method accounting for the assessment of required operations for the design optimization is applied to perform the tools selection phase.

Keywords: Automotive | Computer aided design tools | Design for additive manufacturing | Design methods | Topology optimization

Abstract: 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 threedimensional 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.

Keywords: Design for tolerancing (DFT) | Dimensional management (dm) | Geometric dimensioning and tolerancing (gd&t) | Product design

Abstract: 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 simulationdriven 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.

Keywords: Additive manufacturing | Automotive | Design method | Powder bed fusion | Process optimization | Process simulation

Abstract: To implement the CAD platform-based approach of Design for Additive Manufacturing (DfAM) and validate it in a real case, an entire design optimization process of a Formula SAE front brake caliper has been performed, to be printed by Powder Bed Fusion (PBF) process. The DfAM consists in the use of a Ti6Al4V titanium alloy to better resist at high temperatures and a topology optimized shape allowed by the technology to save weight despite the density increase. Structural and thermal behavior has been discussed. DfAM process-specific techniques have been implemented for internal geometrical features and optimized shapes. The design for additive workflow is presented and finally the exploited design approach based on a CAD platform is synthesized.

Keywords: Automotive | Brake caliper | CAD platform | DfAM | Topology optimization

Abstract: 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.

Keywords: CAD platforms | design for additive manufacturing | industrialization | powder bed fusion | process simulation | selective laser melting

Abstract: The development of additive manufacturing allows the transformation of technological processes and the redesign of products. Among the most used methods to support additive manufacturing, the design can be optimised through the integration of topology optimisation techniques, allowing for creating complex shapes. However, there are critical issues (i.e., definition of product and process parameters, selection of redesign variants, optimised designs interpretation, file exchange and data management, etc.) in identifying the most appropriate process and set-ups, as well as in selecting the best variant on a functional and morphological level. Therefore, to fully exploit the technological potentials and overcome the drawbacks, this paper proposes a systematic redesign approach based on additive manufacturing technologies that integrate topology optimisation and a tool for selecting design variants based on the optimisation of both product and process features. The method leads to the objective selection of the best redesigned configuration in accordance with the key performance indicators (KPIs) (i.e., functional and production requirements). As a case study, the redesign of a medical assistive device is proposed, previously developed in fused filament fabrication and now optimised for being 3D printed with selective laser melting.

Keywords: Assistive device | Design for additive manufacturing | Design method | Design optimisation | Design variants selection | Redesign | Selective laser melting | Topology optimisation

Abstract: Use of Additive Manufacturing provides great potentials to settings focused on high performance products. It allows feasibility of sundry innovative features to completely rethink geometries and shapes and it leads to embrace new design approaches. The enhanced design freedom can be exploited to optimize products, using techniques such as topology optimization. The study of methods for development of optimized components to be produced by AM becomes therefore fundamental. A framework for the methodological approach to operations to be carried out from the concept model to the printed component has been analyzed and it is clear that issues and research efforts relapse both the global level of the workflow and the local level of singular tasks to be performed. Problems related to management of Design for Additive Manufacturing workflow can be solved with holistic approach, through the use of computer aided integrated tools. The aim of this work is to test the effectiveness at local level of such tools with respect to operations for both design and industrialization optimization, working on an automotive case study. In particular, specific tools for topology optimization, product simulation, printing preparation and process simulation are taken as reference and results obtained with an integrated CAD platform are discussed.

Keywords: CAD based integrated platform | Design for Additive Manufactruing | High performance automotive components | Powder Bed Fusion

Abstract: Collaborative robotics and additive manufacturing are two enabling technologies of the Industry 4.0 manufacturing paradigm. Their synergic integration requires novel and effective design approaches, aiming to the development of new reconfigurable solutions for customised processes and products. This work presents an integrated approach that exploits the capabilities of Cobots to mimic the repetitive and exhausting operator’s movements as well as the competitive advantages offered by additive manufacturing to realize tailored equipment. In particular, the case study shows the development of a customised device for the manipulation of biomedical components by means of a Cobot, which is introduced in a workstation to replace manual operations. Moreover, the flexibility and the effectiveness of a Cobot can be improved thanks to customised devices for gripping and pick-and-place operations based on a specific application. During the development phase, we simulated the assembly process, and tested different options. The final configuration, with conformal circuits and suction cups, can pick, manipulate and assembly the biomedical components, and thanks to a Fused Filament Fabrication technology is additively manufactured. In conclusion, this developed prototypal solution proves the real capabilities offered by integrating Cobots and additive manufacturing for the lean automation of a biomedical workstation.

