scholarly journals The electropolishing of electron beam melting, additively manufactured TI6AL4V titanium : relevance, process parameters and surface finish.

Author(s):  
Austin Lassell
2016 ◽  
Vol 22 (3) ◽  
pp. 495-503 ◽  
Author(s):  
Rebecca Klingvall Ek ◽  
Lars-Erik Rännar ◽  
Mikael Bäckstöm ◽  
Peter Carlsson

Purpose The surface roughness of products manufactured using the additive manufacturing (AM) technology of electron beam melting (EBM) has a special characteristic. Different product applications can demand rougher or finer surface structure, so the purpose of this study is to investigate the process parameters of EBM to find out how they affect surface roughness. Design/methodology/approach EBM uses metal powder to manufacture metal parts. A design of experiment plan was used to describe the effects of the process parameters on the average surface roughness of vertical surfaces. Findings The most important electron beam setting for surface roughness, according to this study, is a combination of “speed and current” in the contours. The second most important parameter is “contour offset”. The interaction between the “number of contours” and “contour offset” also appears to be important, as it shows a much higher probability of being active than any other interaction. The results show that the “line offset” is not important when using contours. Research limitations/implications This study examined “contour offset”, “number of contours”, “speed in combination with current” and “line offset”, which are process parameters controlling the electron beam. Practical implications The surface properties could have an impact on the product’s performance. A reduction in surface processing will not only save time and money but also reduce the environmental impact. Originality/value Surface properties are important for many products. New themes containing process parameters have to be developed when introducing new materials to EBM manufacturing. During this process, it is very important to understand how the electron beam affects the melt pool.


Author(s):  
Luping Long ◽  
Wensheng Liu ◽  
Yunzhu Ma ◽  
Ye Liu ◽  
Shuhua Liu

AbstractElectron beam melting (EBM) technology has been considered as one of the key steps for preparing high purity tungsten, and reasonable setting of process parameters is the premise. In this paper, the optimum process parameters obtained from thermal equilibrium calculation and evaporation loss control of tungsten are presented. Effective power is closely related to melting temperature, and the required power for maintaining the superheating melt linearly increases with the increase of melt superheat temperature. The evaporation loss behavior of tungsten is significantly influenced by melting rate and melting temperature. Analysis of experiments show that the best results are realized at melting rate of 1.82 g/s, melting temperature of 4200 K, and the corresponding melting power of 130 kW, in which the main impurity elements in tungsten, such as As, Cd, Mg and Sn, present high removal ratio of 90%, 95%, 85.7% and 90%, respectively.


2017 ◽  
Author(s):  
Adrien Dolimont ◽  
Sebastien Michotte ◽  
Edouard Rivière-Lorphèvre ◽  
François Ducobu ◽  
Solange Vivès ◽  
...  

2016 ◽  
Vol 22 (3) ◽  
pp. 609-620 ◽  
Author(s):  
Dana H. Abdeen ◽  
Bruce R. Palmer

Purpose This paper aims to study the effect of processing parameters of an electron beam melting (EBM) machine on the surface roughness, critical pitting temperature and density of Ti-6Al-4V parts produced from the EBM machine. Design/methodology/approach In this study, statistically designed experiments were used to manufacture Ti-6Al-4V samples in the EBM machine under different process parameters of beam current, beam speed and offset focus. Surface roughness was measured for as-built samples using a 3D profilometer. Then, a potentiostatic test was conducted under 2.40 V vs saturated calomel electrode to determine the critical pitting temperature (CPT) in 3.5 per cent mass NaCl solution for the samples of different processing parameters. Next, density was measured for these samples. Finally, model equations were established to relate EBM’s process parameters to measured properties of surface roughness, CPT and density. Findings Results showed that offset focus had the main influence on surface roughness more than the beam current and the beam speed. Changing processing parameters did not affect corrosion behavior of EBM Ti-6Al-4V as CPT did not vary widely, although a slight effect on CPT values obtained from the beam current and the beam speed. Density was greatly affected by the offset focus more than the other parameters. It can be concluded that uniform and precise measurements of roughness and density are not achievable through this machine; only a range of these properties can be attained. Originality/value EBM machine produces 3D parts in a layer-based building process under high temperature and vacuum atmosphere. Due to the manufacturing technique and conditions, the resulting object has irregularities on the exterior surface and voids that are formed within the part, both of which affect samples’ properties like surface roughness, CPT and density. This study established model equations that can relate parts’ properties to processing parameters so that parts of specific properties are obtained to fit the application they are used for. For each property, ANOVA fits vs linear energy were also obtained.


