Additive manufacturing of metallic components – Process, structure and properties

Additive manufacturing (AM) technology has been researched and developed for more than 20 years. Rather than removing materials, AM processes make three-dimensional parts directly from CAD models by adding materials layer by layer, offering the beneficial ability to build parts with geometric and material complexities that could not be produced by subtractive manufacturing processes. Through intensive research over the past two decades, significant progress has been made in the development and commercialization of new and innovative AM processes, as well as numerous practical applications in aerospace, automotive, biomedical, energy and other fields. This paper reviews the main processes, materials and applications of the current AM technology and presents future research needs for this technology.

Additive manufacturing: technology, applications and research needs

Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following a...

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Review of selective laser melting : materials and applications

Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

The German manufacturing industry has to withstand an increasing global competition on product quality and production costs. As labor costs are high, several industries have suffered severely under the relocation of production facilities towards aspiring countries, which have managed to close the productivity and quality gap substantially. Established manufacturing companies have recognized that customers are not willing to pay large price premiums for incremental quality improvements. As a consequence, many companies from the German manufacturing industry adjust their production focusing on customized products and fast time to market. Leveraging the advantages of novel production strategies such as Agile Manufacturing and Mass Customization, manufacturing companies transform into integrated networks, in which companies unite their core competencies. Hereby, virtualization of the processand supply-chain ensures smooth inter-company operations providing real-time access to relevant product and production information for all participating entities. Boundaries of companies deteriorate, as autonomous systems exchange data, gained by embedded systems throughout the entire value chain. By including Cyber-PhysicalSystems, advanced communication between machines is tantamount to their dialogue with humans. The increasing utilization of information and communication technology allows digital engineering of products and production processes alike. Modular simulation and modeling techniques allow decentralized units to flexibly alter products and thereby enable rapid product innovation. The present article describes the developments of Industry 4.0 within the literature and reviews the associated research streams. Hereby, we analyze eight scientific journals with regards to the following research fields: Individualized production, end-to-end engineering in a virtual process chain and production networks. We employ cluster analysis to assign sub-topics into the respective research field. To assess the practical implications, we conducted face-to-face interviews with managers from the industry as well as from the consulting business using a structured interview guideline. The results reveal reasons for the adaption and refusal of Industry 4.0 practices from a managerial point of view. Our findings contribute to the upcoming research stream of Industry 4.0 and support decisionmakers to assess their need for transformation towards Industry 4.0 practices. Keywords—Industry 4.0., Mass Customization, Production networks, Virtual Process-Chain. Malte Brettel, chairholder, is with the Aachen University (RWTH), Kackertstraße 7, 52072 Aachen (e-mail: brettel@win.rwth-aachen.de). Niklas Friederichsen is with the Aachen University (RWTH), Kackertstraße 7, 52072 Aachen, (corresponding author; phone: +49/(0)241 80 99397; e-mail: friederichsen@win.rwth-aachen.de). Michael Keller and Marius Rosenberg are with the Aachen University (RWTH), Kackertstraße 7, 52072 Aachen (e-mail: keller@win.rwthaachen.de, rosenberg@win.rwth-aachen.de).

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How Virtualization, Decentralization and Network Building Change the Manufacturing Landscape: An Industry 4.0 Perspective

This paper provides an overview on the main additive manufacturing/3D printing technologies suitable for many satellite applications and, in particular, radio-frequency components. In fact, nowadays they have become capable of producing complex net-shaped or nearly net-shaped parts in materials that can be directly used as functional parts, including polymers, metals, ceramics, and composites. These technologies represent the solution for low-volume, high-value, and highly complex parts and products.

Overview on Additive Manufacturing Technologies

Direct metal laser sintering (DMLS) is an additive manufacturing technique for the fabrication of near net-shaped parts directly from computer-aided design data by melting together different layers with the help of a laser source. This paper presents an investigation of the surface roughness of aluminum samples produced by DMLS. A model based on an L18 orthogonal array of Taguchi design was created to perform experimental planning. Some input parameters, namely laser power, scan speed, and hatching distance were selected for the investigation. The upper surfaces of the samples were analyzed before and after shot peening. The morphology was analyzed by means of field emission scanning electron microscope. Scan speed was found to have the greatest influence on the surface roughness. Further, shot peening can effectively reduce the surface roughness.

Influence of process parameters on surface roughness of aluminum parts produced by DMLS.

Purpose – The purpose of this paper is to verify the feasibility and evaluate the dimensional accuracy of two rapid casting (RC) solutions based on 3D printing technology: investment casting starting from 3D‐printed starch patterns and the ZCast process for the production of cavities for light‐alloys castings.Design/methodology/approach – Starting from the identification and design of a benchmark, technological prototypes were produced with the two RC processes. Measurements on a coordinate measuring machine allowed calculating the dimensional tolerances of the proposed technological chains. The predictive performances of computer aided engineering (CAE) software were verified when applied to the ZCast process modelling.Findings – The research proved that both the investigated RC solutions are effective in obtaining cast technological prototypes in short times and with low costs, with dimensional tolerances that are completely consistent with metal casting processes.Practical implications – The research a...

3D Printing technique applied to Rapid Casting

The Electron Beam Melting (EBM) process is an additive manufacturing process in which an electron beam melts metallic powders to obtain the geometry of a specific part. The use of an electron beam in the AM field is relatively recent. Numerous applications have already been made in the aerospace and medical fields, in which the EBM process is used to produce complex parts, made of an excellent quality material, for which other technologies would be expensive or difficult to apply. Because of the growing interest of industry in this technology, the research community has been dedicating a great deal of effort to making the EBM process more reliable. The modelling of the EBM process is considered of utmost importance as it could help to reduce the process optimisation time, compared with the trial and error approach, which is currently the most widely used method. From this point of view, the aim of this paper has been to provide a literature review of numerical simulation models of the EBM process. The various studies on numerical modelling are presented in detail. These studies are mainly classified according to the level of approximation introduced into the modelling methodology. The simulations have first been categorised according to the powder modelling approach that has been adopted (i.e. mesoscopic or FE approach). The studies have then been categorised, as far as FE-based simulations are concerned, as either uncoupled or coupled modelling approaches. All the current approaches have been compared, and how the researchers have modelled the EBM process has been highlighted, considering the assumptions that have been made, the modelling of the material properties, the material state change, and the heat source. Moreover, the adopted validation approaches and the results have been described in order to point out any important achievements. Deviations between numerical and experimental results have been discussed as well as the current level of development of the simulation of the EBM process.

Luca Iuliano

Papers

Overview on Additive Manufacturing Technologies

Influence of process parameters on surface roughness of aluminum parts produced by DMLS.

3D Printing technique applied to Rapid Casting

A literature review of powder-based electron beam melting focusing on numerical simulations

Benchmarking of Rapid Prototyping Techniques in Terms of Dimensional Accuracy and Surface Finish