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In the packaging industry, cutting dies are used to process paper based material. The dies are mainly manufactured via steel strip principle, which consists of many manual steps and is difficult to automate. Laser material processing represents a promising approach to simplify manufacturing. This study realized additively manufactured cutting edges post-processed by laser ablation to achieve a defined final profile shape. First verification shows that laser ablation appears to be attractive for finishing of additively manufactured cutting edges.

Additive manufacturing, or 3D printing, is an emerging type of production technology that is seen as the core technology for future high-value engineered products. Due to the additive nature of stacking and unifying individual layers, the part and process design is substantially different from conventional production methods. This paper addresses one of the challenging design aspects for additive manufacturing, namely the determination of the build orientation. The build orientation has a large impact on the final part quality and must therefore be chosen wisely. This paper presents an approach to support the build orientation selection by a feature-based design algorithm. After automated part tessellation and the detection of outer part surfaces, the algorithm determines candidate build orientations through a ray-tracing and convex hull method. Candidate solutions are ranked based on minimizing overhang structures, as this also minimizes the need for additional support structures.

Additive manufactured components provide a new level of shape flexibility. However, this process has shortcomings in surface quality and dimensional accuracy. As a result post-processing is often necessary. In this paper, a combined finishing operation of machining shaping and force-controlled burnishing is used for prismatic form elements. Therefore, a corresponding control strategy was implemented for this on a CNC machine tool. The focus lies on the process characteristics between the pre-machined surface structures and the force-controlled machining and in the resulting surface properties. The aim of the work is the investigation and application of the process combination on additive manufactured metallic structural elements.

Additive manufacturing (AM) currently evolves from a prototyping process to an alternative manufacturing process for end-use parts, advancing into fabrication of low to medium product volumes. Moreover, increasing awareness of environmental impacts of manufacturing lead to the necessity of holistic evaluation among traditional evaluation criteria in the technical and economic domains. However, existing evaluation approaches seldom consider a complete AM process chain and are lacking a production-oriented notation which enables comparability across technologies and support in identification of improvement potentials on technical and environmental level. To address this gap, this paper highlights the way from structured data acquisition to setup of an energy value stream map (EVSM) for AM process chains in end-use part production, augmenting methods of lean manufacturing by the energy dimension. Consequently, it contributes to a holistic and transparent process chain perspective to assess AM as a manufacturing alternative. The proposed methodology is applied to a case study covering two different process chains, a first based on powder bed fusion via Multi-jet Fusion (MJF) and a second utilizing vat-photopolymerization via Continuous Liquid Interphase Printing (CLIP). While the MJF process chain's energetical hot spot is situated in the printing process itself, the hot spot for CLIP is found in thermal post-processing, exceeding the comparably efficient printing process by magnitudes and ultimately resulting in higher energy intensity per part compared to the MJF process chain. These results highlight the necessity of a holistic evaluation method for complete AM-based process chains and their influence on the product properties. Insights may help engineers, designers and decision makers in pre-selection of suitable manufacturing strategies with a more complete view on AM process chains.

The combination of functions in a single component, efficient use of limited space, comprehensive acquisition of process and sensor data and development of passive, wireless monitoring systems are all at the focus of current research. Additive manufacturing is playing an increasingly important role in these developments, because it acts as an enabler for free-form structures, allows access to the interior of the component through its layer-by-layer build-up, and facilitates the processing of a wide variety of materials. Within this work, the aspects mentioned are jointly addressed by the development of a monitored additively manufactured gear (material: 16MnCr5) that communicates wirelessly. This paper shows how an RFID-antenna can be optimized by simulation, incorporated in the design of a metallic gear, then built up in a single manufacturing process and linked to an in-situ inserted sensor board. The approach is validated by fabrication of a sensor-monitored prototype and verified in respect of its functionality and internal structure.