2017 ◽  
Vol 92 (9-12) ◽  
pp. 3349-3361 ◽  
Author(s):  
Naveed Ahmed ◽  
Basem M. Abdo ◽  
Saied Darwish ◽  
Khawaja Moiduddin ◽  
Salman Pervaiz ◽  
...  

Author(s):  
Mahdi Jamshidinia ◽  
Fanrong Kong ◽  
Radovan Kovacevic

Electron beam melting® (EBM) is one of the fastest growing additive manufacturing processes capable of building parts with complex geometries, made predominantly of Ti-alloys. Providing an understanding of the effects of process parameters on the heat distribution in a specimen built by EBM®, could be the preliminary step toward the microstructural and consequently mechanical properties control. Numerical modeling is a useful tool for the optimization of processing parameters, because it decreases the level of required experimentation and significantly saves on time and cost. So far, a few numerical models are developed to investigate the effects of EBM® process parameters on the heat distribution and molten pool geometry. All of the numerical models have ignored the material convection inside the molten pool that affects the real presentation of the temperature distribution and the geometry of molten pool. In this study, a moving electron beam heat source and temperature dependent properties of Ti-6Al-4V were used in order to provide a 3D thermal-fluid flow model of EBM®. The influence of process parameters including electron beam scanning speed, electron beam current, and the powder bed density were studied. Also, the effects of flow convection in temperature distribution and molten pool geometry were investigated by comparing a pure-thermal with the developed thermal-fluid flow model. According to the results, the negative temperature coefficient of surface tension in Ti-6Al-4V was responsible for the formation of an outward flow in the molten pool. Also, results showed that ignoring the material convection inside the molten pool resulted in the formation of a molten pool with narrower width and shorter length, while it had a deeper penetration and higher maximum temperature in the molten pool. Increasing the powder bed density was accompanied with an increase in the thermal conductivity of the powder bed that resulted in a reduction in the molten pool width on the powder bed top surface. Experimental measurements of molten pool width and depth are performed to validate the numerical model.


2021 ◽  
Vol 396 (1) ◽  
pp. 2000307
Author(s):  
Alessandro De Luca ◽  
Giuseppe Lamanna ◽  
Francesco Caputo ◽  
Rosario Borrelli ◽  
Stefania Franchitti ◽  
...  

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1211 ◽  
Author(s):  
Wadea Ameen ◽  
Muneer Khan Mohammed ◽  
Abdulrahman Al-Ahmari

The addition of support structures is essential for the successful fabrication of overhang structures through additive manufacturing (AM). The support structures protect the overhang portion from distortions. They are fabricated with the functional parts and are removed later after the fabrication of the AM part. While structures bearing insufficient support result in defective overhangs, structures with excessive support result in higher material consumption, time and higher post-processing costs. The objective of this study is to investigate the effects of design and process parameters of support structures on support removability during the electron beam melting (EBM)-based additive manufacturing of the Ti6Al4V overhang part. The support design parameters include tooth parameters, no support offset, fragmentation parameters and perforation parameters. The EBM process parameters consist of beam current, beam scan speed and beam focus offset. The results show that both support design and process parameters have a significant effect on support removability. In addition, with the appropriate selection of design and process parameters, it is possible to significantly reduce the support removal time and protect the surface quality of the part.


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