https://popups.uliege.be/esaform21/index.php?id=1305 Index terms fr 0 https://popups.uliege.be/esaform21/index.php?id=403 In recent years, recycling the powder leftover within the additive manufacturing process has been attractive for both research, development and industry production. Powder recycling can significantly enhance the sustainability of the manufacturing process, reduce the cost and avoid producing metallic waste as a potential environmental hazard. The first step in reusing the recycled powders in the 3D printing process is to characterize the microstructure and surface quality of the powder for oxidation and impurity analysis. Here, scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) have been used for the morphology and surface composition analysis of the 316L powders within the Aconity 3D printer. A new powder collection strategy has been introduced to collect powders from different locations in the powder bed: from the top most and surface of the parts and powder bed after the print terminated, from between the printed parts at different heights. The XPS measurements revealed that oxidation is a common in all the powders compared to virgin powder and more oxidation was detected from the powders collected on the very top of the leftover powder and from surface of the bed. The size of the particles does not change much but larger particles remained at the topmost surface. This finding would help in designing a protocol for collecting the recycled powder from the powder bed and it is suggested to follow a a procedure of collecting powders from the different sections of the powder bed in order to avoid mixing the most and least affected particles. Fri, 19 Mar 2021 18:38:11 +0100 Mon, 12 Apr 2021 12:00:54 +0200 https://popups.uliege.be/esaform21/index.php?id=403 https://popups.uliege.be/esaform21/index.php?id=3972 In milling operations, the weight of the milling tool greatly affects the motion speed of the mandrel, especially when a complex tool path must be performed. Thus, it is essential to realize more lightweight tools, without a significant decrease in the mechanical and production performance. Traditionally, due to the limitation of the conventional manufacturing processes, the design of a new milling tool cannot be too much complex and thus cannot fully satisfy the mentioned goals. Nowadays, thanks to the topology optimization technique and the additive manufacturing (AM) technologies, such as the selective laser melting (SLM), it is possible to realize more complex part geometries to obtain more lightweight and high-performance tools. In this paper, a new design of a milling tool with a weight reduced by 30% is presented; SLM process has been selected to realize the milling tool. In order to minimize the use of support structures, required by the SLM process to correctly realize the desired part, the new geometry has been little modified. A more lightweight milling tool has been produced and every support structure has been successfully removed from the component. Tue, 30 Mar 2021 09:22:16 +0200 Mon, 12 Apr 2021 11:24:59 +0200 https://popups.uliege.be/esaform21/index.php?id=3972 https://popups.uliege.be/esaform21/index.php?id=2124 Additive manufacturing (AM) has many advantages compared to conventional processes. Of particular interest is the tool-less manufacturing of components, which allows one component to differ from the next completely and has the possibility of producing complex geometries. At the same time, however, AM has deficits such as long production times, low production tolerances and low surface qualities compared to conventional processes. Therefore, a finishing process using machining is often necessary, which extends the manufacturing time and produces waste. Thus, the avoidance of machining rework is of high interest, especially with expensive materials such as stainless steel or titanium. One approach to avoid machining processes is to use forming technology. By applying a forming operation, surfaces can be smoothened and geometrical aspects can be defined more sharply. Especially for functional surfaces, this procedure is favorable because of the work hardening, which in turn increases the strength of the material. Using the example of laser-based powder bed fusion (PBF-LB) followed by a cup backward extrusion process, two materials, which are frequently used in AM are investigated. On the one hand, the titanium alloy Ti-6Al-4V, as a material with low machinability and low formability at room temperature, and the stainless steel 316 L. Compared to Ti-6Al-4V, 316 L has a higher formability. Cylinders are built using PBF-LB and then formed to smoothen the surface and achieve a higher geometrical accuracy concerning edges. Formed, additively made parts have a more defined geometry, namely sharp edges and a surface roughness reduced by up to 90 %. Tue, 23 Mar 2021 12:56:32 +0100 Mon, 12 Apr 2021 10:35:39 +0200 https://popups.uliege.be/esaform21/index.php?id=2124 https://popups.uliege.be/esaform21/index.php?id=2089 Powder bed fusion techniques enable the production of customized and complex devices that meet the requirements of the end user and target application. The medical industry relies on these additive manufacturing technologies for the advantages that these methods offer to accurately fit the patients’ needs. Besides the recent improvements, the production process of 3D printed bespoke implants still requires optimization to achieve the optimal properties that can mimic both the chemical and mechanical characteristics of the anatomical region of interest. In particular, the surface properties of an implant device are crucial to obtain a strong interface and connection with the physiological environment. The layer by