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Authors:

Yan Liu (Simtec Soft Sweden AB, Sweden), Seyed B. Hosseini (Research Institutes of Sweden AB (RISE AB) | Chalmers University of Technology, Sweden), Mats Persson (Digital Metal, Höganäs AB, Sweden), Zhenghua Yan (Simtec Soft Sweden AB, Sweden)

Abstract:

Binder jetting process is a prominent 3D printing technology due to its cost-effectiveness and capability to scale up the production in terms of batch sizes. However, the green parts need several post-processes including curing, debinding and sintering to improve the parts' density and mechanical strength. These post-processes bring many challenges affecting the final part size and dimensional accuracy. To get the best result and desired material properties, precise temperature and atmosphere control are vital during each individual post-processes. This work shows 3D computational fluid dynamics (CFD) as a powerful tool to obtain such an objective. A full-scale 3D CFD simulation method of a sintering furnace in operation will be presented. This method allows 3D calculation of all the important processes including thermal gradients, gas flowing, thermal radiation, convection and conjugate heat transfer in solids and fluids so that sintering processes of metal binder jetting products can be well simulated.

DOI:

https://doi.org/10.59499/WP225367863

Authors:

Ariadna Marin (1), Rocío Muñoz Moreno (1), María Teresa Pérez-Prado (2), Sergi Bafaluy Ojea (2), Federico Sket (2)

1- HP Printing and Computing Solutions S.L., Spain

2- IMDEA Materials Institute, Eric Kandel, Spain

Abstract:

3D Metal Binder Jetting is currently disrupting manufacturing and accelerating mass production of 3D-printed parts. Its excellent balance between part quality and productivity rates is founded on powerful R&D investigations and metrics development to support applications for industrial cases. In this study, the technical physics description of the binder jet fundamentals and its role on parts consolidation will be explained. In particular, the focus will be on describing novel metrics of green parts microstructure obtained by scanning electron microscope (SEM) and X-ray computed tomography (XCT) as binder and porosity local fractions and their spatial distributions. These unique metrics will be evaluated for different powders and R&D print modes. The use of this set of metrics to support print mode development and materials integration, as a predictive and more sustainable method will be discussed.

DOI:

https://doi.org/10.59499/EP246280667

Authors:

Jordan Lacorne (Université de Lyon, INSA Lyon, France), Eric Maire (Université de Lyon, INSA Lyon, France), Xavier Boulnat (Université de Lyon, INSA Lyon, France), Romain Faye (Nanoe SAS, France), Sandra Simon (Université de Lyon, ECAM Lasalle Lyon, France)

Abstract:

Additive Manufacturing is a growing sector in industrial production. Fused Filament Fabrication (FFF) technology is developing by using new materials such as filaments incorporating metal powder (40 to 60%vol) and thermoplastic binders. After 3D printing, FFF needs two more steps: debinding, where the binder is removed, and sintering, where the porous part is densified. The nature of the protective atmosphere is critical because it influences the binder removal and also the sintering|oxidation behavior of the metal powders. This work aims to study the influence of atmosphere (gas type and flow rate) during debinding and sintering on the properties of the final parts in work tool steel (AISI H13). The link between atmosphere and carbon|oxygen uptakes, porosity, microstructure, and mechanical properties will be described.

DOI:

https://doi.org/10.59499/WP225371420

Authors:

Emil Strandh (Swerim AB, Sweden), Cameron Blackwell (MTC, United Kingdom), Martina Meisnar (ESA, United Kingdom), Laurent Pambaguian (ESA, Netherlands), Christian Lockowandt (Swedish Space Corporation, Sweden), Dominique Daab (Swedish Space Corporation, Sweden), Irma Heikkilä (Swerim AB, Sweden)

Abstract:

The effect of variability of metal laser powder bed fusion (L-PBF) processes and raw materials for the shape accuracy of the part is a poorly understood area. A suite of designs covering bulky designs of complex shape and delicate fine features were created and manufactured by different machine hardware, process parameters and four AlSi10Mg powders sourced from different suppliers. The designs were relevant for use in space applications. The aim was to evaluate the relationship between the process and powder characteristics for the shape accuracy using a systematic approach for the investigation. The results showed the shape accuracy was clearly connected to the applied process and indirectly to the powder.