Keywords: Additive manufacturing | Biomedical components | Collaborative robot | Design approach | Industry 4.0

Abstract: 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.

Keywords: Collaborative robotics | Depth sensing | Human-machine interface | Industrial cell | Polishing | Safe human–robot interaction

Abstract: 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.

Keywords: Computer-aided assessment | Human-robot collaboration | Indutrial robots | Safey countermeasures | Speed and separation monitoring

Abstract: 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..

Keywords: Automotive. | Design methods | DfAM | Topology Optimization

Abstract: 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.

Keywords: Additive Manufacturing | CAD-based methods | Human Robot Collaboration | Safety index | Task scheduling

Abstract: 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.

Keywords: CAE-based model | TEP analysis | Termo-elasto-plastic model | Welding process

Abstract: 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.

Keywords: Finishing | Grinding | Moulds | Vibration-assisted

Abstract: 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.

Keywords: Automotive | CAD platform | Design for Additive Manufacturing | Topology optimization

Abstract: Augmented reality is considered one of the enabling technologies of the fourth industrial revolution, within the Industry 4.0 program and beyond. Indeed, augmented reality solutions can increase the working quality and the productivity and allow a better use of the human resources. This technology can help the operator in the industrial applications during the crucial phases of the processes. Since the quality assessment of the surfaces is recognized to be a key phase in the polishing process, in this paper we propose a novel method that exploits augmented reality to support the operators during this phase. The metrology data measured by a surface measurement system are directly projected on the polished component through an augmented reality headset worn by the operators and used to assess the quality of the worked surfaces. Rather than imagine how a certain parameter change can affect the result achieved, the information is directly there on the component's surface. Users can see from the data where refinements are required and make better and faster decisions, which is compelling for its potential beyond industrial polishing. The proposed method is implemented and validated on an industrial cell, where the robot automatically perform the polishing task and move the head of the surface measurement system along the surface to measure the metrology parameters. Thanks to the proposed approach, the end-user and the operator can directly see on the component if the quality reached satisfies the specifications or if some parts of the surface require further refinements through additional polishing steps.

Keywords: Augmented reality | Industrial robotic solutions | Robotic polishing

Abstract: 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.

Keywords: Collaborative Robotics | Computer Integrated Manufacturing | Polishing Processes | Reconfigurable Systems | Robotics

Abstract: 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.

Keywords: Collaborative robots | Human–robot collaboration | Industrial applications | Intuitive robot programming | Safety | User interfaces

Abstract: In nearly every sector of industrial manufacturing, especially the mould and die making industry, polishing techniques are used. Most often, manual polishing is the only option because the tasks are too complex to be automated in terms of surface quality demands, geometrical features and restricted tool accessibility. Therefore, the European H2020 Project SYMPLEXITY 'Symbiotic Human-Robot Solutions for Complex Surface Finishing Operations' developed a CNC-machine-based machining concept comprising a composition of different finishing technologies. The solution is complemented with an objective metrology surface qualification device, which is capable to also measure big parts holistically. The SYMPLEXITY approach combines both a collaborative, intelligence-based and a cooperative human-robot-based technological approach. The demonstrator machine concept is being introduced and first fine machining experiments, comprising polishing and measurements have been conducted to generate an initial parameter set-up. The experiments have been conducted on an empiric basis to identify the main steering parameters for a future semi-analytic, model-based finishing approach.

Keywords: Abrasive Finishing | Human-Robot Interaction | Objective Surface Qualification | Robotic polishing

Abstract: 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.

Keywords: Design methodology for HMS | Human operator support | Intelligent interfaces | Multi-modal interaction | Robotics technology

Abstract: In recent years, Human Robot Cooperation (HRC) has found an increasing adoption in manufacturing, especially to help humans in the execution of manual assembly tasks. An effective employment of HRC encompasses human relief from exhausting operations. Therefore, the design of cooperative solutions should be developed accordingly to ergonomic aspects. The present work proposes an approach to support the integration of ergonomic evaluation of manual operations in the design of HRC solution, based on modelling and simulation of the human body along the manufacturing tasks. The proposed modified model integrates the ergonomic metrics and returns a fatigue level along the working shift scheduling. A real manual assembly of biomedical products has been selected to validate the proposed approach. As a result, the suggested fatigue model provides an objective ergonomic evaluation of manual operations which verifies the impact of the HRC solution on the production goals.