layer manufacturing processes lead to the production of complex and high-performance substrates but always require surface treatments during post-processing to improve the implant interaction with the natural tissues and promote a shorter assimilation for the fast recovery and wellness of the patient. Although the surface finishing can be tailored to enhance cells adhesion, proliferation and differentiation in contact with a metal implant, the same surface properties can have a different outcome when dealing with bacteria. This work aims to provide a preliminary analysis on how different post-processing techniques have distinct effects on cells and bacteria colonization of 3D printed titanium implants. The goal of the paper is to highlight the importance of the identification of an optimized methodology for the surface treatment of Ti6Al4V samples produced by Selective Laser Melting (SLM) that improves the implant antimicrobial properties and promotes the osseointegration in a long-term period. Tue, 23 Mar 2021 12:46:45 +0100 Mon, 12 Apr 2021 10:31:32 +0200 https://popups.uliege.be/esaform21/index.php?id=2089 https://popups.uliege.be/esaform21/index.php?id=1931 Cold forging tools become increasingly complex and require enhanced functionality, especially in the context of digitisation. Conventional subtractive manufacturing processes often reach their limits when the geometric complexity of the workpiece increases, hence additive manufacturing processes have become increasingly important in the last decades. Additive manufacturing processes have already been used in many fields of manufacturing technology to produce tool components with promising results, but the potentials of additive manufacturing processes have not yet been applied to cold forging tools. Therefore, the Institute for Metal Forming Technology (IFU) of the University of Stuttgart has developed an additive manufactured cold extrusion tool with integrated functional features. As functional features in the additive manufactured extrusion tool, a close contour glass fiber sensor for temperature measurement, a cooling system and a lubrication system for the controlled injection of minimal lubricant amounts during the forming process were integrated. Due to the integrated functional features, structural degradation appears in the tool, therefore the structural-mechanical tool properties were analyzed numerically with the FE-Software DEFORM 3D™ in this report as well. Furthermore, the additive manufactured cold extrusion tool was experimentally evaluated in sequentially executed extrusion operations. Thereby the integrated functional features were used and gathered data were recorded. As a result of the experimental forming tests, near-contour temperature measurements in the extrusion tool with and without the use of the integrated cooling system as well as the modification of the maximum punch forces by an inline lubricant application were obtained. In addition, the experimentally determined temperature fields in the extrusion die are validated with numerically calculated results. Tue, 23 Mar 2021 10:41:38 +0100 Mon, 12 Apr 2021 10:08:38 +0200 https://popups.uliege.be/esaform21/index.php?id=1931 https://popups.uliege.be/esaform21/index.php?id=3894 With the advent of 3D printing, it is now possible to produce any part or system with an approach than makes design much deeply interlaced with production. In this scenario, CAE has gained power thanks to the possibility of thinking and then manufacture ideas that go well beyond what was possible in the past. This design approach is perfectly suitable to push forward mould conformal cooling performance. In this work, a coupling of CAD, CFD and 3D printing supported by experimental tests was applied to define a design procedure for conformal cooling channels. In particular, cooling channels for a mould were engineered via CAD, then tested via CFD and, after an initial optimization procedure, the chosen design was 3D printed in specimens suitable to be mounted on a heat exchanger (HX) experimental test rig that was especially adapted for the scope. Fluids temperature, volume flow rates and heat transfer performance were measured. A feedback loop was considered to link measurements and channels redesign. Results together with design and testing procedures are reported and commented. Mon, 29 Mar 2021 14:56:38 +0200 Thu, 08 Apr 2021 21:24:50 +0200 https://popups.uliege.be/esaform21/index.php?id=3894 https://popups.uliege.be/esaform21/index.php?id=3807 The economical production of lightweight structures with tailor-made properties and load-adapted geometry is limited using conventional technologies. Additive manufacturing processes offer a high potential to meet these requirements, where the established solutions are based primarily on thermoplastics matrix systems. From a process-technological point of view, thermoplastics enable simplified processing, but only a limited range of applications for high-performance components. These limitations are due to their comparatively low heat resistance, low melting temperatures and limited adhesion to embedded reinforcing fibers. In contrast, thermosets show high potential for realization of high- performance lightweight structures with adaptable properties. The present work employs a UV-curing thermoset resin for the impregnation of a continuous filament strand for 3D printing. The main challenge is to reconcile the crosslinking reaction of the thermoset and the process velocity during impregnation and cure. The liquid polymer must provide low initial viscosity to impregnate the filaments and a sufficiently high cure rate and dimensional stability after discharge from the print head to ensure sufficient bonding strength to the