DOI:

https://doi.org/10.59499/WP225370222

Authors:

Aditya Gopaluni (1), Pasi Puukko (1), Atte Antikainen (1), Hepo-oja Lotta (1), Joni Reijonen (1)

1- VTT Technical Research Centre of Finland, Finland 02044

Abstract:

Additive Manufacturing (AM) is considered as one of the most suitable methods for building parts with complex designs. AM is described as an efficient and sustainable manufacturing method, when compared to the traditional manufacturing methods. To understand the credibility of AM as a sustainable process, a study of the life cycle assessment (LCA) was conducted for PBF-LB, BJT-M and CNC machining for manufacturing of an impeller. The LCA calculations were made for different scenarios with respect to feedstock. It was observed that BJT-M had the largest CO2 footprint compared to PBF-LB, followed by CNC machining. It was concluded that the BJT footprint is highest owing to the extra steps involved in making the part user ready, mainly sintering. This study has been conducted as natural extension of a previous study conducted on LCI of PBF-LB and CNC processes and approaches the LCA from the point of view of raw material.

DOI:

https://doi.org/10.59499/EP246275974

Authors:

Theophile Vié (Laboratoire 3SR, France), Barthelemy Harthong (Laboratoire 3SR, France), Philippe François (Rio Tinto Fer et Titane, Canada), Jean Reid (Hl Blachford Ltd, Canada), Jürgen Voglhuber (Miba Sinter Austria GmbH, Austria), Vincent Paris (Rio Tinto Fer et Titane, Canada), Robert Hellein (Miba Sinter Austria GmbH, Austria)

Abstract:

Frictional characteristics of an iron-based mixture were studied using a specifically designed friction test bench allowing (after prior compaction) the measurement of the friction coefficient during the sliding of a compact on a bar simulating the die surface. Temperature and sliding speed were controlled. An experimental campaign was conducted with four high-performance lubricants and a conventional EBS wax, based on a single FL-4400 mix formulation. The experimental parameters included: mix temperatures from 40 to 80°C; density of 7.20g|cc; normal pressure between 150 and 240MPa; sliding distance 80mm; sliding velocity 20mm.s-1. The analyses focused on the evolution of the friction coefficient and the compact’s surface degradation. After multiple repetitions, a steady state was established with a sliding distance beyond which degradation became critical. The degradation depended on the lubricant and experimental conditions. This study aims at better understanding how the friction coefficient evolves during the ejection of a production part.

DOI:

https://doi.org/10.59499/WP225366255

Authors:

Markus Mirz (Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Germany), Marie Franke-Jurisch (Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Germany), Anke Kaletsch (Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Germany), Christoph Broeckmann (Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Germany)

Abstract:

The main purpose of evacuation tubes in powder metallurgically-based (PM) Hot Isostatic Pressing (HIP) lies in the evacuation and outgassing of the capsule. Conventional HIP capsules are made of sheet-metal which exhibits good weldability and therefore, it is easy to join the evacuation tube. With the emerging technologies of Additive Manufacturing (AM) it is now possible to design more complex capsules for HIP. Additionally, wear-resistant materials can be utilized. Yet, these materials are known to be difficult to weld. This study compares three different approaches to bond an AISI 304 evacuation tube to a HIP capsule made by Electron Beam Melting (EBM) from high carbon tool steel AISI A11. Capsules were bonded by TIG welding as well as brazing with conventional and a customized filler material based on thermodynamic calculations. Subsequent consolidation by HIP, microstructural analysis and argon-measurements revealed the feasibility and limits of all three approaches for gas-tight bonds.

DOI:

https://doi.org/10.59499/WP225370176

Authors:

S. Sauceda (1,2), S. Lascano (3), C. Arévalo (2), I. Montealegre (2), E.M. Pérez-Soriano (2), P. Pedrosa (2), A. Machuca (3), R. Chavez (3), N. Araya (1)

1- Departamento de Ingeniería de Materiales, Universidad de Concepción, Chile.

2- Departamento de Ingeniería y Ciencia de los Materiales y del Transporte, Escuela Politécnica Superior, Universidad de Sevilla, Spain.

3- Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Chile.

Abstract:

Applications such as high-power contacts or nuclear fusion reactors frequently rely on W-Cu composites when demanding exceptional electrical and thermal conductivity under extreme conditions. Powder metallurgy serves to create this type of material with different melting points. However, there is a discussion in the literature about the most suitable powder metallurgy techniques. Spark Plasma Sintering (SPS) and Rapid Sintering Process (RSP) make it possible to produce materials within minutes and at lower temperatures on an industrial scale. This study undertakes a comparative analysis of two different sintering techniques at 600°C while varying the pressure and sintering time for W-Cu samples containing 25% and 75%wt. of W. Results show that it is possible to sinter composite W-Cu at 600°C. The material's density, hardness, and microstructure are significantly affected by sintering time. Furthermore, RSP tends to generate higher densities, hardness and Young's modulus.