Predictive models are crucially relevant for the design and control of manufacturing processes, particularly when process quality is highly sensitive to unknown physical parameters. This paper describes a method to model industrial processes using neural networks and physical prior knowledge. The approach is applied to heat transfer problems, particularly relevant for additive manufacturing processes, and the results are compared to alternative methodologies. Obtained results show that the integration of partial differential equations in the neural network model leads to reduced amounts of required training data and increases the model stability. Such outcomes represent promising characteristics for novel model predictive control strategies., Procedia CIRP, 102, ISSN:2212-8271, 18th CIRP Conference on Modeling of Machining Operations (CMMO)

In the last years the industrial application of selective laser melting (SLM) has been increased. Main advantages of SLM are the reduction of production time for small batches and the freedom to generate complex designs. However, the rough surface quality of SLM parts currently limits their use and hinders the application in several industry sectors such as the hygienic and food industry. Due to the high complexity of SLM parts, the application of conventional processes is limited. Electropolishing (EP) is a promising process for reducing the roughness of simple SLM parts. However, it has not yet been explored intensively on complex SLM parts. Additionally, design constraints for the design of SLM parts to enable post processing are not yet existent. This experimental study investigates the resulting roughness of EP on different SLM design elements. Three types of EP were investigated, direct current, pulse/pulse reverse current and pulsed current EP. Additionally, the current density and processing time were varied. The SLM test sample (316L) contains internal pipe surfaces with different diameters in different orientations, overhangs and a lattice structure. To analyze the surface roughness, the arithmetic mean height of the roughness (Sa) was measured. At the end of the paper the findings on the process and the design constraints for SLM parts are summarized. The results show a significant improvement of the roughness on the external surfaces of the test sample for all parameter sets. The orientation of the surfaces with respect to the build direction influences the reduction of Sa. Increasing the pipe diameter leads to an increasing effect of internal EP. Finally, the DC parameter set showed a significantly better improvement of the Sa value on the internal lattice structure., Procedia CIRP, 91, ISSN:2212-8271, Enhancing design through the 4th Industrial Revolution Thinking

Part representation in additive manufacturing (AM) is dominated by the stereolithography (STL) file format as a universal mode for communicating and transferring part geometry from one system to another. However, when the CAD model is converted to the triangle mesh constituting the STL file the topology is no longer explicitly defined hence the design intent is lost together with any tolerancing information. Computer aided tolerancing of actual part geometry is hindered by the sparse information about the nominal geometry directly available in STL data, therefore the feature information is often assumed or recreated through reverse engineering methods. This paper investigates how nominal geometry can be deduced from STL data to support quality control by the identification of geometric elements from a triangle mesh. We further discuss how vectorial tolerancing can extend the scope of feature recognition to tolerancing and quality assessment. A method for automatic extraction and tolerancing of features from STL files is described and an application example is provided. The outlined method enables the automation of tolerancing activities and facilitates the integration of STL files into the digital pipeline of modern manufacturing systems. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

At present, economic and technological design criteria for products and processes should be matched with the minimization of environmental impact objectives. Manufacturing, material production, and product design are strictly connected stages. The choice of a production system over another could result in significant material and energy/resource savings, particularly if the component has been properly designed for manufacturing. In this scenario, Additive Manufacturing, which has been identified as a potential disruptive technology, gained an increasing interest for the creation of complex metal parts. The paper focuses on the tools, based on the holistic modelling of additive and subtractive approaches, which could be used to identify the production route allowing the lowest energy demand or CO2 emissions. The models account for the main process variables as well as the impacts due to the re-design for AM for the creation of components made of Ti-6Al-4 V.

Even though journalists write about the 4th industrial revolution, the metal additive manufacturing (AM) machines are still “that awkward machine in the corner”. However, the research community and the European Commission have seen that hybrid solutions are necessary to improve the competitive factor of additive machines, making them an integrated supplementary part of the production plant, as other manufacturing processes are today. Hence, a discussion is raised on changing the way additive machines are operated. The paper discusses new planning systems and support systems for reliable operation of AM processes.

Bioprinting is an emerging technology that offers the unique ability to deposit and pattern different cells and matrix materials to fabricate three-dimensional (3-D) tissue constructs. Markedly, bioprinting demonstrated great potential for skin tissue engineering ranging from the development of 3-D skin tissue models to in-situ bioprinting of skin directly over the wound site. Nevertheless, one of the major challenges that impede the progress in this field is the limited choices of printable biomaterials. In this paper, we report the development of printable polyelectrolyte chitosan-gelatin hydrogel for potential applications in tissue engineering of skin. The oppositely charged functional groups from chitosan and gelatin respectively first interacted at a specific pH range to form a polyelectrolyte complex, followed by further pH-dependent crosslinking. The pH-crosslinked polyelectrolyte chitosan-gelatin hydrogel was then evaluated in terms of its rheological behavior, biocompatibility, printability and lastly material stability under physiological conditions. The polyelectrolyte chitosan-gelatin hydrogel remained in a robust gel-state over the temperature range of 20-40 o C and facilitated cellular attachment and proliferation. Furthermore, it demonstrated good printability and the multi-layered hydrogel construct was mechanically stable after subjecting it to physiological conditions for 7 days.

