Analysis of the machinability when milling AlSi10Mg additively manufactured via laser-based powder bed fusion

Marco Zimmermann,Daniel Müller,Jan C Aurich,Sebastian Greco,Benjamin Kirsch

doi:10.1007/s00170-020-06391-7

Marco Zimmermann, Daniel Müller + Show 3 more

Open Access

https://doi.org/10.1007/s00170-020-06391-7

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Abstract

Laser-based powder bed fusion (L-PBF) is a promising technology for the production of near net–shaped metallic components. The high surface roughness and the comparatively low-dimensional accuracy of such components, however, usually require a finishing by a subtractive process such as milling or grinding in order to meet the requirements of the application. Materials manufactured via L-PBF are characterized by a unique microstructure and anisotropic material properties. These specific properties could also affect the subtractive processes themselves. In this paper, the effect of L-PBF on the machinability of the aluminum alloy AlSi10Mg is explored when milling. The chips, the process forces, the surface morphology, the microhardness, and the burr formation are analyzed in dependence on the manufacturing parameter settings used for L-PBF and the direction of feed motion of the end mill relative to the build-up direction of the parts. The results are compared with a conventionally cast AlSi10Mg. The analysis shows that L-PBF influences the machinability. Differences between the reference and the L-PBF AlSi10Mg were observed in the chip form, the process forces, the surface morphology, and the burr formation. The initial manufacturing method of the part thus needs to be considered during the design of the finishing process to achieve suitable results.

Highlights

In laser-based powder bed fusion (L-PBF), components are produced from a powdery raw material by the defined layerby-layer joining of individual volume elements
Depending on the manufacturing parameters used for L-PBF, typically documented average surface roughness values Ra of as-built parts are in the range of Ra = 3–40 μm [14, 15], and common dimensional errors are between 0.01 and 34% of the target values [11, 16]
The chip morphology, the resultant forces, the surface roughness, the microhardness, and the burr formation are analyzed in dependence on the manufacturing parameters used for L-PBF and the direction of feed motion of the end mill relative to the build-up direction of the workpieces

Summary

Introduction

In laser-based powder bed fusion (L-PBF), components are produced from a powdery raw material by the defined layerby-layer joining of individual volume elements. This manufacturing principle enables new possibilities for the user with regard to the freedom in design, the manufacturing of highly customized parts, and the tailoring of products to the requirements of particular applications [1,2,3]. Functional surfaces of L-PBFmanufactured components usually require a finishing by means of a subtractive process such as milling, grinding, laser machining, or polishing in order to improve the part quality characteristics [17,18,19]. The properties of L-PBF materials significantly differ from cast or wrought components due to the large temperature gradients in the material during L-PBF and the complex heat transfer to the material due to the cyclic processing [12]

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