Keywords: Biomedical | Ergonomic evaluation | Human Robot Cooperation | Simulation

Abstract: Industrial robotics provides high flexibility and reconfigurability supported by a user-friendly programming, but still lacks in accuracy. An effective workcell calibration reduces errors in robot manufacturing and enables robot machining applications. A novel workcell calibration method is embedded in an integrated design framework for an in-depth exploitation of CAD-based simulations and offline programming. The method is composed of two steps: first calibration of the workpiece-independent equipment in the workcell layout and final automated online calibration of workpiece-dependent equipment. The method is finally applied to a changeable robotic workcell for finishing aluminium cast housings for aerospace gear transmissions characterised by complex shapes and by close dimensional and geometrical specifications. Experimental results prove the method effectiveness in enhancing accuracy in robot machining.

Keywords: Aerospace industry | Industrial robotics | Integrated design | Workcell calibration

Abstract: 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.

Keywords: Cool roof | Emissivity | Emissometer | Infrared emittance | Infrared radiation | Measurement | Slide method | Thermal emittance

Abstract: Human Robot Collaboration (HRC) have proved to be effective if compared to traditional hybrid automation in assembly tasks, especially when human-like sensitivity and high quality are required. However, a rigorous engineering design is mandatory in order to successfully apply HRC to Industry. Academy and Industry are asked to jointly work for exploiting the technical opportunities given by robots and humans. Scientific literature often describes the application of HRC in manufacturing but rarely presents systematic engineering design approaches. The present paper investigates and describes the systematic design of a HRC workcell for assembling bio-medical products. Moreover, productivity and profitability of the developed solution are evaluated and discussed.

Keywords: Assembly | Biomedical products | Human-Robot Collaboration

Abstract: Recent trends in industrial manufacturing impose the adoption of changeable systems, based on reconfigurable and flexible equipment. In this scenario, industrial robotics platforms are central to design highly reconfigurable systems. A Robotic Reconfigurable Machining Platform (RRMP), as defined, is a modular architecture for robotic workcells, designed in order to exploit the flexibility features of robots and extend their field of application to high precision machining. RRMP calibration is a key task, which involves calibration of tools, workpieces and peripherals. However, state-of-the-art calibration methods and tools lead to hardly predictable system downtime, which impacts the reconfiguration phase. A novel method to perform the workpiece calibration is proposed for the reduction of the reconfiguration efforts in RRMPs. The method is addressed through a full integration with a virtual environment for robot simulation and programming. The method is finally applied to an industrial case study and compared to the most widely diffused online approach.

Keywords: Robot offline programming | Robotic machining | Workpiece calibration

Abstract: This paper proposes a fast and on-site method for the dynamic identification of industrial robots from low-sampled position and torque data. Owing to the basic architecture of the employed controller, only trapezoidal-velocity trajectories can be enforced for identification purposes. Differently from previous literature, where this kind of trajectories were performed with limited joint velocities and range of motions, the procedure proposed hereafter is characterized by fast movements performed on wide angular ranges. Furthermore, in order to identify the influence of friction without deriving complex friction models, a novel method is outlined that decouples frictional torques from gravitational, centrifugal and inertial ones. Finally, although multiple experiments of different kinds have been performed, inertial parameters are determined in one singular step, thus avoiding possible error increase due to sequential identification algorithms. © (2013) Trans Tech Publications, Switzerland.

Keywords: Friction decoupling | Industrial robots | Low frequency sampling | System identification

Abstract: Actual industrial robotic systems offer performance to effectively cope with the requirements in manufacturing dealing with flexibility and quality. However, their known limits in accuracy do not allow to extend their field of application to high-accuracy machining, actually covered by state-of-the-art CNC machine tools. The European Project COMET has recently proposed an approach to develop a robotic reconfigurable workcell with enhanced accuracy for machining, through the full integration of different theoretical models, technological solutions and manufacturing strategies. The present paper presents and demonstrates the effectiveness of a demo reconfigurable machining workcell for one of its possible configurations, based on CAM off-line programming. In particular, an experimental campaign has been designed and realized in order to discuss the dimensional and geometrical quality obtained for an aluminium automotive part in comparison with quality and costs offered by a standard 5-axis CNC machine tool. © 2013 IEEE.