As Additive Manufacturing (AM) is viewed more and more as a production-capable technology, data and information needs have made the costs of AM complexity increasingly apparent. Techniques available in current GD&T practices do not fully support product definitions needs in additive manufacturing. The fully model-driven process introduces new intricacies and complexities that must be addressed to facilitate the reproducibility of AM parts. Machine-readability needs must trump human interpretation requirements. In this paper, we discuss the future directions of GD&T and semantic annotations as they relate to satisfying AM product definition requirements.

Sharp corners in additive manufactured (AM) bifurcated vascular networks cause mechanical aggregation and unrealistic numerical results. A novel parametric bifurcation model was adapted in this paper to generate 3D rounded bifurcations that would solve this problem. Parameters and control variables in the parametric model were selected according to the design rules and the extended parametric map. Preliminary computational fluid dynamic studies were carried out in order to link hydrodynamic risks with local geometry designs. Both positive and negative aspects were found in such designs.

Wire-Arc-Additive-Manufacturing (WAAM) is an Additive-Manufacturing (AM) process, allowing to produce metal components layer by layer by means of Gas-Metal-Arc-Welding (GMAW) technology. The advantages of this technology are the capability to create large parts with a higher deposition rate with respect to other AM technologies. Despite these great benefits, WAAM components are affected by severe distortions and residual stresses issues. Finite element process simulation provides an efficient way to study mitigation strategies for such issues. In this paper, a WAAM modelling strategy is proposed based on a novel heat source model that takes into account the actual power distribution between filler and base materials. In order to prove the effectiveness of proposed modelling, an experimental validation is provided by comparing the measured distortions of a WAAM tests-case with the simulated ones, highlighting the accuracy of proposed model.

3D-printing has been used to create prototypes during the development phase for more than 20 years. Now, functional parts can be printed directly in specific metal powders using similar layer-by-layer techniques. The additive method is unlike traditional mass production manufacturing methods in many ways, creating new possibilities for designers to realise new and different design ideas previously impossible to manufacture. When products are mass produced, there is a desire to improve manufacturability. This is traditionally done by a designer with knowledge about certain manufacturing methods altering design choices to make it cheaper to manufacture. This paper shows different design for AM (DfAM) methods where performance and part cost are both of interest. It adds to existing research by classifying design for additive manufacturing in two different classes; process-driven and designer-driven shaping of parts. A cost-prediction model for Selective Laser Melting (SLM) printed parts is suggested as an initial step to choose parts for redesign from an economical perspective. A case study of a missile launcher beam redesigned for additive manufacturing using three different approaches is presented. Differences and similarities in design methods are discussed and the redesigned parts are compared for mass and cost. It is shown that redesigning for AM can reduce mass but depending on part size and print speed, the part can become more expensive than the original design, creating a need to know the customer value of what the redesigned part provides, in this case, the value of reduced mass.

The paper presents the evaluation of the drillability characteristics of the Ti6Al4 V titanium alloy produced through the Additive Manufacturing (AM) technology called Direct Metal Laser Sintering (DMLS). Holes of 1.6 mm diameter were drilled on a 5-axis high-precision micro-milling machine under dry cutting conditions at varying cutting speed and feed rate. A specific measurement procedure was developed to quantify and compare the most representative geometrical features (diameter and perpendicularity) of the machined holes as well as the quantification of burrs. The influence of the AM material on the geometrical quality of high precision holes is discussed, taking into account the requirements of the following threading operations. Finally, thread milling experiments were carried out to prove the threading feasibility and performances based on the previous drilling experiments. From the results within the tested range of cutting conditions, the lowest values of the cutting speed and feed rate seem to be the best trade-off for achieving the required hole quality.

