scholarly journals A Novel Laser-Aided Machining and Polishing Process for Additive Manufacturing Materials with Multiple Endmill Emulating Scan Patterns

2021 ◽  
Vol 11 (20) ◽  
pp. 9428
Author(s):  
Mohammad Masud Parvez ◽  
Sahil Patel ◽  
Sriram Praneeth Isanaka ◽  
Frank Liou
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Energy Density ◽  
Dimensional Accuracy ◽  
High Energy ◽  
Primary Energy ◽  
High Energy Density ◽  
Average Roughness ◽  
Induce Process ◽  
Surface Improvement

In additive manufacturing (AM), the surface roughness of the deposited parts remains significantly higher than the admissible range for most applications. Additionally, the surface topography of AM parts exhibits waviness profiles between tracks and layers. Therefore, post-processing is indispensable to improve surface quality. Laser-aided machining and polishing can be effective surface improvement processes that can be used due to their availability as the primary energy sources in many metal AM processes. While the initial roughness and waviness of the surface of most AM parts are very high, to achieve dimensional accuracy and minimize roughness, a high input energy density is required during machining and polishing processes although such high energy density may induce process defects and escalate the phenomenon of wavelength asperities. In this paper, we propose a systematic approach to eliminate waviness and reduce surface roughness with the combination of laser-aided machining, macro-polishing, and micro-polishing processes. While machining reduces the initial waviness, low energy density during polishing can minimize this further. The average roughness (Ra=1.11μm) achieved in this study with optimized process parameters for both machining and polishing demonstrates a greater than 97% reduction in roughness when compared to the as-built part.

Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness

2020 ◽  
Vol 19 (01) ◽  
pp. 107-130 ◽  
Author(s):  
R. Borrelli ◽  
S. Franchitti ◽  
C. Pirozzi ◽  
L. Carrino ◽  
L. Nele ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Electron Beam Melting ◽  
Complex Shape ◽  
Electron Beam Welding ◽  
Raw Materials ◽  
Dimensional Accuracy ◽  
High Energy ◽  
Quality Certification

Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

Porosity Analysis in Metal Additive Manufacturing by Micro-CT

2018 ◽  
Author(s):  
Subin Shrestha ◽  
Thomas Starr ◽  
Kevin Chou
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Pore Formation ◽  
Total Pore Volume ◽  
High Energy ◽  
High Energy Density ◽  
Process Conditions ◽  
Micro Ct ◽  
Ct Scanner ◽  
Porosity Level

This study aims at analyzing process-induced pores in selective laser melting (SLM), a laser powder-bed fusion additive manufacturing (AM) process. Porosity is one of the most problematic defects in SLM parts; it impairs the part performance, and yet, is sharply sensitive to the parameters of the SLM process itself. Detailed analysis of SLM pore formations using a computed tomography (CT) technique is desired in order to understand the porosity level under different process conditions. In this study, an SLM system was used to fabricate samples, using Ti-6Al-4V powder, with single tracks formed, at 60 μm layer thickness, with different laser powers and scanning speeds to vary the energy density. A micro-CT (μ-CT) scanner was used to measure the internal features of the SLM specimens without any post-build treatments and to analyze the porosity inside single tracks formed with different energy densities. There are different mechanisms of pore formation in SLM, in particular, this study first focuses on the pore formation due to the keyhole phenomenon, caused by a high energy density. μ-CT scanning at a 6 μm resolution is able to clearly reveal the pores in the SLM samples. From the CT scan and analysis results, it is observed that increasing the energy density increases the volume of pores. For example, with 195 W and 200 mm/s, the number of pores is 93 and the total pore volume is 0.014 mm3 for a scanning length of 12 mm. On the other hand, if the energy density is less than 0.24 J/mm, few or no pores were observed, because possibly the melting process changes from the keyhole mode to the conduction mode.

scholarly journals Late-Time Mixing Sensitivity to Initial Broadband Surface Roughness in High-Energy-Density Shear Layers

2016 ◽  
Vol 117 (22) ◽  
Author(s):  
K. A. Flippo ◽  
F. W. Doss ◽  
J. L. Kline ◽  
E. C. Merritt ◽  
D. Capelli ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
High Energy ◽  
Shear Layers ◽  
High Energy Density ◽  
Late Time

Additive Manufacturing of Aqueous‐Processed LiMn 2 O 4 Thick Electrodes for High‐Energy‐Density Lithium‐Ion Batteries

2020 ◽  
Vol 3 (10) ◽  
pp. 1040-1050 ◽  
Author(s):  
Lorenzo Airoldi ◽  
Umberto Anselmi‐Tamburini ◽  
Barbara Vigani ◽  
Silvia Rossi ◽  
Piercarlo Mustarelli ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density

scholarly journals Cover Feature: Additive Manufacturing of Aqueous‐Processed LiMn 2 O 4 Thick Electrodes for High‐Energy‐Density Lithium‐Ion Batteries (Batteries & Supercaps 10/2020)

2020 ◽  
Vol 3 (10) ◽  
pp. 963-963
Author(s):  
Lorenzo Airoldi ◽  
Umberto Anselmi‐Tamburini ◽  
Barbara Vigani ◽  
Silvia Rossi ◽  
Piercarlo Mustarelli ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density

scholarly journals Challenges in path planning of high energy density beams for additive manufacturing

2020 ◽  
Vol 759 ◽  
pp. 012012
Author(s):  
K P Karunakaran ◽  
Seema Negi ◽  
Arun Nambolan ◽  
Ashik Patel ◽  
Yogesh Patil ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Path Planning ◽  
High Energy ◽  
High Energy Density

scholarly journals Effect of Gradient Energy Density on the Microstructure and Mechanical Properties of Ti6Al4V Fabricated by Selective Electron Beam Additive Manufacture

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1509 ◽  
Author(s):  
Ta-I Hsu ◽  
Yu-Ting Jhong ◽  
Meng-Hsiu Tsai
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Positive Effects ◽  
Microstructure And Mechanical Properties ◽  
Gradient Energy

Selective Electron Beam Additive Manufacturing (SEBAM) is a promising powder bed fusion additive manufacturing technique for titanium alloys that select particular area melting in different energy density for producing complexly shaped biomedical devices. For most commercial Ti6Al4V porous medical devices, the gradient energy density is usually applied to manufacture in one component during the SEBAM process which selects different energy density built on particular zones. This paper presents gradient energy density base characterization study on an SEBAM built rectangular specimen with a size of 3 mm × 20 mm × 60 mm. The specimen was divided into three zones were built in gradient energy density from 16 to 26.5 J/mm3. The microstructure and mechanical properties were investigated by means of scanning electron microscopy, X-ray diffraction, transmission electron microscopy and mechanical test. The α′ martensitic and lack of fusion were observed in the low energy density (LED) built zone. However, no α′ phase and no irregular pores were observed both in overlap energy density (OED) and high energy density (HED) built zones located at the middle and bottom of the specimen respectively. This implies the top location and lower energy density have positive effects on the cooling rate but negative effects on densification. The subsequence mechanical properties result also supports this point. Moreover, the intermetallic Ti3Al found in the bottom may be due to the heat transfer from the following melting layer. Furthermore, the microstructure evolution in gradient energy built zones is discussed based on the findings of the microstructure and thermal history correlation analysis.

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