Process optimization for directed energy deposition of SS316L components
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ORIGINAL ARTICLE
Process optimization for directed energy deposition of SS316L components Pei-Yi Lin1 · Fang-Cheng Shen2 · Kuo-Tsai Wu2 · Sheng-Jye Hwang2 · Huei-Huang Lee1 Received: 19 February 2020 / Accepted: 16 September 2020 © Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract Directed energy deposition (DED), also known as laser cladding, is a metal additive manufacturing process in which a highpower laser combined with a coaxial powder delivery system is used to additively manufacture a three-dimensional metal component layer-by-layer. Due to its convenience and superior quality, DED has gained popularity in recent years. However, despite many advantages, it has low deposition efficiency and produces parts with poor surface evenness, high porosity, and poor mechanical properties. This study performs one-factor-at-a-time experiments to valuate five DED processing parameters, namely the laser and powder focus point positions, laser head raising height (Z-offset), laser power, powder feed rate, and laser scanning speed. The laser and powder focus point positions and the Z-offset are first adjusted to maximize the surface evenness and deposition efficiency. Several experiments are then performed to investigate the effects of laser power, powder feed rate, and laser cladding speed on the porosity and dilution of DED-built parts. Finally, a mathematical model is proposed to predict the quality (i.e., dilution) of DED-built parts as a function of DED processing parameters. Based on the results, the optimal focus point positions and Z-offset are found. The variations of porosity and dilution with three processing parameters are shown. The proposed model can be used to set up DED processing parameters to produce higher quality parts on the first attempt. Keywords Directed energy deposition · Surface unevenness · Deposition efficiency · Dilution · Pores
1 Introduction Additive manufacturing (AM) is a technique for manufacturing three-dimensional parts layer-by-layer using discrete materials such as liquids, powder, and plastic. It can rapidly and flexibly manufacture high-performance metal products, and is thus widely used in the medical and aerospace fields for the direct fabrication of parts [1, 2]. According to the ISO/ASTM52900:2015 standard [3], AM technology can be classified into seven types, namely binder jetting, material extrusion, material jetting, powder bed fusion, sheet Sheng-Jye Hwang
[email protected] 1
Department of Engineering Science, National Cheng Kung University, No.1, University Road, Tainan, 70101, Taiwan
2
Department of Mechanical Engineering, National Cheng Kung University, No. 1, University Road, Tainan, 70101, Taiwan
lamination, vat photopolymerization, and directed energy deposition (DED). DED is regarded as one of the most promising AM technologies due to its ability to produce large metal parts with complex geometries [4]. However, the quality of DED-built parts depend on many factors, as shown in Fig. 1 [5]. The optimization of parameters to maximize part
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