DOI:

https://doi.org/10.59499/EP246280921

Authors:

Ali Rajaei (1), Valérian Iss (1), Christoph Broeckmann (1)

1- Institute for materials applications in mechanical engineering (IWM) of the RWTH Aachen University

Abstract:

The performance of Powder metallurgical (PM) gears must be increased towards the level of the conventional high strength gears for a reliable application in automotive transmission. To this end, the potentials of the PM production of gears must be fully utilized. Surface densification and hardening of sintered gears are examples of economically plausible measures to increase the strength of these components. However, a comprehensive consideration of the strength relevant parameters such as geometry, porosity, hardness and residuals stresses is required to define an optimized choice of particular material and process chain for higher gear strength. In this work, a computational approach is developed, which integrates the numerical modelling of the case hardening and the tooth loading, and the calculation of the load bearing capacity using different fatigue limit criteria. The results of the simulation are evaluated by comparing with available experimental findings.

DOI:

https://doi.org/10.59499/EP235765090

Authors:

M. Bemani (1,2,4), S. Parareda (1), D. Casellas (1,3), D. Frómeta (1), A. Mateo (2), R. Das (4), A. Molotnikov (4)

1- Eurecat, Centre Tecnològic de Catalunya, Metal Digital Manufacturing JRU, 08243 Manresa, Spain

2- CIEFMA – Department of Materials Science and Engineering, EEBE, Universitat Politècnica de Catalunya, Barcelona-Tech, 08019 Barcelona, Spain

3- Luleå University of Technology, Division of Mechanics of Solid Materials, 971 87 Luleå, Sweden

4- School of Engineering, RMIT University, Melbourne 3001, Australia

Abstract:

This work addresses the application of such a newly established rapid fatigue testing method to evaluate the fatigue resistance of a Ti6Al4V alloy manufactured by Selective Laser Melting (SLM). The evaluation of fatigue resistance requires expensive and time-consuming tests, which often limit the generation of fatigue data. This is especially relevant for Additive Manufacturing (AM) parts, in which many processing parameters, and their inherent anisotropy, influence fatigue resistance. Accelerated or more straightforward testing procedures would help to develop fatigue-optimized AM parts. Recently, a method based on damage mechanics has been successfully applied to evaluate the fatigue limit in a wide range of steel and aluminum alloy sheets. It gives a good estimation of the fatigue limit in less than one day using a conventional universal testing machine and digital image correlation techniques. A good agreement with the results obtained by the conventional fatigue method is found.

DOI:

https://doi.org/10.59499/EP235764573

Authors:

Oliver Schenk (RWTH Aachen University, Germany), Yuanbin Deng (RWTH Aachen University, Germany), Christoph Broeckmann (RWTH Aachen University, Germany)

Abstract:

A digital twin offers the potential of understanding and improving production processes by using numerical models. Although multiple approaches of digital twins were reported, most of them only focus on the macroscale. However, the microstructural evolution is often crucial for the application of products. For instance, the pore morphology which determines the final mechanical properties is highly affected by the compaction and sintering steps in the PM process chain. In this work, a digital twin was developed to model the compaction and sintering of water-atomized Astaloy 85Mo on a mesoscale. Scanning electron microscopy images of green body microstructures were used to train a generative adversarial network to predict the microstructure dependent on the powder particle size. The evolution of these artificial microstructures during sintering due to surface diffusion was subsequently simulated with the level-set-method. The obtained sintering kinetic agrees well with that calculated by analytical equations of sinter neck growth.

DOI:

https://doi.org/10.59499/WP225371655

Authors:

Lucia De Bortoli (University of Trento, Italy), Sasan Amirabdollahian (University of Trento, Italy), Stefano Rappo (Lincotek Medical, Italy), Matteo Perini (ProM facility, Trentino Sviluppo, Italy), Alberto Fabrizi (University of Padova, Italy), Alberto Molinari (University of Trento, Italy)

Abstract:

In the production of Co alloy | Ti alloy bimetallic components by Laser Directed Energy Deposition (L-DED), one critical issue is the microstructure of the metallurgical bonding layer produced by the melting of the substrate. This layer has a complex microstructure resulting from the mixing of the two alloys in liquid state and solidification. To investigate such a microstructure, specimens with a different content of the two alloys were produced by SPS and melted by laser, with the working parameters typical of the L-DED process. The solidified microstructure is quite complex. The SEM-EDXS and EBDS analyses show the partitioning of Ti, Co and the alloying elements in different compounds and phases depending on the relative amount of the two alloys. The tendency to cracking shows a dependence on the microstructure.

DOI:

https://doi.org/10.59499/WP225371926