This paper proposes a novel fused-coating based additive manufacturing (FCAM) that builds three dimensional metal parts by depositing the material in a layer by layer manner according to the CAD model. It provides a good method to build metal parts with the advantage of using cheap and easy-get material, building parts with high efficiency and without high equipment costs. To study the effect of different processing parameters, the FCAM experimental system is established. It included a molten metal generator, a fused-coating nozzle, a three-axis motion platform, an inert atmosphere protection and process control unit, a temperature and pressure measurement unit. A heat transfer model based on volume of fluid method is developed to investigate the FCAM process. The study on the influence of process parameters, such as the nozzle and substrate temperature and the speed of the substrate in forming metal parts is made. The results of the study prove that the processing parameters will significantly affect the surface finish and bonding strength of the metal parts. What's more, the temperature and speed of the substrate are the main parameters that influence the FCAM process.

Additive Manufacturing (AM) has become an enticing and rapidly growing manufacturing method for the production of components due to its unique advantages over conventional manufacturing (CM), including complex geometric capabilities and functional features. Sustainability concerns for AM products are still among the major technological challenges. A holistic sustainability analysis of such products covering the entire life cycle is lacking in the current literature. This paper presents the total life cycle sustainability analysis of AM products, through the recently established Product Sustainability Index ( ProdSI ) framework. A case study is presented with two iterations of AM product validating the ProdSI metrics for AM products.

The additive manufacturing (AM) model factory's aim is to establish a leading-edge learning academy for the digital and generative production of innovative mechatronic products, where the complete value chain is integrated on a single site. Short courses and deep dives enable easier access to the state of the art technologies and increase the awareness for their potentials. Anchored in key industries such as automotive, aerospace, and medical by major OEMs and regional SMEs, the AM model factory cooperates with world-class partners and leading market players. This paper displays the model factory's setup, selected technologies, exemplary courses, and benefits.

Among emerging additive manufacturing technologies for metallic components, WAAM (Wire and Arc Additive Manufacturing) is one of the most promising. It is an arc based technology characterized by high productivity, high energy efficiency and low raw material cost. Anyway, it has some drawbacks limiting its diffusion in the industry. One is the open issue about the layer deposition strategy that must be manually optimized in order to reduce as possible the residual stress and strains, efficiently matching the geometrical characteristics of the component to build and assure a constant height for each layer. This work deals with the definition of deposition paths for WAAM. The choice of a path must be carried out as a compromise between productivity and material usage efficiency. In the present paper, the process to select an optimized strategy for the manufacturing of T-crossing features will be shown.

Due to shorter product-life-cycles, innovations in production engineering have to keep pace with today's technologies. As a result, factory planning is more and more challenged by technologies being immature for series production. Usually, these immature technologies place special demands on production layout and quality management, for example. These demands have to be considered in the factory planning process. Moreover, technologies are part of the production process that is created by a series of technologies. Hence, a planning process has to ensure that the positive aspects of a new technology are not negated by arrangements to protect the technology chain against failure due to immature technologies. With Selective Laser Melting (SLM) used as example for an additive manufacturing technology, this paper presents a method of planning a production system by taking the technology maturity into account. Possible requirements of an immature technology interacting with the process chain will be addressed as well as adjustments to be made to the factory planning process.

Selective Laser melting (SLM) is an additive manufacturing technology that uses laser as a power source to sinter powdered metals to produce solid structures. The application of SLM permits engineers to develop and implement components with topologically optimized designs and resultant material properties in comparison to conventionally produced casting parts. Current aviation programs as ACARE 2020 (Advisory Council for Aviation Research and Innovation in the EU) and Flightpath 2050 request a reduction of fuel consumption as well as CO2 and NOx emissions in the next years. To meet these requirements there is a clear trend to produce light-weight components for engines and structural parts of aircrafts through SLM. Since SLM process is a key technology for aeronautical application, this paper focusses on the qualification of a high performance titanium alloy as well as on the investigation of optimized process parameters and positioning strategies of the structures produced in the SLM machine.