Abstract: Industrial robotics provides high flexibility and reconfigurability, cost effectiveness and user friendly programming for many applications but still lacks in accuracy. An effective workcell calibration reduces the errors in robotic manufacturing and contributes to extend the use of industrial robots to perform high quality finishing of complex parts in the aerospace industry. A novel workcell calibration method is embedded in an integrated design framework for an in-depth exploitation of CAD-based simulation and offline programming. The method is composed of two steps: a first offline calibration of the workpiece-independent elements in the workcell layout and a final automated online calibration of workpiece-dependent elements. The method is finally applied to a robotic workcell for finishing aluminum housings of aerospace gear transmissions, characterized by complex and non-repetitive shapes, and by severe dimensional and geometrical accuracy demands. Experimental results demonstrate enhanced performances of the robotic workcell and improved final quality of the housings. © Springer-Verlag Berlin Heidelberg 2013.

Keywords: Aerospace industry | Industrial robotics | Integrated design | Workcell calibration

Abstract: Deburring of aerospace components is a complex task in case of large single pieces designed and optimized to deliver many mechanical functions. A constant high quality requires accurate 3D surface contouring operations with engineered tool compliance and cutting power. Moreover, aeronautic cast part production is characterized by small lot sizes with high variability of geometries and defects. Despite robots are conceived to provide the necessary flexibility, reconfigurability and efficiency, most robotic workcells are very limited by too long programming and setup times, especially at changeover. The paper reports a design method dealing with the integrated development of process and production system, and analyzes and compares a CAD-based and a digitizer-based offline programming strategy. The deburring of gear transmission housings for aerospace applications serves as a severe test field. The strategies are compared by the involved costs and times, learning easiness, production downtimes and machining accuracy. The results show how the reconfigurability of the system together with the exploitation of offline programming tools improves the robotic deburring process. © Springer-Verlag Berlin Heidelberg 2013.

Keywords: CAD-based tools | Digitizers | Industrial robotics | Integrated design | Offline programming

Abstract: Changeability accomplishes the engineering design of competitive sustainable manufacturing systems, considered as industrial products characterized by inherent life cycle. Main drivers for changeability are manufacturing system reconfigurability and hybridization. A Hybrid Reconfigurable System (H-RS) is characterized by the coexistence and cooperation of industrial robots and skilled human workers to perform complex tasks within a common reconfigurable production environment. H-RSs rise use-productivity along their total system life cycle, fostering the evaluation and implementation of feasible and innovative technologies, and increasing the utilization ratio and the multiple use-or re-use-of resources. The paper proposes an engineering method which aims at enhancing changeability in H-RSs through the application of a multi level reconfigurability approach within a digital environment. The method includes the advanced design and modeling of digital devices which embed mechanics, electronics, control logic and software code. Advanced models are exploited to analyze the system performance in the system domain of changes and to realize an effective human training. An industrial case study describes the application of the method to the design of a hybrid reconfigurable workcell for manufacturing and assembly of top class car chassis. © 2012 Springer-Verlag.

Keywords: Automotive | Changeability | Digital environment | Hybrid Reconfigurable System

Abstract: Engineering changeability-oriented and cost-driven approaches are needed by enterprises to design and optimize manufacturing and assembly systems for the demanding production requirements of the present industrial scenario. The integrated design of Reconfigurable Systems addresses tailored flexibility through modularity, integrability of resources, product and process customization, and system convertibility and diagnosability. The cooperation of robot and humans in hybrid environments offers a good trade-off between changeability, high quality and low costs, by exploiting the human dexterity and cognitive proactivity, together with robotic accuracy and performances. Virtual prototyping methods and digital manufacturing solutions are now mature and effective enough to play a strategic role within the hybrid reconfigurable system (H-RS) design and optimization process. The present research work proposes an engineering method to design and optimize H-RSs, by using virtual prototyping and digital manufacturing as a strategic support for the analysis and synthesis of the technical solutions, especially those related to human-robot cooperation. An industrial case study on a hybrid reconfigurable assembly system of a top class car aluminum chassis is finally presented. © 2011 Springer-Verlag.

Keywords: Automotive industry | Digital manufacturing | Hybrid reconfigurable system | Virtual prototyping