Micro milling of additively manufactured AISI 316L: impact of the layerwise microstructure on the process results
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ORIGINAL ARTICLE
Micro milling of additively manufactured AISI 316L: impact of the layerwise microstructure on the process results Sebastian Greco 1
&
Sonja Kieren-Ehses 1 & Benjamin Kirsch 1 & Jan C. Aurich 1
Received: 3 July 2020 / Accepted: 9 November 2020 # The Author(s) 2020
Abstract In the field of metal additive manufacturing (AM), one of the most used methods is selective laser melting (SLM)—building components layer by layer in a powder bed via laser. The process of SLM is defined by several parameters like laser power, laser scanning speed, hatch spacing, or layer thickness. The manufacturing of small components via AM is very difficult as it sets high demands on the powder to be used and on the SLM process in general. Hence, SLM with subsequent micromilling is a suitable method for the production of microstructured, additively manufactured components. One application for this kind of components is microstructured implants which are typically unique and therefore well suited for additive manufacturing. In order to enable the micromachining of additively manufactured materials, the influence of the special properties of the additive manufactured material on micromilling processes needs to be investigated. In this research, a detailed characterization of additive manufactured workpieces made of AISI 316L is shown. Further, the impact of the process parameters and the build-up direction defined during SLM on the workpiece properties is investigated. The resulting impact of the workpiece properties on micromilling is analyzed and rated on the basis of process forces, burr formation, surface roughness, and tool wear. Significant differences in the results of micromilling were found depending on the geometry of the melt paths generated during SLM. Keywords Machining . Micromilling . Additive manufacturing . Selective laser melting
1 Introduction Additive manufacturing (AM) is becoming more and more established in industrial applications. The extended freedom of design of additively manufactured components is combined with a tool-less and near-net-shape production [1]. Producing components without the need for specific tools enables costefficient production of small quantities down to batch size one [2]. One of the most used processes for AM of metal parts is selective laser melting (SLM), in which a component is built layer by layer in a powder bed [3]; a layer of new material and defined thickness is applied from a powder supply by a scraper. The cross section of the later workpiece is then exposed by a laser, which melts the powder material and creates the
* Sebastian Greco [email protected] 1
Institute for Manufacturing Technology and Production Systems, TU Kaiserslautern, Gottlieb-Daimler-Str., 67663 Kaiserslautern, Germany
material cohesion. These steps are repeated until the completion of the component [4]. The process parameters used during SLM have a large impact on the material properties of the additively manufactured workpieces [5]. For example, the balling effect may occur as a r
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