In this paper the joinability of titanium Additive Manufactured (AM) parts is explored. Keyhole welding, using a pulsed laser beam, of conventionally produced parts is compared to AM parts. Metal AM parts are notorious for having remaining porosities and other non-isotropic properties due to the layered manufacturing process. This study shows that due to these deficiencies more energy per unit weld length is required to obtain a similar keyhole geometry for titanium AM parts. It is also demonstrated that, with adjusted laser process parameters, good quality welds for aerospace applications in terms of pressure resistance and leak tightness are achievable.Video abstract

The emergence of Additive Manufacturing (AM) has greatly liberated the designers’ hands, since the usual design constraints in machining or other traditional processing technologies partially or even totally disappeared in AM and it seems that AM can form any desired very complex geometries through a layer by layer construction manner. However, AM processes still have their own processing characteristics and limits. To help designers to benefit more from the unique characteristics of AM and avoid the processing limits or low down the later processing difficulty after design, this paper proposes a two-level evaluation framework to assess the design from a process planning perspective. The proposed evaluation framework is associated with a two-level process planning framework for AM, and within each level, several indicators for assessment are defined and used to convey the information from process planning for improving the design.

Rapid prototyping (RP) has evolved to Additive Manufacturing (AM) in recent years. It can produce functional or end-use parts with small or even medium quantities. And further, due to its unique layer-by-layer construction principle, it can produce different parts at the same time in a same AM machine. To improve the productivity and machine utilization of AM processes under multiple parts production context, this paper propose the conception of ‘Grouping parts’. Based on the Group Technology (GT) used in traditional processing technologies, a modified Group Technology for AM under multiple parts manufacturing context is presented. To group parts, a set of key attributes affecting the AM production time, cost, quality and work preparation are identified to represent the parts, and then a Grey Clustering method is adopted to conduct the similarity analysis. A simple case study is presented in the end to illustrate the proposed conception and its methodology.

Currently, the main field of application of additive manufacturing processes is shifting from research laboratories to production facilities. Simulation models can foster this transition by providing support in process development and design. This paper introduces approaches to modelling the beam-material interaction in laser beam melting on a level of detail that allows the simulation of the whole build-up process of parts, not only of single laser tracks. Thus both the achievable result accuracy and the needed calculation time are discussed. For this purpose, fundamental correlations to link process characteristics with model parameters are explained. Subsequently, four modelling approaches are analysed. After an introduction of the well-known method of applying a uniform load on a whole layer compound (e. g. [1]), the developed methods are discussed which allow modelling the beam-material interaction on a more detailed level. Thereby, the focus lies on the ability to model load gradients perpendicular to the build direction. This article is completed with a discussion of simulated temperature curves for selected monitoring points using two different modelling approaches.

Laser cladding is a method of material deposition used to envelop a substrate with a surface of material which has superior characteristics, such as corrosion or abrasion resistance. There are several process parameters to be adjusted to generate a deposited bead or a layer, and developing a model to predict a bead shape is challenging due to the highly level of coupling between the manufacturing process parameters and the bead geometry. This paper will present results for an experimental study where P420 steel cladding powder (a steel commonly used in injection molding) is deposited on low carbon structural steel plates using the coaxial powder flow laser cladding method. Five process parameters such as laser power, scanning speed and powder flow rate etc. are varied to explore their impact on the bead height, width, penetration, area, dilution area, and the bead shape. The bead shape to process parameter relationships are explored and predictive models are developed using analysis of variance, a ‘lumped parameter model, and artificial neural network (ANN) approaches. The best fit for a predictive model is achieved with the ANN approach. This work will be extended to incorporate a variety of substrate and clad materials, and layering parameters.

Ultrasonic Additive Manufacturing (UAM), or Ultrasonic Consolidation as it is also referred, is a hybrid form of manufacture, primarily for metal components. The unique nature of the process permits extremely novel functionality to be realised such as multi-material structures with embedded componentry. UAM has been subject to research and investigation at Loughborough University since 2001. This paper introduces UAM then details a number of key findings in a number of areas that have been of particular focus at Loughborough in recent years. These include; the influence of pre-process material texture on interlaminar bonding, secure fibre positioning through laser machined channels, and freeform electrical circuitry integration. © 2013 The Authors. Funding: Engineering and Physical Sciences Research Council (EPSRC) in UAM research at Loughborough University.

International audience; Additive manufacturing technologies can now be used to manufacture metallic parts. This breakthrough in manufacturing technology makes possible the fabrication of new shapes and geometrical features. Although the manufacturing feasibility of sample parts with these processes has been the subject of several studies, the breakthrough in manufacturing is yet to be followed by a breakthrough in designing process. In this paper, after reviewing the principle of additive manufacturing of metallic parts, the manufacturing capabilities and constraints of these processes will be examined. A designing methodology will then be suggested and illustrated with the redesign of an example part.