substrate. To demonstrate feasibility, a prototypic print head with UV-LED activation was designed and implemented. With a robot-guided printing platform, the 3D-deposition of continuous fiber-reinforcements without additional supporting structures can be realized. To derive initial process parameters, reaction and thermos-mechanical properties are determined by rheometer measurements. Impregnation and cure behavior of the glass fiber reinforced resin is investigated. The presented results provide a reliable process window and a straightforward process monitoring method for further enhancement of the conceived 3D printing process. Mon, 29 Mar 2021 14:43:22 +0200 Thu, 08 Apr 2021 20:40:09 +0200 https://popups.uliege.be/esaform21/index.php?id=3807 https://popups.uliege.be/esaform21/index.php?id=3723 The capability and applicability of additive manufacturing have mesmerized the entire manufacturing world. One major technique of additive manufacturing is extrusion-based additive manufacturing (EAM), which has been recently employed for the rapid production of ceramic components, among other applications. This study focused on establishing the process-property relations for extrusion-based additively manufactured ceramics, namely Alumina (Al2O3) and Zirconia (ZrO2), and then optimization of the relations to get the desired mechanical properties for applicability. Extrusion-based additive manufacturing was used to obtain the ceramic sample parts from ceramic-binder mixtures and by subsequent post-processing. The process parameters chosen for the study were extrusion velocity and part orientation whereas the mechanical properties selected were hardness and flexural strength. Extrusion velocity was varied at three levels i.e. 7.5 mm/s, 12.5 mm/s and 17.5 mm/s. Two levels selected for part orientation were horizontal and vertical. The design of experiments technique was used to establish the process-property relations by highlighting the most significant process parameters affecting the selected mechanical properties. Optimization was achieved by highlighting those levels of significant process parameters that provided the desired values of mechanical properties. Part orientation came out to be a significant factor affecting both the hardness and flexural strength of the two ceramics whereas extrusion velocity was found to be insignificant for both mechanical properties. Among the two levels of part orientation, vertical orientation samples showed higher values of hardness while horizontal samples showed higher flexural strength thus, aiding in the optimization of the process-property relations. Mon, 29 Mar 2021 14:20:30 +0200 Thu, 08 Apr 2021 19:56:29 +0200 https://popups.uliege.be/esaform21/index.php?id=3723 https://popups.uliege.be/esaform21/index.php?id=3627 The additive manufacturing has initially gained popularity for production of non-loadbearing parts and components or in the fields where the material strength and ductility are less important such as modelling and rapid prototyping. But as the technology develops, availability of metal additive manufacturing naturally dictates the desire to use the produced components in load-bearing parts. This requires not-only a thorough documentation on the mechanical properties but also additional and independent research to learn the expected level of variation of the mechanical properties and what factors affect them. The presented paper investigates strength, ductility, hardness, and microstructure of the AlSi10Mg alloy produced by the selective laser melting (SLM). The mechanical properties were determined through a series of uniaxial tension tests and supplementary hardness tests and rationalized with the microstructure evolution with regard to printing direction and heat treatment. The paper also addresses the effect of surface roughness on the mechanical properties of the material, by comparing the machined and net shape tension samples. As expected, the as-manufactured AlSi10Mg-alloy appears to be a semi-brittle alloy, but its microstructure can be altered, and ductility increased by a proper heat-treatment. The effect of surface layer removal on the measured mechanical properties is of particular interest. Mon, 29 Mar 2021 13:43:07 +0200 Thu, 08 Apr 2021 18:39:38 +0200 https://popups.uliege.be/esaform21/index.php?id=3627 https://popups.uliege.be/esaform21/index.php?id=1505 In manufacturing, hybrid systems of metal additive manufacturing and cutting in the same platform have been attractive in terms of low volume production of customized parts, complex shape, and fine surface finish. Milling is conducted to finish rough surface fabricated in additive process. The fundamental machinability of the additive workpiece should be studied because the material properties are different from metals produced in the conventional process. The paper discusses the cutting forces in milling of AISI 420 stainless steel fabricated in additive process. The cutting tests were conducted to measure the cutting forces and the chip morphologies for tool geometries. The cutting forces were also analyzed in an energy-based force model. In the analysis model, three-dimensional chip flow is interpreted as a piling up of orthogonal cuttings in the planes containing the cutting velocities and the chip flow velocities, where the cutting model is made by the orthogonal cutting data acquired in cutting tests. The chip flow direction is determined to minimize the cutting energy. The cutting forces, then, were predicted in the determined chip flow model. The cutting force model was validated in comparison of simulated forces with the actual ones. Mon, 22 Mar 2021 20:04:28 +0100 Mon, 05 Apr 2021 18:46:22 +0200 https://popups.uliege.be/esaform21/index.php?id=1505